Interim phase 1 results for SQ3370 in advanced solid tumors

3085

Background: SQ3370, a novel therapy, utilizes Shasqi’s proprietary Click Activated Protodrugs Against Cancer (CAPAC) platform where mutually-reactive click chemistry groups release Doxorubicin (Dox) at the tumor site minimizing systemic exposure. In animals, SQ3370 enhanced survival, T-cell infiltration and antitumor responses in injected and non-injected tumors. Minimal to no toxicity, including no cardiotoxicity was seen in up to 9-fold dose increases in animals. Conventional Dox can induce cardiomyopathy at incidences of 1-20% for cumulative doses from 300-500 mg/m2 in humans and re-treatment with Dox is less effective in heavily pre-treated patients (pts). Here we report interim results of the Phase 1 ( NCT04106492 ). Methods: SQ3370 has 2 components: 1) Intratumoral injection of a protodrug-activating biopolymer (SQL70: 10 mL or 20 mL); 2) 5 consecutive daily IV infusions of an attenuated protodrug of Dox (SQP33). Key eligibility includes locally advanced or metastatic solid tumors, ≤300 mg/m2 prior exposure to Dox, ECOG 0-1 and no limit to prior systemic therapies. Primary objectives include safety and determining Phase 2 dose. Dose escalation was assessed in 2 stages: 1) accelerated titration; 2) 3+3 design. Results: As of 31JAN2022 data cut, 26 pts were treated, 21 with 10 mL biopolymer (bp) and 5 with 20 mL bp over 9 dose escalation protodrug cohorts. MTD has not been reached. Median age was 61 years (26-84), 62% were females, and 69% were ECOG 1. Prior procedures included surgery (89%) and radiation (62%). At study entry, 77% of pts had metastases with a median number of metastatic sites being 2 (1-5); most frequently lung (50%). Tumors were sarcoma (73%), breast cancer (7.7%), gyne (7.7%) and other (11.5%). Twenty-four of 26 (92%) pts received prior systemic therapies with 50% receiving prior Dox. Median number of prior systemic therapies was 2 (1-7). Of the 26 pts, 62% received > 500 mg/m2 cumulative Dox given as SQP33. Median duration of treatment was 2 cycles (1-12). Most frequent AEs, regardless of causality, for the 10 mL bp group included nausea (n = 11), fatigue (n = 9) and anemia (n = 6), and for the 20 mL bp group included anemia (n = 3) and nausea (n = 2). Ejection fraction (LVEF) remained normal during the study period. No AEs that led to discontinuation or death were related to SQ3370 by investigator. At a median follow-up of 9.2 wks (3-37), 21 pts were evaluable. SD was best response in 71%. Median duration of SD was 80-dys (37-186) corresponding to an overall disease control rate (CR+ PR+ SD x 30-dys) of 71% (68% in 10 mL bp; 100% in 20 mL bp). The remainder of pts had PD as best response. Over 38% of pts remain on drug. Conclusions: SQ3370 with 10 mL or 20 mL biopolymer was well tolerated in pts with half being re-treated with Dox. Although > 60% of pts received > 500 mg/m2 cumulative Dox given as SQP33, LVEF remained normal. Preliminary evidence of disease control was observed in pts despite heavy prior pre-treatment and high cancer burden. Dose escalation is ongoing. Clinical trial information: NCT04106492.

Five-year overall survival from the anti-PD1 brain collaboration (ABC Study): Randomized phase 2 study of nivolumab (nivo) or nivo+ipilimumab (ipi) in patients (pts) with melanoma brain metastases (mets)

