Enfortumab Vedotin and Pembrolizumab in Untreated Advanced Urothelial Cancer

BACKGROUND

No treatment has surpassed platinum-based chemotherapy in improving overall survival in patients with previously untreated locally advanced or metastatic urothelial carcinoma.

METHODS

We conducted a phase 3, global, open-label, randomized trial to compare the efficacy and safety of enfortumab vedotin and pembrolizumab with the efficacy and safety of platinum-based chemotherapy in patients with previously untreated locally advanced or metastatic urothelial carcinoma. Patients were randomly assigned in a 1:1 ratio to receive 3-week cycles of enfortumab vedotin (at a dose of 1.25 mg per kilogram of body weight intravenously on days 1 and 8) and pembrolizumab (at a dose of 200 mg intravenously on day 1) (enfortumab vedotin-pembrolizumab group) or gemcitabine and either cisplatin or carboplatin (determined on the basis of eligibility to receive cisplatin) (chemotherapy group). The primary end points were progression-free survival as assessed by blinded independent central review and overall survival.

RESULTS

A total of 886 patients underwent randomization: 442 to the enfortumab vedotin-pembrolizumab group and 444 to the chemotherapy group. As of August 8, 2023, the median duration of follow-up for survival was 17.2 months. Progression-free survival was longer in the enfortumab vedotin-pembrolizumab group than in the chemotherapy group (median, 12.5 months vs. 6.3 months; hazard ratio for disease progression or death, 0.45; 95% confidence interval [CI], 0.38 to 0.54; P<0.001), as was overall survival (median, 31.5 months vs. 16.1 months; hazard ratio for death, 0.47; 95% CI, 0.38 to 0.58; P<0.001). The median number of cycles was 12 (range, 1 to 46) in the enfortumab vedotin-pembrolizumab group and 6 (range, 1 to 6) in the chemotherapy group. Treatment-related adverse events of grade 3 or higher occurred in 55.9% of the patients in the enfortumab vedotin-pembrolizumab group and in 69.5% of those in the chemotherapy group.

CONCLUSIONS

Treatment with enfortumab vedotin and pembrolizumab resulted in significantly better outcomes than chemotherapy in patients with untreated locally advanced or metastatic urothelial carcinoma, with a safety profile consistent with that in previous reports. (Funded by Astellas Pharma US and others; EV-302 ClinicalTrials.gov number, NCT04223856.).

Pembrolizumab with or Without Lenvatinib as First-line Therapy for Patients with Advanced Urothelial Carcinoma (LEAP-011): A Phase 3, Randomized, Double-Blind Trial

BACKGROUND

Pembrolizumab plus lenvatinib has shown antitumor activity and acceptable safety in patients with platinum-refractory urothelial carcinoma (UC).

OBJECTIVE

To evaluate pembrolizumab plus either lenvatinib or placebo as first-line therapy for advanced UC in the phase 3 LEAP-011 study.

DESIGN, SETTING, AND PARTICIPANTS

Patients with advanced UC who were ineligible for cisplatin-based therapy or any platinum-based chemotherapy were enrolled.

INTERVENTION

Patients were randomly assigned (1:1) to pembrolizumab 200 mg intravenously every 3 wk plus either lenvatinib 20 mg or placebo orally once daily.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Dual primary endpoints were progression-free survival (PFS) and overall survival (OS). An external data monitoring committee (DMC) regularly reviewed safety and efficacy data every 3 mo.

RESULTS AND LIMITATIONS

Between June 25, 2019 and July 21, 2021, 487 patients were allocated to receive lenvatinib plus pembrolizumab (n = 245) or placebo plus pembrolizumab (n = 242). The median time from randomization to the data cutoff date (July 26, 2021) was 12.8 mo (interquartile range, 6.9-19.3). The median PFS was 4.5 mo in the combination arm and 4.0 mo in the pembrolizumab arm (hazard ratio [HR] 0.90 [95% confidence interval {CI} 0.72-1.14]). The median OS was 11.8 mo for the combination arm and 12.9 mo for the pembrolizumab arm (HR 1.14 [95% CI 0.87-1.48]). Grade 3-5 adverse events attributed to trial treatment occurred in 123 of 241 patients (51%) treated with lenvatinib plus pembrolizumab and in 66 of 242 patients (27%) treated with placebo plus pembrolizumab. This trial was terminated earlier than initially planned based on recommendation from the DMC.

CONCLUSIONS

The benefit-to-risk ratio for first-line lenvatinib plus pembrolizumab was not considered favorable versus pembrolizumab plus placebo as first-line therapy in patients with advanced UC.

PATIENT SUMMARY

Lenvatinib plus pembrolizumab was not more effective than pembrolizumab plus placebo in patients with advanced urothelial carcinoma.

A plain language summary exploring a new treatment combination for untreated locally advanced or metastatic urothelial cancer: enfortumab vedotin plus pembrolizumab

WHAT IS THIS SUMMARY ABOUT?

This summary provides the results of a study of two treatments for cancer, enfortumab vedotin and pembrolizumab, that were studied together against locally advanced or metastatic urothelial cancer (la/mUC), a cancer that occurs most commonly in the bladder.

WHAT WERE THE RESULTS?

In the 45 patients studied, around 16% did have serious side effects, but most side effects were manageable. Twenty-four percent of patients, however, stopped the study treatment because of their side effects. Within about 2 months of starting treatment, most patients' (73%) tumors were smaller and stayed smaller, on average, for more than 2 years.

WHAT DO THE RESULTS MEAN?

The combination of enfortumab vedotin plus pembrolizumab is a new treatment option for patients with locally advanced or metastatic urothelial cancer when they cannot receive the typical treatment, cisplatin. Advanced or metastatic urothelial cancer is a type of cancer where the cancer has already spread outside of the bladder or urinary tract.

Temporal changes in treatment patterns by age group and functional status before and after PD-1/L1 inhibitor approvals in advanced urothelial carcinoma

Introduction

Metastatic urothelial carcinoma (mUC) has poor prognosis. A high unmet need exists for novel treatment for those who are unfit for platinum-based chemotherapy.

Methods

We aimed to describe real-world temporal changes in patient characteristics and 1L treatment selection for mUC patients in the United States following the approval of anti-PD-1/L1 treatments. This study was a retrospective, observational study using anonymized and structured oncology electronic medical record (EMR) data from IQVIA and the US Oncology Network iKnowMed (USON).

Results

After approval of 1L anti-PD-1/L1 treatment for mUC, there is a marked increase in the use of 1L anti-PD-1/L1 monotherapies, accompanied by a proportional decrease in 1L platinum-based treatments and non-guideline-based therapy; particularly among the elderly (> 75 years) and those with poor ECOG performance status (ECOG PS 2+).

Discussion

Anti-PD-1/L1 monotherapies fulfill the prior unmet need of frail mUC patients who are ineligible for platinum-based therapies.

Enfortumab Vedotin With or Without Pembrolizumab in Cisplatin-Ineligible Patients With Previously Untreated Locally Advanced or Metastatic Urothelial Cancer

PURPOSE

Patients with locally advanced or metastatic urothelial cancer (la/mUC) who are ineligible for cisplatin-based therapy have limited first-line (1L) treatment options and significant need for improved therapies. Enfortumab vedotin (EV) and pembrolizumab (Pembro) individually have shown a survival benefit in urothelial cancer in second-line + la/mUC settings. Here, we present data from the pivotal trial of EV plus Pembro (EV + Pembro) in the 1L setting.

PATIENTS AND METHODS

In Cohort K of the EV-103 phase Ib/II study, cisplatin-ineligible patients with previously untreated la/mUC were randomly assigned 1:1 to receive EV as monotherapy or in combination with Pembro. The primary end point was confirmed objective response rate (cORR) per blinded independent central review. Secondary end points included duration of response (DOR) and safety. There were no formal statistical comparisons between treatment arms.

RESULTS

The cORR was 64.5% (95% CI, 52.7 to 75.1) and 45.2% (95% CI, 33.5 to 57.3) for patients treated with EV + Pembro (N = 76) and EV monotherapy (N = 73), respectively. The median DOR was not reached for the combination and was 13.2 months for monotherapy; 65.4% and 56.3% of patients who responded to the combination and monotherapy, respectively, maintained a response at 12 months. The most common grade 3 or higher treatment-related adverse events (TRAEs) in patients treated with the combination were maculopapular rash (17.1%), fatigue (9.2%), and neutropenia (9.2%). EV TRAEs of special interest (any grade) in the combination arm included skin reactions (67.1%) and peripheral neuropathy (60.5%).

CONCLUSION

EV + Pembro showed a high cORR with durable responses as 1L treatment in cisplatin-ineligible patients with la/mUC. Patients who received EV monotherapy had a response and safety profile consistent with previous studies. Adverse events for EV + Pembro were manageable, with no new safety signals observed.

Abstract 4528: Evaluation of plasma circulating tumor DNA (ctDNA)-based whole genome sequencing (pWGS) and whole exome sequencing (pWES) and concordance with tumor tissue whole exome sequencing (tWES): a pilot study in patients with recurrent or metastatic head and neck squamous cell carcinoma or metastatic urothelial carcinoma

Background: The genetic heterogeneity and clonal evolution of tumors is hypothesized to influence disease response and acquisition of resistance during treatment. However, comprehensive analysis of the changing tumor molecular landscape to support evaluation of such a hypothesis is often difficult to quantify due to the lack of accessibility to longitudinal biopsy samples in a large number of patients (pts). Longitudinal analyses using pWGS or pWES may allow the delineation of the genetic evolution of tumors and its impact on treatment outcomes. We conducted a pilot study to evaluate the feasibility of obtaining pWGS and pWES data from ctDNA in pretreatment samples from pts enrolled in 2 phase 3 trials that evaluated second-line pembrolizumab versus chemotherapy/standard-of-care therapy: KEYNOTE-040 (recurrent or metastatic head and neck squamous cell carcinoma; NCT02252042) and KEYNOTE-045 (metastatic urothelial carcinoma, NCT02256436). Concordance between pWES and tWES was also evaluated.

Methods: Cell-free DNA was isolated from 1-3 mL of plasma; pWGS (via low-pass WGS) and pWES were performed on samples from pts with available tWES data generated as part of planned tissue biomarker analyses for the respective studies. Tumor burden in ctDNA was estimated from pWES data using single nucleotide variant (SNV)-based maximum somatic allele frequency (MSAF) and from pWGS data using a copy number variation-based measure of mutational burden in the tumor fraction. Concordance between the pWES and tWES mutational spectrum was determined using the Jaccard index. Concordance of key driver somatic events (FGFR3, TP53, and HPV status) was evaluated.

Results: Plasma samples from 47 pts (KEYNOTE-040, n = 24; KEYNOTE-045, n = 23) were analyzed. Tumor burden estimates from pWGS (median coverage, 5.84; range, 4.28-8.18) and pWES (median coverage, 1806; range, 1038-2413) data were highly correlated (Spearman ρ = 0.94). A range of 0 to 956 nonsynonymous SNVs (median, 50) per pt was identified in ctDNA. When the ctDNA tumor burden was high (MSAF ≥5%, observed in two-thirds of pts), a relatively high concordance was observed for individual alterations in TP53, FGFR3, and HPV status (overall agreement: 0.87, 0.97, and 0.96, respectively); between tissue- and plasma-based tumor mutational burden (R = 0.49); and in overall mutational landscape overlap (Jaccard index: median, 0.30; range, 0.002-0.53).

Conclusions: These data show that pWES exhibits reasonably high concordance with tWES when the tumor burden in ctDNA is relatively high and may be informative regarding tumor genomic characteristics. Extensive longitudinal studies are still needed to understand tumor genetic evolution using plasma ctDNA.

Citation Format: Razvan Cristescu, Andrew Albright, Steven Townson, Cai Chen, Blanca Homet Moreno, Nati Lerman, Z. Alexander Cao, Carol Peña. Evaluation of plasma circulating tumor DNA (ctDNA)-based whole genome sequencing (pWGS) and whole exome sequencing (pWES) and concordance with tumor tissue whole exome sequencing (tWES): a pilot study in patients with recurrent or metastatic head and neck squamous cell carcinoma or metastatic urothelial carcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4528.

Efficacy and safety of pembrolizumab in metastatic urothelial carcinoma: results from KEYNOTE-045 and KEYNOTE-052 after up to 5 years of follow-up

BACKGROUND

Immune checkpoint inhibitors are a standard therapy in metastatic urothelial carcinoma (UC). Long-term follow-up is necessary to confirm durability of response and identify further safety concerns.

PATIENTS AND METHODS

In KEYNOTE-045, patients with metastatic UC that progressed on platinum-containing chemotherapy were randomly assigned 1:1 to receive pembrolizumab or investigator's choice of paclitaxel, docetaxel, or vinflunine. Primary endpoints were progression-free survival per RECIST version 1.1 by blinded independent central review (BICR) and overall survival. In KEYNOTE-052, cisplatin-ineligible patients with metastatic UC received first-line pembrolizumab. The primary endpoint was objective response rate per RECIST version 1.1 by BICR.

RESULTS

A total of 542 patients (pembrolizumab, n = 270; chemotherapy, n = 272) were randomly assigned in KEYNOTE-045. The median follow-up was 62.9 months (range 58.6-70.9 months; data cut-off 1 October 2020). At 48 months, overall survival rates were 16.7% for pembrolizumab and 10.1% for chemotherapy; progression-free survival rates were 9.5% and 2.7%, respectively. The median duration of response (DOR) was 29.7 months (range 1.6+ to 60.5+ months) for pembrolizumab and 4.4 months (range 1.4+ to 63.1+ months) for chemotherapy; 36-month DOR rates were 44.4% and 28.3%, respectively. A total of 370 patients were enrolled in KEYNOTE-052. The median follow-up was 56.3 months (range 51.2-65.3 months; data cut-off 26 September 2020). The confirmed objective response rate was 28.9% (95% confidence interval 24.3-33.8), and the median DOR was 33.4 months (range 1.4+ to 60.7+ months); the 36-month DOR rate was 44.8%. Most treatment-related adverse events for pembrolizumab in either study were grade 1 or 2 and manageable, which is consistent with prior reports.

CONCLUSION

With ∼5 years of follow-up, pembrolizumab monotherapy continued to demonstrate durable efficacy with no new safety signals in patients with platinum-resistant metastatic UC and as first-line therapy in cisplatin-ineligible patients.

CLINICAL TRIAL REGISTRY AND ID

With ClinicalTrials.gov NCT02256436 (KEYNOTE-045); https://clinicaltrials.gov/ct2/show/NCT02256436 and NCT02335424 (KEYNOTE-052); https://clinicaltrials.gov/ct2/show/NCT02335424.

