Pembrolizumab and Enzalutamide in Patients with Abiraterone Acetate-Pretreated Metastatic Castration-Resistant Prostate Cancer: Cohort C of the Phase 1b/2 KEYNOTE-365 Study

BACKGROUND

Limited responses have been observed in patients treated with enzalutamide after disease progression on abiraterone for metastatic castration-resistant prostate cancer (mCRPC), but androgen receptor signaling impacts T-cell function.

OBJECTIVE

To evaluate the efficacy and safety of pembrolizumab plus enzalutamide in mCRPC.

DESIGN, SETTING, AND PARTICIPANTS

Patients in cohort C of the phase 1b/2 KEYNOTE-365 study, who received ≥4 wk of treatment with abiraterone acetate in the prechemotherapy mCRPC state and experienced treatment failure or became drug-intolerant, were included.

INTERVENTION

Pembrolizumab 200 mg intravenously every 3 wk plus enzalutamide 160 mg orally once daily.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoints were safety, the confirmed prostate-specific antigen (PSA) response rate, and the objective response rate (ORR) according to Response Evaluation Criteria in Solid Tumors version 1.1 on blinded independent central review (BICR). Secondary endpoints included radiographic progression-free survival (rPFS) on BICR and overall survival (OS).

RESULTS AND LIMITATIONS

A total of 102 patients received pembrolizumab plus enzalutamide. Median follow-up was 51 mo (interquartile range 37-56). The confirmed PSA response rate was 24% (95% confidence interval [CI] 16-33%). The confirmed ORR was 11% (95% CI 2.9-25%; 4/38 patients; two complete responses). Median rPFS was 6.0 mo (95% CI 4.1-6.3). Median OS was 20 mo (95% CI 17-24). Treatment-related adverse events (TRAEs) occurred in 94 patients (92%); grade 3-5 TRAEs occurred in 44 patients (43%). The incidence of treatment-related rash was higher with combination therapy than expected from the safety profile of each drug. One patient (1.0%) died of a TRAE (cause unknown). Study limitations include the single-arm design.

CONCLUSIONS

Pembrolizumab plus enzalutamide had limited antitumor activity in patients who received prior abiraterone treatment without previous chemotherapy for mCRPC, with a safety profile consistent with the individual profiles of each agent.

PATIENT SUMMARY

Pembrolizumab plus enzalutamide showed limited antitumor activity and manageable safety in patients with metastatic castration-resistant prostate cancer. The KEYNOTE-365 trial is registered on ClinicalTrials.gov as NCT02861573.

A Signal-finding Study of Abemaciclib in Heavily Pretreated Patients with Metastatic Castration-Resistant Prostate Cancer: Results from CYCLONE 1

BACKGROUND

Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors radically changed the treatment paradigm for breast cancer. Similar to estrogen receptor in breast cancer, androgen receptor signaling activates cyclin D-CDK4/6, driving proliferation and resistance to hormonal manipulation in prostate cancer. This study was designed to detect signals of clinical activity for abemaciclib in treatment-refractory metastatic castration-resistant prostate cancer (mCRPC).

METHODS

Eligible patients had progressive mCRPC, measurable disease, and previously received ≥1 novel hormonal agent(s) and 2 lines of taxane chemotherapy. Abemaciclib 200 mg BID was administered on a continuous dosing schedule. Primary endpoint was objective response rate (ORR) without concurrent bone progression. This study was designed to detect a minimum ORR of 12.5%.

RESULTS

At trial entry, forty (90.9%) of 44 patients had objective radiographic disease progression, four (9.1%) had prostate-specific antigen (PSA)-only progression, and 20 (46.5%) had visceral metastases (of these, 60% had liver metastases). Efficacy analyses are as follows: ORR without concurrent bone progression: 6.8%; disease control rate: 45.5%; median time to PSA progression: 6.5 months (95% CI: 3.2, NA); median radiographic PFS; 2.7 months (95% CI: 1.9, 3.7); and median OS: 8.4 months (95% CI: 5.6, 12.7). Most frequent grade ≥3 TEAEs were neutropenia (25.0%), anemia, and fatigue (11.4% each). No grade 4 or 5 AEs were related to abemaciclib.

CONCLUSION

Abemaciclib monotherapy was well tolerated and showed clinical activity in this heavily pretreated population, nearly half with visceral metastases. This study is considered preliminary proof-of-concept and designates CDK4/6 as a valid therapeutic target in prostate cancer.

Overall survival from tebentafusp versus nivolumab plus ipilimumab in first-line metastatic uveal melanoma: a propensity score-weighted analysis

BACKGROUND

Tebentafusp demonstrated a superior overall survival (OS) benefit [hazard ratio (HR) 0.51] compared to investigator's choice (82% pembrolizumab) in a randomized, phase III trial (IMCgp100-202; N = 378) in untreated metastatic uveal melanoma (mUM). The 1-year OS rates for tebentafusp and pembrolizumab were 73% and 59%, respectively. In the single-arm GEM1402 (N = 52), the 1-year OS rate for nivolumab plus ipilimumab (N+I) in mUM was 52%. Due to limitations in conducting randomized trials in mUM, we compared OS on tebentafusp or pembrolizumab (IMCgp100-202) to N+I (GEM1402) in untreated mUM using propensity scoring methods.

PATIENTS AND METHODS

Analyses were adjusted using propensity score-based inverse probability of treatment weighting (IPTW), balancing age, sex, baseline lactate dehydrogenase (LDH), baseline alkaline phosphatase, disease location, Eastern Cooperative Oncology Group status, and time from primary diagnosis to metastasis. OS was assessed using IPT-weighted Kaplan-Meier and Cox proportional hazard models. Sensitivity analyses using alternative missing data and weights methods were conducted.

RESULTS

The primary IPTW analysis included 240 of 252 patients randomized to tebentafusp from IMCgp100-202 and 45 of 52 N+I-treated patients from GEM-1402. Key baseline covariates, including LDH, were generally well balanced before weighting. The IPTW-adjusted OS favored tebentafusp, HR 0.52 [95% confidence interval (CI) 0.35-0.78]; 1-year OS was 73% for tebentafusp versus 50% for N+I. Sensitivity analyses showed consistent superior OS for tebentafusp with all IPTW HRs ≤0.61. IPTW analysis of pembrolizumab versus N+I showed no significant difference in OS (HR 0.72; 95% CI 0.50-1.06).

CONCLUSIONS

Tebentafusp was previously shown to provide an OS benefit compared to checkpoint inhibitors or chemotherapy in untreated mUM. Propensity score analysis demonstrated a similar OS benefit for tebentafusp compared with N+I. These data further support tebentafusp as the standard of care in previously untreated human leukocyte antigen (HLA)-A∗02:01+ adult patients with mUM.

1,4-dihydroxy quininib activates ferroptosis pathways in metastatic uveal melanoma and reveals a novel prognostic biomarker signature

Uveal melanoma (UM) is an ocular cancer, with propensity for lethal liver metastases. When metastatic UM (MUM) occurs, as few as 8% of patients survive beyond two years. Efficacious treatments for MUM are urgently needed. 1,4-dihydroxy quininib, a cysteinyl leukotriene receptor 1 (CysLT1) antagonist, alters UM cancer hallmarks in vitro, ex vivo and in vivo. Here, we investigated the 1,4-dihydroxy quininib mechanism of action and its translational potential in MUM. Proteomic profiling of OMM2.5 cells identified proteins differentially expressed after 1,4-dihydroxy quininib treatment. Glutathione peroxidase 4 (GPX4), glutamate-cysteine ligase modifier subunit (GCLM), heme oxygenase 1 (HO-1) and 4 hydroxynonenal (4-HNE) expression were assessed by immunoblots. Biliverdin, glutathione and lipid hydroperoxide were measured biochemically. Association between the expression of a specific ferroptosis signature and UM patient survival was performed using public databases. Our data revealed that 1,4-dihydroxy quininib modulates the expression of ferroptosis markers in OMM2.5 cells. Biochemical assays validated that GPX4, biliverdin, GCLM, glutathione and lipid hydroperoxide were significantly altered. HO-1 and 4-HNE levels were significantly increased in MUM tumor explants from orthotopic patient-derived xenografts (OPDX). Expression of genes inhibiting ferroptosis is significantly increased in UM patients with chromosome 3 monosomy. We identified IFerr, a novel ferroptosis signature correlating with UM patient survival. Altogether, we demontrated that in MUM cells and tissues, 1,4-dihydroxy quininib modulates key markers that induce ferroptosis, a relatively new type of cell death driven by iron-dependent peroxidation of phospholipids. Furthermore, we showed that high expression of specific genes inhibiting ferroptosis is associated with a worse UM prognosis, thus, the IFerr signature is a potential prognosticator for which patients develop MUM. All in all, ferroptosis has potential as a clinical biomarker and therapeutic target for MUM.

Three-Year Overall Survival with Tebentafusp in Metastatic Uveal Melanoma

BACKGROUND

Tebentafusp, a T-cell receptor-bispecific molecule that targets glycoprotein 100 and CD3, is approved for adult patients who are positive for HLA-A*02:01 and have unresectable or metastatic uveal melanoma. The primary analysis in the present phase 3 trial supported a long-term survival benefit associated with the drug.

METHODS

We report the 3-year efficacy and safety results from our open-label, phase 3 trial in which HLA-A*02:01-positive patients with previously untreated metastatic uveal melanoma were randomly assigned in a 2:1 ratio to receive tebentafusp (tebentafusp group) or the investigator's choice of therapy with pembrolizumab, ipilimumab, or dacarbazine (control group), with randomization stratified according to the lactate dehydrogenase level. The primary end point was overall survival.

RESULTS

At a minimum follow-up of 36 months, median overall survival was 21.6 months in the tebentafusp group and 16.9 months in the control group (hazard ratio for death, 0.68; 95% confidence interval, 0.54 to 0.87). The estimated percentage of patients surviving at 3 years was 27% in the tebentafusp group and 18% in the control group. The most common treatment-related adverse events of any grade in the tebentafusp group were rash (83%), pyrexia (76%), pruritus (70%), and hypotension (38%). Most tebentafusp-related adverse events occurred early during treatment, and no new adverse events were observed with long-term administration. The percentage of patients who discontinued treatment because of adverse events continued to be low in both treatment groups (2% in the tebentafusp group and 5% in the control group). No treatment-related deaths occurred.

CONCLUSIONS

This 3-year analysis supported a continued long-term benefit of tebentafusp for overall survival among adult HLA-A*02:01-positive patients with previously untreated metastatic uveal melanoma. (Funded by Immunocore; IMCgp100-202 ClinicalTrials.gov number, NCT03070392; EudraCT number, 2015-003153-18.).

Detection of the Uveal Melanoma-Associated Mutation GNAQ Q209P from Liquid Biopsy Using CRISPR/Cas12a Technology

Uveal melanoma (UM) is a rare ocular tumor characterized by high metastasis risk and poor prognosis. The in-depth characterization of UM's molecular profile is critical for better disease classification and prognosis. Furthermore, the development of detection tools to monitor UM evolution upon treatment is of great interest for designing optimal therapeutic strategies. However, commonly used techniques, such as ddPCR or NGS, are costly, and they involve sophisticated equipment and complex experimental design. The development of alternative sensing methods that are fast, simple, and inexpensive would be of great benefit to improve UM's diagnosis and management, especially when combined with liquid biopsy. Samples from liquid biopsy can be obtained with minimal invasiveness, and the detection of circulating tumor DNA (ctDNA) in UM patients' plasma has proven useful for the diagnosis of metastasis, prognosis prediction, and disease monitoring. In this context, CRISPR/Cas12a-derived molecular sensors, thanks to their high specificity and sensitivity and their potential for point of care diagnosis, are particularly interesting. Here, we developed a CRISPR/Cas12a-based approach for the specific detection of the UM-related mutation GNAQ Q209P that relies on the design of highly specific crRNAs. Coupled with allele-specific PCR, it constitutes a sensitive platform for liquid biopsy detection, capable of sensing GNAQ Q209P in plasma samples with a low ctDNA concentration and fractional abundance. Finally, our method was validated using plasma samples from metastatic UM patients.