9508

Background: Preliminary data from the ABC (76 pts) and CheckMate 204 (94 pts) trials showed that nivo and nivo+ipi have activity in active melanoma brain metastases, with durable responses in a subset of pts. Here, we report updated 5-yr data from all pts enrolled on the ABC trial (NCT02374242). Methods: This open-label ph2 trial enrolled 3 cohorts of pts with active melanoma brain mets naïve to anti-PD1/PDL1/PDL2/CTLA4 from Nov 2014-Apr 2017. Pts with asymptomatic brain mets with no prior local brain therapy were randomised to cohort A (nivo 1mg/kg + ipi 3mg/kg, Q3Wx4, then nivo 3mg/kg Q2W) or cohort B (nivo 3mg/kg Q2W). Cohort C (nivo 3mg/kg Q2W) had brain mets i) that failed local therapy, ii) with neuro symptoms and/or iii) with leptomeningeal disease. Prior BRAF inhibitor (BRAFi) was allowed. The primary endpoint was best intracranial response (ICR) ≥wk12. Key secondary endpoints were IC PFS, overall PFS, OS, & safety. Results: A total of 76 pts (med f/u 54 mo) were enrolled; median age 59y, 78% male. For cohorts A, B and C: elevated LDH 51%, 58% and 19%; V600BRAF 54%, 56% and 81%; prior BRAFi 23%, 24%, 75%. Efficacy and toxicity are shown in the table. There were no treatment-related deaths. 1/17 deaths in cohort A & 4/16 in cohort B were due to IC progression only. Conclusions: Nivo monotherapy and ipi+nivo are active in melanoma brain mets, with durable responses in the majority of patients who received ipi+nivo upfront. A study of upfront ipi+nivo+/-SRS is underway (NCT03340129). Clinical trial information: NCT02374242. [Table: see text]

Pathological response and tumour bed histopathological features correlate with survival following neoadjuvant immunotherapy in stage III melanoma

BACKGROUND

Guidelines for pathological evaluation of neoadjuvant specimens and pathological response categories have been developed by the International Neoadjuvant Melanoma Consortium (INMC). As part of the Optimal Neo-adjuvant Combination Scheme of Ipilimumab and Nivolumab (OpACIN-neo) clinical trial of neoadjuvant combination anti-programmed cell death protein 1/anti-cytotoxic T-lymphocyte-associated protein 4 immunotherapy for stage III melanoma, we sought to determine interobserver reproducibility of INMC histopathological assessment principles, identify specific tumour bed histopathological features of immunotherapeutic response that correlated with recurrence and relapse-free survival (RFS) and evaluate proposed INMC pathological response categories for predicting recurrence and RFS.

PATIENTS AND METHODS

Clinicopathological characteristics of lymph node dissection specimens of 83 patients enrolled in the OpACIN-neo clinical trial were evaluated. Two methods of assessing histological features of immunotherapeutic response were evaluated: the previously described immune-related pathologic response (irPR) score and our novel immunotherapeutic response score (ITRS). For a subset of cases (n = 29), cellular composition of the tumour bed was analysed by flow cytometry.

RESULTS

There was strong interobserver reproducibility in assessment of pathological response (κ = 0.879) and percentage residual viable melanoma (intraclass correlation coefficient = 0.965). The immunotherapeutic response subtype with high fibrosis had the strongest association with lack of recurrence (P = 0.008) and prolonged RFS (P = 0.019). Amongst patients with criteria for pathological non-response (pNR, >50% viable tumour), all who recurred had ≥70% viable melanoma. Higher ITRS and irPR scores correlated with lack of recurrence in the entire cohort (P = 0.002 and P ≤ 0.0001). The number of B lymphocytes was significantly increased in patients with a high fibrosis subtype of treatment response (P = 0.046).

CONCLUSIONS

There is strong reproducibility for assessment of pathological response using INMC criteria. Immunotherapeutic response of fibrosis subtype correlated with improved RFS, and may represent a biomarker. Potential B-cell contribution to fibrosis development warrants further study. Reclassification of pNR to a threshold of ≥70% viable melanoma and incorporating additional criteria of <10% fibrosis subtype of response may identify those at highest risk of recurrence, but requires validation.

Health-related quality of life (HRQL) in patients with advanced cutaneous squamous cell carcinoma (CSCC) treated with cemiplimab: Post hoc exploratory analyses of a phase II clinical trial

