MOONSTONE/GOG-3032: Interim analysis of a phase 2 study of niraparib + dostarlimab in patients (pts) with platinum-resistant ovarian cancer (PROC)

5573

Background: PROC is poorly responsive to anticancer therapy. PARP inhibitors such as niraparib may increase neoantigen load and synergize with anti-PD-1 agents. TOPACIO reported a preliminary objective response rate (ORR: 18%) and disease control rate (DCR: 65%) to niraparib + pembrolizumab in pts with OC of any BRCA status. MOONSTONE sought to determine efficacy in pts without BRCA mutation ( BRCAm). Methods: In this phase 2 open-label, single-arm study, eligible pts received 1–3 prior lines of therapy including platinum, taxane, and bevacizumab, had RECIST v1.1 radiographic progression within 6 mo of last platinum line and had no known germline BRCAm. Pts were treated with niraparib 300/200 mg PO daily (based on weight/platelets) and 500 mg dostarlimab IV Q3W (cycles 1–4) followed by 1000 mg Q6W until disease progression, toxicity or consent withdrawal. Programmed death-ligand 1 (PD-L1) positive status was determined by Ventana SP263 assay using visually-estimated combined positive score ≥5%. The primary endpoint was investigator-assessed ORR per RECIST v1.1. Secondary endpoints included duration of response (DOR), progression-free survival (PFS), DCR, and safety. Futility was prespecified as ≤5 responses in the first 40 pts. Results: At interim analysis (data cutoff Oct 6, 2021), 41 pts were enrolled; median age was 65.0 y (range 35–77). At baseline, 8 (20%)/22 (54%)/11 (27%) pts had received 1/2/3 prior lines of therapy, respectively; 26 (63%) pts had primary resistance to platinum therapy and 15 (37%) were sensitive to first platinum treatment. Overall, tumors were PD-L1+/PD-L1–/unknown in 13 (32%)/25 (61%)/3 (7%), respectively. Efficacy results are shown in the Table. Treatment-related adverse events were reported in 95% of pts, most commonly nausea (56%), fatigue (34%), vomiting (32%), and anemia (29%). Conclusions: PROC remains difficult to treat; the ORR observed with niraparib + dostarlimab did not reach the threshold for 2nd-stage accrual in this cohort of pts with PROC, no known BRCAm, and prior bevacizumab treatment. PD-L1 status did not predict response; HRD testing is in process. Although DCR was 29%, futility was declared based on low ORR. The safety of the combination was similar to the safety profile of each monotherapy. Clinical trial information: NCT03955471. [Table: see text]

Pembrolizumab in Patients With Microsatellite Instability-High Advanced Endometrial Cancer: Results From the KEYNOTE-158 Study

PURPOSE

Pembrolizumab demonstrated durable antitumor activity in patients with previously treated, advanced microsatellite instability-high or mismatch repair-deficient (MSI-H/dMMR) tumors, including endometrial cancer, in the nonrandomized, open-label, multicohort, phase II KEYNOTE-158 study (NCT02628067). We report efficacy and safety outcomes for patients with MSI-H/dMMR endometrial cancer enrolled in KEYNOTE-158.

METHODS

Eligible patients from cohorts D (endometrial cancer, regardless of MSI-H/dMMR status) and K (any MSI-H/dMMR solid tumor, except colorectal) with previously treated, advanced MSI-H/dMMR endometrial cancer received pembrolizumab 200 mg once every 3 weeks for 35 cycles. The primary end point was objective response rate per RECIST version 1.1 by independent central radiologic review. Secondary end points included duration of response, progression-free survival, overall survival, and safety.

RESULTS

As of October 5, 2020, 18 of 90 treated patients (20%) had completed 35 cycles of pembrolizumab and 52 (58%) had discontinued treatment. In the efficacy population (patients who received ≥ 1 dose of pembrolizumab and had ≥ 26 weeks of follow-up; N = 79), the median time from first dose to data cutoff was 42.6 (range, 6.4-56.1) months. The objective response rate was 48% (95% CI, 37 to 60), and median duration of response was not reached (2.9-49.7+ months). Median progression-free survival was 13.1 (95% CI, 4.3 to 34.4) months, and median overall survival was not reached (95% CI, 27.2 months to not reached). Among all treated patients, 76% had ≥ 1 treatment-related adverse event (grades 3-4, 12%). There were no fatal treatment-related events. Immune-mediated adverse events or infusion reactions occurred in 28% of patients (grades 3-4, 7%; no fatal events).