MBD4-associated neoplasia syndrome: screening of cases with suggestive phenotypes

Germline mutations in MBD4, which, like MUTYH and NTHL1, encodes a glycosylase of the DNA based excision repair system, cause an autosomal recessive syndrome characterised by increased risk of acute myeloid leukaemia, gastrointestinal polyposis, colorectal cancer (CRC) and, to a lesser extent, uveal melanoma and schwannomas. To better define the phenotypic spectrum and tumour molecular features associated with biallelic MBD4-associated cancer predisposition, and study if heterozygous variants are associated with gastrointestinal tumour predisposition, we evaluated germline MBD4 status in 728 patients with CRC, polyposis, and other suggestive phenotypes (TCGA and in-house cohorts). Eight CRC patients carried rare homozygous or heterozygous germline variants in MBD4. The information gathered on mode of inheritance, variant nature, functional effect of the variant, and tumour mutational characteristics suggested that none of the patients included in the study had an MBD4-associated hereditary syndrome and that the heterozygous variants identified were not associated with the disease.

Rucaparib for the Treatment of Metastatic Castration-resistant Prostate Cancer Associated with a DNA Damage Repair Gene Alteration: Final Results from the Phase 2 TRITON2 Study

BACKGROUND

Initial TRITON2 (NCT02952534) results demonstrated the efficacy of rucaparib 600 mg BID in patients with metastatic castration-resistant prostate cancer (mCRPC) associated with a BRCA1 or BRCA2 (BRCA) or other DNA damage repair (DDR) gene alteration.

OBJECTIVE

To present the final data from TRITON2.

DESIGN, SETTING, AND PARTICIPANTS

TRITON2 enrolled patients with mCRPC who had progressed on one or two lines of next-generation androgen receptor-directed therapy and one taxane-based chemotherapy.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoint was objective response rate (ORR; as per the modified Response Evaluation Criteria in Solid Tumor Version 1.1/Prostate Cancer Clinical Trials Working Group 3 criteria in patients with measurable disease by independent radiology review [IRR]); prostate-specific antigen (PSA) response rate (≥50% decrease from baseline [PSA50]) was a key secondary endpoint.

RESULTS AND LIMITATIONS

As of July 27, 2021 (study closure), TRITON2 had enrolled 277 patients, grouped by mutated gene: BRCA (n = 172), ATM (n = 59), CDK12 (n = 15), CHEK2 (n = 7), PALB2 (n = 11), or other DDR gene (Other; n = 13). ORR by IRR was 46% (37/81) in the BRCA subgroup (95% confidence interval [CI], 35-57%), 100% (4/4) in the PALB2 subgroup (95% CI, 40-100%), and 25% (3/12) in the Other subgroup (95% CI, 5.5-57%). No patients within the ATM, CDK12, or CHEK2 subgroups had an objective response by IRR. PSA50 response rates (95% CI) in the BRCA, PALB2, ATM, CDK12, CHEK2, and Other subgroups were 53% (46-61%), 55% (23-83%), 3.4% (0.4-12), 6.7% (0.2-32%), 14% (0.4-58%), and 23% (5.0-54%), respectively.

CONCLUSIONS

The final TRITON2 results confirm the clinical benefit and manageable safety profile of rucaparib in patients with mCRPC, including those with an alteration in BRCA or select non-BRCA DDR gene.

PATIENT SUMMARY

Almost half of TRITON2 patients with BRCA-mutated metastatic castration-resistant prostate cancer had a complete or partial tumor size reduction with rucaparib; clinical benefits were also observed with other DNA damage repair gene alterations.

SWI/SNF Complex Alterations in Tumors with Rhabdoid Features: Novel Therapeutic Approaches and Opportunities for Adoptive Cell Therapy

The SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin-remodeling complex is one of the most remarkably altered epigenetic regulators in cancer. Pathogenic mutations in genes encoding SWI/SNF-related proteins have been recently described in many solid tumors, including rare and aggressive malignancies with rhabdoid features with no standard therapies in advanced or metastatic settings. In recent years, clinical trials with targeted drugs aimed at restoring its function have shown discouraging results. However, preclinical data have found an association between these epigenetic alterations and response to immune therapy. Thus, the rationale for immunotherapy strategies in SWI/SNF complex alteration-related tumors is strong. Here, we review the SWI/SNF complex and how its dysfunction drives the oncogenesis of rhabdoid tumors and the proposed strategies to revert this alteration and promising novel therapeutic approaches, including immune checkpoint inhibition and adoptive cell therapy.

Differences in glucose metabolic activity in liver metastasis separates two groups of metastatic uveal melanoma patients with different prognosis

BACKGROUND

Uveal melanoma metastasizes to the liver. We aimed to explore the metabolic activity of liver metastases (LM) as a biomarker for survival.

METHODS

We analyzed newly diagnosed patients with metastatic UM (MUM) with LM detected by liver-directed imaging and had undergone a PET/CT at diagnosis.

FINDINGS

51 patients were identified between 2004 and 2019. Median age was 62 years, 41% male and 22% ECOG ≥1. LDH, ALP, and GGT were elevated in 49%, 37%, and 57% of patients. Median LM SUVmax was 8.5 (3-42.2). Same size lesions presented a wide range of metabolic activity. Median OS was 17.3 m (95% CI:10.6-23.9). Patients with SUVmax ≥8.5 had an OS of 9.4 m (95% CI:6.4-12.3), whereas patients with SUVmax <8.5 had an OS of 38.4 m (95% CI:21.4-55.5; p < 0.0001, HR = 2.9). We observed similar results when studying M1a disease separately. Multivariate analysis showed SUVmax as an independent prognostic factor for the whole population and those with M1a disease.

INTERPRETATION

Increased metabolic activity of LM seems to be an independent predictor of survival. MUM is a heterogeneous disease and metabolic activity probably reflects a different intrinsic behavior.

A hotspot for posttranslational modifications on the androgen receptor dimer interface drives pathology and anti-androgen resistance

Mutations of the androgen receptor (AR) associated with prostate cancer and androgen insensitivity syndrome may profoundly influence its structure, protein interaction network, and binding to chromatin, resulting in altered transcription signatures and drug responses. Current structural information fails to explain the effect of pathological mutations on AR structure-function relationship. Here, we have thoroughly studied the effects of selected mutations that span the complete dimer interface of AR ligand-binding domain (AR-LBD) using x-ray crystallography in combination with in vitro, in silico, and cell-based assays. We show that these variants alter AR-dependent transcription and responses to anti-androgens by inducing a previously undescribed allosteric switch in the AR-LBD that increases exposure of a major methylation target, Arg⁷⁶¹. We also corroborate the relevance of residues Arg⁷⁶¹ and Tyr⁷⁶⁴ for AR dimerization and function. Together, our results reveal allosteric coupling of AR dimerization and posttranslational modifications as a disease mechanism with implications for precision medicine.

Rucaparib or Physician's Choice in Metastatic Prostate Cancer

BACKGROUND

In a phase 2 study, rucaparib, an inhibitor of poly(ADP-ribose) polymerase (PARP), showed a high level of activity in patients who had metastatic, castration-resistant prostate cancer associated with a deleterious BRCA alteration. Data are needed to confirm and expand on the findings of the phase 2 study.

METHODS

In this randomized, controlled, phase 3 trial, we enrolled patients who had metastatic, castration-resistant prostate cancer with a BRCA1, BRCA2, or ATM alteration and who had disease progression after treatment with a second-generation androgen-receptor pathway inhibitor (ARPI). We randomly assigned the patients in a 2:1 ratio to receive oral rucaparib (600 mg twice daily) or a physician's choice control (docetaxel or a second-generation ARPI [abiraterone acetate or enzalutamide]). The primary outcome was the median duration of imaging-based progression-free survival according to independent review.

RESULTS

Of the 4855 patients who had undergone prescreening or screening, 270 were assigned to receive rucaparib and 135 to receive a control medication (intention-to-treat population); in the two groups, 201 patients and 101 patients, respectively, had a BRCA alteration. At 62 months, the duration of imaging-based progression-free survival was significantly longer in the rucaparib group than in the control group, both in the BRCA subgroup (median, 11.2 months and 6.4 months, respectively; hazard ratio, 0.50; 95% confidence interval [CI], 0.36 to 0.69) and in the intention-to-treat group (median, 10.2 months and 6.4 months, respectively; hazard ratio, 0.61; 95% CI, 0.47 to 0.80; P<0.001 for both comparisons). In an exploratory analysis in the ATM subgroup, the median duration of imaging-based progression-free survival was 8.1 months in the rucaparib group and 6.8 months in the control group (hazard ratio, 0.95; 95% CI, 0.59 to 1.52). The most frequent adverse events with rucaparib were fatigue and nausea.

CONCLUSIONS

The duration of imaging-based progression-free survival was significantly longer with rucaparib than with a control medication among patients who had metastatic, castration-resistant prostate cancer with a BRCA alteration. (Funded by Clovis Oncology; TRITON3 ClinicalTrials.gov number, NCT02975934.).

Phase 2 study (AARDVARC) of AZD4635 in combination with durvalumab and cabazitaxel in patients (pts) with progressive metastatic castrate-resistant prostate cancer (mCRPC)

173

Background: Pts with mCRPC who progress on docetaxel and new hormonal agents (NHAs) have few therapeutic options. In the CARD study of cabazitaxel, 35.7% of pts had PSA responses and 36.5% of pts had tumor responses. While immune checkpoint inhibitors have limited single-agent activity in mCRPC, the combination of the adenosine 2A receptor antagonist, AZD4635, with durvalumab may improve response to chemotherapy. This study assessed AZD4635 in combination with durvalumab (Arm A) or with durvalumab + cabazitaxel (Arm B) in pts with mCRPC. We report interim analysis results from Arm B (Arm A to be reported elsewhere). Methods: Eligible pts had histologically confirmed mCRPC, disease progression ≤6 months prior to enrollment, and were previously treated with docetaxel and 1 NHA. Pts received AZD4635 75 mg PO QD + durvalumab 1500 mg IV Q3W + cabazitaxel Q3W (dosed per locally approved label) for up to 10 cycles. The primary endpoint was radiographic progression-free survival (rPFS), by RECIST v1.1 (soft tissue) or PCWG3 (bone). Secondary endpoints included safety, pharmacokinetics, confirmed PSA50 response, and objective response rate by RECIST v1.1. A futility analysis was planned based on PSA50 responses (confirmed + unconfirmed) after approximately 30 pts were treated. Results: As of August 10, 2021, 28 pts received AZD4635 + durvalumab + cabazitaxel, and 21 pts were still on treatment. Most common adverse events (AEs) possibly related to treatment were nausea (50.0%), diarrhea (46.4%), asthenia, and vomiting (each 28.6%). Treatment-related febrile neutropenia occurred in 7.1% pts. Twelve (42.9%) pts had a serious AE possibly related to treatment. One AE possibly related to treatment led to death (myositis). Exposures of cabazitaxel and/or durvalumab did not change when combined with AZD4635. Median rPFS was 4.4 months (95% CI: 4.2–not calculable) with low percent maturity. Of 28 PSA-evaluable pts, 8 (28.6%) had PSA50 responses (4 confirmed). There were 5 unconfirmed partial responses by RECIST v1.1. Conclusions: Although efficacy data are immature, enrollment was stopped for futility. Safety of the combination was consistent with the known safety profiles of the individual agents. Clinical trial information: NCT04089553 .