Perioperative enfortumab vedotin (EV) plus pembrolizumab (pembro) versus chemotherapy in cisplatin-eligible patients (pts) with muscle-invasive bladder cancer (MIBC): Phase 3 KEYNOTE-B15/EV-304

TPS588

Background: Neoadjuvant cisplatin-based chemotherapy followed by radical cystectomy + pelvic lymph node dissection (RC+PLND) is the standard of care for cisplatin-eligible pts with MIBC; however, up to 50% of pts will experience disease recurrence or progression following treatment. Pembro and EV monotherapies are approved for use in select pts with metastatic urothelial carcinoma (mUC). Furthermore, results of the phase 1/2 KEYNOTE-869/EV-103 study showed encouraging antitumor activity and an acceptable safety profile with first-line combination therapy EV + pembro in cisplatin-ineligible pts with mUC. The open-label, multicenter, phase 3, randomized KEYNOTE-B15/EV-304 study (NCT04700124) will compare the efficacy and safety of perioperative EV + pembro versus neoadjuvant cisplatin-based chemotherapy in cisplatin-eligible pts with MIBC. Methods: Eligible pts will have histologically confirmed UC/MIBC (T2-T4aN0M0 or T1-T4aN1M0) with predominant urothelial histology (≥50%), nonmetastatic disease (N≤1, M0) confirmed by blinded independent central review (BICR), ECOG performance status of 0-1, no prior systemic therapy for MIBC, and agree to undergo curative RC+PLND. Approximately 784 pts will be randomly assigned 1:1 to Arm A (4 cycles of neoadjuvant EV + pembro, followed by RC+PLND, followed by 5 cycles of adjuvant EV + 13 cycles of adjuvant pembro) or Arm B (4 cycles of neoadjuvant chemotherapy [gemcitabine + cisplatin] followed by RC+PLND, followed by observation). Neoadjuvant and adjuvant pembro 200 mg + EV 1.25 mg/kg will be administered intravenously every 3 weeks (Q3W) on day 1 (pembro + EV) and day 8 (EV) of each cycle. Neoadjuvant chemotherapy is gemcitabine 1000 mg/m2 + cisplatin 70 mg/m2 Q3W on day 1 (gemcitabine + cisplatin) and day 8 (gemcitabine) of each cycle. Stratification factors are disease stage (T2N0 vs T3/T4aN0 vs T1-T4aN1), PD-L1 combined positive score (≥10 vs <10), and geographic region (United States vs European Union vs most of the world). Imaging by CT (preferred) or MRI will be performed ≤6 weeks before cystectomy and 6 weeks after cystectomy. Imaging will occur following cystectomy then Q12W through year 2 and at discontinuation, then Q24W in year 3 and beyond. Adverse events (AEs) will be monitored throughout the study and for 30 days following cessation of treatment (90 days for serious AEs). The primary end points are pathologic complete response rate and event-free survival by BICR. Secondary end points are OS, DFS, pathologic downstaging rate, safety and tolerability, and patient-reported outcomes. KEYNOTE-B15/EV-304 is enrolling in Africa, Asia, Australia, Europe, and North America. © 2021 American Society of Clinical Oncology, Inc. Reused with permission. This abstract was accepted and previously presented at the 2021 ASCO Annual Meeting. All rights reserved. Clinical trial information: NCT04700124 .

Uptake of maintenance immunotherapy and changes in upstream treatment selection in patients with advanced urothelial cancer (aUC)

466

Background: In July 2020, the FDA approved avelumab, an immune checkpoint inhibitor (ICI), for maintenance treatment of aUC that has not progressed with first-line (1L) platinum-containing chemotherapy (chemo). Availability of avelumab may have influenced upstream treatment selection between 1L chemo and 1L ICI (pembrolizumab or atezolizumab). We described avelumab use in real-world practice and determined whether 1L treatment choice changed following its approval. Methods: This cohort study used Flatiron Health’s nationwide de-identified EHR-derived database. Included patients started 1L therapy for aUC in the US before (April 1 2017 to June 30 2020) or after (July 1 2020 to May 31 2022) avelumab approval. We calculated the proportion of patients initiating 1L chemo (carboplatin- or cisplatin-based) or ICI during the pre- and post- avelumab approval periods. Time trends were estimated using multinomial logistic regression for 1L treatment choice regressed on time modeled via a natural cubic spline, allowing for a discontinuity in the time trend at the time of FDA approval. Differences in probabilities of 1L treatment in July 2020 (immediately following approval) compared to June 2020 (immediately prior to approval) were calculated. Maintenance avelumab use was described among patients treated with 1L chemo in the post-approval period, and in a sensitivity analysis, among ‘maintenance eligible’ patients defined as those who were progression-free 28 weeks after 1L chemo start. Results: Among all 1L treatment initiators (n=3,507), the FDA approval of maintenance avelumab was followed by increased use of 1L carboplatin-based chemo (+9.9%; 95% CI 1.1-17.2%) but no significant changes in the use of ICI (-5.8%; 95% CI -15.9-4.4%) or cisplatin-based chemo (-4.2%; 95% CI -12.7-5.2%) (Table). Among patients treated with 1L platinum-chemo (n=485), probability of initiating maintenance avelumab increased over time. In the 22 months after approval, approximately 20.4% (n=99/485) of all 1L chemo-treated patients and 24.3% (n=78/321) of maintenance eligible patients received maintenance avelumab. Conclusions: We found modest uptake of maintenance avelumab for aUC after FDA approval. Potential reasons include limited clinician awareness of maintenance immunotherapy and/or patient preferences against long-term treatment after response to initial chemo. Our finding of higher treatment starts with carboplatin-based chemo in the post-maintenance period suggests increasing preference by clinicians of a strategy that provides patients an opportunity for two effective treatment options. Real-world data can provide important insights on community response to regulatory approvals. [Table: see text]

Phase 3 KEYNOTE-905/EV-303: Perioperative pembrolizumab (pembro) or pembro + enfortumab vedotin (EV) for muscle-invasive bladder cancer (MIBC)

TPS585

Background: Standard of care for MIBC is neoadjuvant cisplatin-based chemotherapy followed by radical cystectomy + pelvic lymph node dissection (RC + PLND). However, a substantial proportion of patients (pts) with MIBC are ineligible to receive cisplatin-based chemotherapy. In the phase 1b/2 KEYNOTE-869/EV-103 study, promising antitumor activity was shown in cisplatin-ineligible pts with metastatic urothelial carcinoma treated with the PD-1 inhibitor pembro combined with the nectin-4–directed antibody-drug conjugate EV. This multicenter, open-label, randomized, phase 3 KEYNOTE-905/EV-303 study (NCT03924895) is designed to evaluate the efficacy and safety of perioperative pembro alone or in combination with EV compared with RC + PLND alone in pts with MIBC who are ineligible for or decline cisplatin-based treatment. Methods: Approximately 857 adults who are cisplatin ineligible or decline cisplatin-based treatment with treatment-naive MIBC (T2-T4aN0M0 or T1-T4aN1M0), have an Eastern Cooperative Oncology Group performance status score of 0-2, and have a predominant (≥50%) urothelial histology will be randomly assigned to arm A (neoadjuvant pembro 200 mg intravenously [IV] every 3 weeks [Q3W] up to 3 cycles followed by RC + PLND and adjuvant pembro 200 mg IV Q3W up to 14 cycles), arm B (RC + PLND followed by observation), or arm C (neoadjuvant EV 1.25 mg/kg + pembro 200 mg IV Q3W up to 3 cycles followed by RC + PLND and adjuvant EV + pembro up to 6 cycles and adjuvant pembro 200 mg IV Q3W up to 8 cycles). In both the neoadjuvant and adjuvant phases of arm C, pembro will be administered on day 1 and EV will be administered on days 1 and 8 of each cycle. Dual primary end points are pathologic complete response as assessed by central pathologic review and event-free survival. Secondary end points include overall survival, disease-free survival, pathologic downstaging rates, and safety and tolerability. Enrollment is ongoing in Africa, Asia, Europe, and North America. Clinical trial information: NCT03924895 .

Enfortumab vedotin (EV) alone or in combination with pembrolizumab (P) in previously untreated cisplatin-ineligible patients with locally advanced or metastatic urothelial cancer (la/mUC): Subgroup analyses of confirmed objective response rate (cORR) from EV-103 cohort K

499

Background: In EV-103 Cohort K (NCT03288545), EV and P in combination (EV+P) showed encouraging antitumor activity and a manageable safety profile when used as 1L therapy in patients (pts) w/ la/mUC who are ineligible for cisplatin, a population w/ high unmet need. Here we report results of an analysis of prespecified Cohort K subgroups known to be associated w/ poor outcomes. Methods: Pts who are cisplatin-ineligible w/ previously untreated la/mUC were randomized 1:1 to EV (1.25 mg/kg) as monotherapy on Days 1 and 8 or in combination w/ P (200 mg) on Day 1 of 3-week cycles. Primary endpoint is cORR per RECIST v1.1 by blinded independent central review w/ no formal statistical comparison between arms. Secondary endpoints included duration of response and safety (e.g. treatment-related adverse events, TRAEs). The cORR analysis was performed in prespecified subgroups including age, ECOG PS, liver metastasis, PD-L1 expression status, metastatic disease site at baseline, and primary disease site of origin. Results: 149 pts were treated: EV+P n=76; EV n=73; cORRs across key subgroups for both EV+P and EV monotherapy are shown in the table. For EV+P overall cohort, cORR (95%CI): 64.5% (52.7, 75.1); median DOR was not reached. cORRs were consistent across subgroups for EV+P including those w/ ECOG PS score of 1-2: 62.8% (46.7, 77.0) and presence of liver metastasis: 53.8% (25.1, 80.8). Among TRAEs of special interest in the EV+P arm, skin reactions occurred in n=51 (67.1%); peripheral neuropathy occurred in n=46 (60.5%). For EV+P, 68.4% of pts had TRAEs leading to interruption of either EV or P; 48.7% of pts had TRAEs leading to EV dose reduction. Median duration of EV+P treatment was 11 cycles. Conclusions: EV+P showed promising cORR in 1L cisplatin-ineligible pts w/ la/mUC; activity was consistently observed across a range of pre-specified subgroups including those with poor prognosis. EV+P TRAEs were manageable w/ close monitoring and appropriate dose modifications w/ a meaningful duration of treatment. EV+P has the potential to address high unmet needs in 1L la/mUC and MIBC and is being further evaluated in 3 Phase 3 trials (NCT04223856, NCT04700124, NCT03924895). Clinical trial information: NCT03288545 . [Table: see text]

Enfortumab Vedotin Plus Pembrolizumab in Previously Untreated Advanced Urothelial Cancer

PURPOSE

Cisplatin-based combination chemotherapy remains the standard of care for locally advanced or metastatic urothelial cancer (la/mUC); however, toxicity is substantial, responses are rarely durable, and many patients with la/mUC are ineligible. Each enfortumab vedotin and pembrolizumab have shown a survival benefit versus chemotherapy in UC, are not restricted by cisplatin eligibility, and warrant investigation as a first-line (1L) combination therapy in patients ineligible for cisplatin.

METHODS

In this ongoing phase Ib/II, multicenter, open-label study, 1L cisplatin-ineligible patients with la/mUC received enfortumab vedotin 1.25 mg/kg once daily on days 1 and 8 and pembrolizumab 200 mg (day 1) intravenously once daily in 3-week cycles. The primary end point was safety. Key secondary end points included confirmed objective response rate, duration of response (DOR), and overall survival (OS).

RESULTS

Forty-five patients received enfortumab vedotin plus pembrolizumab. The most common treatment-related adverse events (TRAEs) were peripheral sensory neuropathy (55.6%), fatigue (51.1%), and alopecia (48.9%). Twenty-nine patients (64.4%) had grade 3 or higher TRAEs; the most common were increased lipase (17.8%), maculopapular rash (11.1%), and fatigue (11.1%). One death (2.2%) was classified as a TRAE. The confirmed objective response rate after a median of nine cycles was 73.3% with a complete response rate of 15.6%. The median DOR and median OS were 25.6 months and 26.1 months, respectively.

CONCLUSION

Enfortumab vedotin plus pembrolizumab showed a manageable safety profile. Most patients experienced tumor shrinkage. The median DOR and median OS exceeding 2 years in a cisplatin-ineligible patient population make this a promising combination currently under investigation in a phase III study (ClinicalTrials.gov identifier: NCT04223856).

Putative Biomarkers of Clinical Benefit With Pembrolizumab in Advanced Urothelial Cancer: Results from the KEYNOTE-045 and KEYNOTE-052 Landmark Trials

PURPOSE

In an exploratory analysis, we investigated the association between programmed death ligand 1 (PD-L1), tumor mutational burden (TMB), T-cell-inflamed gene expression profile (TcellinfGEP), and stromal signature with outcomes of pembrolizumab in urothelial carcinoma (UC).

PATIENTS AND METHODS

Patients with advanced UC received first-line pembrolizumab 200 mg every 3 weeks in the single-arm phase II KEYNOTE-052 trial (NCT02335424) and salvage pembrolizumab 200 mg every 3 weeks or chemotherapy (paclitaxel/docetaxel/vinflunine) in the randomized phase III KEYNOTE-045 trial (NCT02256436). The association of each biomarker (continuous variable) with objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) was evaluated using logistic regression (ORR) and Cox PH (PFS, OS), adjusted for ECOG PS; nominal P values were calculated without multiplicity adjustment (one-sided, pembrolizumab; two-sided, chemotherapy). Significance was prespecified at α = 0.05.

RESULTS

In KEYNOTE-052, PD-L1, TMB, and TcellinfGEP were significantly associated with improved outcomes; stromal signature was significantly associated with worse outcomes. In KEYNOTE-045, although findings for TMB and TcellinfGEP with pembrolizumab were consistent with those of KEYNOTE-052, PD-L1 was not significantly associated with improved outcomes, nor was stromal signature associated with worse outcomes with pembrolizumab; chemotherapy was not associated with outcomes in a consistent manner for any of the biomarkers. Hazard ratio (HR) estimates at prespecified cutoffs showed an advantage for pembrolizumab versus chemotherapy regardless of PD-L1 or TMB, with a trend toward lower HRs in the combined positive score ≥10 and the TMB ≥175 mutation/exome subgroup. For TcellinfGEP, PFS and OS HRs were lower in the TcellinfGEP-nonlow subgroup regardless of treatment.

CONCLUSIONS

Multiple biomarkers characterizing the tumor microenvironment may help predict response to pembrolizumab monotherapy in UC, and potential clinical utility of these biomarkers may be context-dependent.