10033

Background: Cemiplimab-rwlc (cemiplimab), a PD-1 Inhibitor, showed a robust clinical response in patients (pts) with metastatic (mCSCC) or locally advanced (laCSCC) CSCC not eligible for curative surgery/radiation. This post hoc exploratory analysis examined data from the EORTC cancer specific 30-item HRQL questionnaire (QLQ-C30) for pts participating in a cemiplimab phase 2 clinical trial (clinicaltrials.gov NCT02760498). Methods: Adults (N = 193) with invasive CSCC, ≥1 lesion and ECOG performance status ≤1 received IV cemiplimab 3mg/kg q2w (mCSCC n = 59; laCSCC n = 78) or 350mg q3w (mCSCC n = 56). At baseline (BL) and day 1 of each treatment cycle, pts were administered the QLQ-C30. Mixed effects repeated measures (MMRM) models were used to estimate mean change from BL to cycle 5 (C5) for domains/items of the QLQ-C30. For pts with data from BL to C5, the proportion who reported clinically meaningful improvement or worsening (≥10 points) or maintenance (those who did not have ≥10 point change) on each domain was determined for combined and individual treatment groups. Results: BL scores indicated moderate to high levels of functioning and low symptom burden. From BL to C5, a clinically meaningful improvement in pain score was observed (least squares [LS] mean [standard error] change -12.1 [2.1]; P< .0001); other domains/items remained stable or showed a trend towards improvement (LS mean changes < 10 points). By C5, the majority of pts experienced clinically meaningful improvement or remained stable across key domains (Table). Similar findings were observed on individual symptoms (85%-94% for dyspnea, nausea/vomiting, diarrhea, constipation, appetite loss) and in each treatment group. Conclusions: Cemiplimab-treated patients achieved a clinically meaningful reduction in pain and most pts either improved or maintained their HRQL, function with low symptom burden. Clinical trial information: NCT02760498. [Table: see text]

Phase II study of cemiplimab in patients (pts) with advanced cutaneous squamous cell carcinoma (CSCC): Longer follow-up

10018

Background: Cemiplimab monotherapy achieves clinically meaningful activity in pts with advanced CSCC (metastatic [mCSCC] or locally advanced [laCSCC] not amenable to curative surgery or curative radiation) and has a safety profile consistent with other anti–PD-1 agents. Based on initial data (median follow-up of 9.4 months in the pivotal study, NCT02760498), cemiplimab (cemiplimab-rwlc in the US) was approved for the treatment of pts with advanced CSCC. Historical data shows median overall survival (OS) of approximately 15 months with conventional chemotherapy or EGFR inhibitors (ASCO 2019, e21033). We present ~1-year additional follow-up from the largest prospective data set in advanced CSCC. Methods: Pts received cemiplimab 3 mg/kg Q2W (Group [Gp] 1; mCSCC; Gp 2, laCSCC) or cemiplimab 350 mg Q3W (Gp 3, mCSCC). The primary endpoint was objective response rate (ORR; complete response + partial response) per independent central review (ICR). Data presented here are per investigator review (INV); ICR data will be available at the meeting. Results: 193 pts were enrolled (Gp 1, n = 59; Gp 2, n = 78; Gp 3, n = 56). 128 pts had received no prior anti-cancer systemic therapy, 65 pts were previously treated. As of Oct 11, 2019 (data cut-off), median duration of follow-up was 15.7 months (range: 0.6–36.1) among all pts; 18.5 months (range: 1.1–36.1) for Gp 1, 15.5 months (range: 0.8–35.0) for Gp 2, and 17.3 months (range: 0.6–26.3) for Gp 3. ORR per INV was 54.4% (95% CI: 47.1–61.6) for all pts; 50.8% (95% CI: 37.5–64.1) for Gp 1, 56.4% (95% CI: 44.7–67.6) for Gp 2, and 55.4% (95% CI: 41.5–68.7) for Gp 3. ORR per INV was 57.8% (95% CI: 48.8–66.5) among treatment-naïve pts and 47.7% (95% CI: 35.1–60.5) among previously treated pts. Median duration of response (DOR) has not been reached (observed DOR range: 1.8–34.2 months). In responding pts, estimated proportion of pts with ongoing response at 24 months was 76.0% (95% CI: 64.1–84.4). Median OS has not been reached. Estimated OS at 24 months was 73.3% (95% CI: 66.1–79.2). The most common treatment-emergent adverse events (TEAEs) by any grade were fatigue (34.7%), diarrhea (27.5%), and nausea (23.8%). The most common grade ≥3 TEAEs were hypertension (4.7%) and anemia and cellulitis (each 4.1%). Conclusions: For pts with advanced CSCC, cemiplimab achieves ORRs, DOR and survival superior to what has been reported with other agents. Clinical trial information: NCT02760498.