Rucaparib for metastatic castration-resistant prostate cancer (mCRPC): TRITON3 interim overall survival and efficacy of rucaparib vs docetaxel or second-generation androgen pathway inhibitor therapy

18

Background: TRITON3 (NCT02975934) is a randomized, multicenter, open-label, phase 3 study of rucaparib vs physician’s choice (docetaxel [DTX], abiraterone [ABI] or enzalutamide [ENZ]) in patients (pts) with chemotherapy-naïve mCRPC with BRCA1/2 (BRCA) or ATM alterations. It was previously reported that rucaparib significantly improved the primary endpoint of radiographic progression-free survival (rPFS) vs physician’s choice in pts with BRCA or ATM alterations. We report here the interim overall survival (OS) and also report on efficacy of rucaparib compared individually with either DTX or ABI/ENZ. Methods: Pts had disease progression after 1 prior second-generation androgen pathway inhibitor therapy in any setting and were randomized 2:1 to rucaparib 600 mg BID or physician’s choice of DTX, ABI or ENZ. An ordered step-down multiple comparisons procedure was used to control the overall error rate. OS was a key secondary endpoint with rPFS as the primary endpoint tested first in the BRCA subgroup, then the intent-to-treat (ITT) population. Subgroup analyses based on physician’s choice were exploratory. Results: As of August 25, 2022, 302 pts with BRCA and 103 pts with ATM alterations were randomized. OS maturity was 54% in the BRCA subgroup and 59% in the ITT population. rPFS and OS are shown. The most frequent treatment-emergent adverse event (TEAE) in the rucaparib, DTX and ABI/ENZ groups was asthenia/fatigue (61.1%, 67.6% and 57.6%, respectively). The most frequent grade ≥3 TEAE in the rucaparib, DTX and ABI/ENZ groups was anemia (23.7%), neutropenia (14.1%), and hypertension (10.2%), respectively. Conclusions: Rucaparib significantly improved rPFS vs either DTX or ABI/ENZ; safety was consistent with prior reports. Interim OS results suggest a trend towards improvement for rucaparib vs DTX or ABI/ENZ in pts with mCRPC and BRCA alterations. Clinical trial information: NCT02975934 . [Table: see text]

CYCLONE 3: A phase 3, randomized, double-blind, placebo-controlled study of abemaciclib in combination with abiraterone plus prednisone in men with high-risk, metastatic, hormone-sensitive prostate cancer (mHSPC)

TPS289

Background: Landmark trials have established a survival benefit for novel hormonal agents (NHA) added to androgen deprivation therapy (ADT) for mHSPC. Yet, there is a significant medical need to expand therapeutic options, especially for pts with high-risk mHSPC who experience poorer outcomes. Abemaciclib is an oral selective inhibitor of cyclin-dependent kinase 4 and 6 (CDK4 & 6) dosed on a continuous schedule, approved for the treatment of node-positive high-risk early-stage and advanced or metastatic HR+, HER2- breast cancer. Analogous to the estrogen receptor signaling pathway in breast cancer, there is evidence that the androgen receptor axis activates CDK4 & 6 to sustain prostate cancer cell proliferation, and upregulation of cyclin D1 is a potential mechanism of resistance to NHA therapy. In preclinical models, abemaciclib induces cell cycle arrest and inhibition of prostate tumor growth. Methods: CYCLONE 3 (NCT05288166) is a global, randomized, double-blind, placebo-controlled study evaluating the addition of abemaciclib to abiraterone+prednisone (AP) in pts with high-risk mHSPC. Approximately 900 pts with high-risk mHSPC defined by ≥4 bone metastasis and/or visceral disease will be randomised in a 1:1 ratio to the AP + abemaciclib or AP + placebo arm. Up to 3 months of ADT prior to randomization is permitted; prior D for mHSPC will be excluded per planned protocol amendment. Pts who have not undergone orchiectomy will continue ADT. Stratification factors are de novo mHSPC and visceral metastases. Primary endpoint is investigator-assessed radiographic progression-free survival (rPFS). Key secondary endpoints include rPFS assessed by blinded independent central review, castration-resistant prostate cancer-free survival, overall survival, time to pain progression, safety and pharmacokinetics. Enrollment is open at approximately 270 sites across 25 countries. Clinical trial information: NCT05288166 .

Orthotopic murine xenograft model of uveal melanoma with spontaneous liver metastasis

Uveal melanoma is the most common intraocular malignancy in adults. Despite the effective primary treatment, up to 50% of patients with uveal melanoma will develop metastatic lesions mainly in the liver, which are resistant to conventional chemotherapy and lead to patient's death. To date, no orthotopic murine models of uveal melanoma which can develop spontaneous metastasis are available for preclinical studies. Here, we describe a spontaneous metastatic model of uveal melanoma based on the orthotopic injection of human uveal melanoma cells into the suprachoroidal space of immunodeficient NSG mice. All mice injected with bioluminescent OMM2.5 ( n  = 23) or MP41 ( n  = 19) cells developed a primary tumor. After eye enucleation, additional bioluminescence signals were detected in the lungs and in the liver. At necropsy, histopathological studies confirmed the presence of lung metastases in 100% of the mice. Liver metastases were assessed in 87 and in 100% of the mice that received OMM2.5 or MP41 cells, respectively. All tumors and metastatic lesions expressed melanoma markers and the signaling molecules insulin-like growth factor type I receptor and myristoylated alanine-rich C-kinase substrate, commonly activated in uveal melanoma. The novelty of this orthotopic mouse xenograft model is the development of spontaneous metastases in the liver from the primary site, reproducing the organoespecificity of metastasis observed in uveal melanoma patients. The faster growth and the high metastatic incidence may be attributed at least in part, to the severe immunodeficiency of NSG mice. This model may be useful for preclinical testing of targeted therapies with potential uveal melanoma antimetastatic activity and to study the mechanisms involved in liver metastasis.

1,4-dihydroxy quininib modulates the secretome of uveal melanoma tumour explants and a marker of oxidative phosphorylation in a metastatic xenograft model

Uveal melanoma (UM) is an intraocular cancer with propensity for liver metastases. The median overall survival (OS) for metastatic UM (MUM) is 1.07 years, with a reported range of 0.84-1.34. In primary UM, high cysteinyl leukotriene receptor 1 (CysLT₁) expression associates with poor outcomes. CysLT₁ antagonists, quininib and 1,4-dihydroxy quininib, alter cancer hallmarks of primary and metastatic UM cell lines in vitro. Here, the clinical relevance of CysLT receptors and therapeutic potential of quininib analogs is elaborated in UM using preclinical in vivo orthotopic xenograft models and ex vivo patient samples. Immunohistochemical staining of an independent cohort (n = 64) of primary UM patients confirmed high CysLT₁ expression significantly associates with death from metastatic disease (p = 0.02; HR 2.28; 95% CI 1.08-4.78), solidifying the disease relevance of CysLT₁ in UM. In primary UM samples (n = 11) cultured as ex vivo explants, 1,4-dihydroxy quininib significantly alters the secretion of IL-13, IL-2, and TNF-α. In an orthotopic, cell line-derived xenograft model of MUM, 1,4-dihydroxy quininib administered intraperitoneally at 25 mg/kg significantly decreases ATP5B expression (p = 0.03), a marker of oxidative phosphorylation. In UM, high ATP5F1B is a poor prognostic indicator, whereas low ATP5F1B, in combination with disomy 3, correlates with an absence of metastatic disease in the TCGA-UM dataset. These preclinical data highlight the diagnostic potential of CysLT₁ and ATP5F1B in UM, and the therapeutic potential of 1,4-dihydroxy quininib with ATP5F1B as a companion diagnostic to treat MUM.

Facts and Hopes in Immunotherapy of Endometrial Cancer

Immunotherapy with checkpoint inhibitors has changed the paradigm of treatment for many tumors, and endometrial carcinoma is not an exception. Approved treatment options are pembrolizumab or dostarlimab for mismatch repair deficient tumors, pembrolizumab for tumors with high mutational load, and, more recently, pembrolizumab/lenvatinib for all patients with endometrial cancer. Endometrial cancer is a heterogeneous disease with distinct molecular subtypes and different prognoses. Differences between molecular subgroups regarding antigenicity and immunogenicity should be relevant to develop more tailored immunotherapeutic approaches. In this review, we aim to summarize and discuss the current evidence-Facts, and future opportunities-Hopes-of immunotherapy for endometrial cancer, focusing on relevant molecular and tumor microenvironment features of The Cancer Genome Atlas endometrial cancer subtypes.

Generation and Integrated Analysis of Advanced Patient-Derived Orthoxenograft Models (PDOX) for the Rational Assessment of Targeted Therapies in Endometrial Cancer

Clinical management of endometrial cancer (EC) is handicapped by the limited availability of second line treatments and bona fide molecular biomarkers to predict recurrence. These limitations have hampered the treatment of these patients, whose survival rates have not improved over the last four decades. The advent of coordinated studies such as The Cancer Genome Atlas Uterine Corpus Endometrial Carcinoma (TCGA_UCEC) has partially solved this issue, but the lack of proper experimental systems still represents a bottleneck that precludes translational studies from successful clinical testing in EC patients. Within this context, the first study reporting the generation of a collection of endometrioid-EC-patient-derived orthoxenograft (PDOX) mouse models is presented that is believed to overcome these experimental constraints and pave the way toward state-of-the-art precision medicine in EC. The collection of primary tumors and derived PDOXs is characterized through an integrative approach based on transcriptomics, mutational profiles, and morphological analysis; and it is demonstrated that EC tumors engrafted in the mouse uterus retain the main molecular and morphological features from analogous tumor donors. Finally, the molecular properties of these tumors are harnessed to assess the therapeutic potential of trastuzumab, a human epidermal growth factor receptor 2 (HER2) inhibitor with growing interest in EC, using patient-derived organotypic multicellular tumor spheroids and in vivo experiments.

Incidence of drug-drug interactions of QT-prolonging drugs in an onco-hematological outpatient

Background

Oral anticancer therapy is increasingly integrated into the care of patients (pts) with cancer. Recognition and management of pharmacodynamic drug-drug interactions is critical to provide efficacious and safe anticancer treatment.

Purpose

We aimed to gain insight into the real-world prevalence of potentially significant drug-drug interactions of QT-prolonging with oral antineoplastic agents used in an Oncohematological Hospital

Methods

We performed a prospective observational study in an oncohematological hospital between October 2020 and June 2021. Consecutive pts diagnosed with an oncohematological neoplasia and who were evaluated before start treatment with an oral anticancer drug or suport treatment (antibiotics, antivirals) were included. Cancer treatment data were obtained from our prescription software System. Demographic data and concomitant medication were obtained from our electronic medical record software. Micromedex was used to find potencial QT-prolonging interactions between anticancer drugs and chronic medication, and were classified as major or moderate.