Association of TMB and PD-L1 with efficacy of first-line pembrolizumab (pembro) or pembro + chemotherapy (chemo) versus chemo in patients (pts) with advanced urothelial carcinoma (UC) from KEYNOTE-361

540

Background: The 3-arm, open-label, phase 3 KEYNOTE-361 study (NCT02853305) evaluated first-line pembro ± chemo vs chemo in advanced UC regardless of PD-L1 status. The trial did not meet its primary end points of superior PFS and OS with pembro + chemo vs chemo and thus analysis of pembro monotherapy (mono) vs chemo was exploratory. We explored the association of TMB status and PD-L1 combined positive score (CPS) with clinical outcomes in KEYNOTE-361. Methods: In pts with TMB and/or PD-L1 data, the association between TMB (via whole exome sequencing) and PD-L1 (via PD-L1 IHC 22C3 pharmDx) and clinical outcomes (ORR, PFS, and OS) was evaluated. In each treatment arm, the hypotheses regarding the associations were evaluated using logistic regression (ORR) and Cox proportional hazards regression (PFS; OS), and 1-sided (pembro; pembro + chemo) and 2-sided (chemo) P values were calculated; significance was prespecified at α = 0.05 without multiplicity adjustment. Clinical utility was assessed using prespecified cutoffs of 175 mut/exome (TMB) and CPS 10 (PD-L1). Clinical data cutoff was April 29, 2020. Results: 820/993 pts (82.6%) had evaluable TMB data (pembro, 252; pembro + chemo, 282; chemo, 286). TMB (log10) was significantly positively associated with ORR, PFS, and OS for pembro ( P < 0.001, < 0.001, and 0.007, respectively) and PFS and OS for pembro + chemo ( P= 0.007 and 0.010, respectively). The area under the receiver operating characteristics (AUROC) curve (95% CI) for discriminating response was 0.64 (0.56-0.71) for pembro, 0.53 (0.46-0.60) for pembro + chemo, and 0.52 (0.45-0.59) for chemo. Efficacy by TMB cutoff is reported in the Table. All 993 pts had PD-L1 data (pembro, 302; pembro + chemo, 349; chemo, 342). PD-L1 was significantly positively associated with PFS for pembro ( P= 0.006) and ORR for pembro + chemo ( P= 0.042) but not chemo. Efficacy by PD-L1 CPS is reported in the Table. Conclusions: Strong associations were observed between TMB and all 3 clinical outcomes (ORR, PFS, and OS) with pembro mono in the first-line setting and a reduced association was observed between TMB and clinical outcomes with pembro + chemo. No consistent associations were observed between PD-L1 and clinical outcomes with pembro mono or pembro + chemo. Clinical trial information: NCT02853305. [Table: see text]

Post hoc pooled analysis of first-line (1L) pembrolizumab (pembro) for advanced urothelial carcinoma (UC): Outcomes by response at week nine in KEYNOTE-052 and KEYNOTE-361

519

Background: Pembro is a 1L treatment for cisplatin-ineligible pts with UC. This post hoc landmark analysis evaluated clinical outcomes by response at 9 wk to 1L pembro monotherapy in pts with advanced/unresectable or metastatic UC from the single-arm phase 2 KEYNOTE-052 (NCT02335424) and the randomized phase 3 KEYNOTE-361 (NCT02853305) trials. Methods: Cisplatin-ineligible pts with advanced UC were enrolled in KEYNOTE-052 and received pembro (200 mg Q3W for ≤2 y). Platinum-eligible pts with advanced UC who had not previously received systemic chemotherapy (chemo) were enrolled in KEYNOTE-361 and randomly assigned 1:1:1 to receive pembro (200 mg Q3W for ≤2 y), pembro + chemo (1000 mg/m2 gemcitabine on d1 and d8 + cisplatin [70 mg/m2] or carboplatin [AUC 5] on d1 of each 3-wk cycle), or chemo. The primary analysis group included pembro monotherapy–treated pts; the sensitivity analysis group included pembro monotherapy–treated pts from KEYNOTE-052 and the choice of carboplatin subpopulation of pembro monotherapy–treated pts from KEYNOTE-361. Landmark analyses of OS by pts with CR, PR, SD, or PD per RECIST v1.1 by BICR at first imaging assessment (wk 9) were pooled for the ITT populations. Duration of CR/PR/SD and OS were estimated using the Kaplan-Meier method. Data cutoffs were Sep 26, 2020 (KEYNOTE-052) and Apr 29, 2020 (KEYNOTE-361). Results: The primary analysis group included 681 pembro-treated pts (KEYNOTE-052, N = 374; KEYNOTE-361, N = 307); the sensitivity analysis group included 544 pembro-treated pts (KEYNOTE-052, N = 374; KEYNOTE-361, N = 170). Median time from randomization to cutoff was 51.9 mo (range, 22.0-65.3) and 53.7 mo (range, 22.0-65.3) for the primary and sensitivity analysis groups, respectively. Twenty-five pts (4.6%) had CR and 135 (24.6%) had PR (primary group); 17 pts (3.9%) had CR and 105 (24.1%) had PR (sensitivity group). Median DOR was 25.9 mo for pts with CR/PR at wk 9; pts with CR/PR or SD at wk 9 had longer OS than pts with PD at wk 9 (Table). Conclusions: In this post hoc analysis, pts with advanced UC in KEYNOTE-052 and KEYNOTE-361 with CR/PR at wk 9 had better clinical outcomes with pembro monotherapy than pts with SD or PD; 1L pembro monotherapy continues to show efficacy in advanced UC. Clinical trial information: NCT02335424 and NCT02853305. [Table: see text]

Impact of primary tumor location on efficacy and safety of pembrolizumab (pembro) in patients (pts) with locally advanced or metastatic urothelial carcinoma (UC) enrolled in the phase 2 KEYNOTE-052 and phase 3 KEYNOTE-045 trials

516

Background: Pembro showed antitumor activity in 1L and 2L for pts with UC in the single-arm, phase 2 KEYNOTE-052 study (NCT02335424) and the randomized phase 3 KEYNOTE-045 (NCT02256436) study, respectively. This post hoc exploratory analysis evaluated whether primary tumor location affected efficacy and safety of pembro (KEYNOTE-052; KEYNOTE-045) and chemotherapy (chemo; KEYNOTE-045). Methods: KEYNOTE-052 enrolled cisplatin-ineligible pts with advanced/metastatic UC who had not previously received systemic therapy; they received pembro (200 mg IV Q3W). KEYNOTE-045 enrolled pts with advanced/metastatic UC who had received platinum-containing chemo; pts were randomly assigned 1:1 to receive pembro (200 mg IV Q3W) or investigator’s choice of chemo (paclitaxel, docetaxel, or vinflunine). Both studies required pts to have measurable disease per RECIST v1.1. Upper tract (UT) UC included primary tumors in the renal pelvis or ureter; lower tract (LT) UC included primary tumors in the bladder or urethra. Pts with UT and LT disease (UT/LT) were classified as LT. Pts receiving pembro were treated until disease progression, unacceptable toxicity, or withdrawal of consent, for up to 2y. End points were PFS, ORR, and DOR per RECIST v1.1 by central radiology assessment and OS. Results: A total of 369 pembro-treated pts (68 UT; 301 LT [79 UT/LT]) from KEYNOTE-052 plus 270 pembro-treated pts (93 UT; 177 LT [33 UT/LT]) and 272 chemo-treated pts (94 UT; 178 LT) from KEYNOTE-045 were evaluated. Median follow-up from randomization to data cutoff (09/26/20 and 10/1/20, respectively) was ≥56 mo. Both studies enrolled a similar percentage of pts with PD-L1–positive tumors (25%-30%). PFS, ORR, DOR, and OS for pembro were consistent regardless of tumor location, although ORR for KEYNOTE-045 was lower for the UT group (Table). In the chemo arm of KEYNOTE-045, similar efficacy was observed regardless of tumor location or regimen. Grade 3-5 TRAEs occurred at similar rates in KEYNOTE-052 (19.1% UT; 21.6% LT) and KEYNOTE-045 (17.2% UT; 16.8% LT). Conclusions: In this exploratory analysis, pembro showed similar clinical activity and manageable safety regardless of primary UC tumor location. Clinical trial information: NCT02256436 and NCT02335424. [Table: see text]

First-line pembrolizumab in advanced urothelial carcinoma: Clinical parameters associated with efficacy in the phase 2 KEYNOTE-052 and phase 3 KEYNOTE-361 trials

521

Background: First-line treatment with pembrolizumab (pembro) monotherapy has shown durable clinical activity in selected patients (pts) with advanced/unresectable or metastatic urothelial carcinoma (UC). In a pooled population of pts with advanced UC from the single-arm phase 2 KEYNOTE-052 (NCT02335424) and the randomized, open-label, phase 3 KEYNOTE-361 (NCT02853305) studies, this exploratory analysis evaluated the relationship between baseline characteristics and clinical outcomes of first-line pembro monotherapy. Methods: Cisplatin-ineligible pts with advanced UC were enrolled in KEYNOTE-052 and chemotherapy-naive pts with advanced UC were enrolled in KEYNOTE-361. For analysis of predictive factors for ORR and OS in pembro-treated pts, the purposeful selection method was used to build the multivariable logistic regression model (ORR) and multivariable Cox model (OS), beginning with a univariable analysis of each independent variable. Any variable in the univariate model with P < 0.10 was a candidate for the multivariate model. The stepwise selection method was used to select the variables in the final model. Significance of the final model was set at P < 0.05. Data cutoff dates were September 26, 2020 (KEYNOTE-052) and April 29, 2020 (KEYNOTE-361). Results: This pooled analysis included 681 pts treated with pembro monotherapy (KEYNOTE-052, N = 374; KEYNOTE-361, N = 307 [170 were cisplatin ineligible]). Median follow-up was 51.9 mo (range, 22.0-65.3). ORR was 29.4% (95% CI, 26.0-32.9; 69 CRs, 131 PRs), and median DOR was 33.2 mo (range, 1.4+ to 60.7+). Median OS was 12.5 mo (95% CI, 11.0-14.6). By multivariate analysis, independent factors significantly associated with higher ORR were PD-L1 status (combined positive score [CPS] ≥10 vs CPS < 10; odds ratio [OR], 1.90 [95% CI, 1.33-2.71]; P = 0.0004), site of metastasis (lymph node only vs visceral disease; OR, 1.66 [95% CI, 1.06-2.59]; P = 0.0265), liver involvement (absent vs present; OR, 1.75 [95% CI, 1.06-2.89]; P = 0.0294), and baseline hemoglobin level ≥10 vs < 10 g/dL; OR, 2.17 [95% CI, 1.09-4.31]; P = 0.0276). Multivariate analysis of OS is displayed in the Table. Conclusions: This exploratory multivariate analysis identified numerous factors, including PD-L1–positive status (CPS ≥10), lymph node only metastasis, and lower ECOG PS score, associated with improved clinical outcomes in pts with advanced UC treated with first-line pembro monotherapy. Clinical trial information: NCT02335424 and NCT02853305. [Table: see text]

Post hoc analysis of the efficacy of pembrolizumab retreatment after progression of advanced urothelial carcinoma (UC) in KEYNOTE-045 and KEYNOTE-052

512

Background: Pembrolizumab (pembro) has shown efficacy in advanced/unresectable and metastatic UC (mUC). There is interest in determining whether pts should be treated subsequently with checkpoint inhibitors such as anti–PD-1 therapy if mUC responds then later progresses. Pembro retreatment after disease progression has shown efficacy in melanoma and NSCLC. This post hoc exploratory analysis investigated the efficacy of pembro retreatment for pts with advanced UC or mUC enrolled in KEYNOTE-045 and KEYNOTE-052 with a best overall response (BOR) of SD or better and whose disease progressed after discontinuation or completion of 2 y of therapy. Methods: The phase 3 KEYNOTE-045 trial (NCT02256436) was designed to compare the efficacy and safety of pembro vs chemotherapy (chemo) in pts with mUC that recurred/progressed on platinum containing chemo; ≤2 prior lines of systemic chemo for mUC were permitted. The phase 2 KEYNOTE-052 trial (NCT02335424) was designed to evaluate the efficacy and safety of first-line pembro in cisplatin-ineligible pts with advanced UC. In both studies, pembro was administered for up to 2 y; pts were eligible for retreatment if they stopped pembro after CR or had a BOR of CR, PR, or SD and completed 2 y of treatment. Pts must have investigator-confirmed radiographic PD after therapy cessation, have ECOG PS score 0-1, and not have received anticancer treatment after the last pembro dose. BOR to retreatment is reported. Results: At data cutoff for KEYNOTE-045 (Oct 1, 2020), 11 pts were retreated: 5 (45%) achieved objective response to retreatment (3 CR; 2 PR; Table) and 6 had SD, for a disease control rate (DCR; CR+PR+SD) of 100%. Median treatment-free interval was 7.7 mo (IQR, 3.6-16.5); median duration of retreatment was 11.4 mo (IQR, 7.6-12.0). Seven pts (64%) were alive at cutoff. At data cutoff for KEYNOTE-052 (Sep 26, 2020), 10 pts were retreated; 5 (50%) had objective response to retreatment (1 CR; 4 PR) and 4 had SD, for a DCR of 90%. Retreatment BOR was PD for 1 pt (10%). Median treatment-free interval was 13.0 mo (9.2-16.6); median duration of retreatment was 6.0 mo (IQR, 4.9-9.2). Four pts (40%) were alive at cutoff. Conclusions: Although the number of pts who received retreatment was small, objective responses were observed. The findings are generally consistent with observations from retreatment in other tumor types (e.g., melanoma). Clinical trial information: NCT02256436 and NCT02335424. [Table: see text]

Standard-Dose Pembrolizumab Plus Alternate-Dose Ipilimumab in Advanced Melanoma: KEYNOTE-029 Cohort 1C, a Phase 2 Randomized Study of Two Dosing Schedules

PURPOSE

Standard-dose pembrolizumab plus alternative-dose ipilimumab (1 mg/kg Q3W for 4 doses) were tolerable and had robust antitumor activity in advanced melanoma in cohort B of the phase 1 KEYNOTE-029 study. Cohort C evaluated standard-dose pembrolizumab with two other alternative ipilimumab regimens.

PATIENTS AND METHODS

Patients with treatment-naive unresectable stage III/IV melanoma were randomly assigned 1:1 to pembrolizumab 200 mg Q3W for ≤24 months plus ipilimumab 50 mg Q6W for 4 doses (PEM200+IPI50), or the same pembrolizumab regimen plus ipilimumab 100 mg Q12W for 4 doses (PEM200+IPI100). Primary end points were incidence of grade 3-5 treatment-related adverse events (TRAE) and objective response rate (ORR) per RECIST v1.1 by independent central review. Per protocol-defined thresholds, grade 3-5 TRAE incidence ≤26% indicated meaningful toxicity reduction and ORR ≥48% indicated no decrease in efficacy versus data reported for other PD-1 inhibitor/ipilimumab combinations.