CONCLUSION

Pembrolizumab demonstrated robust and durable antitumor activity and encouraging survival outcomes with manageable toxicity in patients with previously treated, advanced MSI-H/dMMR endometrial cancer.

Dual PD-1 and CTLA-4 Checkpoint Blockade Using Balstilimab and Zalifrelimab Combination as Second-Line Treatment for Advanced Cervical Cancer: An Open-Label Phase II Study

PURPOSE

Balstilimab (antiprogrammed death-1) and zalifrelimab (anticytotoxic T-lymphocyte-associated antigen-4) are two new checkpoint inhibitors emerging as promising investigational agents for the treatment of advanced cervical cancer. This phase II trial (ClinicalTrials.gov identifier: NCT03495882) evaluated the combination of balstilimab plus zalifrelimab in patients with recurrent and/or metastatic cervical cancer who relapsed after prior platinum-based therapy.

PATIENTS AND METHODS

Patients were intravenously dosed with balstilimab 3 mg/kg once every 2 weeks and zalifrelimab 1 mg/kg once every 6 weeks, for up to 24 months. The primary end point was objective response rate (ORR, RECIST version 1.1, assessed by independent central review). Secondary end points included duration of response, safety and tolerability, and survival.

RESULTS

In total, 155 women (median age, 50 years [range, 24-76 years]) were enrolled and treated with balstilimab plus zalifrelimab; 125 patients had measurable disease at baseline and one prior line of platinum-based therapy in the advanced setting, and these patients constituted the efficacy-evaluable population. The median follow-up was 21 months. The confirmed ORR was 25.6% (95% CI, 18.8 to 33.9), including 10 complete responders and 22 partial responders, with median duration of response not reached (86.5%, 75.5%, and 64.2% at 6, 9, and 12 months, respectively). The ORRs were 32.8% and 9.1% in patients with programmed death ligand-1-positive and programmed death ligand-1-negative tumors, respectively. For patients with squamous cell carcinoma, the ORR was 32.6%. The overall disease control rate was 52% (95% CI, 43.3 to 60.6). Hypothyroidism (14.2%) and hyperthyroidism (7.1%) were the most common immune-mediated adverse events.

CONCLUSION

Promising and durable clinical activity, with favorable tolerability, was seen in this largest trial to date evaluating dual programmed death-1/cytotoxic T-lymphocyte-associated antigen-4 blockade in patients with recurrent and/or metastatic cervical cancer. Further investigation of the balstilimab and zalifrelimab combination in this setting is continuing.

Trametinib versus standard of care in patients with recurrent low-grade serous ovarian cancer (GOG 281/LOGS): an international, randomised, open-label, multicentre, phase 2/3 trial

BACKGROUND

Low-grade serous carcinoma of the ovary or peritoneum is characterised by MAPK pathway aberrations and its reduced sensitivity to chemotherapy relative to high-grade serous carcinoma. We compared the MEK inhibitor trametinib to physician's choice standard of care in patients with recurrent low-grade serous carcinoma.

METHODS

This international, randomised, open-label, multicentre, phase 2/3 trial was done at 84 hospitals in the USA and UK. Eligible patients were aged 18 years or older with recurrent low-grade serous carcinoma and measurable disease, as defined by Response Evaluation Criteria In Solid Tumors version 1.1, had received at least one platinum-based regimen, but not all five standard-of-care drugs, and had received an unlimited number of previous regimens. Patients with serous borderline tumours or tumours containing low-grade serous and high-grade serous carcinoma were excluded. Eligible patients were randomly assigned (1:1) to receive either oral trametinib 2 mg once daily (trametinib group) or one of five standard-of-care treatment options (standard-of-care group): intravenous paclitaxel 80 mg/m2 by body surface area on days 1, 8, and 15 of every 28-day cycle; intravenous pegylated liposomal doxorubicin 40-50 mg/m2 by body surface area once every 4 weeks; intravenous topotecan 4 mg/m2 by body surface area on days 1, 8, and 15 of every 28-day cycle; oral letrozole 2·5 mg once daily; or oral tamoxifen 20 mg twice daily. Randomisation was stratified by geographical region (USA or UK), number of previous regimens (1, 2, or ≥3), performance status (0 or 1), and planned standard-of-care regimen. The primary endpoint was investigator-assessed progression-free survival while receiving randomised therapy, as assessed by imaging at baseline, once every 8 weeks for 15 months, and then once every 3 months thereafter, in the intention-to-treat population. Safety was assessed in patients who received at least one dose of study therapy. This trial is registered with ClinicalTrials.gov, NCT02101788, and is active but not recruiting.