Results

Oncohematological treatment was started in 1.217 pts during the study period. A total of 266 potential drug-drug interactions were detected in 171 patients (14.5%). A total of 46 drug-drug interactions of QT-prolonging (17.3%) were detected in 37 pts (21.6%), 22 men and 15 women, with a median age of 66.6 (range 40.9–87.3). Twenty-one (45.7%) and 25 (56.3%) drug interactions of QT-prolonging were classified as major and moderate, respectively, with a median interaction per pts 1.24 (1–3). The 3 most common cancers were: Renal carcinoma in 12 pts (32.4%), non-small cell lung carcinoma in 9 pts (24.7%) and prostate carcinoma in 4 pts (10.8%). The most commonly detected interacting drugs were sunitinib 12 pts (26.1%), osimertinib 10 pts (21.7%), and cabozantinib 5 pts (10.9%) among oncohematological drugs, and citalopram 8 (17.4%), quetiapine 6 (13%) and tramadol 5 (10.8%) among concomitant drugs.

Conclusion

Drug-drug interactions can play a significant role in drugs' cardiac safety in oncohematological pts, specially in renal, lung and prostate cancers, with more than one potential interacting drug or at least one major interaction. Cardiac monitorizacion should be considered when potential drug drug interaction is detected.

Funding Acknowledgement

Type of funding sources: None.

Radium-223 for patients with metastatic castration-resistant prostate cancer with asymptomatic bone metastases progressing on first-line abiraterone acetate or enzalutamide: A single-arm phase II trial

PURPOSE

The paper aims to evaluate the efficacy and safety of ²²³Ra in patients who progressed after first-line androgen deprivation therapy.

PATIENTS AND METHODS

EXCAAPE (NCT03002220) was a multicentre, single-arm, open-label, non-controlled phase IIa trial in 52 patients with metastatic castration-resistant prostate cancer and asymptomatic bone metastases who have progressed on abiraterone acetate or enzalutamide, up to six doses of ²²³Ra (55 kBq/kg of body weight per month). The primary end-point was radiographic progression-free survival (rPFS). Secondary end-points included rPFS based on androgen receptor splice variant 7 (AR-V7) expression in circulating tumour cells (CTCs), overall survival, and safety.

RESULTS

Median rPFS was 5.5 months (95% CI 5.3-5.5). Median rPFS of patients with AR-V7(-) CTCs was longer than that of patients with AR-V7(+) CTCs (5.5 versus 2.2 months, respectively; P = 0.056). Median overall survival was 14.8 months (95% CI 11.2-not reached) and was significantly greater for AR-V7(-) patients than for AR-V7(+) patients (14.8 months versus 3.5 months, respectively; P < 0.01). ²²³Ra was well tolerated; anaemia and thrombocytopenia were the most common grade 3/4 adverse events (5.8% and 11.5%, respectively).

CONCLUSIONS

²²³Ra seems to be a reasonable treatment for patients with metastatic castration-resistant prostate cancer and asymptomatic bone metastases progressing on novel hormonal therapy and had an acceptable safety profile.

Pembrolizumab Plus Docetaxel and Prednisone in Patients with Metastatic Castration-resistant Prostate Cancer: Long-term Results from the Phase 1b/2 KEYNOTE-365 Cohort B Study

BACKGROUND

Patients with metastatic castration-resistant prostate cancer (mCRPC) frequently receive docetaxel after they develop resistance to abiraterone or enzalutamide and need more efficacious treatments.

OBJECTIVE

To evaluate the efficacy and safety of pembrolizumab plus docetaxel and prednisone in patients with mCRPC.

DESIGN, SETTING, AND PARTICIPANTS

The trial included patients with mCRPC in the phase 1b/2 KEYNOTE-365 cohort B study who were chemotherapy naïve and who experienced failure of or were intolerant to ≥4 wk of abiraterone or enzalutamide for mCRPC with progressive disease within 6 mo of screening.

INTERVENTION

Pembrolizumab 200 mg intravenously (IV) every 3 wk (Q3W), docetaxel 75 mg/m² IV Q3W, and prednisone 5 mg orally twice daily.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoints were safety, the prostate-specific antigen (PSA) response rate, and the objective response rate (ORR) according to Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) by blinded independent central review (BICR). Secondary endpoints included time to PSA progression; the disease control rate (DCR) and duration of response (DOR) according to RECIST v1.1 by BICR; ORR, DCR, DOR, and radiographic progression-free survival (rPFS) according to Prostate Cancer Working Group 3-modified RECIST v1.1 by BICR; and overall survival (OS).

RESULTS AND LIMITATIONS

Among 104 treated patients, 52 had measurable disease. The median time from allocation to data cutoff (July 9, 2020) was 32.4 mo, during which 101 patients discontinued treatment, 81 (78%) for disease progression. The confirmed PSA response rate was 34% and the confirmed ORR (RECIST v1.1) was 23%. Median rPFS and OS were 8.5 mo and 20.2 mo, respectively. Treatment-related adverse events (TRAEs) occurred in 100 patients (96%). Grade 3-5 TRAEs occurred in 46 patients (44%). Seven AE-related deaths (6.7%) occurred (2 due to treatment-related pneumonitis). Limitations of the study include the single-arm design and small sample size.

CONCLUSIONS

Pembrolizumab plus docetaxel and prednisone demonstrated antitumor activity in chemotherapy-naïve patients with mCRPC treated with abiraterone or enzalutamide for mCRPC. Safety was consistent with profiles for the individual agents. Further investigation is warranted.

PATIENT SUMMARY

We evaluated the efficacy and safety of the anti-PD-1 antibody pembrolizumab combined with the chemotherapy drug docetaxel and the steroid prednisone for patients with metastatic prostate cancer resistant to androgen deprivation therapy , and who never received chemotherapy. The combination showed antitumor activity and manageable safety in this patient population. This trial is registered on ClinicalTrials.gov as NCT02861573.

Overall survival (OS) in metastatic uveal melanoma: A summary of recent prospective trials

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Background: Metastatic uveal melanoma (mUM) historically has a poor prognosis where chemotherapy and checkpoint blockade, including combination, has had no impact on OS. Tebentafusp (tebe), a TCR bispecific (gp100 x CD3), is the first therapy to demonstrate an OS benefit in a mUM randomized trial (IMCgp100-202) against pembrolizumab (pembro), ipilimumab (ipi) or dacarbazine. Here we present a summary of OS from recent prospective trials in mUM in both previously untreated (1L) and previously treated (2L+) mUM including cross trial comparison with checkpoint blockade combination. Methods: A literature review of prospective Ph2/3 clinical trials of systemic therapies in mUM published recently (2019-2021) identified 8 trials: in 1L mUM (n = 2) a randomized Ph3 of tebe (N = 252) vs investigator’s choice (IC; N = 126) of pembro, ipi or dacarbazine (IMCgp100-202) and a single arm Ph2 of nivolumab (nivo) + ipi (N = 52; Piulats, 2021) (Table); in 2L+ mUM (n = 1) a single arm Ph2 of tebe (N = 127; IMCgp100-102); and in mixed line mUM (n = 5) a randomized Ph2 of cabozantinib (N = 31) vs chemotherapy (N = 15; Luke, 2019), a single arm Ph2 of nivo + ipi (N = 35; Pelster, 2021), a single arm Ph2 of pembro + entinostat (N = 29; Ny, 2021), a single arm Ph2 of glembatumumab (N = 37; Hasanov, 2020), and a single arm Ph2 of IMC-A12 (IGF-1 receptor inhibitor; N = 18; Mattei, 2020). The PUMMA (Khoja, 2019; N = 912) and Rantala, 2019 (N = 2494; n = 510 1L pts) meta-analyses were included to provide historical benchmarks for OS. Results: In previously untreated mUM, 1-yr and median OS were 73% and 21.7 months for tebe, 59% and 15.7 months for pembro, 52% and 12.7 months for nivo + ipi and 45% and 11.3 months for conventional chemotherapy. In previously treated mUM, 1-yr and median OS were 61% and 16.8 months for tebe, 34% and 7.0 months for checkpoint inhibitors, and 43% and 10.5 months for conventional chemotherapy. In mixed line (1L+) mUM, 1-yr and median OS were 56% and 19.1 months for nivo + ipi and 59% and 13.4 months for pembro + entinostat, 13.8 months for IMC-A12, 11.9 months for glembatumumab and 6.4 months for cabozantinib. Related AEs (any grade) leading to discontinuation and death for tebe were 2% and 0% vs 5% and 0% for IC control, and 23% and 3.8% for nivo + ipi in 1L pts. Conclusions: Tebe is the only therapy demonstrated to prolong OS in mUM. The 1-yr OS for tebe in 1L and 2L+ is superior to all recent published studies, including nivo + ipi. Both tebe and checkpoint combination therapy have high rate of any grade AEs, although checkpoint combination has a higher rate of treatment related discontinuations and deaths.[Table: see text]

CYCLONE 2: A phase 2/3, randomized, placebo-controlled study of abiraterone acetate plus prednisone with or without abemaciclib in patients with metastatic castration-resistant prostate cancer

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Background: Despite recent advances, nearly all patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) experience disease progression and cancer-specific mortality. Persistent or reactivated androgen receptor (AR) signaling and/or activation of pathways in cross-talk with AR signaling are key drivers of mCRPC progression. Evidence suggests that AR signaling promotes translation of D-type cyclins resulting in cyclin-dependent kinase 4 and 6 (CDK4&6) activation and cell cycle progression. Abemaciclib is an oral selective inhibitor of CDK4&6 dosed on a continuous schedule, that is FDA-approved in combination with endocrine therapy or as monotherapy to treat HR+, HER2- metastatic breast cancer pts. Preclinical studies with prostate cancer cell lines and xenograft models showed that abemaciclib induces cell cycle arrest and tumor growth inhibition. The hypothesis is that addition of abemaciclib to AR targeted therapy may be an effective treatment for mCRPC pts. Methods: CYCLONE 2 (NCT03706365) is a phase 2/3, randomized, double-blind, multicenter, placebo-controlled study to assess the safety and efficacy of abemaciclib in combination with abiraterone acetate plus prednisone (AA+P) in pts with mCRPC. CYCLONE 2 is an adaptive study which is designed in three parts. Part 1 is a 30-patient safety lead-in to determine the recommended phase 2 dose (RP2D; 150 mg or 200 mg, twice daily) of abemaciclib in combination with AA (1000 mg, once daily) + P (5 mg, twice daily). In part 2, 150 pts are randomized 1:1 to AA+P with abemaciclib at the RP2D or placebo. The study expands to enroll an additional 170 pts in Part 3 if prespecified expansion criteria are met at a planned adaptive interim analysis performed by an independent data monitoring committee (IDMC). Pts with mCRPC evidenced by radiographic and/or PSA progression during continuous ADT are eligible. Prior docetaxel for mHSPC is permitted. Systemic anti-cancer therapy for mCRPC and prior novel hormonal agents are exclusionary. The primary objective is radiographic progression free survival (rPFS; per RECIST1.1 for soft tissue and PCWG3 for bone). Secondary objectives include safety, objective response rate, duration of response, time to symptomatic and PSA progression, overall survival, and pharmacokinetics. Status: Enrollment in Part 1 & 2 is completed. Based on the recommendation from the IDMC, Part 3 was opened in June 2021 and enrolls pts from about 112 sites across 12 countries. Clinical trial information: NCT03706365.