RESULTS

Median follow-up on February 18, 2019, was 16.3 months in PEM200+IPI50 (N = 51) and 16.4 months in PEM200+IPI100 (N = 51). Grade 3-5 TRAEs occurred in 12 (24%) patients in PEM200+IPI50 and 20 (39%) in PEM200+IPI100. One patient in PEM200+IPI50 died from treatment-related autoimmune myocarditis. Immune-mediated AEs or infusion reactions occurred in 21 (42%) patients in PEM200+IPI50 and 28 (55%) in PEM200+IPI100. ORR was 55% in PEM200+IPI50; 61% in PEM200+IPI100.

CONCLUSIONS

Pembrolizumab 200 mg Q3W plus ipilimumab 50 mg Q6W or 100 mg Q12W demonstrated antitumor activity above the predefined threshold; pembrolizumab plus ipilimumab 50 mg Q6W had lower incidence of grade 3-5 TRAEs than the predefined threshold, suggesting a reduction in toxicity. See related commentary by Jameson-Lee and Luke, p. 5153.

Long-term outcomes in patients with advanced melanoma who had initial stable disease with pembrolizumab in KEYNOTE-001 and KEYNOTE-006

Objective:

Patients with melanoma and early stable disease (SD) with pembrolizumab have unclear prognosis. We present post hoc analyses of long-term outcomes for patients with early SD, partial response (PR) or complete response (CR) with pembrolizumab.

Patients and methods:

Patients who received pembrolizumab in the KEYNOTE-001 and KEYNOTE-006 studies and had SD, PR or CR at weeks 12 or 24 were included.

Results:

Of 294 patients in the week 12 analysis, 107 (36.4%) had SD at week 12, of whom 7 (6.5%) had a best overall response of CR, 43 (40.2%) had PR and 57 (53.3%) had SD. Forty-eighte–month overall survival (OS) rates were 95.2%, 73.0% and 47.7%, respectively, for patients with CR, PR and SD at week 12. Similar results were observed in the 241 patients in the week 24 analysis. Forty-eight–month OS rates were 72.1% for patients with SD at week 12 followed by subsequent response and 75.0% for patients with PR at week 12 followed by no change in response or progression. Thirty-six–month and 48-month OS rates were 11.6% and not reached, respectively, for patients with SD at week 12 followed by progression before week 24.

Conclusions:

A substantial proportion of patients (46.7%) with early (week 12) SD with pembrolizumab achieved subsequent PR or CR. Patients with SD at week 12 and subsequent CR/PR had similar survival to those who maintained PR. In contrast, patients with SD at week 12 and subsequent progression had poor survival outcomes. These findings may guide treatment decisions for patients achieving early SD.

Trial registration:

Clinicaltrials.gov: NCT01295827 (KEYNOTE-001); NCT01866319 (KEYNOTE-006).

Pembrolizumab alone or combined with chemotherapy versus chemotherapy as first-line therapy for advanced urothelial carcinoma (KEYNOTE-361): a randomised, open-label, phase 3 trial

BACKGROUND

PD-1 and PD-L1 inhibitors are active in metastatic urothelial carcinoma, but positive randomised data supporting their use as a first-line treatment are lacking. In this study we assessed outcomes with first-line pembrolizumab alone or combined with chemotherapy versus chemotherapy for patients with previously untreated advanced urothelial carcinoma.

METHODS

KEYNOTE-361 is a randomised, open-label, phase 3 trial of patients aged at least 18 years, with untreated, locally advanced, unresectable, or metastatic urothelial carcinoma, with an Eastern Cooperative Oncology Group performance status of up to 2. Eligible patients were enrolled from 201 medical centres in 21 countries and randomly allocated (1:1:1) via an interactive voice-web response system to intravenous pembrolizumab 200 mg every 3 weeks for a maximum of 35 cycles plus intravenous chemotherapy (gemcitabine [1000 mg/m²] on days 1 and 8 and investigator's choice of cisplatin [70 mg/m²] or carboplatin [area under the curve 5] on day 1 of every 3-week cycle) for a maximum of six cycles, pembrolizumab alone, or chemotherapy alone, stratified by choice of platinum therapy and PD-L1 combined positive score (CPS). Neither patients nor investigators were masked to the treatment assignment or CPS. At protocol-specified final analysis, sequential hypothesis testing began with superiority of pembrolizumab plus chemotherapy versus chemotherapy alone in the total population (all patients randomly allocated to a treatment) for the dual primary endpoints of progression-free survival (p value boundary 0·0019), assessed by masked, independent central review, and overall survival (p value boundary 0·0142), followed by non-inferiority and superiority of overall survival for pembrolizumab versus chemotherapy in the patient population with CPS of at least 10 and in the total population (also a primary endpoint). Safety was assessed in the as-treated population (all patients who received at least one dose of study treatment). This study is completed and is no longer enrolling patients, and is registered at ClinicalTrials.gov, number NCT02853305.

FINDINGS

Between Oct 19, 2016 and June 29, 2018, 1010 patients were enrolled and allocated to receive pembrolizumab plus chemotherapy (n=351), pembrolizumab monotherapy (n=307), or chemotherapy alone (n=352). Median follow-up was 31·7 months (IQR 27·7-36·0). Pembrolizumab plus chemotherapy versus chemotherapy did not significantly improve progression-free survival, with a median progression-free survival of 8·3 months (95% CI 7·5-8·5) in the pembrolizumab plus chemotherapy group versus 7·1 months (6·4-7·9) in the chemotherapy group (hazard ratio [HR] 0·78, 95% CI 0·65-0·93; p=0·0033), or overall survival, with a median overall survival of 17·0 months (14·5-19·5) in the pembrolizumab plus chemotherapy group versus 14·3 months (12·3-16·7) in the chemotherapy group (0·86, 0·72-1·02; p=0·0407). No further formal statistical hypothesis testing was done. In analyses of overall survival with pembrolizumab versus chemotherapy (now exploratory based on hierarchical statistical testing), overall survival was similar between these treatment groups, both in the total population (15·6 months [95% CI 12·1-17·9] with pembrolizumab vs 14·3 months [12·3-16·7] with chemotherapy; HR 0·92, 95% CI 0·77-1·11) and the population with CPS of at least 10 (16·1 months [13·6-19·9] with pembrolizumab vs 15·2 months [11·6-23·3] with chemotherapy; 1·01, 0·77-1·32). The most common grade 3 or 4 adverse event attributed to study treatment was anaemia with pembrolizumab plus chemotherapy (104 [30%] of 349 patients) or chemotherapy alone (112 [33%] of 342 patients), and diarrhoea, fatigue, and hyponatraemia (each affecting four [1%] of 302 patients) with pembrolizumab alone. Six (1%) of 1010 patients died due to an adverse event attributed to study treatment; two patients in each treatment group. One each occurred due to cardiac arrest and device-related sepsis in the pembrolizumab plus chemotherapy group, one each due to cardiac failure and malignant neoplasm progression in the pembrolizumab group, and one each due to myocardial infarction and ischaemic colitis in the chemotherapy group.

INTERPRETATION

The addition of pembrolizumab to first-line platinum-based chemotherapy did not significantly improve efficacy and should not be widely adopted for treatment of advanced urothelial carcinoma.

FUNDING

Merck Sharp and Dohme, a subsidiary of Merck, Kenilworth, NJ, USA.

KEYNOTE-B15/EV-304: Randomized phase 3 study of perioperative enfortumab vedotin plus pembrolizumab versus chemotherapy in cisplatin-eligible patients with muscle-invasive bladder cancer (MIBC)

TPS4587

Background: Standard of care for MIBC is neoadjuvant cisplatin-based chemotherapy followed by radical cystectomy and pelvic lymph node dissection (RC+PLND); however, in time, patients experience disease recurrence or progression. Enfortumab vedotin (EV) is a Nectin-4–directed antibody–drug conjugate comprising a fully human, monoclonal antibody and the microtubule-disrupting agent monomethyl auristatin E. The KEYNOTE-869/EV-103 phase 1/2 study (NCT03288545) showed that the PD-1 inhibitor pembrolizumab + EV had encouraging antitumor activity and acceptable safety as first-line treatment for cisplatin-ineligible patients with metastatic urothelial cancer (Rosenberg JE et al. J Clin Oncol. 2020;38[15 suppl]:5044). Based on these data, investigating EV + pembrolizumab in an earlier setting such as MIBC and in a perioperative fashion is appropriate. KEYNOTE-B15/EV-304 (NCT04700124) is a randomized, open-label, phase 3 study to evaluate the efficacy and safety of perioperative EV + pembrolizumab versus neoadjuvant chemotherapy using gemcitabine/cisplatin in cisplatin-eligible patients with MIBC. Methods: Patients must have histologically confirmed urothelial cancer/MIBC (clinical stage T2-T4aN0M0 or T1-T4aN1M0) with predominant (≥50%) urothelial histology, have nonmetastatic disease (≥N2 disease and/or M1 excluded) confirmed by blinded independent central review (BICR), have ECOG PS 0 or 1, and not have previously received systemic therapy for MIBC. Approximately 784 patients will be randomly assigned 1:1 to receive either 4 cycles of neoadjuvant EV + pembrolizumab followed by 5 cycles of adjuvant EV + 13 cycles of adjuvant pembrolizumab after RC+PLND or 4 cycles of neoadjuvant cisplatin-based chemotherapy followed by observation after RC+PLND. Neoadjuvant and adjuvant pembrolizumab 200 mg + EV 1.25 mg/kg will be administered intravenously every 3 weeks (Q3W), and neoadjuvant chemotherapy will consist of gemcitabine 1000 mg/m2 + cisplatin 70 mg/m2 Q3W. Randomization will be stratified by centrally determined (pathology or imaging) initial T and N stage (T2N0 or T3/T4aN0 or T1-T4aN1), PD-L1 combined positive score (CPS ≥10 or CPS < 10), and geographic region (United States or Europe or most of world). Imaging (CT or MRI) will be performed ≤6 weeks before cystectomy and 6 weeks after cystectomy. After postcystectomy imaging, additional imaging will be performed Q12W up to the end of year 2 (week 96) and at discontinuation. In year 3 and beyond, imaging will be performed Q24W. Primary end points are pathological complete response and event-free survival by BICR. Secondary end points are overall survival, disease-free survival, pathological downstaging, and safety and tolerability. Clinical trial information: NCT04700124.

First-line pembrolizumab (pembro) in cisplatin-ineligible patients with advanced urothelial cancer (UC): Response and survival results up to five years from the KEYNOTE-052 phase 2 study

4508

Background: Pembro was approvedfor cisplatin-ineligible patients with untreated advanced UC based on initial results of the phase 2 KEYNOTE-052 study (NCT02335424), which showed an ORR of 29%. Updated results after up to 5 years of follow-up are presented. Methods: KEYNOTE-052 is a single-arm, multi-site, open-label trial. Patients had advanced or metastatic UC, were cisplatin ineligible (criteria: ECOG PS 2, CrCl ≥30 to ̃60 mL/min, grade ≥2 peripheral neuropathy/hearing loss, NYHA class III heart failure), and had not previously received chemotherapy for advanced/metastatic disease. Patients received pembro 200 mg IV Q3W until progression, unacceptable toxicity, withdrawal, or 24 mo of therapy, whichever occurred first. PD-L1 status was determined by combined positive score (CPS, number of PD-L1–staining cells [tumor cells, lymphocytes, macrophages] divided by the total number of viable tumor cells, multiplied by 100); PD-L1–positive was CPS ≥10. The primary end point was confirmed ORR (RECIST v1.1, independent central review). Key secondary end points were duration of response (DOR), OS, and safety. Results: Among 370 enrolled patients, median age was 74 y, 315 (85.1%) had visceral disease, and 43 (11.6%) completed 24 mo of therapy. Median time from enrollment to data cutoff (Sep 26, 2020) was 56.3 mo (range, 51.2-65.3) for all patients and 56.0 mo (range, 51.4-65.2) for the 110 patients (29.7%) with CPS ≥10. Confirmed ORR for all patients was 28.9% (95% CI, 24.3-33.8); complete response, 9.5% (n=35); partial response, 19.5% (n=72). Median DOR was 33.4 mo (range, 1.4+ to 60.7+); 44.8% and 39.4% of patients had DOR ≥36 and ≥48 mo, (Kaplan-Meier estimates). Median OS was 11.3 mo (95% CI, 9.7-13.1); 24- and 36-mo OS rates were 31.5% and 22.1%. Patients with CPS ≥10 had better outcomes than patients with CPS <10 (Table). Treatment-related adverse events (AEs) occurred in 67.3% of patients; 21.1% of treatment-related AEs were grade ≥3, including 1 death (myositis). Conclusions: After up to 5 y of follow-up, pembro continued to elicit clinically meaningful, durable antitumor activity in cisplatin-ineligible patients with advanced UC. These effects were more pronounced in patients with CPS ≥10. Clinical trial information: NCT02335424. [Table: see text]

Pembrolizumab (pembro) versus investigator’s choice of paclitaxel, docetaxel, or vinflunine in recurrent, advanced urothelial cancer (UC): 5-year follow-up from the phase 3 KEYNOTE-045 trial

4532

Background: Pembro was approved for the treatment of locally advanced or metastatic UC that progressed during or after a platinum-containing regimen, based on the phase 3 KEYNOTE-045 (NCT02256436) trial that showed significantly improved OS with use of pembro. Updated results are presented from KEYNOTE-045 after >5 y of follow-up since the last patient (pt) was randomized. Methods: KEYNOTE-045 is a randomized, multisite, open-label, phase 3 trial. Pts with histologically or cytologically confirmed UC, progression after platinum-containing chemo, ECOG PS 0-2, measurable disease per RECIST v1.1, and ≤2 prior lines of systemic therapy were eligible. Pts were randomly assigned 1:1 to receive pembro 200 mg Q3W or investigator’s choice of paclitaxel 175 mg/m2 Q3W, docetaxel 75 mg/m2 Q3W, or vinflunine 320 mg/m2 Q3W. Primary end points are PFS (RECIST v1.1, blinded central review) and OS. ORR and duration of response (DOR) were key secondary end points. Results: As of Oct 1, 2020, among 542 enrolled pts, median time from randomization to data cutoff was 62.9 mo (range 58.6-70.9). 9.4% and 0% of pts in the pembro and chemo arms, respectively, completed 2 years of therapy. Median OS was longer for pembro vs chemo (10.1 vs 7.2 mo; HR, 0.71 [95% CI, 0.59-0.86]) overall and in pts with CPS ≥10 (8.0 vs 4.9 mo; HR, 0.59 [95% CI, 0.40-0.86]). For pts with CR or PR, median OS was not reached and 16.4 (95% CI, 11.3-25.1) mo in the pembro and chemo arms, respectively (Table). OS rates at 48 mo were 16.7% for pembro and 10.1% for chemo; 60-mo OS rates were 14.9% and 8.7%, respectively. OS benefit with pembro vs chemo continued regardless of age, ECOG PS, prior therapy, liver metastases, baseline hemoglobin, time from last chemo, histology, risk factors, and chemo choice. Median DOR for responders was longer for pembro vs chemo (29.7 mo [1.6+ to 60.5+] vs 4.4 mo [1.4+ to 63.1+]), and a greater proportion of responses lasted ≥48 mo (40.9% vs 28.3%, Kaplan-Meier) and ≥60 mo (32.8% vs 28.3%). ORR was higher for pembro vs chemo (21.9% vs 11.0%; difference 10.8% [95% CI, 4.6-17.0]). Fewer pts given pembro vs chemo experienced a treatment-related AE of any grade (62.0% vs 90.6%) or grade ≥3 (16.9% vs 50.2%). Conclusions: After 5 y, pembro maintained clinically meaningful OS benefit vs chemo in pts with locally advanced or metastatic UC that progressed during or after platinum-based chemo. Pts who responded to pembro experienced a durable response (median >2 y). Clinical trial information: NCT02256436 .[Table: see text]

Three-year survival, correlates and salvage therapies in patients receiving first-line pembrolizumab for advanced Merkel cell carcinoma

Background

Merkel cell carcinoma (MCC) is an aggressive skin cancer associated with poor survival. Programmed cell death-1 (PD-1) pathway inhibitors have shown high rates of durable tumor regression compared with chemotherapy for MCC. The current study was undertaken to assess baseline and on-treatment factors associated with MCC regression and 3-year survival, and to explore the effects of salvage therapies in patients experiencing initial non-response or tumor progression after response or stable disease following first-line pembrolizumab therapy on Cancer Immunotherapy Trials Network-09/KEYNOTE-017.