FINDINGS

Between Feb 27, 2014, and April 10, 2018, 260 patients were enrolled and randomly assigned to the trametinib group (n=130) or the standard-of-care group (n=130). At the primary analysis, there were 217 progression-free survival events (101 [78%] in the trametinib group and 116 [89%] in the standard-of-care group). Median progression-free survival in the trametinib group was 13·0 months (95% CI 9·9-15·0) compared with 7·2 months (5·6-9·9) in the standard-of-care group (hazard ratio 0·48 [95% CI 0·36-0·64]; p<0·0001). The most frequent grade 3 or 4 adverse events in the trametinib group were skin rash (17 [13%] of 128), anaemia (16 [13%]), hypertension (15 [12%]), diarrhoea (13 [10%]), nausea (12 [9%]), and fatigue (ten [8%]). The most frequent grade 3 or 4 adverse events in the standard-of-care group were abdominal pain (22 [17%]), nausea (14 [11%]), anaemia (12 [10%]), and vomiting (ten [8%]). There were no treatment-related deaths.

INTERPRETATION

Trametinib represents a new standard-of-care option for patients with recurrent low-grade serous carcinoma.

FUNDING

NRG Oncology, Cancer Research UK, Target Ovarian Cancer, and Novartis.

Safety and antitumor activity of dostarlimab in patients with advanced or recurrent DNA mismatch repair deficient/microsatellite instability-high (dMMR/MSI-H) or proficient/stable (MMRp/MSS) endometrial cancer: interim results from GARNET—a phase I, single-arm study

Background

Dostarlimab is a humanized monoclonal antibody that binds with high affinity to PD-1, resulting in inhibition of binding to PD-L1 and PD-L2. We report interim data from patients with endometrial cancer (EC) participating in a phase I trial of single-agent dostarlimab.

Methods

GARNET, an ongoing, single-arm, open-label, phase I trial of intravenous dostarlimab in advanced solid tumors, is being undertaken at 123 sites. Two cohorts of patients with EC were recruited: those with dMMR/MSI-H disease (cohort A1) and those with proficient/stable (MMRp/MSS) disease (cohort A2). Patients received dostarlimab 500 mg every 3 weeks for 4 cycles, then dostarlimab 1000 mg every 6 weeks until disease progression. The primary endpoints were objective response rate (ORR) and duration of response (DOR) per RECIST V.1.1, as assessed by blinded independent central review.

Results

Screening began on April 10, 2017, and 129 and 161 patients with advanced EC were enrolled in cohorts A1 and A2, respectively. The median follow-up duration was 16.3 months (IQR 9.5–22.1) for cohort A1 and 11.5 months (IQR 11.0–25.1) for cohort A2. In cohort A1, ORR was 43.5% (95% CI 34.0% to 53.4%) with 11 complete responses and 36 partial responses. In cohort A2, ORR was 14.1% (95% CI 9.1% to 20.6%) with three complete responses and 19 partial responses. Median DOR was not reached in either cohort. In the combined cohorts, the majority of treatment-related adverse events (TRAEs) were grade 1–2 (75.5%), most commonly fatigue (17.6%), diarrhea (13.8%), and nausea (13.8%). Grade≥3 TRAEs occurred in 16.6% of patients, and 5.5% discontinued dostarlimab because of TRAEs. No deaths were attributable to dostarlimab.

Conclusion

Dostarlimab demonstrated durable antitumor activity in both dMMR/MSI-H (ORR 43.5%) and MMRp/MSS EC (ORR 14.1%) with a manageable safety profile.

Trial registration number

NCT02715284.