Pembrolizumab with chemoradiotherapy as treatment for muscle invasive bladder cancer: A planned interim analysis of safety and efficacy of the PCR-MIB phase II clinical trial (ANZUP 1502)

485

Background: In patients (pts) with muscle invasive bladder (MIBC) suitable for curative definitive chemoradiotherapy (CRT), we hypothesise that the addition of pembrolizumab may be safe and improve efficacy. A pre-planned safety analysis was performed after the first 10 of planned 30 pts were enrolled and completed treatment. Methods: Patients with maximally resected non-metastatic MIBC and ECOG 0-1, who desire bladder preservation or are ineligible for cystectomy were treated with 64Gy in 32 daily radiation fractions to the whole bladder alone over 6.5 weeks in combination with 6 concurrent doses of weekly cisplatin at 35mg/m2 IV. Pembrolizumab was commenced concurrently with radiation and given flat-dose 200mg IV q21 days for 7 doses. Surveillance cystoscopy, urine cytology and CT chest-abdomen-pelvis were performed 12 & 24 weeks post CRT. The primary endpoint is feasibility, defined by a satisfactory low rate of unacceptable toxicity of a) G3-4 non-urinary adverse events (AE) or b) failure of completion of planned CRT according to defined parameters. Secondary endpoints include complete cystoscopic response without metastatic disease at 12 & 24 weeks, loco-regional PFS, metastatic DFS, and overall survival. A 2-stage design was planned, with accrual to be halted if >5 of the first 10 pts experienced unacceptable toxicity up to 12 weeks post treatment. Results: All 10 pts completed the course of CRT and pembrolizumab without alteration in radiation dose or schedule. 1 patient had a dose of cisplatin withheld. 4/10 pts experienced G3-4 non-urinary adverse events within 12 weeks of completing treatment. One immune related AE interrupted pembrolizumab delivery (G2 nephritis). By week 24, 9/10 pts achieved a complete cystoscopic response to treatment post CRT and were free of distant metastatic disease. Conclusions: Interim results indicate that pembrolizumab and CRT shows satisfactory safety, and promising efficacy. There were no unexpected safety signals. Follow up of these and additional pts will better define the efficacy and safety of the combination. Enrolment is ongoing with 20 pts recruited out of a planned total of 30. Clinical trial information: NCT02662062.

A phase II, open-label study of durvalumab in combination with stereotactic body radiotherapy in androgen-intact patients with oligometastatic prostate cancer

TPS263

Background: With the introduction of Ga68-PSMA PET, a new cohort of androgen-intact men with oligometastatic prostate cancer (PCa) recurrence has been identified. These men have normal traditional imaging and a disease-free interval usually measured in years from their definitive treatment. Recent data supports the use of metastasis-directed stereotactic body radiotherapy (SBRT) in oligometastatic PCa. Based on our institutional data in 57 patients treated with SBRT alone in the PSMA era, the median PSA progression free survival (PFS) is 11 months. Despite 100% local control, 80% relapsed by 18 months. Improving the PFS for these men is an important clinical need. Achieving this without the introduction of androgen deprivation therapy (ADT) will likely improve quality of life and minimise the adverse consequences of androgen deprivation. Radiotherapy results in cell stress and release of damage associated molecular patterns (DAMPs) with activation of antigen presenting cells. This stimulates a tumour antigen specific T-cell response and abscopal effect which can be heightened with PD-(L)1 inhibition. Most PD-(L)1 inhibition trials in PCa are in men with a high burden of castrate resistant disease. However, data suggests the castrate state can impair host anti-tumour immune response. PD-(L)1 inhibition combined with SBRT in androgen-intact men may result in improved PFS compared with our historical cohort treated with SBRT alone. Methods: This is a non-randomized, open label, phase II study of durvalumab (1500 mg IV every 4 weeks) starting 1 month prior to SBRT in men with recurrent PCa not immediately requiring ADT and with Ga68-PSMA PET detected oligometastasis. SBRT will be delivered with 30Gy/3# to lymph nodes or 24Gy/2# to bone metastasis. Durvalumab will be continued to a maximum of 12 months. Primary outcomes will be freedom from biochemical failure and toxicity. Secondary objectives include biochemical response rate, magnitude of response, overall survival, time and response to subsequent treatments and quality of life. The study is recruiting at Royal North Shore Hospital in Sydney with 18 of the planned 30 patients enrolled. Clinical trial information: ACTRN12619000097145.

FDG-PET response and outcome from anti-PD-1 therapy in metastatic melanoma

Background

Immune checkpoint inhibitor therapy has resulted in impressive and durable clinical activity for many cancers including melanoma; however, there remain few reliable predictors for long-term response. This study investigated whether [18F]2-fluoro-2-deoxy-D-glucose (FDG-PET) imaging may better predict long-term outcomes compared with standard computed tomography (CT) response criteria.