Pembrolizumab (pembro) plus abiraterone acetate (abi) and prednisone (p) in patients with chemotherapy-naive metastatic castration-resistant prostate cancer (mCRPC): Results from KEYNOTE-365 cohort D

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Background: Abi + p is a standard of care for mCRPC. Cohort D of the phase 1b/2 KEYNOTE-365 study (NCT02861573) was used to evaluate safety and efficacy of the PD-1 inhibitor pembro + abi and p in patients (pts) who had not received chemotherapy for mCRPC. Methods: Chemotherapy-naive pts who had not previously used next-generation hormonal agents (NHAs) for mCRPC or were intolerant to enzalutamide or for whom enzalutamide was ineffective for mCRPC, whose disease progressed ≤6 months before screening, and who had ECOG PS score 0/1 were eligible. Enrolled pts received pembro 200 mg IV Q3W + abi 1000 mg PO QD and p 5 mg PO BID. Primary end points were PSA response rate (PSA decrease ≥50% from baseline), confirmed ORR per RECIST v1.1 by blinded independent central review, and safety. Secondary end points included rPFS per PCWG3-modified RECIST v1.1, DCR (CR + PR + SD or non-CR/non-PD ≥6 mo), DOR, OS, time to symptomatic skeletal-related event, radiographic bone progression, and radiographic soft tissue progression. Results: Of 103 treated pts, 35.9% had RECIST-measurable disease and 26.2% had previously received enzalutamide. Median (range) time from enrollment to data cutoff was 17.6 (9.7-27.0) months. Confirmed PSA response rate in all 103 pts was 56.3%. Overall, 78.6% of pts had a reduction in PSA level from baseline (confirmed and unconfirmed). For 37 pts with RECIST-measurable disease, ORR was 16.2% (1 CR; 5 PRs) overall, 7.7% for those who previously received enzalutamide (n = 13) and 21.7% for those who had not previously received NHAs (n = 23). Two pts with RECIST-nonmeasurable disease had a CR. DOR was not reached (NR; range, 2.1+ to 19.4+ mo); 4 pts had a response ≥12 months. DCR was 44.7% overall, 11.1% in pts who previously received enzalutamide (n = 27), and 57.3% in pts who had not previously used NHAs (n = 75). Additional analyses are listed in the table. Treatment-related AEs (TRAEs) were experienced by 90.3% of pts; 36.9% experienced grade 3-5 TRAEs. Overall, 18.4% of pts had a grade 3/4 ALT laboratory elevation and 12.6% had a grade 3/4 AST elevation. Five pts died of AEs; 1 was treatment-related (myasthenic syndrome). Conclusions: Pembro + abi and p showed antitumor activity in chemotherapy-naive pts with mCRPC. Safety was generally consistent with individual profiles of each agent, although there was an increased incidence of grade 3/4 ALT/AST laboratory elevations than reported for the individual treatments. Clinical trial information: NCT02861573. [Table: see text]

Atezolizumab with enzalutamide versus enzalutamide alone in metastatic castration-resistant prostate cancer: a randomized phase 3 trial

Early clinical data indicate that some patients with castration-resistant prostate cancer may benefit from program death ligand-1 (PD-L1) inhibition, especially with enzalutamide. The IMbassador250 trial (no. NCT03016312) enrolled 759 men with metastatic castration-resistant prostate cancer whose disease progressed on abiraterone. The addition of atezolizumab to enzalutamide in an open-label randomized trial did not meet the primary endpoint of improved overall survival in unselected patients (stratified hazard ratio 1.12, 95% confidence interval (0.91, 1.37), P = 0.28), despite an acceptable safety profile. In archival tumor samples, prostate tumors showed comparatively low expression of key immune biomarkers. DNA damage-response alterations, phosphatase and tensin homolog status and PD-L1 expression levels were similar between hormone-sensitive and castration-resistant prostate cancers. In planned biomarker analysis, longer progression-free survival was seen with atezolizumab in patients with high PD-L1 IC2/3, CD8 expression and established immune gene signatures. Exploratory analysis linked progression-free survival in the atezolizumab arm with immune genes such as CXCL9 and TAP1, together with other potentially relevant biomarkers including phosphatase and tensin homolog alterations. Together these data indicate that the expected biology associated with response to immune checkpoint inhibitors is present in prostate cancer, albeit in fewer patients. Careful patient selection may be required for immune checkpoint inhibitors to identify subgroups of patients who may benefit from this treatment approach.

Clinical and molecular response to tebentafusp in previously treated patients with metastatic uveal melanoma: a phase 2 trial

In patients with previously treated metastatic uveal melanoma, the historical 1 year overall survival rate is 37% with a median overall survival of 7.8 months. We conducted a multicenter, single-arm, open-label phase 2 study of tebentafusp, a soluble T cell receptor bispecific (gp100×CD3), in 127 patients with treatment-refractory metastatic uveal melanoma (NCT02570308). The primary endpoint was the estimation of objective response rate based on RECIST (Response Evaluation Criteria in Solid Tumours) v1.1. Secondary objectives included safety, overall survival, progression-free survival and disease control rate. All patients had at least one treatment-related adverse event, with rash (87%), pyrexia (80%) and pruritus (67%) being the most common. Toxicity was mostly mild to moderate in severity but was greatly reduced in incidence and intensity after the initial three doses. Despite a low overall response rate of 5% (95% CI: 2-10%), the 1 year overall survival rate was 62% (95% CI: 53-70%) with a median overall survival of 16.8 months (95% CI: 12.9-21.3), suggesting benefit beyond traditional radiographic-based response criteria. In an exploratory analysis, early on-treatment reduction in circulating tumour DNA was strongly associated with overall survival, even in patients with radiographic progression. Our findings indicate that tebentafusp has promising clinical activity with an acceptable safety profile in patients with previously treated metastatic uveal melanoma, and data suggesting ctDNA as an early indicator of clinical benefit from tebentafusp need confirmation in a randomized trial.

Response to Rucaparib in BRCA-Mutant Metastatic Castration-Resistant Prostate Cancer Identified by Genomic Testing in the TRITON2 Study

PURPOSE

The PARP inhibitor rucaparib is approved in the United States for patients with metastatic castration-resistant prostate cancer (mCRPC) and a deleterious germline and/or somatic BRCA1 or BRCA2 (BRCA) alteration. While sequencing of tumor tissue is considered the standard for identifying patients with BRCA alterations (BRCA+), plasma profiling may provide a minimally invasive option to select patients for rucaparib treatment. Here, we report clinical efficacy in patients with BRCA+ mCRPC identified through central plasma, central tissue, or local genomic testing and enrolled in TRITON2.

PATIENTS AND METHODS

Patients had progressed after next-generation androgen receptor-directed and taxane-based therapies for mCRPC and had BRCA alterations identified by central sequencing of plasma and/or tissue samples or local genomic testing. Concordance of plasma/tissue BRCA status and objective response rate and prostate-specific antigen (PSA) response rates were summarized.

RESULTS

TRITON2 enrolled 115 patients with BRCA+ identified by central plasma (n = 34), central tissue (n = 37), or local (n = 44) testing. Plasma/tissue concordance was determined in 38 patients with paired samples and was 47% in 19 patients with a somatic BRCA alteration. No statistically significant differences were observed between objective and PSA response rates to rucaparib across the 3 assay groups. Patients unable to provide tissue samples and tested solely by plasma assay responded at rates no different from patients identified as BRCA+ by tissue testing.

CONCLUSIONS

Plasma, tissue, and local testing of mCRPC patients can be used to identify men with BRCA+ mCRPC who can benefit from treatment with the PARP inhibitor rucaparib.

Health-Related Quality of Life of Patients with Recurrent or Metastatic Cutaneous Squamous Cell Carcinoma Treated with Pembrolizumab in KEYNOTE-629

INTRODUCTION

Pembrolizumab provided durable responses and acceptable safety in recurrent or metastatic (R/M) cutaneous squamous cell carcinoma (cSCC) in the KEYNOTE-629 study. In this elderly, fragile population with disfiguring tumours, preservation of health-related quality of life (HRQoL) is critical. Here, we present pre-specified exploratory HRQoL analyses from the first interim analysis of KEYNOTE-629.

METHODS

Patients with R/M cSCC not amenable to surgery or radiation therapy received pembrolizumab 200 mg every 3 weeks for ≤ 24 months. HRQoL end points included change from baseline to week 12 in European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) global health status (GHS)/QoL, functioning, symptom and European Quality of Life 5-Dimension 5-Level (EQ-5D-5L) scores and change from baseline through week 48 in EORTC QLQ-C30 GHS/QoL and physical functioning scores. Improvement (≥ 10-point increase post-baseline with confirmation) was assessed using the exact binomial method.

RESULTS

Analyses included 99 patients for EORTC QLQ-C30 and 100 for EQ-5D-5L. Compliance was > 80% at week 12. Mean scores were stable from baseline to week 12 for GHS/QoL (4.95 points; 95% confidence interval, -1.00 to 10.90) and physical functioning (-3.38 points; 95% confidence interval, -8.80 to 2.04). EORTC-QLQ-C30 functioning, symptom, and EQ-5D-5L scores remained stable at week 12. Post-baseline scores were improved in 29.3% of patients for GHS/QoL, 17.2% for physical functioning, and in a numerically higher proportion of responders versus non-responders (GHS/QoL, 55.6% versus 16.1%; physical functioning, 36.1% versus 7.1%).

CONCLUSIONS

In elderly patients with R/M cSCC, the clinical efficacy of pembrolizumab translates into a benefit validated by HRQoL preservation or improvement during treatment.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03284424.

Overall Survival Benefit with Tebentafusp in Metastatic Uveal Melanoma

BACKGROUND

Uveal melanoma is a disease that is distinct from cutaneous melanoma, with a low tumor mutational burden and a 1-year overall survival of approximately 50% in patients with metastatic uveal melanoma. Data showing a proven overall survival benefit with a systemic treatment are lacking. Tebentafusp is a bispecific protein consisting of an affinity-enhanced T-cell receptor fused to an anti-CD3 effector that can redirect T cells to target glycoprotein 100-positive cells.

METHODS

In this open-label, phase 3 trial, we randomly assigned previously untreated HLA-A*02:01-positive patients with metastatic uveal melanoma in a 2:1 ratio to receive tebentafusp (tebentafusp group) or the investigator's choice of therapy with single-agent pembrolizumab, ipilimumab, or dacarbazine (control group), stratified according to the lactate dehydrogenase level. The primary end point was overall survival.

RESULTS

A total of 378 patients were randomly assigned to either the tebentafusp group (252 patients) or the control group (126 patients). Overall survival at 1 year was 73% in the tebentafusp group and 59% in the control group (hazard ratio for death, 0.51; 95% confidence interval [CI], 0.37 to 0.71; P<0.001) in the intention-to-treat population. Progression-free survival was also significantly higher in the tebentafusp group than in the control group (31% vs. 19% at 6 months; hazard ratio for disease progression or death, 0.73; 95% CI, 0.58 to 0.94; P = 0.01). The most common treatment-related adverse events in the tebentafusp group were cytokine-mediated events (due to T-cell activation) and skin-related events (due to glycoprotein 100-positive melanocytes), including rash (83%), pyrexia (76%), and pruritus (69%). These adverse events decreased in incidence and severity after the first three or four doses and infrequently led to discontinuation of the trial treatment (2%). No treatment-related deaths were reported.

CONCLUSIONS

Treatment with tebentafusp resulted in longer overall survival than the control therapy among previously untreated patients with metastatic uveal melanoma. (Funded by Immunocore; ClinicalTrials.gov number, NCT03070392; EudraCT number, 2015-003153-18.).