Impact of veliparib, paclitaxel dosing regimen, and germline BRCA status on the primary treatment of serous ovarian cancer - an ancillary data analysis of the VELIA trial

OBJECTIVE

In the Phase 3 VELIA trial (NCT02470585), veliparib added to carboplatin plus paclitaxel concomitantly and as maintenance for women with newly-diagnosed advanced ovarian cancer significantly improved progression-free survival (PFS) versus chemotherapy alone. Here we present exploratory analyses by paclitaxel dosing schedule and germline BRCA (gBRCA) status.

METHODS

Women with untreated ovarian carcinoma were randomized (1:1:1) to: veliparib during chemotherapy and maintenance (veliparib-throughout), veliparib during chemotherapy followed by placebo maintenance (veliparib-combination only), or placebo during chemotherapy and maintenance (control). Chemotherapy included carboplatin plus dose-dense (DD; weekly) or every-3-week (Q3W) paclitaxel (a stratification factor at randomization), selected at the investigator's discretion pre-randomization. PFS was assessed by paclitaxel dosing schedule using a Cox proportional hazard model adjusted by treatment arm and stratification factors; safety was analyzed based on paclitaxel dosing schedule and gBRCA status.

RESULTS

1132 patients were analyzed by paclitaxel schedule. Pooled treatment arms demonstrated longer median PFS with DD (n = 586) versus Q3W (n = 546) paclitaxel (ITT: 20.5 vs 15.7 months, hazard ratio [HR] 0.77; homologous recombination proficient cancer: 15.1 vs 11.8 months, HR 0.64; BRCAwt: 18.0 vs 12.9 months, HR 0.70). Comparison between arms favored veliparib-throughout versus control in both DD (PFS, 24.2 vs 18.3 months, hazard ratio 0.67) and Q3W (19.3 vs 14.6, hazard ratio 0.69) subgroups. DD paclitaxel was associated with higher incidence of Grade 3/4 neutropenia, fatigue, and anemia versus Q3W. There were no differences in toxicity between gBRCAm (n = 211) and gBRCAwt (n = 902) subgroups.

CONCLUSIONS

DD paclitaxel was tolerable and associated with longer PFS in the HR proficient and gBRCAwt groups, versus Q3W. gBRCA status did not impact safety.

Impact of homologous recombination status and responses with veliparib combined with first-line chemotherapy in ovarian cancer in the Phase 3 VELIA/GOG-3005 study

OBJECTIVE

In the Phase 3 VELIA trial (NCT02470585), PARP inhibitor (PARPi) veliparib was combined with first-line chemotherapy and continued as maintenance for patients with ovarian carcinoma enrolled regardless of chemotherapy response or biomarker status. Here, we report exploratory analyses of the impact of homologous recombination deficient (HRD) or proficient (HRP) status on progression-free survival (PFS) and objective response rates during chemotherapy.

METHODS

Women with Stage III-IV ovarian carcinoma were randomized to veliparib-throughout, veliparib-combination-only, or placebo. Stratification factors included timing of surgery and germline BRCA mutation status. HRD status was dichotomized at genomic instability score 33. During combination therapy, CA-125 levels were measured at baseline and each cycle; radiographic responses were assessed every 9 weeks.

RESULTS

Of 1140 patients randomized, 742 had BRCA wild type (BRCAwt) tumors (HRP, n = 373; HRD/BRCAwt, n = 329). PFS hazard ratios between veliparib-throughout versus control were similar in both BRCAwt populations (HRD/BRCAwt: 22.9 vs 19.8 months; hazard ratio 0.76; 95% confidence interval [CI] 0.53-1.09; HRP: 15.0 vs 11.5 months; hazard ratio 0.765; 95% CI 0.56-1.04). By Cycle 3, the proportion with ≥90% CA-125 reduction from baseline was higher in those receiving veliparib (pooled arms) versus control (34% vs 23%; P = 0.0004); particularly in BRCAwt and HRP subgroups. Complete response rates among patients with measurable disease after surgery were 24% with veliparib (pooled arms) and 18% with control.

CONCLUSIONS

These results potentially broaden opportunities for PARPi utilization among patients who would not qualify for frontline PARPi maintenance based on other trials.