Patients and methods

Retrospective analysis of metastatic melanoma patients treated with anti-PD-1-based immunotherapy with baseline and 1-year FDG-PET and CT imaging at Melanoma Institute Australia. One-year response was determined using RECIST for CT and EORTC criteria for PET, coded as complete response (CR or CMR), partial response (PR or PMR), stable disease (SD or SMD) or progressive disease (PD or PMD). Progression-free survival (PFS) was determined from the 1-year landmark.

Results

Patients (n = 104) were evaluated with median follow-up 30.1 months and 98% remain alive. Most received anti-PD-1 as monotherapy (67%) or combined with ipilimumab (31%). At 1 year, 28% had CR, 66% had PR and 6% had SD on CT, while 75% had CMR, 16% PMR and 9% SMD/PMD on PET. CMR was observed in 68% of patients with PR on CT. RECIST PFS post 1-year landmark was similar in patients with CR versus PR/SD, but improved in patients with CMR versus non-CMR {median not reached [NR] versus 12.8 month; hazard ratio [HR] 0.06 [95% confidence interval (CI) 0.02-0.23]; P < 0.01}. In patients with PR on CT, PFS was improved in patients with PR + CMR versus PR + non-CMR (median NR versus 12.8 months; HR 0.07 [95% CI 0.02-0.27]; P < 0.01). In the 78 CMR patients, 78% had discontinued treatment and 96% had ongoing response.

Conclusions

Whilst only a small proportion of patients have a CR at 1 year, most patients with a PR have CMR on PET. Almost all patients with CMR at 1 year have ongoing response to therapy thereafter. PET may have utility in predicting long-term benefit and help guide discontinuation of therapy.

Primary analysis of phase 2 results of cemiplimab, a human monoclonal anti-PD-1, in patients (pts) with locally advanced cutaneous squamous cell carcinoma (laCSCC)

6015

Background: Cemiplimab (REGN2810) produced substantial antitumor activity with durable responses in Phase 1 CSCC expansion cohorts and Phase 2 metastatic (m) CSCC cohort. We now present the primary analysis of the Phase 2 laCSCC cohort (NCT02760498; data cutoff date: Oct 10, 2018). Methods: Pts with laCSCC received cemiplimab 3 mg/kg IV every 2 weeks (Q2W). Tumor measurements were performed Q8W. The primary objective was to evaluate objective response rate (ORR; complete response [CR] + partial response [PR]) according to independent central review (per RECIST 1.1 for scans; modified WHO criteria for photos). Results: 78 pts were enrolled (59 M/ 19 F; median age: 74 years; ECOG PS: 0 in 38 pts, 1 in 40 pts; primary CSCC site: head/neck in 79.5%; prior systemic therapy: 15.4%; prior radiotherapy: 55.1%). Median duration of follow-up was 9.3 months (range: 0.8–27.9). ORR by central review was 43.6% (95% CI: 32.4–55.3; 10 CRs and 24 PRs); investigator-assessed (INV) ORR was 52.6% (95% CI: 40.9–64.0; 13 CRs and 28 PRs). Median duration of response (DOR) has not been reached. The longest DOR at data cut-off was 24.2 months and was still ongoing. Durable disease control rate (stable disease or response for ≥16 weeks) was 62.8% (95% CI: 51.1–73.5). Median observed time to response was 1.9 months (range: 1.8–8.8). Median progression-free and overall survival have not been reached. Tumor PD-L1 status is available for 48/78 pts, tumor mutational burden analysis (from targeted exome panel) is ongoing for ≥40/78 pts; response correlation analyses are planned. The most common treatment-emergent adverse events (AEs; all grades, Grade ≥3) were fatigue (42.3%, 1.3%), diarrhea and pruritus (both 26.9%, 0%), and nausea (21.8%, 0%). INV grade ≥3 immune-related AEs occurred in 10.3% of pts. One pt died due to an unknown cause that was assessed as treatment-related. Conclusions: Cemiplimab 3 mg/kg Q2W showed substantial antitumor activity, durable responses, and acceptable safety profile in pts with laCSCC. These data strongly support the recent FDA approval of cemiplimab-rwlc for pts with mCSCC or laCSCC who are not candidates for curative surgery or curative radiation. Clinical trial information: NCT02760498.