A single-cell tumor immune atlas for precision oncology

The tumor immune microenvironment is a main contributor to cancer progression and a promising therapeutic target for oncology. However, immune microenvironments vary profoundly between patients, and biomarkers for prognosis and treatment response lack precision. A comprehensive compendium of tumor immune cells is required to pinpoint predictive cellular states and their spatial localization. We generated a single-cell tumor immune atlas, jointly analyzing published data sets of >500,000 cells from 217 patients and 13 cancer types, providing the basis for a patient stratification based on immune cell compositions. Projecting immune cells from external tumors onto the atlas facilitated an automated cell annotation system. To enable in situ mapping of immune populations for digital pathology, we applied SPOTlight, combining single-cell and spatial transcriptomics data and identifying colocalization patterns of immune, stromal, and cancer cells in tumor sections. We expect the tumor immune cell atlas, together with our versatile toolbox for precision oncology, to advance currently applied stratification approaches for prognosis and immunotherapy.

SMARCA4 deficient tumours are vulnerable to KDM6A/UTX and KDM6B/JMJD3 blockade

Despite the genetic inactivation of SMARCA4, a core component of the SWI/SNF-complex commonly found in cancer, there are no therapies that effectively target SMARCA4-deficient tumours. Here, we show that, unlike the cells with activated MYC oncogene, cells with SMARCA4 inactivation are refractory to the histone deacetylase inhibitor, SAHA, leading to the aberrant accumulation of H3K27me3. SMARCA4-mutant cells also show an impaired transactivation and significantly reduced levels of the histone demethylases KDM6A/UTX and KDM6B/JMJD3, and a strong dependency on these histone demethylases, so that its inhibition compromises cell viability. Administering the KDM6 inhibitor GSK-J4 to mice orthotopically implanted with SMARCA4-mutant lung cancer cells or primary small cell carcinoma of the ovary, hypercalcaemic type (SCCOHT), had strong anti-tumour effects. In this work we highlight the vulnerability of KDM6 inhibitors as a characteristic that could be exploited for treating SMARCA4-mutant cancer patients.

SMARCA4 is commonly inactivated in lung and ovarian cancers. Here the authors show that SMARCA4-deficient tumours have significantly reduced levels of the histone demethylases KDM6s and a strong dependency on these demethylases for tumour growth, so that they are vulnerable to KDM6s inhibition.

KEYNOTE-921: Phase III study of pembrolizumab plus docetaxel for metastatic castration-resistant prostate cancer

Despite recent advances, treatment options for men with metastatic castration-resistant prostate cancer (mCRPC) progressing after next-generation hormonal agents (NHAs) are limited and provide only modest survival benefit. Thus, an unmet need remains for mCRPC patients after treatment with targeted endocrine therapy or NHA therapy. Pembrolizumab, a humanized monoclonal antibody for PD-1, has been found to have activity as monotherapy in patients with mCRPC and as combination therapy in a Phase Ib/II study with docetaxel and prednisone/prednisolone for patients previously treated with enzalutamide or abiraterone acetate. The aim of the randomized, double-blind, Phase III KEYNOTE-921 study is to evaluate the efficacy and safety of pembrolizumab plus docetaxel in patients with mCRPC who were previously treated with an NHA. Clinical trial registration: NCT03834506 (ClinicalTrials.gov).

Characterization of liver function tests (LFTs) following tebentafusp (tebe) in previously treated (2L+) metastatic uveal melanoma (mUM) patients (pts)

e21513

Background: Tebe is a bispecific gp100-targeted T cell receptor fusion protein that can redirect polyclonal T cells to target gp100+ cells leading to T cell activation and release of inflammatory mediators. Hepatocytes do not express gp100 and tebe did not redirect T cells against normal hepatocytes in preclinical in vitro studies. However, since most mUM pts have liver metastases, tebe may result in secondary effects from localized tumor-related inflammation. Here we describe LFT kinetics and outcomes for pts in the IMCgp100-102 study (NCT02570308). Methods: 127 HLA-A*02:01+ pts with 2L+ mUM received tebe, administered weekly at the RP2D following intra-patient dose escalation (C1D1: 20μg; C1D8: 30μg; C1D15+: 68μg). Pts were eligible if ALT/AST ≤ 3 x ULN and bilirubin ≤ 1.5 x ULN. LFTs were measured at baseline (BL) and weekly prior to each dose using local laboratories. AE grading was based on CTCAE v4.03. This analysis was conducted on the primary analysis snapshot dated 04Jun20. Results: At BL,125/127 (98%) pts had ALT/AST ≤ grade(G)1 and 122/127 (96%) had liver metastasis. 68/127 (54%) had an increase in post-BL grade for ALT, AST or both. Of these 48/68 (71%) increased to G1, 9/68 (13%) to G2, 7/68 (10%) to G3, and 4/68 (6%) to G4. 67 of these 68 pts (99%) had liver metastasis and most had largest liver metastasis > 3cm (38 pts > 3 cm, 29 pts < 3cm and 1 pt without). ALT/AST increases occurred early in treatment in 36/68 (53%) including at Dose 1 (12/68; 18%), Dose 2 (10/68; 15%), or Dose 3 (14/68; 21%). In the other 32/68 pts (47%), ALT/AST increases occurred at or after Dose 4 (4-65), and most of these events (21/32; 66%) were associated temporally with increase in size of liver metastases. Among the 11 pts with G3/4 ALT/AST increases post-BL, most pts experienced these events early (Doses 1-3) (8/11; 73%) and in the context of either increase in size of liver metastases / disease progression or biliary obstruction (9/11; 82%). Most pts, 60/68 (88%), continued treatment despite an increase in ALT/AST grade. Among 8 pts who discontinued treatment, 3 were due to disease progression and 3 were due to adverse events. Median time for ALT/AST to return to BL was 9 days and there were no temporal increases in albumin or INR. Conclusions: Approximately 1/2 of tebe treated pts experienced an increase in post-BL CTCAE grade for ALT/AST. Among these pts, most ALT/AST increases were mild. Most of the pts with G3/4 ALT/AST increase (9/11) were explained by increase in size of liver metastases or biliary obstruction. Increase in LFT are not unusual at time of disease progression in mUM given high frequency of liver metastases. In summary, ALT/AST increases occurred early in about half of the pts, were generally self-limiting, permitted treatment to continue, and did not appear to impact liver synthetic function (INR/Albumin). Clinical trial information: NCT02570308.

Characterization of cytokine release syndrome (CRS) following treatment with tebentafusp in patients (pts) with previously treated (2L+) metastatic uveal melanoma (mUM)

9531

Background: Cytokine-mediated adverse events (AEs) are commonly reported in pts treated with T cell engaging therapies. Tebentafusp (tebe), a bispecific consisting of an affinity-enhanced T cell receptor fused to an anti-CD3 effector that can redirect T cells to target gp100+ cells, has shown an overall survival benefit for pts with untreated mUM in a Ph3 trial (NCT03070392). Here we reviewed the incidence, kinetics, and outcome of CRS in tebe-treated pts on the IMCgp100-102 trial of 2L+ pts with mUM (NCT02570308). Methods: 127 HLA-A*02:01+ 2L+ mUM pts were treated with tebe at the RP2D of 68mcg following intra-patient dose escalation of 20 mcg dose 1 and 30 mcg dose 2. Pts were monitored overnight to allow management of hypotension and other cytokine-related AEs. Because the rate of severe CRS was low in Ph1, prophylactic corticosteroids, antihistamines or acetaminophen were not mandated. CRS was evaluated post-hoc according to ASTCT Consensus Grading criteria [1]. Circulating cytokines in serum were measured before and at 8hr and 12-24hr after dosing for the 1st, 3rd and 4th doses (n=105). This analysis was conducted on the primary analysis snapshot dated 04Jun20. Results: The most frequent treatment-related AEs that were likely cytokine-mediated included fever (80%), chills (64%), nausea (59%), hypotension (41%) and hypoxia (4%). In a post-hoc review using ASTCT criteria, 86% of pts (n=109) had any grade CRS. The majority of these 109 pts had either grade (G) 1 (n=42; 33%) or G2 (n=62; 49%), with few G3 (n=4; 3.1%), one G4 (0.8%), and no deaths. Onset of CRS began within 24 hours of administration and G≥2 hypotension or hypoxia typically resolved within 2 days of onset. Most CRS events occurred after the first 3 doses with a marked reduction in the frequency and severity of CRS thereafter; G3-4 CRS was limited to first two doses. Only 2 pts discontinued tebe due to CRS (1 G3 and 1 G4). Treatment of G≥2 CRS included iv fluids (n=45), iv steroids (n=18), oxygen (n=8), and vasopressor use (n=2). No pts received tocilizumab. Tebe induced a transient increase in peripheral cytokines, including IFNγ, IL-10, IL-6 and TNFα, within hours of tebe dosing, which were several fold higher in pts with CRS compared to pts without CRS. Higher levels of TNFα trended with severity of CRS. Conclusions: CRS, a common AE observed with all T cell engaging therapies, was frequently observed within 24 hours of initial tebe treatment. Most CRS events were mild or moderate in severity even without the use of prophylactic premedications, were reversible with standard management strategies, decreased in frequency and severity with subsequent doses, and rarely led to treatment discontinuation. Pts with CRS tended to have greater increases in serum cytokines, consistent with tebe’s proposed mechanism of action. [1] Lee, DW et al. Biol Blood Marrow Transplant 2019. Clinical trial information: NCT02570308.

Overall survival benefit from tebentafusp in patients with best response of progressive disease

9509

Background: Tebentafusp (tebe) is the first T cell receptor (TCR) therapeutic to demonstrate an overall survival (OS) benefit in a randomized Phase 3 (Ph3) study [ NCT03070392 ]. In Ph2, 42% of pts with best overall response (BOR) of progressive disease (PD) survived > 1 year (yr), suggesting RECIST-based radiographic assessments underestimate OS benefit of tebe. Here we analyzed OS in the Ph3 study in a cohort of pts with BOR of PD by comparing tebe to the control arm of investigator’s choice (IC). Methods: 378 pts were randomized in a 2:1 ratio to tebe vs. IC. BOR was assessed by investigators using RECIST v1.1. Treatment beyond first disease progression (TBP) was permitted for both arms. On the IC arm, only patients receiving pembrolizumab (pembro) continued with TBP and were included in the TBP-related analyses. No crossover to tebe was permitted; investigators were free to choose subsequent therapy. This analysis was conducted on the first interim analysis (data extracted Nov-2020). Kaplan-Meier estimates of OS were based on Day 100 landmark to eliminate immortal time bias and to capture majority of the PDs. Results: By Day 100, PD as BOR occurred in 52% (130/252) of tebe pts (PD-tebe) vs. 60% (76/126) of IC pts (PD-IC). Key baseline characteristics including lactate dehydrogenase, alkaline phosphatase, ECOG performance, age, and sex were similar between PD-tebe vs PD-IC. The proportion of pts with PD due to progression of target lesions (TL), non-TL, or new lesions were also similar between the two groups. More pts received TBP among PD-tebe 53% (69/130) vs PD-pembro 16% (10/61). Median duration of TBP was longer for PD-tebe (7 weeks) vs PD-Pembro (3 weeks). The safety profile of PD-tebe pts during TBP was similar to all tebe-treated pts. OS was superior for PD-tebe vs PD-IC, HR = 0.41 (95%CI 0.25-0.66), even when considering key baseline covariates. While some pts had regression of TL despite diagnosis of PD ( < 10% of pts), the OS benefit remained even when limited to pts with best change of tumor growth of TL, HR 0.46 (0.29, 0.73). 58% (75/130) PD-tebe and 52% (40/76) PD-IC pts received subsequent therapies. In a landmark OS analysis of these pts beginning on 1st day of subsequent therapy, prior tebe was associated with better OS vs. prior IC, HR 0.59 (95%CI 0.36-0.96). Conclusions: Tebe is the first TCR therapeutic to demonstrate an OS benefit in a solid tumor. Surprisingly, a strong OS benefit from tebe is observed even in pts with BOR of PD, suggesting that RECIST-based radiographic assessments do not capture the complete benefit from tebe. The safety profile of tebe during TBP was consistent with that for long-term tebe treatment. Clinical trial information: NCT03070392.