Methods

In this multicenter phase II trial, 50 patients with advanced unresectable MCC received pembrolizumab 2 mg/kg every 3 weeks for ≤2 years. Patients were followed for a median of 31.8 months.

Results

Overall response rate to pembrolizumab was 58% (complete response 30%+partial response 28%; 95% CI 43.2 to 71.8). Among 29 responders, the median response duration was not reached (NR) at 3 years (range 1.0+ to 51.8+ months). Median progression-free survival (PFS) was 16.8 months (95% CI 4.6 to 43.4) and the 3-year PFS was 39.1%. Median OS was NR; the 3-year OS was 59.4% for all patients and 89.5% for responders. Baseline Eastern Cooperative Oncology Group performance status of 0, greater per cent tumor reduction, completion of 2 years of treatment and low neutrophil-to-lymphocyte ratio were associated with response and longer survival. Among patients with initial disease progression or those who developed progression after response or stable disease, some had extended survival with subsequent treatments including chemotherapies and immunotherapies.

Conclusions

This study represents the longest available follow-up from any first-line anti-programmed death-(ligand) 1 (anti-PD-(L)1) therapy in MCC, confirming durable PFS and OS in a proportion of patients. After initial tumor progression or relapse following response, some patients receiving salvage therapies survived. Improving the management of anti-PD-(L)1-refractory MCC remains a challenge and a high priority.

Trial registration number

NCT02267603.

Impact of subsequent therapy on survival in KEYNOTE-361: Pembrolizumab (pembro) plus chemotherapy (chemo) or pembro alone versus chemo as first-line therapy for advanced urothelial carcinoma (UC)

439

Background: The phase III KEYNOTE-361 study examined the efficacy and safety of 1L pembro + chemo or pembro alone vs chemo for pts with advanced UC. The PFS and OS benefit of pembro + chemo vs chemo did not reach statistical significance; no further formal tesing was done. We present an exploratory analysis of OS by subsequent therapy in KEYNOTE-361 (NCT02853305) to assess how 1L and 2L therapy selection affected survival outcomes; no formal comparisons were conducted. Methods: OS was estimated for pts by whether they received subsequent therapy, and by whether subsequent therapy included an anti–PD-(L)1 agent. Results: 351 pts were randomized to pembro + chemo, 307 pts to pembro, and 352 pts to chemo. As of Apr 29, 2020, the median (range) time from randomization to data cutoff was 31.7 (22.0-42.3) mo. 124/351 pts (35%) in the pembro + chemo arm, 126/307 pts (41%) in the pembro arm, and 215/352 pts (61%) in the chemo arm received any subsequent therapy. Similar rates of subsequent therapy (pembro + chemo: 32%; pembro: 43%; chemo: 59%) were observed for pts who experienced progressive disease (PD) by blinded independent central review (BICR). A higher rate of pts (169/352 [48%]) in the chemo arm received subsequent anti–PD-(L)1 therapy than in either the pembro + chemo arm (23/351 [7%]) or pembro arm (14/307 [5%]). Due to the small pt numbers, pts in the pembro + chemo or pembro arms who received subsequent anti−PD-(L)1 were not considered further. This analysis included all pts who received 2L therapy (465/1010 pts [46%]); the rate of 2L therapy was similar in pts with PD by BICR (274/615 [45%]). Chemo agents alone or in combination, specifically carboplatin, cisplatin, docetaxel, doxorubicin, gemcitabine, and paclitaxel, were the most commonly received subsequent therapies for pts who did not receive anti–PD-(L)1 in 2L. Pts who received 1L chemo followed by subsequent anti–PD-(L)1 had longer mOS (19.1 mo [95% CI 16.2-22.2]) than pts with 1L pembro followed by 2L therapy not including an anti−PD-(L)1 agent (16.0 mo [95% CI 11.8-19.2]) (Table). Conclusions: In this exploratory analysis, favorable survival outcomes were observed for pts who received 1L chemo followed by anti–PD-(L)1 compared with pts who received 1L pembro followed by 2L therapy not including an anti–PD-(L)1 agent. These data underline the continued importance of immunotherapy as 2L therapy for advanced UC. Clinical trial information: NCT02853305 . Research Sponsor: Merck & Co., Inc[Table: see text]

Analysis of PFS2 by subsequent therapy in KEYNOTE-361: Pembrolizumab (pembro) plus chemotherapy (chemo) or pembro alone versus chemo as 1L therapy for advanced urothelial carcinoma (UC)

448

Background: 1L pembro + chemo did not show statistically superior PFS and OS vs chemo for pts with advanced UC in the phase III KEYNOTE-361 study; OS for pembro vs chemo was not formally tested. We analyzed PFS2 (time from randomization to progressive disease [PD] on first subsequent therapy, or death from any cause, whichever occurs first) by study treatment and subsequent therapy in KEYNOTE-361 (NCT02853305) to determine the effects, if any, of therapy sequence on PFS2. Methods: PFS2 was estimated for pts in each treatment arm, who received any subsequent therapy including any anti–PD-(L)1, any therapy other than anti–PD-(L)1, or no therapy. These were exploratory analyses; no formal comparisons were done. Results: 1010 pts were randomized: 351 pts to receive pembro + chemo, 307 to pembro, and 352 to chemo. As of Apr 29, 2020, the median (range) time from randomization to data cutoff was 31.7 (22.0-42.3) mo. Subsequent therapy was received by 124/351 (35%), 126/307 (41%), and 215/352 (61%) pts in the pembro + chemo, pembro, and chemo arms, respectively. Subsequent anti–PD-(L)1 therapy was received by 169/352 (48%) pts in the chemo arm vs 23/351 (7%) in the pembro + chemo arm and 14/307 (5%) in the pembro arm. Of pts in the pembro arm who received subsequent therapy, >90% received 2L cisplatin-based or carboplatin-based treatment. Median (m) PFS2 (95% CI) for all pts by treatment arm was 14.1 mo (12.6-16.2) with pembro + chemo, 10.9 mo (9.5-12.9) with pembro, and 10.4 mo (9.8-11.2) with chemo. Across treatment arms, pts in the pembro + chemo arm had the longest mPFS2 with any subsequent therapy (14.5 mo [95% CI 13.1-16.6]) (Table). Pts in the pembro arm who received no subsequent therapy had a longer mPFS2 (12.9 mo [95% CI 8.1-17.9]) vs pts in the chemo arm who received no subsequent therapy (9.4 mo [95% CI 7.6-10.6]). Finally, pts treated with 1L pembro in the trial followed by 2L therapy other than anti−PD-(L)1 had comparable mPFS2 (10.2 mo [95% CI 8.6-12.1]) to pts treated with 1L chemo in the trial followed by 2L anti−PD-(L)1 (11.1 mo [95% CI 10.2-12.9]). Conclusions: In this exploratory analysis, treatment sequence of chemo followed by anti−PD-(L)1 upon PD vs anti–PD-(L)1 followed by chemo upon PD did not appear to impact mPFS2. Among pts who did not receive 2L therapy, 1L pembro appeared to be associated with longer mPFS2 than chemo, potentially driven by long-term responders to pembro. Clinical trial information: NCT02853305 . [Table: see text]

KEYNOTE-905/EV-303: Perioperative pembrolizumab or pembrolizumab plus enfortumab vedotin (EV) and cystectomy compared to cystectomy alone in cisplatin-ineligible patients with muscle-invasive bladder cancer (MIBC)

TPS507

Background: Patients with MIBC who are ineligible for neoadjuvant cisplatin-based chemotherapy receive the standard-of-care treatment of radical cystectomy (RC) and pelvic lymph node dissection (PLND); however, RC + PLND alone is associated with high rates of recurrence and relatively poor overall survival (OS). The PURE-01 study (NCT02736266) demonstrated a pathologic complete response (pCR) rate of 37% (95% CI, 28%-36%) with neoadjuvant pembrolizumab in MIBC (Necchi, Eur Urol, 2020). The combination of pembrolizumab plus EV demonstrated encouraging antitumor activity in metastatic urothelial cancer (Rosenberg, ASCO GU, 2020). KEYNOTE-905/EV-303 (NCT03924895) is a randomized, multinational phase 3 study that will assess efficacy and safety of perioperative pembrolizumab plus RC + PLND versus perioperative EV with pembrolizumab plus RC + PLDN versus RC + PLND alone for patients with MIBC. Methods: Approximately 836 patients will be randomly assigned 1:1:1 to 3 cycles of neoadjuvant pembrolizumab followed by RC + PLND and 14 cycles of adjuvant pembrolizumab or 3 cycles of neoadjuvant EV and pembrolizumab followed by RC+PLND and 6 cycles of adjuvant EV and pembrolizumab and then 8 cycles of adjuvant pembrolizumab or RC + PLND alone. Neoadjuvant or adjuvant pembrolizumab 200 mg will be administered intravenously every 3 weeks (Q3W). Neoadjuvant or adjuvant EV 1.25 mg/kg will be administered on days 1 and 8 Q3W. Stratification factors will be PD-L1 status (combined positive score [CPS] ≥10 vs < 10), disease stage (T2N0 vs T3/T4N0 vs T1-T4aN1), and region (United States vs European Union vs most of the world). Adults with histologically confirmed MIBC (T2-T4aN0M0 or T1-T4aN1M0) with predominant (≥50%) urothelial histology will be enrolled. These patients must also be previously untreated with systemic therapies for MIBC, be ineligible for cisplatin, have Eastern Cooperative Oncology Group performance status of 0-2, and have tumor tissue for histology and PD-L1 analysis. Imaging (CT or MRI) will be performed 5 weeks or fewer before cystectomy and at 6 weeks after cystectomy. Scans will then be performed every 12 weeks up to year 2 after cystectomy and at discontinuation. At year 3 and beyond imaging will be every 24 weeks. Coprimary end points are pCR and event-free survival (EFS) (expressing PD-L1 [CPS ≥10] and all patients regardless of CPS). Secondary end points are OS, disease-free survival, pathologic downstaging, safety, and patient-reported outcomes. Adverse events graded according to Common Terminology Criteria for Adverse Events v4.0 will be monitored from randomization through 30 days after last dose of study drug (90 days for serious adverse events). KEYNOTE-905/EV-303 is ongoing or planned in 25 countries across Asia, Australia, Europe, and North America. Clinical trial information: NCT03924895.

1L pembrolizumab (pembro) versus chemotherapy (chemo) for choice-of-carboplatin patients with advanced urothelial carcinoma (UC) in KEYNOTE-361

450

Background: 1L pembro is approved in advanced UC for cisplatin-ineligible pts with PD-L1 combined positive score (CPS) ≥10 and any platinum-ineligible pts regardless of CPS in the United States based on single-arm trial data. In the phase III KEYNOTE-361 study, 1L pembro + chemo did not statistically significantly improve PFS or OS vs chemo for pts with advanced UC; formal testing of 1L pembro vs chemo was not performed. We present an exploratory analysis of outcomes with pembro vs chemo for choice-of-carboplatin (carbo) pts in KEYNOTE-361 (NCT02853305). Methods: At randomization, choice of platinum agent (cisplatin or carbo) plus gemcitabine for each pt was selected based on investigator’s assessment of cisplatin ineligibility. ORR/DOR per RECIST v1.1 by blinded independent central review and OS were determined for all pts selected for carbo (“choice-of-carbo”) and also choice-of-carbo pts with CPS ≥10. Risk difference assessment for select AEs for pembro vs chemo was conducted in choice-of-carbo pts who received ≥1 dose study treatment. Results: As of Apr 29, 2020, the median (range) time from randomization to data cutoff in the full study cohort was 31.7 (22.0-42.3) mo. At randomization, renal impairment was the most common reason for choice of carbo by investigators (36% of all pts). 170 choice-of-carbo pts were randomized to the pembro arm, and 196 choice-of-carbo pts to the chemo arm. Median OS in this subgroup was 14.6 mo with pembro vs 12.3 mo with chemo (HR 0.83 [95% CI 0.65-1.06]). 18-mo OS rate was 42% with pembro vs 40% with chemo. ORR to pembro vs chemo was 27.6% vs 41.8%. Median (range) DOR with pembro vs chemo was not reached (NR) (3.2+-36.1+ mo) vs 6.3 (1.8+-33.8+) mo. 84/170 (49%) and 89/196 (45%) choice-of-carbo pts in the pembro and chemo arms, respectively, had CPS ≥10. In this subgroup, median OS was 15.6 mo with pembro vs 13.5 mo with chemo (HR 0.82 [95% CI 0.57-1.17]). 18-mo OS rate was 44% with pembro vs 43% with chemo. ORR to pembro vs chemo was 29.8% vs 46.1%. Median (range) DOR with pembro vs chemo was NR (4.2-36.1+ mo) vs 8.3 (2.1+-33.8+) mo. Among treated pts (N=166 for pembro, N=190 for chemo), 112 pts (68%) in the pembro arm and 163 pts (86%) in the chemo arm had grade 3-5 AEs of any cause. Pembro was associated with a higher risk of pruritus, while chemo was associated with a higher risk of decreased white blood cell, neutrophil, and platelet counts, nausea, thrombocytopenia, neutropenia, and anemia. Conclusions: Due to the trial design, this subset was not statistically tested and is exploratory. Median OS and 18-mo OS rates did not appear markedly different in the two arms; some parameters such as DOR favored pembro, although longer follow-up is needed to determine median DOR for pembro. The PD-L1 CPS ≥10 did not clearly enrich for responders to pembro in choice-of-carbo pts. Pembro was associated with a lower rate of grade 3-5 AEs of any cause than chemo. Clinical trial information: NCT02853305.