Phase 2 study of cemiplimab, a human monoclonal anti-PD-1, in patients (pts) with metastatic cutaneous squamous cell carcinoma (mCSCC; Group 1): 12-month follow-up

9526

Background: Primary analysis (Oct 2017) of cemiplimab (REGN2810) in pts with mCSCC in a Phase 2 study demonstrated substantial antitumor activity, durable responses, and acceptable safety profile. We now report 12-month follow-up data from these pts (NCT02760498; data cutoff date: Sep 20, 2018). Methods: Pts with mCSCC received cemiplimab 3 mg/kg IV every 2 weeks (Q2W). Tumor measurements were performed Q8W. The primary objective was to evaluate objective response rate (ORR; complete response [CR] + partial response [PR]) according to independent central review (per RECIST 1.1 for scans; modified WHO criteria for photos). Results: 59 pts (median age: 71 years) were enrolled. Median duration of follow-up was 16.5 months (range: 1.1–26.6). ORR by central review was 49.2% (95% CI: 35.9–62.5; 10 CRs and 19 PRs [4 CRs and 25 PRs by investigator-assessment (INV)]). Median duration of response (DOR) has not been reached. The longest DOR at data cut-off was 21.6 months and was still ongoing. Observed DOR exceeded 12 months in 22/29 pts (75.9%) with response. Durable disease control rate (stable disease or response for ≥16 weeks) was 62.7% (95% CI: 49.1–75.0). Median observed time to response was 1.9 months (range: 1.7–9.1). Median progression-free survival was 18.4 months (95% CI: 7.3–not evaluable); median overall survival has not been reached. The most common treatment-emergent adverse events (all grades, Grade ≥3) were diarrhea (28.8%, 1.7%), fatigue (25.4%, 1.7%), and nausea (23.7%, 0%). By INV, grade ≥3 immune-related adverse events occurred in 13.6% of pts. Conclusions: This analysis demonstrates substantial antitumor activity and increasing DOR with cemiplimab 3 mg/kg Q2W in pts with mCSCC. There were no new safety signals. These data strongly support the recent FDA approval of cemiplimab-rwlc for pts with mCSCC or locally advanced CSCC who are not candidates for curative surgery or curative radiation. Clinical trial information: NCT02760498.

Analysis of circulating tumor DNA (ctDNA) in pseudoprogression in anti-PD1 treated metastatic melanoma (MM)

9546

Background: We have previously shown that undetectable ctDNA either at baseline or during therapy predicted response in mm patients (pts) treated with anti-PD1 antibodies (aPD1). Pseudoprogression, defined as radiological progression prior to response, occurs in 8% of pts treated with aPD1. We sought to determine if ctDNA could differentiate pseudoprogression from true progression, defined as continued clinical or radiological disease progression. Methods: Between July 2014 and May 2016, pts receiving aPD1 had serial bloods for ctDNA. Included pts either had RECIST PD at first restaging or early clinical progression. Those with untreated brain metastases were excluded from the analysis. ctDNA was quantified using digital droplet PCR for mutations (BRAF/NRAS) at baseline and during the first 12 wks of treatment. Based on our prior studies, ctDNA results were grouped in to ‘favorable’ and ‘unfavorable’ ctDNA profiles (see Table), and these were compared in pts with true and pseudoprogression. Results: 29 pts were included, 28 with RECIST PD at first restaging and one with early clinical progression. 9 (31%) pts had a subsequent RECIST PR or SD and were considered pseudoprogression and 20 (69%) had true progression. Of the pseudoprogressors, 7/9 pts remained in response with a median follow-up of 20 months (mths). 2/9 pts had disease progression at 7 and 18 mths, with ctDNA that remained detectable with a > 10-fold decrease during treatment in both patients. Of those with true progression and a favourable profile, 1 had a > 10-fold decrease in ctDNA by wk 12 and was switched to MAPK therapy prior to further imaging, and the other had an undetectable ctDNA at wk 6 which increased again at wk 12. The latter pt had a new lesion on first restaging CT scan despite PR in all existing lesions with true PD on second restaging at wk 24. Conclusions: ctDNA in patients with mm at baseline and early on aPD1 treatment differentiates pseudo from true progression. [Table: see text]