Radiotherapy Versus Inguinofemoral Lymphadenectomy as Treatment for Vulvar Cancer Patients With Micrometastases in the Sentinel Node: Results of GROINSS-V II

PURPOSE

The Groningen International Study on Sentinel nodes in Vulvar cancer (GROINSS-V)-II investigated whether inguinofemoral radiotherapy is a safe alternative to inguinofemoral lymphadenectomy (IFL) in vulvar cancer patients with a metastatic sentinel node (SN).

METHODS

GROINSS-V-II was a prospective multicenter phase-II single-arm treatment trial, including patients with early-stage vulvar cancer (diameter < 4 cm) without signs of lymph node involvement at imaging, who had primary surgical treatment (local excision with SN biopsy). Where the SN was involved (metastasis of any size), inguinofemoral radiotherapy was given (50 Gy). The primary end point was isolated groin recurrence rate at 24 months. Stopping rules were defined for the occurrence of groin recurrences.

RESULTS

From December 2005 until October 2016, 1,535 eligible patients were registered. The SN showed metastasis in 322 (21.0%) patients. In June 2010, with 91 SN-positive patients included, the stopping rule was activated because the isolated groin recurrence rate in this group went above our predefined threshold. Among 10 patients with an isolated groin recurrence, nine had SN metastases > 2 mm and/or extracapsular spread. The protocol was amended so that those with SN macrometastases (> 2 mm) underwent standard of care (IFL), whereas patients with SN micrometastases (≤ 2 mm) continued to receive inguinofemoral radiotherapy. Among 160 patients with SN micrometastases, 126 received inguinofemoral radiotherapy, with an ipsilateral isolated groin recurrence rate at 2 years of 1.6%. Among 162 patients with SN macrometastases, the isolated groin recurrence rate at 2 years was 22% in those who underwent radiotherapy, and 6.9% in those who underwent IFL (P = .011). Treatment-related morbidity after radiotherapy was less frequent compared with IFL.

CONCLUSION

Inguinofemoral radiotherapy is a safe alternative for IFL in patients with SN micrometastases, with minimal morbidity. For patients with SN macrometastasis, radiotherapy with a total dose of 50 Gy resulted in more isolated groin recurrences compared with IFL.

Characterization of patients with long-term responses to rucaparib treatment in recurrent ovarian cancer

OBJECTIVE

To describe molecular and clinical characteristics of patients with high-grade recurrent ovarian carcinoma (HGOC) who had long-term responses to the poly(ADP-ribose) polymerase (PARP) inhibitor rucaparib.

METHODS

This post hoc analysis pooled patients from Study 10 (NCT01482715; Parts 2A and 2B; n = 54) and ARIEL2 (NCT01891344; Parts 1 and 2; n = 491). Patients with investigator-assessed complete or partial response per RECIST were classified based on duration of response (DOR): long (≥1 year), intermediate (6 months to <1 year), or short (<6 months). Next-generation sequencing was used to detect deleterious mutations and loss of heterozygosity (LOH) in tumors.

RESULTS

Overall, 25.3% (138/545) of enrolled patients were responders. Of these, 27.5% (38/138) had long-term responses; 28.3% (39/138) were intermediate- and 34.8% (48/138) were short-term responders. Most of the long-term responders harbored a BRCA1 or BRCA2 (BRCA) mutation (71.1%, 27/38), and BRCA structural variants were most frequent among long-term responders (14.8%; 4/27). Responders with HGOC harboring a BRCA structural variant (n = 5) had significantly longer DOR than patients with other mutation types (n = 81; median not reached vs 0.62 years; HR, 0.21; 95% CI, 0.10-0.43; unadjusted p = 0.014). Among responders with BRCA wild-type HGOC, most long- and intermediate-term responders had high genome-wide LOH: 81.8% (9/11) and 76.9% (10/13), respectively, including 7 with deleterious RAD51C, RAD51D, or CDK12 mutations.

CONCLUSION

Among patients who responded to rucaparib, a substantial proportion achieved responses lasting ≥1 year. These analyses demonstrate the relationship between DOR to PARP inhibitor treatment and molecular characteristics in HGOC, such as presence of reversion-resistant BRCA structural variants.