CYCLONE 1: A phase 2 study of abemaciclib in patients with metastatic castration-resistant prostate cancer (mCRPC) previously treated with a novel hormonal agent and taxane-based chemotherapy

TPS5086

Background: In cancer cells, the cyclin-dependent kinases 4 and 6 (CDK4 & 6)/retinoblastoma protein (Rb) pathway is commonly altered, resulting in uncontrolled cell cycle entry and proliferation. CDK4 & 6 inhibitors represent a major advance in the management of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced or metastatic breast cancer (ABC or MBC, respectively). Abemaciclib is an oral selective inhibitor of CDK4 & 6 administered on a continuous dosing schedule, approved in combination with endocrine therapy for HR+, HER2- ABC or MBC. In addition, abemaciclib is also approved by the FDA as monotherapy for HR+, HER2- ABC or MBC following endocrine therapy and prior chemotherapy in the metastatic setting. Similar to the estrogen receptor signaling pathway in breast cancer cells, there is evidence that the androgen receptor axis activates CDK4 & 6 to sustain prostate cancer cell proliferation and survival. Preclinical studies in prostate cancer cell lines and xenograft models showed that abemaciclib exhibits single agent activity by inducing cell cycle arrest and tumor growth inhibition. Clinical activity of abemaciclib in combination with abiraterone and prednisone is investigated in a randomized phase 2 study in the first-line mCRPC setting (CYCLONE 2, NCT03706365). Despite recent advances, management of heavily pretreated mCRPC remains a major clinical challenge. Herein, we hypothesize that mCRPC patients whose disease progressed after novel hormonal agents (NHA) and taxane therapies may derive therapeutic benefit from single agent abemaciclib. Methods: CYCLONE 1 is a phase 2, single-arm, multicenter study to assess the safety and efficacy of abemaciclib monotherapy in 40 patients with mCRPC progressing after ≥1 NHA and 2 taxane regimens. Patients will be enrolled at time of prostate specific antigen (PSA) or radiographic progression per PCWG3 criteria and have at least 1 measurable lesion per RECIST 1.1. Metastatic tumor tissue (fresh biopsy or archival material <12 weeks) is required at baseline for biomarker analysis. Patients will receive abemaciclib 200 mg twice daily until unacceptable adverse events or disease progression. The primary objective is investigator-assessed objective response rate (ORR). Key secondary objectives include safety, radiographic progression-free survival, overall survival, PSA response rate, time to PSA progression, time to symptomatic progression, Ki-67 expression, patient-reported outcomes, and pharmacokinetics. Assuming an ORR of 15%, the study has over 73% power to observe a response rate of at least 12.5%. Accrual began in January 2021. Clinical trial information: NCT04408924.

Survival in small choroidal melanocytic lesions with risk factors managed by initial observation until detection of tumour growth

BACKGROUND

The main objective was to describe metastatic and survival rates in patients with small choroidal melanocytic lesions initially managed by observation.

METHODS

Retrospective, observational study of consecutive cases recruited from 2001 through 2018, followed for a median (mean, range) of 81.0 (89.3, 10-204) months in a tertiary referral centre for ocular oncology. Seventy-five consecutive patients diagnosed with small choroidal melanocytic lesions with risk factors for growth initially observed and who showed progression during follow-up. Treatment was performed (plaque radiotherapy or enucleation in 96% and 4% of cases, respectively) at detection of tumour growth.

RESULTS

Median (mean, range) tumour thickness was 2.2 (2.23, 1.08-3.40) mm, and median maximum basal diameter was 8.5 (8.16, 4-12) mm. At diagnosis, a median (mean, range) of 5 (5.48, 1-8) risk factors for progression were present. Lesions grew at a median (mean, range) rate of 0.42 mm/y (1.12, 0-7.68) in thickness and 1.05 mm/y (3.14, 0-4.8) in maximum diameter. Median (mean, range) time until growth was 17.00 (32.6, 1-161) months post-diagnosis, at which time tumours were treated. Five patients developed local recurrence after brachytherapy requiring enucleation. Four patients developed hepatic metastasis. Melanoma-specific survival was 98% at 5 years (95% CI, 94.2-100%) and 91.6% (95% CI, 82-100%) at 10 and 15 years.

CONCLUSION

In small melanocytic lesions with risk factors for growth, initial observation until detection of tumour growth results in a seemingly low risk of metastasis, suggesting that this may be an initial approach to consider in tumours with indeterminate malignant potential.

Association of co-occurring gene alterations and clinical activity of rucaparib in patients with BRCA1 or BRCA2 mutated (BRCA+) metastatic castration-resistant prostate cancer (mCRPC)

80

Background: The poly(ADP-ribose) polymerase (PARP) inhibitor rucaparib was granted accelerated approval by the US Food and Drug Administration for patients with BRCA+ mCRPC based on results from the phase 2 TRITON2 study (NCT02952534). The TP53 tumor suppressor gene is among the most frequently mutated genes in human cancers, including mCRPC, and alterations in TP53, PTEN, and RB1 are associated with poor prognosis in patients with prostate cancer and other tumor types. We present data on co-occurring alterations in patients with BRCA+ mCRPC treated with rucaparib in TRITON2. Methods: Patients had progressed on 1–2 lines of androgen receptor-directed therapy and 1 taxane-based chemotherapy and were treated with rucaparib 600 mg BID. Tissue and/or cell-free DNA extracted from plasma samples were profiled comprehensively for genomic alterations using Foundation Medicine, Inc., next-generation sequencing assays. Objective response rate (ORR) was assessed per modified Response Evaluation Criteria in Solid Tumors and Prostate Cancer Working Group 3 criteria by independent radiologic review of patients with measurable disease. Prostate-specific antigen (PSA) response rate (≥50% decrease from baseline) was assessed in all patients. Results: Tissue and/or plasma samples were available for 114/115 patients with BRCA+ mCRPC (visit cutoff date: Dec. 23, 2019). Among patients with BRCA+ mCRPC who had samples available for comprehensive genomic profiling, 36.8% (42/114) had a co-occurring alteration in TP53. Deleterious alterations in PTEN were observed in 34.2% (39/114) of patients, 44% (17/39) of which were homozygous deletions of PTEN. RB1 loss was observed in 12.3% (14/114) of patients and was seen more frequently in patients with measurable disease (18.0%, 11/61) than in patients with non-measurable disease (5.7%, 3/53). Although patients with and without TP53 mutations had generally similar baseline demographics and disease characteristics, visceral disease was more prevalent in patients with TP53 mutations (54.8%; 23/42) than in those without them (29.2%; 21/72). Similar ORR and PSA response rates were seen in patients with BRCA+ mCRPC with or without TP53 mutation, with a non-significant trend towards lower response rates in patients with co-occurring TP53 alterations. Conclusions: Results from TRITON2 showed antitumor activity for rucaparib in patients with BRCA+ mCRPC associated with or without co-occurring alterations in TP53. Demographics and additional efficacy analyses in genomic subgroups with co-occurring alterations in TP53, PTEN, and RB1 will be reported. Clinical trial information: NCT02952534. [Table: see text]

KEYNOTE-365 cohort B: Pembrolizumab (pembro) plus docetaxel and prednisone in abiraterone (abi) or enzalutamide (enza)–pretreated patients with metastatic castration-resistant prostate cancer (mCRPC)—New data after an additional 1 year of follow-up

10

Background: For men with mCRPC, systemic therapies such as docetaxel and cabazitaxel improve survival, but more effective treatments are needed. KEYNOTE-365 (NCT02861573) is a phase 1b/2 study to examine the safety and efficacy of pembro in combination with 4 different study medications (cohorts A, B, C, D) in mCRPC. Previous data from cohort B with a median of 20 months of follow-up showed that pembro + docetaxel and prednisone was well tolerated and had antitumor activity in patients (pts) with mCRPC previously treated with abi or enza. New efficacy and safety data after an additional year of follow-up are presented. Methods: Cohort B enrolled pts who did not respond to or were intolerant to ≥4 weeks of abi or enza in the prechemotherapy mCRPC state and whose disease progressed within 6 months of screening (determined by PSA progression or radiologic bone/soft tissue progression). Pts received pembro 200 mg IV every 3 weeks (Q3W), docetaxel 75 mg/m2 IV Q3W, and oral prednisone 5 mg twice daily. Primary end points were safety, PSA response rate (PSA decrease >50% from baseline), and ORR per RECIST v1.1 by blinded independent central review. Efficacy and safety were assessed in all pts as treated. Results: Of the 104 treated pts, median age was 68.0 years (range, 50-86), 23.1% had PD-L1–positive tumors (combined positive score ≥1), 25.0% had visceral disease, and 50.0% had measurable disease. Median time from enrollment to data cutoff was 32.4 months (range 13.9-40.3); 101 pts discontinued, primarily because of disease progression (77.9%). Efficacy outcomes are reported in the table below. Treatment-related adverse events (TRAEs) occurred in 100 pts (96.2%); the most frequent (≥30%) were diarrhea (41.3%), fatigue (41.3%), and alopecia (40.4%). Grade 3-5 TRAEs occurred in 46 pts (44.2%). Five pts (4.8%) died of AEs; 2 were treatment-related pneumonitis. Conclusions: After another year of follow-up, pembro + docetaxel and prednisone showed improved ORR and PSA response rates compared to the prior dataset in pts with mCRPC previously treated with abi or enza. Safety was consistent with known profiles of each agent and will be further evaluated in a phase 3 study (KEYNOTE-921). Clinical trial information: NCT02861573. [Table: see text]

Clinical practice guidelines for BRCA1 and BRCA2 genetic testing

BRCA1 and BRCA2 gene pathogenic variants account for most hereditary breast cancer and are increasingly used to determine eligibility for PARP inhibitor (PARPi) therapy of BRCA-related cancer. Because issues of BRCA testing in clinical practice now overlap with both preventive and therapeutic management, updated and comprehensive practice guidelines for BRCA genotyping are needed. The integrative recommendations for BRCA testing presented here aim to (1) identify individuals who may benefit from genetic counselling and risk-reducing strategies; (2) update germline and tumour-testing indications for PARPi-approved therapies; (3) provide testing recommendations for personalised management of early and metastatic breast cancer; and (4) address the issues of rapid process and tumour analysis. An international group of experts, including geneticists, medical and surgical oncologists, pathologists, ethicists and patient representatives, was commissioned by the French Society of Predictive and Personalised Medicine (SFMPP). The group followed a methodology based on specific formal guidelines development, including (1) evaluating the likelihood of BRCAm from a combined systematic review of the literature, risk assessment models and expert quotations, and (2) therapeutic values of BRCAm status for PARPi therapy in BRCA-related cancer and for management of early and advanced breast cancer. These international guidelines may help clinicians comprehensively update and standardise BRCA testing practices.