Characteristics and outcomes of oncology patients requiring admission to an Australian intensive care unit

e21653

Background: Patients with advanced malignancies have historically been considered poor candidates for the intensive care unit (ICU), however survival and prognosis is continually improving and requirements for use of intensive care services is increasing. This study aimed to understand the characteristics and outcomes of oncology patients admitted to an Australian ICU and identify potential prognostic factors. Methods: A single-centre, retrospective, cohort study was conducted at Royal North Shore Hospital, a tertiary public hospital in Sydney, Australia with a 58-bed quaternary ICU. All patients aged > 18 years, admitted under the medical oncology team requiring ICU admission between June 2014 and June 2016 were evaluated. Data collected included basic demographics, cancer type and status, performance status (ECOG) and co-morbidities (ACE-27 score). Clinical outcomes were determined including ICU and hospital mortality, requirements (ventilation, dialysis, vasopressors, infection) and APACHE II scores. Results: There were 96 patients admitted to the ICU during the study period. Mean age was 61 years, 58% were male and 76% had metastatic disease. Most patients were receiving palliative treatment (89%), with recent chemotherapy (43%), immunotherapy (10%) and other therapies (5%). Of the 10 patients with recent immunotherapy, three (all melanoma) required ICU admission due to immunotoxicity with all three alive at time of data collection (mean 222 days follow-up). 13% were admitted due to an oncological emergency. Most common primary tumour site was thoracic (20%), genitourinary (11%), breast (10%) and melanoma (10%). Mean APACHE II score was 17 (SD 5.33), mean SOFA score was 4 (SD 2.70), ICU mortality was 5% and hospital mortality was 22%. For the 75 patients (78%) discharged from hospital, 42 (56%) were still alive at time of data collection (mean 321 days follow-up). Conclusions: Our patient population had good short-term outcomes for survival despite most receiving palliative treatment, although prognostic scores were also favourable. This suggests cancer patients can achieve positive outcomes after ICU admission with appropriate selection of patients crucial.

A randomized phase II study of nivolumab or nivolumab combined with ipilimumab in patients (pts) with melanoma brain metastases (mets): The Anti-PD1 Brain Collaboration (ABC)

9508

Background: Nivolumab (nivo) and the combination of nivo + ipilimumab (ipi) improve response rates (RR) and progression-free survival (PFS) compared with ipi alone in clinical trials of metastatic melanoma pts, but pts with untreated brain mets were excluded. Brain mets are a major cause of morbidity and mortality in melanoma and their management is critical. We sought to determine the antitumour activity and safety of nivo and nivo+ipi in pts with active melanoma brain mets (NCT02374242). Methods: This open-label, ph II trial enrolled 3 cohorts of pts naïve to anti-PD1/PDL1/PDL2/CTLA4 from Nov 2014 - Feb 2017. Pts with asymptomatic melanoma brain mets with no prior local brain therapy were randomised to cohort A (nivo 1mg/kg + ipi 3mg/kg, Q3W x4, then nivo 3mg/kg Q2W) or cohort B (nivo 3mg/kg Q2W). Cohort C (nivo 3mg/kg Q2W) had brain mets 1) that failed local therapy (new +/- progressed in previously treated met), 2) were neurologically symptomatic and/or 3) with leptomeningeal disease. Prior BRAF inhibitor (BRAFi) was allowed. The primary endpoint was best intracranial response (ICR) ≥ wk12. Secondary endpoints were best extracranial response (ECR), best overall response (OR), IC PFS, EC PFS, overall PFS, OS, and safety. Results: A total of 66 pts (med f/u 14 mo) were included in this analysis of total 76 planned; median age 60y, 77% male. For cohorts A, B and C: elevated LDH 48%, 58% and 19%; V600BRAF 44%, 56% and 81%; prior BRAFi 24%, 24%, 75%. Table shows RR, PFS and OS. ICR in cohort A treatment naïve vs prior BRAFi was 53% vs 16%. Treatment-related gd 3/4 toxicity in cohorts A, B and C were 68%, 40% and 56%, respectively. There were no treatment-related deaths. Conclusions:Nivo monotherapy and ipi+nivo and are active in melanoma brain mets. Ipi+nivo had reduced activity in pts who progressed on BRAFi. Pts with symptomatic brain mets, leptomeningeal mets or previous local therapy responded poorly to nivo alone. Clinical trial information: NCT02374242. [Table: see text]

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

9545

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

Open-label, multicenter safety study of vemurafenib in patients with BRAFV600 mutation–positive metastatic melanoma