Post-hoc analysis of long-term outcomes in patients with CR, PR, or SD to pembrolizumab (pembro) or platinum-based chemotherapy (chemo) as 1L therapy for advanced urothelial carcinoma (UC) in KEYNOTE-361

435

Background: The phase III KEYNOTE-361 study compared efficacy and safety of 1L pembro + chemo or pembro vs chemo in pts with advanced UC. The trial did not meet its primary endpoints of PFS or OS superiority for pembro + chemo vs chemo; formal testing for OS for pembro vs chemo was not performed. We present a post hoc landmark analysis to examine the durability of CR/PR/SD and long-term survival in pts with CR, PR, or SD to pembro vs chemo at week 9 in KEYNOTE-361 (NCT02853305). Methods: Landmark analyses of OS by CR/PR/SD at 9 weeks after randomization in the ITT population were performed. Pts were included if they had a best response of CR/PR/SD per RECIST v1.1 by blinded independent central review at the landmark date of week 9 (first imaging assessment per study protocol). Duration of CR/PR/SD and OS were estimated by the Kaplan-Meier method. No formal comparisons were performed. Results: 307 pts were randomized to receive pembro and 352 pts to receive chemo in the KEYNOTE-361 study. As of Apr 29, 2020, the median (range) time from randomization to data cutoff was 32.5 (22.0-42.4) mo for the pembo arm and 31.4 (22.1-41.6) mo for the chemo arm. In the landmark analysis, fewer pts had CR/PR/SD at week 9 with pembro (n=137 [45%]) than with chemo (n=253 [72%]). Median (range) duration of response for pembro vs chemo was 18.7 (4.4+-35.4+) vs 12.3 (0.0+-29.7+) mo for pts with CR, and 35.0 (1.1-36.1+) vs 6.1 (0.0+-36.3+) mo for pts with PR. Median (range) duration of SD was 4.8 mo (0.0-38.2+) with pembro and 4.6 mo (0.0-16.1+) with chemo. Median OS (95% CI) for pembro vs chemo was not reached (NR) (25.5-NR) vs NR (19.1-NR) for pts with CR; NR (NR-NR) vs 14.8 mo (12.1-21.0) for pts with PR; and 18.5 mo (13.8-28.8) vs 11.1 mo (8.1-14.6) for pts with SD, respectively. Long-term OS rates were higher with pembro vs chemo across all groups (CR/PR/SD) at week 9 (Table). Conclusions: In this post hoc landmark analysis, chemo was associated with more initial responses than pembro, whereas pembro was associated with longer median duration of CR and PR, and generally longer median OS than chemo. Among pts who achieved CR/PR/SD at week 9, the relative OS benefit for pembro vs chemo increased over time. Clinical trial information: NCT02853305. [Table: see text]

Association of BRAF V600E/K Mutation Status and Prior BRAF/MEK Inhibition With Pembrolizumab Outcomes in Advanced Melanoma: Pooled Analysis of 3 Clinical Trials

Importance

The optimal sequencing of immune checkpoint inhibitors and targeted therapy for BRAF V600E/K-mutant melanoma is not well established.

Objective

To assess the association of BRAF wild-type (WT) or BRAF V600E/K-mutant status and BRAF inhibitor (BRAFi) with or without MEK inhibitor (MEKi) therapy with response to pembrolizumab.

Design, Setting, and Participants

This study is a post hoc subgroup analysis of pooled data from 3 multinational, multisite studies: KEYNOTE-001 (data cutoff September 1, 2017), KEYNOTE-002 (data cutoff May 30, 2018), and KEYNOTE-006 (data cutoff December 4, 2017). Patients included in this analysis were adults with advanced melanoma and known BRAF V600E/K tumor status who had received pembrolizumab.

Interventions

Patients received pembrolizumab in dosages of 2 mg/kg every 3 weeks, 10 mg/kg every 2 weeks, or 10 mg/kg every 3 weeks.

Main Outcomes and Measures

End points were objective response rate (ORR) and progression-free survival (PFS) assessed by Response Evaluation Criteria in Solid Tumors, version 1.1, and overall survival (OS). Objective response rates, 4-year PFS, and OS rates were compared in the following patient subgroups: BRAF WT vs BRAF V600E/K-mutant melanoma and BRAF V600E/K-mutant melanoma with vs without previous treatment with BRAFi with or without MEKi therapy.

Results

The overall study population (N = 1558) included 944 men (60.6%) and 614 women (39.4%). The mean (SD) age was 60.0 years (14.0). The ORR was 38.3% (596/1558), 4-year PFS rate was 22.0%, and 4-year OS rate was 36.9%. For patients with BRAF WT (n = 1124) and BRAF V600E/K-mutant melanoma (n = 434), ORR was 39.8% (n = 447) and 34.3% (n = 149), 4-year PFS rate was 22.9% and 19.8%, and 4-year OS rate was 37.5% and 35.1%, respectively. Patients with BRAF V600E/K-mutant melanoma who had (n = 271) vs had not (n = 163) previously received BRAFi with or without MEKi therapy had baseline characteristics with worse prognosis; ORR was 28.4% (n = 77) and 44.2% (n = 72), 4-year PFS rate was 15.2% and 27.8%, and 4-year OS rate was 26.9% and 49.3%, respectively.

Conclusions and Relevance

Results of this subgroup analysis support the use of pembrolizumab for treatment of advanced melanoma regardless of BRAF V600E/K mutation status or receipt of prior BRAFi with or without MEKi therapy.

The cost effectiveness of pembrolizumab versus chemotherapy or atezolizumab as second-line therapy for advanced urothelial carcinoma in the United States

Aims: Pembrolizumab demonstrated significantly prolonged overall survival (OS) vs. chemotherapy in the Phase III KEYNOTE-045 trial, and is approved in the US for the treatment of patients with locally advanced or metastatic urothelial carcinoma (mUC) who progressed after platinum-based chemotherapy. Using longer follow-up and individual patient-data from KEYNOTE-045, this study evaluates the cost-effectiveness of pembrolizumab vs. chemotherapy or atezolizumab from a US payer perspective.Materials and methods: A partitioned-survival model was developed over a 20-year time horizon. Progression-free survival (PFS) and OS for pembrolizumab and chemotherapy were extrapolated using a piecewise modelling approach, where patient-level data from KEYNOTE-045 were used for the initial period followed by parametric distributions. OS of atezolizumab was estimated by indirect treatment comparisons based on KEYNOTE-045 and IMvigor211. Different scenarios were explored in the absence of indirect comparisons on PFS and time-on-treatment (ToT) between pembrolizumab and atezolizumab. Drug acquisition/administration, disease management, adverse events, and terminal care costs were considered.Results: Compared with chemotherapy, pembrolizumab resulted in a mean gain of 1.33 life-years and 1.14 quality-adjusted life-years (QALYs) and an incremental cost of $106,299, yielding an incremental cost-effectiveness ratio of $93,481/QALY gained. Pembrolizumab dominated atezolizumab in extending patients' life by 0.89 years and 0.76 QALYs, while reducing costs by $26,458. Key drivers of cost-effectiveness included survival extrapolation, OS hazard ratio of pembrolizumab vs. atezolizumab, and time horizon. Pembrolizumab had a 66% and 100% probability of being cost-effective vs. chemotherapy and atezolizumab, respectively, at a $100,000 willingness-to-pay threshold.Limitations and conclusions: Uncertainties remain with extrapolated PFS and OS for pembrolizumab, OS indirect comparison, and ToT for atezolizumab. Despite these limitations, the model used robust methods to estimate key clinical endpoints with patient-level data from longer follow-up of KEYNOTE-045. Pembrolizumab dominates atezolizumab and is very likely cost-effective vs. chemotherapy in 2 L mUC at a $100,000 willingness-to-pay threshold.

Cost-effectiveness of Pembrolizumab versus Carboplatin-based Chemotherapy as First-line Treatment of PD-L1-positive Locally Advanced or Metastatic Urothelial Carcinoma Ineligible for Cisplatin-based Therapy in the United States

INTRODUCTION

Pembrolizumab has been approved in the United States (US) for the first-line treatment of patients with advanced or metastatic urothelial carcinoma, who are ineligible for cisplatin-containing chemotherapy and with tumors expressing programmed death-ligand 1 (PD-L1) (Combined Positive Score ≥ 10), or ineligible for any platinum-containing chemotherapy regardless of PD-L1 status. Long-term KEYNOTE-052 data continue to demonstrate pembrolizumab's meaningful, durable, and well-tolerated antitumor activity. This study evaluates the cost-effectiveness of pembrolizumab versus carboplatin plus gemcitabine as first-line treatment for cisplatin-ineligible patients who have PD-L1-positive tumors from a US third-party healthcare payer's perspective.

PATIENTS AND METHODS

A partitioned survival model containing 3 health states (progression-free, progressed, and death) was developed. A simulated treatment comparison and a network meta-analysis were conducted to estimate the comparative efficacy of pembrolizumab versus carboplatin-based chemotherapy. Overall survival, progression-free survival, time on treatment, adverse events, and utilities were modeled using the final analyses of the KEYNOTE-052 trial and 4 studies for carboplatin plus gemcitabine. Cost data were estimated using US standard sources and real-world data. Deterministic, probabilistic, and scenario analyses were conducted to assess the robustness of the results.

RESULTS

Over 20 years, pembrolizumab resulted in a mean gain of 2.58 life-years, 2.01 quality-adjusted life-years, and additional costs of $158,561, leading to an incremental cost-effectiveness ratio of $78,925/quality-adjusted life-year compared with carboplatin plus gemcitabine.

CONCLUSION

This study suggests that pembrolizumab is cost-effective compared with carboplatin plus gemcitabine as a first-line therapy for patients with advanced or metastatic urothelial carcinoma who are PD-L1-positive.

Long-term Follow-up of Standard-Dose Pembrolizumab Plus Reduced-Dose Ipilimumab in Patients with Advanced Melanoma: KEYNOTE-029 Part 1B

PURPOSE

Combination therapy with reduced-dose programmed death 1 inhibitor plus standard-dose cytotoxic T-lymphocyte-associated antigen 4 inhibitor demonstrated efficacy, but substantial toxicity, in melanoma. We present long-term results of part 1B of KEYNOTE-029, which assessed safety and efficacy of standard-dose pembrolizumab plus reduced-dose ipilimumab in advanced melanoma.

PATIENTS AND METHODS

Part 1B was an expansion cohort of the open-label, phase Ib portion of KEYNOTE-029. Eligible patients had advanced melanoma and no previous immune checkpoint inhibitor therapy. Patients received pembrolizumab 2 mg/kg (amended to 200 mg) every 3 weeks plus ipilimumab 1 mg/kg every 3 weeks (four cycles), then pembrolizumab alone for up to 2 years. Primary end point was safety; secondary end points included objective response rate (ORR), progression-free survival (PFS), duration of response (DOR), and overall survival (OS).

RESULTS

A total of 153 patients received at least one dose of pembrolizumab plus ipilimumab. At a median follow-up of 36.8 months, 71.9% had received four doses of ipilimumab and 30.7% had completed 2 years of pembrolizumab; 26.1% completed both treatments. Treatment-related adverse events occurred in 96.1% (47.1% grade 3/4; no deaths), leading to discontinuation of one or both study drugs in 35.9%. ORR was 62.1% with 42 (27.5%) complete and 53 (34.6%) partial responses. Median DOR was not reached; 36-month ongoing response rate was 84.2%. Median PFS and OS were not reached; 36-month rates were 59.1% and 73.4%, respectively.

CONCLUSIONS

Standard-dose pembrolizumab plus reduced-dose ipilimumab demonstrated robust antitumor activity, durable response, and favorable long-term survival with manageable toxicity.

Long-Term Outcomes in KEYNOTE-052: Phase II Study Investigating First-Line Pembrolizumab in Cisplatin-Ineligible Patients With Locally Advanced or Metastatic Urothelial Cancer

PURPOSE

The phase II single-arm KEYNOTE-052 study evaluated the efficacy and safety of first-line pembrolizumab for patients with locally advanced or metastatic cisplatin-ineligible urothelial carcinoma (UC).

PATIENTS AND METHODS

Three hundred seventy patients received pembrolizumab 200 mg intravenously every 3 weeks for up to 24 months. Positive tumor programmed death ligand 1 (PD-L1) expression was defined as combined positive score (CPS) ≥ 10. Response was assessed by independent central review every 9 weeks per RECIST v1.1. The primary end point was objective response rate (ORR).

RESULTS

At data cutoff (September 26, 2018), the minimum follow-up was 2 years since the last patient enrolled. ORR was 28.6% (95% CI, 24.1% to 33.5%); 33 patients (8.9%) and 73 patients (19.7%) achieved complete and partial response, respectively. The median duration of response was 30.1 months (95% CI, 18.1 months to not reached [NR]); responses lasted ≥ 12 and ≥ 24 months in 67% and 52% of patients, respectively. Forty patients with complete or partial response completed 2 years of study treatment, and 32 had ongoing response at completion. Median overall survival (OS) was 11.3 months (95% CI, 9.7 to 13.1 months), and 12- and 24-month OS rates were 46.9% and 31.2%, respectively. In patients with CPS ≥ 10, ORR was 47.3% (95% CI, 37.7% to 57.0%) and median OS was 18.5 months (95% CI, 12.2 to 28.5 months). In patients with lymph node-only disease, ORR was 49.0% (95% CI, 34.8% to 63.4%), and median OS was 27.0 months (12.4 months to NR). There were no new safety signals.

CONCLUSION

First-line pembrolizumab confers meaningful and durable clinical response in cisplatin-ineligible patients with advanced UC and is associated with prolonged OS, particularly with PD-L1 CPS ≥ 10 and lymph node-only disease.