FGFR Inhibition Overcomes Resistance to EGFR-targeted Therapy in Epithelial-like Cutaneous Carcinoma

PURPOSE

Recurrent and/or metastatic unresectable cutaneous squamous cell carcinomas (cSCCs) are treated with chemotherapy or radiotherapy, but have poor clinical responses. A limited response (up to 45% of cases) to EGFR-targeted therapies was observed in clinical trials with patients with advanced and metastatic cSCC. Here, we analyze the molecular traits underlying the response to EGFR inhibitors, and the mechanisms responsible for cSCC resistance to EGFR-targeted therapy.

EXPERIMENTAL DESIGN

We generated primary cell cultures and patient cSCC-derived xenografts (cSCC-PDXs) that recapitulate the histopathologic and molecular features of patient tumors. Response to gefitinib treatment was tested and gefitinib-resistant (GefR) cSCC-PDXs were developed. RNA sequence analysis was performed in matched untreated and GefR cSCC-PDXs to determine the mechanisms driving gefitinib resistance.

RESULTS

cSCCs conserving epithelial traits exhibited strong activation of EGFR signaling, which promoted tumor cell proliferation, in contrast to mesenchymal-like cSCCs. Gefitinib treatment strongly blocked epithelial-like cSCC-PDX growth in the absence of EGFR and RAS mutations, whereas tumors carrying the E545K PIK3CA-activating mutation were resistant to treatment. A subset of initially responding tumors acquired resistance after long-term treatment, which was induced by the bypass from EGFR to FGFR signaling to allow tumor cell proliferation and survival upon gefitinib treatment. Pharmacologic inhibition of FGFR signaling overcame resistance to EGFR inhibitor, even in PIK3CA-mutated tumors.

CONCLUSIONS

EGFR-targeted therapy may be appropriate for treating many epithelial-like cSCCs without PIK3CA-activating mutations. Combined EGFR- and FGFR-targeted therapy may be used to treat cSCCs that show intrinsic or acquired resistance to EGFR inhibitors.

Taxane-induced Attenuation of the CXCR2/BCL-2 Axis Sensitizes Prostate Cancer to Platinum-based Treatment

BACKGROUND

Taxanes are the most active chemotherapy agents in metastatic castration-resistant prostate cancer (mCRPC) patients; yet, resistance occurs almost invariably, representing an important clinical challenge. Taxane-platinum combinations have shown clinical benefit in a subset of patients, but the mechanistic basis and biomarkers remain elusive.

OBJECTIVE

To identify mechanisms and response indicators for the antitumor efficacy of taxane-platinum combinations in mCRPC.

DESIGN, SETTING, AND PARTICIPANTS

Transcriptomic data from a publicly available mCRPC dataset of taxane-exposed and taxane-naïve patients were analyzed to identify response indicators and emerging vulnerabilities. Functional and preclinical validation was performed in taxane-resistant mCRPC cell lines and genetically engineered mouse models (GEMMs).

INTERVENTION

Metastatic CRPC cells were treated with docetaxel, cisplatin, carboplatin, the CXCR2 antagonist SB265610, and the BCL-2 inhibitor venetoclax. Gain and loss of function in culture of CXCR2 and BCL-2 were achieved by overexpression or siRNA silencing. Preclinical assays in GEMM mice tested the antitumor efficacy of taxane-platinum combinations.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Proliferation, apoptosis, and colony assays measured drug activity in vitro. Preclinical endpoints in mice included growth, survival, and histopathology. Changes in CXCR2, BCL-2, and chemokines were analyzed by reverse transcriptase quantitative polymerase chain reaction and Western blot. Human expression data were analyzed using Gene Set Enrichment Analysis, hierarchical clustering, and correlation studies. GraphPad Prism software and R-studio were used for statistical and data analyses.

RESULTS AND LIMITATIONS

Transcriptomic data from taxane-exposed human mCRPC tumors correlate with a marked negative enrichment of apoptosis and inflammatory response pathways accompanied by a marked downregulation of CXCR2 and BCL-2. Mechanistically, we show that docetaxel inhibits CXCR2 and that BCL-2 downregulation occurs as a downstream effect. Further, we demonstrated in experimental models that the sensitivity to cisplatin is dependent on CXCR2 and BCL-2, and that targeting them sensitizes prostate cancer (PC) cells to cisplatin. In vivo taxane-platinum combinations are highly synergistic, and previous exposure to taxanes sensitizes mCRPC tumors to second-line cisplatin treatment.

CONCLUSIONS

The hitherto unappreciated attenuation of the CXCR2/BCL-2 axis in taxane-treated mCRPC patients is an acquired vulnerability with potential predictive activity for platinum-based treatments.

PATIENT SUMMARY

A subset of patients with aggressive and therapy-resistant prostate cancer benefits from taxane-platinum combination chemotherapy; however, we lack the mechanistic understanding of how that synergistic effect occurs. Here, using patient data and preclinical models, we found that taxanes reduce cancer cell escape mechanisms to chemotherapy-induced cell death, hence making these cells more vulnerable to additional platinum treatment.

High Cysteinyl Leukotriene Receptor 1 Expression Correlates with Poor Survival of Uveal Melanoma Patients and Cognate Antagonist Drugs Modulate the Growth, Cancer Secretome, and Metabolism of Uveal Melanoma Cells

Metastatic uveal melanoma (UM) is a rare, but often lethal, form of ocular cancer arising from melanocytes within the uveal tract. UM has a high propensity to spread hematogenously to the liver, with up to 50% of patients developing liver metastases. Unfortunately, once liver metastasis occurs, patient prognosis is extremely poor with as few as 8% of patients surviving beyond two years. There are no standard-of-care therapies available for the treatment of metastatic UM, hence it is a clinical area of urgent unmet need. Here, the clinical relevance and therapeutic potential of cysteinyl leukotriene receptors (CysLT1 and CysLT2) in UM was evaluated. High expression of CYSLTR1 or CYSLTR2 transcripts is significantly associated with poor disease-free survival and poor overall survival in UM patients. Digital pathology analysis identified that high expression of CysLT1 in primary UM is associated with reduced disease-specific survival (p = 0.012; HR 2.76; 95% CI 1.21-6.3) and overall survival (p = 0.011; HR 1.46; 95% CI 0.67-3.17). High CysLT1 expression shows a statistically significant (p = 0.041) correlation with ciliary body involvement, a poor prognostic indicator in UM. Small molecule drugs targeting CysLT1 were vastly superior at exerting anti-cancer phenotypes in UM cell lines and zebrafish xenografts than drugs targeting CysLT2. Quininib, a selective CysLT1 antagonist, significantly inhibits survival (p < 0.0001), long-term proliferation (p < 0.0001), and oxidative phosphorylation (p < 0.001), but not glycolysis, in primary and metastatic UM cell lines. Quininib exerts opposing effects on the secretion of inflammatory markers in primary versus metastatic UM cell lines. Quininib significantly downregulated IL-2 and IL-6 in Mel285 cells (p < 0.05) but significantly upregulated IL-10, IL-1β, IL-2 (p < 0.0001), IL-13, IL-8 (p < 0.001), IL-12p70 and IL-6 (p < 0.05) in OMM2.5 cells. Finally, quininib significantly inhibits tumour growth in orthotopic zebrafish xenograft models of UM. These preclinical data suggest that antagonism of CysLT1, but not CysLT2, may be of therapeutic interest in the treatment of UM.

Pembrolizumab Monotherapy for Recurrent or Metastatic Cutaneous Squamous Cell Carcinoma: A Single-Arm Phase II Trial (KEYNOTE-629)

PURPOSE

Treatment options are limited for patients with recurrent and/or metastatic (R/M) cutaneous squamous cell carcinoma (cSCC); mortality rates exceed 70% in patients with distant metastases. Here, we present the first interim analysis of the R/M cSCC cohort from the 2-cohort-locally advanced and R/M-phase II KEYNOTE-629 study.

PATIENTS AND METHODS

Patients with R/M cSCC not amenable to surgery or radiation received pembrolizumab 200 mg every 3 weeks. The primary end point was objective response rate per RECIST v1.1. Secondary end points were duration of response, disease control rate, progression-free survival, overall survival, and safety.

RESULTS

At data cutoff (April 8, 2019), median follow-up of 105 enrolled patients in the R/M cohort was 11.4 months (range, 0.4 to 16.3 months). Objective response rate was 34.3% (95% CI, 25.3% to 44.2%; 4 complete responses, 32 partial responses), and disease control rate was 52.4% (95% CI, 42.4% to 62.2%). Median duration of response was not reached (range, 2.7 to 13.1+ months; '+' refers to ongoing response at data cutoff). Median progression-free survival was 6.9 months (95% CI, 3.1 months to 8.5 months). Median overall survival was not reached (95% CI, 10.7 months to not reached). Treatment-related adverse events occurred in 66.7% of patients (n = 70), the most common of which were pruritus (n = 15; 14.3%), asthenia (n = 14; 13.3%), and fatigue (n = 13; 12.4%). Grade 3 to 5 treatment-related adverse events occurred in 5.7% (n = 6) of patients. One patient died of treatment-related cranial nerve neuropathy.

CONCLUSION

Pembrolizumab demonstrated effective antitumor activity; clinically meaningful, durable responses; and acceptable safety in primarily elderly patients with R/M cSCC, supporting its use in clinical practice. Pembrolizumab adverse events in this study were consistent with its established safety profile.

Rucaparib in Men With Metastatic Castration-Resistant Prostate Cancer Harboring a BRCA1 or BRCA2 Gene Alteration

PURPOSE

BRCA1 or BRCA2 (BRCA) alterations are common in men with metastatic castration-resistant prostate cancer (mCRPC) and may confer sensitivity to poly(ADP-ribose) polymerase inhibitors. We present results from patients with mCRPC associated with a BRCA alteration treated with rucaparib 600 mg twice daily in the phase II TRITON2 study.

METHODS

We enrolled patients who progressed after one to two lines of next-generation androgen receptor–directed therapy and one taxane-based chemotherapy for mCRPC. Efficacy and safety populations included patients with a deleterious BRCA alteration who received ≥ 1 dose of rucaparib. Key efficacy end points were objective response rate (ORR; per RECIST/Prostate Cancer Clinical Trials Working Group 3 in patients with measurable disease as assessed by blinded, independent radiology review and by investigators) and locally assessed prostate-specific antigen (PSA) response (≥ 50% decrease from baseline) rate.

RESULTS

Efficacy and safety populations included 115 patients with a BRCA alteration with or without measurable disease. Confirmed ORRs per independent radiology review and investigator assessment were 43.5% (95% CI, 31.0% to 56.7%; 27 of 62 patients) and 50.8% (95% CI, 38.1% to 63.4%; 33 of 65 patients), respectively. The confirmed PSA response rate was 54.8% (95% CI, 45.2% to 64.1%; 63 of 115 patients). ORRs were similar for patients with a germline or somatic BRCA alteration and for patients with a BRCA1 or BRCA2 alteration, while a higher PSA response rate was observed in patients with a BRCA2 alteration. The most frequent grade ≥ 3 treatment-emergent adverse event was anemia (25.2%; 29 of 115 patients).

CONCLUSION

Rucaparib has antitumor activity in patients with mCRPC and a deleterious BRCA alteration, but with a manageable safety profile consistent with that reported in other solid tumor types.