9046

Background: Vemurafenib (VEM), a BRAF kinase inhibitor, has demonstrated high response rates and improved progression-free and overall survival in pts with BRAFV600mutation–positive metastatic melanoma (mM). We present interim results from predefined subgroups from a large multicenter, open-label safety study of VEM in pts with mM (NCT01307397). Methods: Pts with BRAFV600mutation–positive histologically confirmed mM received VEM (960 mg BID) as first-line therapy or subsequent to previous therapies. Assessments for safety and efficacy were made every 28 days. Results: As of Feb 29, 2012, 2,265 pts have received VEM. Pts had a median age of 54.0 (13-95) yrs and median time since diagnosis of mM of 6.2 (0-351.9) mos. 59% had received prior systemic therapy. Median time of exposure to VEM as of the cut-off date was 3 (0.03-11.24) mos for the overall population and majority of subgroups, and approximately 2.5 mos for pts with ECOG ≥2 and age ≥75 yrs. 1537 (68%) pts were still receiving VEM at the cut-off date. 728 (32%) pts discontinued, most frequently because of PD (538/728 pts; 74%). Adverse events (AEs) were reported for 87% of all patients, with arthralgia (32%) and rash (26%) the most frequent. The incidences of AEs in the subgroups are summarized (Table). Although efficacy analyses are limited by the short duration of follow-up, six-month OS rate was 76% (95% CI 72-79%) and median PFS was 4.1 mos (95% CI 3.9-4.5 mos). Postbaseline tumor assessments were available for 63% and 30% of pts at wk 8 and 16, respectively. At wk 8 CR: 2%, PR: 57%, SD: 30%, PD: 6%. At wk 16 CR: 3%, PR: 46%, SD: 31%, PD: 15%. Conclusions: Although the overall safety profile of VEM in this study was consistent with previous clinical data, interim analyses of subgroups suggest that very elderly pts may be at higher risk of G3 AEs. Clinical trial information: NCT01307397. [Table: see text]

Nab-paclitaxel salvage chemotherapy for metastatic ocular melanoma

e19042

Background: Metastatic ocular melanoma is an incurable malignancy characterised by liver predominant involvement. Conventional systemic chemotherapy using drugs such as fotemustine or dacarbizine have low response rates. In liver only disease hepatic arterial infusion of fotemustine has reported a higher response rate. Methods: We report four prospectively followed patients who all received salvage treatment with Nab-paclitaxel after previous intra-arterial fotemustine for metasatic ocular melanoma. Results: One patient who did not respond to to intra-arterial chemotherapy had a radiological response to Nab-paclitaxel with a duration of six months (5 cycles of treatment) with subsequent progression inliver and CNS. Another patient had rapidly progressing liver, peritoneal and nodal metastases with elevated bilirubin. He received dose reduced Nab-paclitaxel sith significant biochemical, radiological and functional improvement. He continues on Nab-paclitaxel in ongoing partial remission and remains clinically improved after six months. Two patients with similarly advanced disease, including one with abnormal bilirubin, did not respond. Subsequent treatments for the three patients progressing after Nab-paclitaxel have been SIR-Spheres followed by Ipilumumab, Ipilumumab and palliation respectively. Typical side effects of Nab-paclitaxel have occurred including alopecia, fatigue, peripheral neuropathy and neutropenia. Conclusions: In summary we have seen clinically useful responses in two of four patients treated. We continue to recruit further patients to better understand the role of Nab-paclitaxel as salvage chemotherapy for metastatic ocular melanoma.

Carboplatin and paclitaxel interact antagonistically in a megakaryoblast cell line--a potential mechanism for paclitaxel-mediated sparing of carboplatin-induced thrombocytopenia

PURPOSE

Clinical observation has shown that paclitaxel ameliorates the antiplatelet toxicity of carboplatin when the two drugs are combined, although antitumour activity and white cell toxicity are at least additive. We hypothesized that this is due to an interaction between the two drugs at the level of the platelet precursor.

METHODS

We measured inhibition of growth of the megakaryoblast cell line MEG-01 following exposure to paclitaxel and carboplatin singly or combined. Drug interaction was assessed by median effect analysis.

RESULTS

An antagonistic interaction was observed, and this was most marked at drug concentrations giving a low level of growth inhibition (P < 0.002, sign test). The interaction was not sequence-dependent. There was no significant difference in whole-cell accumulation of platinum or the amount of platinum adducts on DNA following combined treatment in comparison with carboplatin alone.

CONCLUSIONS

These results provide the first evidence of an antagonistic interaction between paclitaxel and carboplatin in a platelet precursor and provide an explanation for the platelet-sparing effect of the combination of these chemotherapeutic agents. While the mechanisms underlying the interaction described in this report are yet to be fully elucidated, this study provides evidence that the antagonism between paclitaxel and carboplatin in MEG-01 cells is not due to reduced platination of DNA.