Phase III study of first-line pembrolizumab (pembro) plus lenvatinib (len) in patients (pts) with advanced urothelial carcinoma (UC) ineligible for platinum-based chemotherapy: LEAP-011

TPS597

Background: KEYNOTE-052 (NCT02335424) results led to pembro, a PD-1 inhibitor, to become the standard of care for cisplatin-ineligible pts with locally advanced or metastatic UC with tumors expressing PD-L1 and for pts unable to receive platinum-based chemotherapy regardless of PD-L1 status. Len, a potent, multiple-receptor, tyrosine kinase inhibitor has activity in multiple solid tumors. KEYNOTE-146 (NCT02501096) results showed promising efficacy and manageable safety with pembro+len in previously treated pts with advanced UC, regardless of PD-L1 status. Methods: LEAP-011 (NCT03898180) is a randomized phase 3 study to assess efficacy and safety of pembro+len, compared with pembro+placebo, in pts with advanced UC. An estimated 694 pts will be enrolled. Adults (≥18 years) with histologically confirmed locally advanced unresectable or metastatic UC who are either cisplatin-ineligible with tumors expressing PD-L1 (combined positive score [CPS] ≥10) or ineligible to receive any platinum-based chemotherapy are eligible. Pts are required to have an ECOG PS of 0-2 and provide tumor tissue for PD-L1 analysis. Previous treatment with systemic chemotherapy for advanced UC is not permitted, except in cases of recurrence after 1 year of platinum-based chemotherapy for either muscle-invasive bladder cancer (neoadjuvant) or after radical cystectomy (adjuvant). Pts will be randomly assigned 1:1 to receive pembro 200 mg IV every 3 weeks for up to 35 cycles (~2 y) plus either len 20 mg or placebo orally once daily. Pts will be stratified as follows: ineligible for any platinum containing chemotherapy and ECOG PS 2 (CPS ≥10 vs <10); cisplatin ineligibility and CPS ≥10 (ECOG 0-1 vs 2). Radiologic assessment will include CT/MRI of the chest, abdomen, and pelvis, and bone imaging. Responses will be assessed per RECIST v1.1 by blinded independent central review (BICR). Coprimary end points are PFS and OS. Secondary end points are objective response rate, duration of response, and disease control rate per RECIST v1.1 by BICR; patient-reported outcomes; and safety. Tissue-and blood-based biomarkers will be explored. Accrual began May 6, 2019. Clinical trial information: NCT03898180.

Phase III study of perioperative pembrolizumab (pembro) plus neoadjuvant chemotherapy (chemo) versus placebo plus neoadjuvant chemo in cisplatin-eligible patients (pts) with muscle-invasive bladder cancer (MIBC): KEYNOTE-866

TPS599

Background: MIBC prognosis is poor, despite standard neoadjuvant cisplatin-based chemo. PD-1/PD-L1 pathway inhibition is an effective first-line option for cisplatin-ineligible pts and a second-line option for platinum-based chemo pretreated pts. Neoadjuvant chemo + pembro, a PD-1 inhibitor, recently showed encouraging pathologic complete response rates, in cisplatin-eligible patients with MIBC (NCT02365766), warranting further investigation. Methods: KEYNOTE-866 (NCT03924856) is a randomized phase 3 study to assess efficacy and safety of chemo+perioperative pembro versus chemo+perioperative placebo for pts with MIBC. An estimated 790 patients will be randomly assigned 1:1 to neoadjuvant pembro+chemo (4 cycles) followed by adjuvant pembro after radical cystectomy+pelvic lymph node dissection (RC+PLND, 13 cycles) or neoadjuvant placebo+chemo (4 cycles) followed by adjuvant placebo after RC+PLND (13 cycles). Pts will receive neoadjuvant and adjuvant pembro 200 mg IV Q3W; neoadjuvant chemo will be gemcitabine 1000 mg/m2+cisplatin 70 mg/m2 IV Q3W. Pts will be stratified by tumor PD-L1 status (combined positive score [CPS] ≥10 vs CPS <10), disease stage (T2 vs T3/4), and region of treatment (Unites States vs Europe vs most of world). Adults (≥18 y) with histologically confirmed MIBC (T2-T4aN0M0) who are cisplatin-eligible, are clinically nonmetastatic (N0M0), and have an ECOG PS 0 or 1 will be enrolled. Pts are required to provide tumor tissue for histology and PD-L1 analysis. Pts will not be permitted to have previously received systemic antineoplastic treatment for MIBC or radiotherapy to the bladder. Imaging by CT/MRI will be performed Q12W for up to 96 wk after cystectomy, at discontinuation, and during follow-up starting at 3 y (Q24W). Primary end points are pathologic complete response and event-free survival in all pts and pts with PD-L1 CPS ≥10. Secondary end points are OS, disease-free survival, and pathologic downstaging rate in all pts and pts with PD-L1 CPS ≥10, and safety. Accrual began June 13, 2019. Clinical trial information: NCT03924856.

Phase III study of perioperative pembrolizumab (pembro) plus cystectomy versus cystectomy alone in cisplatin-ineligible patients (pts) with muscle-invasive bladder cancer (MIBC): KEYNOTE-905

TPS593

Background: Pts with MIBC ineligible for neoadjuvant cisplatin-based chemotherapy who only receive the standard radical cystectomy+pelvic lymph node dissection (RC+PLND) have a high rate of recurrence and poor prognosis. PD-1/PD-L1 inhibition is an effective first-line option for cisplatin-ineligible pts. Neoadjuvant single-agent pembro, a PD-1 inhibitor, has shown activity in pts with MIBC, with a pathologic complete response (pCR) rate of 42% for all pts and 54% for PD-L1+ pts (PURE-01; NCT02736266). Methods: KEYNOTE-905 (NCT03924895) is a randomized phase 3 trial of preoperative pembro plus RC+PLND versus RC+PLND alone in cisplatin-ineligible pts with MIBC. An estimated 610 pts will be enrolled and randomly assigned 1:1 to either neoadjuvant pembro (3 cycles) followed by RC+PLND and adjuvant pembro (14 cycles) or RC+PLND alone and observation. Pembro 200 mg will be administered IV every 3 weeks. Pts in the RC+PLND group will proceed directly to RC+PLND within 8 weeks from randomization. Pts will be stratified by clinical T stage (T2 vs T3 or T4), PD-L1 expression (combined positive score [CPS] ≥10 vs <10), and geographic region (United States vs Europe vs most of world). Adults (≥18 years) ineligible to receive cisplatin with histologically confirmed MIBC (T2-T4aN0M0), clinically nonmetastatic disease (N0M0), and an ECOG PS score of 0-2 are eligible. Previous systemic anticancer therapies for MIBC are not permitted. CT/MRI will be performed before and after cystectomy. Pts disease free after imaging for cystectomy will continue to undergo serial imaging until disease progression or discontinuation from the study; all imaging will be assessed by blinded independent central review. Coprimary end points are pCR (based on central pathology review) and event-free-survival in all pts and in pts with tumor PD-L1 CPS ≥10. Secondary end points are OS, disease-free survival, and pathologic downstaging in all pts and in pts with tumor PD-L1 CPS ≥10, and safety. Exploratory end points include patient-reported outcomes and biomarkers. Accrual began July 24, 2019. Clinical trial information: NCT03924895.

Combined BRAF and MEK inhibition with PD-1 blockade immunotherapy in BRAF-mutant melanoma

Oncogene-targeted therapy with B-Raf proto-oncogene (BRAF) and mitogen-activated protein kinase kinase (MEK) inhibitors induces a high initial response rate in patients with BRAF^V600-mutated melanoma, with a median duration of response of approximately 1 year^1-3. Immunotherapy with antibodies to programmed death 1 (PD-1) produces lower response rates but with long response duration. Preclinical models suggest that combining BRAF and MEK inhibitors with PD-1 blockade therapy improves antitumor activity^4-6, which may provide additional treatment options for patients unlikely to have long-lasting responses to either mode of therapy alone. We enrolled 15 patients with BRAF^V600-mutated metastatic melanoma in a first-in-human clinical trial of dabrafenib, trametinib and pembrolizumab ( NCT02130466 ). Eleven patients (73%) experienced grade 3/4 treatment-related adverse events, the most common being elevation of liver function tests and pyrexia, most of which resolved with drug interruption or discontinuation of either the anti-PD-1 antibody or the targeted therapy combination. Eleven patients (73%; 95% confidence interval = 45-92%) had an objective response, and six (40%; 95% confidence interval = 16-68%) continued with a response at a median follow-up of 27 months (range = 10.3-38.4+ months) for all patients. This study suggests that this triple-combined therapy may benefit a subset of patients with BRAF^V600-mutated metastatic melanoma by increasing the frequency of long-lasting antitumor responses.

Standard-dose pembrolizumab (pembro) plus alternate-dose ipilimumab (ipi) in advanced melanoma: Initial analysis of KEYNOTE-029 cohort 1C

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Background: KEYNOTE-029 cohort 1B showed substantial efficacy for standard-dose pembro + 4 doses of ipi 1 mg/kg with lower rate of grade 3-5 toxicity than reported for standard-dose nivolumab + ipi in patients (pts) with advanced melanoma. In KEYNOTE-029 cohort 1C, we assessed the toxicity and antitumor activity of standard-dose pembro plus 2 alternate ipi doses (NCT02089685). Methods: Eligible pts with previously untreated stage III/IV melanoma, ECOG PS 0-1, and no active CNS metastases were randomized 1:1 to pembro 200 mg Q3W for 24 mo + 4 doses of ipi 50 mg Q6W (arm A) or pembro 200 mg Q3W for 24 mo + 4 doses of ipi 100 mg Q12W (arm B). Primary endpoints were the grade 3-5 treatment-related AE (TRAE) rate and ORR (RECIST v1.1, central review). With 50 pts per arm and compared with other anti–PD-1 + ipi regimens, a grade 3-5 TRAE rate ≤26% would suggest a meaningful reduction in toxicity and an ORR ≥48% would suggest no decrease in efficacy. Data cutoff date was Jul 17, 2018, and will be updated. Results: 102 pts were randomized: 51 to each arm. Median age was 63.5 y, 70% were male, 15% had ECOG PS 1, 34% had BRAF mutation, and 30% had elevated LDH at baseline. With 9.4 mo median follow-up, 69% of pts in arm A and 71% in arm B remained on treatment. All pts in arm A and 96.1% in arm B had ≥1 TRAE; grade 3-5 TRAE rates were 22% in arm A and 33% in arm B. 1 pt had a grade 5 TRAE (autoimmune myocarditis; arm A). ORR was 49% (95% CI 35-63) in arm A, including 7 CRs and 18 PRs, and 53% (95% CI 39-67) in arm B, including 6 CRs and 21 PRs. An additional 16 pts in each arm had SD or non-CR/non-PD, leading to a DCR of 80% and 84%, respectively. Median response duration was not reached in either arm (range 1.4+ to 9.6+ in arm A, 1.4+ to 9.8+ in arm B). Updated data based on longer follow-up will be presented. Conclusions: Standard-dose pembro + ipi 50 mg Q6W and standard-dose pembro + ipi 100 mg Q12W showed robust antitumor activity in this initial analysis. Both regimens appeared to have a lower rate of grade 3-5 TRAEs than previously observed. Longer follow-up and randomized studies are needed to confirm that these regimens reduce toxicity without compromising efficacy compared with other anti–PD-1 and ipi combinations. Clinical trial information: NCT02089685.

Durable Tumor Regression and Overall Survival in Patients With Advanced Merkel Cell Carcinoma Receiving Pembrolizumab as First-Line Therapy

PURPOSE

Merkel cell carcinoma (MCC) is an aggressive skin cancer often caused by the Merkel cell polyomavirus. Clinical trials of programmed cell death-1 pathway inhibitors for advanced MCC (aMCC) demonstrate increased progression-free survival (PFS) compared with historical chemotherapy data. However, response durability and overall survival (OS) data are limited.

PATIENTS AND METHODS

In this multicenter phase II trial (Cancer Immunotherapy Trials Network-09/Keynote-017), 50 adults naïve to systemic therapy for aMCC received pembrolizumab (2 mg/kg every 3 weeks) for up to 2 years. Radiographic responses were assessed centrally per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1.

RESULTS

Among 50 patients, the median age was 70.5 years, and 64% had Merkel cell polyomavirus-positive tumors. The objective response rate (ORR) to pembrolizumab was 56% (complete response [24%] plus partial response [32%]; 95% CI, 41.3% to 70.0%), with ORRs of 59% in virus-positive and 53% in virus-negative tumors. Median follow-up time was 14.9 months (range, 0.4 to 36.4+ months). Among 28 responders, median response duration was not reached (range, 5.9 to 34.5+ months). The 24-month PFS rate was 48.3%, and median PFS time was 16.8 months (95% CI, 4.6 months to not estimable). The 24-month OS rate was 68.7%, and median OS time was not reached. Although tumor viral status did not correlate with ORR, PFS, or OS, there was a trend toward improved PFS and OS in patients with programmed death ligand-1-positive tumors. Grade 3 or greater treatment-related adverse events occurred in 14 (28%) of 50 patients and led to treatment discontinuation in seven (14%) of 50 patients, including one treatment-related death.

CONCLUSION

Here, we present the longest observation to date of patients with aMCC receiving first-line anti-programmed cell death-1 therapy. Pembrolizumab demonstrated durable tumor control, a generally manageable safety profile, and favorable OS compared with historical data from patients treated with first-line chemotherapy.

Potential markers of response and resistance to programmed cell death-1 blockade in first-line therapy of cisplatin-inilegible advanced urothelial cancer

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Background: Immune checkpoint inhibitors (ICIs) have demonstrated clinical benefit in advanced urothelial cancer (UC) patients. An alert was issued about a decrease in survival for bladder cancer patients with PD-L1-low status receiving immunotherapy versus chemotherapy as first-line therapy. We studied a small series of UC patients treated with first-line PD-1 checkpoint inhibition in order to analyze their characteristics and patterns of response to therapy. Methods: Eleven UC samples were obtained from patients before undergoing therapy with ICIs. Patients were classified according to their benefit from therapy in responders (n=5) and non-responders (n=6). Genomic and immunohistochemistry analyses were performed. Results: Both luminal and basal UC subtypes showed benefit from ICIs. Tumors from non-responders showed increased mutations in chromatin remodelling genes and the amplification of 3q26-28 region. Transcriptome analyses showed that tumors from responders displayed a significant enrichment of genes associated with interferon γ and α response, TNFα via NFκB, genes upregulated by MYC or E2F1, genes involved in G2/M checkpoint and epithelial-mesenchymal transition compared to non-responders. Specific immune cell subsets were present in the tumor microenvironment of tumors from responders and non-responders. Immunohistochemistry showed that none of the immune cell markers analyzed individually was sufficient to discriminate between responders and non-responders. However, the increase in FOXP-3, PD-L1, PD-1, CD8, β2 microglobulin and CD68 and the decrease in CD4 and CD163 cells identified UC patients that responded to ICIs. Conclusions: Our findings confirm that the evaluation of pre-treatment UC tumor samples provides valuable information that could influence treatment decisions. Despite the clinical benefit of PD-1/PD-L1 inhibition in UC, only a fraction of patients benefit from therapy. Our data suggest that responders and non-responders display diverse genomic and transcriptome changes as well as specific immune cell subsets in the tumor microenvironment that can be identified by conventional IHC staining.

Interferon Receptor Signaling Pathways Regulating PD-L1 and PD-L2 Expression

PD-L1 and PD-L2 are ligands for the PD-1 immune inhibiting checkpoint that can be induced in tumors by interferon exposure, leading to immune evasion. This process is important for immunotherapy based on PD-1 blockade. We examined the specific molecules involved in interferon-induced signaling that regulates PD-L1 and PD-L2 expression in melanoma cells. These studies revealed that the interferon-gamma-JAK1/JAK2-STAT1/STAT2/STAT3-IRF1 axis primarily regulates PD-L1 expression, with IRF1 binding to its promoter. PD-L2 responded equally to interferon beta and gamma and is regulated through both IRF1 and STAT3, which bind to the PD-L2 promoter. Analysis of biopsy specimens from patients with melanoma confirmed interferon signature enrichment and upregulation of gene targets for STAT1/STAT2/STAT3 and IRF1 in anti-PD-1-responding tumors. Therefore, these studies map the signaling pathway of interferon-gamma-inducible PD-1 ligand expression.

Development of MK-8353, an orally administered ERK1/2 inhibitor, in patients with advanced solid tumors

BACKGROUND

Constitutive activation of ERK1/2 occurs in various cancers, and its reactivation is a well-described resistance mechanism to MAPK inhibitors. ERK inhibitors may overcome the limitations of MAPK inhibitor blockade. The dual mechanism inhibitor SCH772984 has shown promising preclinical activity across various BRAFV600/RAS-mutant cancer cell lines and human cancer xenografts.

METHODS

We have developed an orally bioavailable ERK inhibitor, MK-8353; conducted preclinical studies to demonstrate activity, pharmacodynamic endpoints, dosing, and schedule; completed a study in healthy volunteers (P07652); and subsequently performed a phase I clinical trial in patients with advanced solid tumors (MK-8353-001). In the P07652 study, MK-8353 was administered as a single dose in 10- to 400-mg dose cohorts, whereas in the MK-8353-001 study, MK-8353 was administered in 100- to 800-mg dose cohorts orally twice daily. Safety, tolerability, pharmacokinetics, pharmacodynamics, and antitumor activity were analyzed.

RESULTS

MK-8353 exhibited comparable potency with SCH772984 across various preclinical cancer models. Forty-eight patients were enrolled in the P07652 study, and twenty-six patients were enrolled in the MK-8353-001 study. Adverse events included diarrhea (44%), fatigue (40%), nausea (32%), and rash (28%). Dose-limiting toxicity was observed in the 400-mg and 800-mg dose cohorts. Sufficient exposure to MK-8353 was noted that correlated with biological activity in preclinical data. Three of fifteen patients evaluable for treatment response in the MK-8353-001 study had partial response, all with BRAFV600-mutant melanomas.

CONCLUSION

MK-8353 was well tolerated up to 400 mg twice daily and exhibited antitumor activity in patients with BRAFV600-mutant melanoma. However, antitumor activity was not particularly correlated with pharmacodynamic parameters.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01358331.

FUNDING

Merck Sharp & Dohme Corp., a subsidiary of Merck & Co. Inc., and NIH (P01 CA168585 and R35 CA197633).

Pembrolizumab Plus Pegylated Interferon alfa-2b or Ipilimumab for Advanced Melanoma or Renal Cell Carcinoma: Dose-Finding Results from the Phase Ib KEYNOTE-029 Study

Purpose: Pembrolizumab monotherapy, ipilimumab monotherapy, and pegylated interferon alfa-2b (PEG-IFN) monotherapy are active against melanoma and renal cell carcinoma (RCC). We explored the safety and preliminary antitumor activity of pembrolizumab combined with either ipilimumab or PEG-IFN in patients with advanced melanoma or RCC.Experimental Design: The phase Ib KEYNOTE-029 study (ClinicalTrials.gov, NCT02089685) included independent pembrolizumab plus reduced-dose ipilimumab and pembrolizumab plus PEG-IFN cohorts. Pembrolizumab 2 mg/kg every 3 weeks (Q3W) plus 4 doses of ipilimumab 1 mg/kg Q3W was tolerable if ≤6 of 18 patients experienced a dose-limiting toxicity (DLT). The target DLT rate for pembrolizumab 2 mg/kg Q3W plus PEG-IFN was 30%, with a maximum of 14 patients per dose level. Response was assessed per RECIST v1.1 by central review.Results: The ipilimumab cohort enrolled 22 patients, including 19 evaluable for DLTs. Six patients experienced ≥1 DLT. Grade 3 to 4 treatment-related adverse events occurred in 13 (59%) patients. Responses occurred in 5 of 12 (42%) patients with melanoma and 3 of 10 (30%) patients with RCC. In the PEG-IFN cohort, DLTs occurred in 2 of 14 (14%) patients treated at dose level 1 (PEG-IFN 1 μg/kg/week) and 2 of 3 (67%) patients treated at dose level 2 (PEG-IFN 2 μg/kg/week). Grade 3 to 4 treatment-related adverse events occurred in 10 of 17 (59%) patients. Responses occurred in 1 of 5 (20%) patients with melanoma and 2 of 12 (17%) patients with RCC.Conclusions: Pembrolizumab 2 mg/kg Q3W plus ipilimumab 1 mg/kg Q3W was tolerable and provided promising antitumor activity in patients with advanced melanoma or RCC. The maximum tolerated dose of pembrolizumab plus PEG-IFN had limited antitumor activity in this population. Clin Cancer Res; 24(8); 1805-15. ©2018 AACR.

Abstract CT065: KEYNOTE 029: A phase I/II randomized trial of pembrolizumab (pembro) plus 2 dose regimens of ipilimumab (ipi) for advanced melanoma

Background: Combination therapy of nivolumab plus full-dose ipi (3 mg/kg) provided greater efficacy than either inhibitor alone but with increased toxicity (55% treatment-related adverse events [TRAEs]). Results from part 1B of the phase I/II KEYNOTE-029 study (ClinicalTrials.gov, NCT02089685) showed preliminary efficacy in pts with melanoma treated with standard-dose pembro (2 mg/kg every 3 weeks [Q3W]) + reduced-dose ipi (1 mg/kg Q3W for 4 doses). This combination appeared superior to historical studies with single-agent anti-PD-1, but 42% of pts had TRAEs. Part 1C of KEYNOTE-029 will explore 2 additional dosing regimens of this combination to further investigate efficacy and minimize the occurrence of the toxicity observed in part 1B.

Methods: Eligibility criteria include age ≥18 yr; histologically confirmed unresectable stage III/IV melanoma not amenable to local therapy; no prior treatment ([neo]adjuvant treatment, excluding PD-1/PD-L1 or BRAF/MEK inhibitors is allowed, provided pts did not discontinue for TRAEs, all related AEs returned to baseline or stabilized, and relapse did not occur during or within 6 mo of treatment discontinuation for anti-CTLA-4 therapy); measurable disease per RECIST v1.1; ECOG performance status 0 or 1; no active brain metastases (baseline brain MRI required); and no active autoimmune disease requiring systemic therapy within the past 2 yr or history of pneumonitis requiring steroids. In part 1C, ~100 pts are to be randomly assigned 1:1 to receive pembro 200 mg Q3W + ipi 50 mg Q6W (arm 1) or ipi 100 mg Q12W (arm 2). Combination treatment will continue for ≤24 wk in arm 1 and ≤48 wk in arm 2, followed by pembro monotherapy for ≤24 mo or until progressive disease (PD), intolerable toxicity, patient withdrawal, or physician decision to discontinue. Tumor imaging will be performed every 6 wk until wk 24, then every 12 wk thereafter. Response will be assessed per RECIST v1.1 by independent central review (for efficacy) and modified RECIST v1.1 by investigator review (for treatment decisions). Survival follow-up will occur every 12 wk. AEs will be graded throughout the study and for 30 d thereafter per NCI CTCAE v4.0. Pts with investigator-determined, confirmed complete response (CR) who received ≥24 wk of pembro and ≥2 doses of pembro after initial CR may discontinue pembro; pts with investigator-determined, confirmed CR or very good partial response (percentage change from baseline in tumor size &gt;60%) who received ≥1 ipi dose may discontinue ipi. Pts experiencing stable disease or better who subsequently experience PD may be eligible for a second treatment course with pembro + ipi or pembro monotherapy (maximum 17 doses of pembro and 4 doses of ipi). Eligible pts with PD may remain on treatment until a confirmatory scan ≥4 wk later. Primary end points are safety and ORR; secondary end points include PFS, OS, and duration of response.

Citation Format: Michael B. Atkins, Matteo S. Carlino, Andrew G. Hill, Catriona M. McNeil, Georgina V. Long, Victoria Atkinson, Jonathan S. Cebon, Michael B. Jameson, Wen-Jen Hwu, John A. Thompson, James Anderson, Blanca Homet Moreno, Nageatte Ibrahim, Antoni Ribas. KEYNOTE 029: A phase I/II randomized trial of pembrolizumab (pembro) plus 2 dose regimens of ipilimumab (ipi) for advanced melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT065. doi:10.1158/1538-7445.AM2017-CT065

Long-term outcomes in patients (pts) with ipilimumab (ipi)-naive advanced melanoma in the phase 3 KEYNOTE-006 study who completed pembrolizumab (pembro) treatment

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Background: Pembro demonstrated superior PFS and OS vs ipi in ipi-naive pts with advanced melanoma in the phase 3 KEYNOTE-006 study (NCT01866319). Here, we present long-term outcomes for all pts and in those pts who completed pembro therapy. Methods: Eligible pts (N = 834) were randomized 1:1:1 to pembro 10 mg/kg Q2W, pembro 10 mg/kg Q3W, or ipi 3 mg/kg Q3W for 4 doses. Treatment was continued for 2 yr (pembro only) or until disease progression, intolerable toxicity, or pt/investigator decision to discontinue. Per protocol, pts could interrupt pembro for ≤12 wk before discontinuation was required. Tumor imaging was performed at wk 12, then every 6 wk up to wk 48 and every 12 wk thereafter. After the prespecified final analysis, response assessments were per immune-related response criteria (irRC) by investigator review. Results: As of the data cutoff (Nov 3, 2016), median follow-up in the total population was 33.9 mo (range, 32.1-37.6). 33-mo OS rates were 50% in the pooled pembro arms (n = 556) and 39% in the ipi arm (n = 278); 33-mo PFS rates were 31% and 14%. ORR was 42% and 16%. Median duration of response was not reached for pembro (range 1.0+ to 33.8+ mo) or ipi (1.1+ to 34.8+ mo); 46 (68%) pembro-treated pts and 7 (58%) ipi-treated pts had a response lasting ≥30 mo. Among the 104/556 (19%) pts who completed pembro, median exposure to pembro was 24.0 mo (range 22.1-25.9). After a median follow-up of 9.0 mo after completion of pembro, 102 (98%) pts were alive. Responses were durable in pts who completed pembro; 9.7 mo after completion of pembro, estimated PFS (95% CI) was 91% (80-96) in all 104 pts, 95% (69-99) in pts with complete response (n = 24), 91% (74-97) in pts with partial response (n = 68), and 83% (48-96) in pts with stable disease (n = 12). Conclusions: Pembro provides durable efficacy after stopping the protocol-specified duration of treatment in pts with ipi-naive advanced melanoma in KEYNOTE-006. The estimated risk for progression or death nearly 10 mo after completing pembro is 9% and does not appear to differ by best response to pembro. Clinical trial information: NCT01866319.

KEYNOTE-029: Efficacy and safety of pembrolizumab (pembro) plus ipilimumab (ipi) for advanced melanoma

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Background: We previously showed that standard-dose pembro plus reduced-dose ipi has manageable safety and robust antitumor activity in patients (pts) with advanced melanoma. Here, we present more mature data, including 1-y landmark PFS and OS estimates. Methods: In the phase 1 KEYNOTE-029 expansion cohort (NCT02089685), pts with advanced melanoma, ECOG PS 0-1, no active brain metastases, and no prior immune checkpoint inhibitor therapy received pembro 2 mg/kg Q3W + ipi 1 mg/kg Q3W for 4 doses, then pembro alone for up to 2 y. Primary end point was safety. Efficacy end points were ORR, PFS, and DOR per RECIST v1.1 by independent central review and OS. Results: 153 pts were enrolled between Jan 13, 2015, and Sep 17, 2015. Median age was 60 y, 66% were male, 25% had elevated LDH, 56% had stage M1c disease, 36% were BRAFV600mutant, and 13% received ≥1 prior therapy. As of Oct 17, 2016, median follow-up was 17 mo, and 64 (42%) pts remained on pembro. 110 (72%) pts received all 4 ipi doses. There were no treatment-related (TR) deaths. TRAEs occurred in all pts, were grade 3/4 in 69 (45%), and led to discontinuation of pembro and ipi in 17 (11%), ipi alone in 11 (7%), and pembro alone after ipi completion or discontinuation in 19 (12%). PD occurred in 1/11 pts who discontinued ipi alone and 4/17 pts who discontinued ipi and pembro. Of the 11 pts who discontinued ipi alone for a TRAE, 0 experienced recurrence of the same TRAE during pembro monotherapy and 2 discontinued pembro for a different TRAE (both elevated lipase). Immune-mediated AEs occurred in 90 (59%) pts and were grade 3/4 in 39 (25%). With 7 mo additional follow-up, there were 6 additional responses for an ORR of 61% (95% CI, 53%-69%); the CR rate increased from 10% to 15%. Median DOR was not reached (range, 1.6+ to 18.1+ mo), with 86/93 responders (92%), including 23/23 (100%) with CR, alive and without subsequent PD at cutoff. Median PFS and OS were not reached; 1-y estimates were 69% for PFS and 89% for OS. Conclusions: Pembro 2 mg/kg plus 4 doses of ipi 1 mg/kg has a manageable toxicity profile and provides robust, durable antitumor activity in pts with advanced melanoma. Clinical trial information: NCT02089685.