ATHENA (GOG-3020/ENGOT-ov45): a randomized, phase III trial to evaluate rucaparib as monotherapy (ATHENA-MONO) and rucaparib in combination with nivolumab (ATHENA-COMBO) as maintenance treatment following frontline platinum-based chemotherapy in ovarian cancer

Background

The optimal treatment strategy for women with newly diagnosed ovarian cancer has yet to be determined. Poly(ADP-ribose) polymerase (PARP) inhibitors have demonstrated substantial improvement in progression-free survival as monotherapy maintenance treatment in the frontline setting versus active surveillance. Furthermore, preclinical and early clinical studies have shown that PARP inhibitors and immune checkpoint inhibitors have synergistic antitumor activity and may provide an additional therapeutic option for patients in this population.

Primary Objectives

In women with newly diagnosed ovarian, fallopian tube, or peritoneal cancer, we wish to assess the efficacy of frontline maintenance treatment with the PARP inhibitor rucaparib versus placebo following response to platinum-based chemotherapy (ATHENA–MONO), and to assess the combination of rucaparib plus nivolumab (a programmed death receptor 1 (PD-1)–blocking monoclonal antibody) versus rucaparib alone (ATHENA–COMBO).

Study Hypothesis

(1) Maintenance therapy with rucaparib monotherapy may extend progression-free survival following standard treatment for ovarian cancer in the frontline setting. (2) The combination of nivolumab plus rucaparib may extend progression-free survival following standard treatment for ovarian cancer in the frontline setting compared with rucaparib alone.

Trial Design

ATHENA is an international, randomized, double-blind, phase III trial consisting of two independent comparisons (ATHENA–MONO and ATHENA–COMBO) in patients with newly diagnosed platinum-sensitive ovarian cancer. Patients are randomized 4:4:1:1 to the following: oral rucaparib+ intravenous nivolumab (arm A); oral rucaparib + intravenous placebo (arm B); oral placebo+ intravenous nivolumab (arm C); and oral placebo + intravenous placebo (arm D). The starting dose of rucaparib is 600 mg orally twice a day and nivolumab 480 mg intravenously every 4 weeks. ATHENA–MONO compares arm B with arm D to evaluate rucaparib monotherapy versus placebo, and ATHENA–COMBO evaluates arm A versus arm B to investigate the effects of rucaparib and nivolumab in combination versus rucaparib monotherapy. ATHENA–MONO and ATHENA–COMBO share a common treatment arm (arm B) but each comparison is independently powered.

Major Inclusion/Exclusion Criteria

Patients ≥18 years of age with newly diagnosed advanced, high-grade epithelial ovarian, primary peritoneal, or fallopian tube cancer who have achieved a response after completion of cytoreductive surgery and initial platinum-based chemotherapy are enrolled. No other prior treatment for ovarian cancer, other than the frontline platinum regimen, is permitted.

Primary Endpoint

The primary endpoint is investigator-assessed progression-free survival by Response Evaluation Criteria in Solid Tumors v1.1.

Sample Size

Approximately 1000 patients have been enrolled and randomized.

Estimated Dates for Completing Accrual and Presenting Results

The trial completed accrual in 2020. While dependent on event rates, primary results of ATHENA–MONO are anticipated in early 2022 and results of ATHENA–COMBO are anticipated to mature at a later date.

Trial Registration

This trial is registered at clinicaltrials.gov (NCT03522246).

Maintenance treatment with rucaparib for recurrent ovarian carcinoma in ARIEL3, a randomized phase 3 trial: The effects of best response to last platinum-based regimen and disease at baseline on efficacy and safety

Background

The efficacy and safety of rucaparib maintenance treatment in ARIEL3 were evaluated in subgroups based on best response to most recent platinum‐based chemotherapy and baseline disease.

Methods

Patients were randomized 2:1 to receive either oral rucaparib at a dosage of 600 mg twice daily or placebo. Investigator‐assessed PFS was assessed in prespecified, nested cohorts: BRCA‐mutated, homologous recombination deficient (HRD; BRCA mutated or wild‐type BRCA/high loss of heterozygosity), and the intent‐to‐treat (ITT) population.

Results

Median PFS for patients in the ITT population with a complete response to most recent platinum‐based chemotherapy was 11.1 months in the rucaparib arm (126 patients) versus 5.6 months in the placebo arm (64 patients) (HR, 0.33 [95% CI, 0.23–0.48]), and in patients with a partial response (249 vs. 125), it was 9.0 versus 5.3 months (HR, 0.38 [0.30–0.49]). In subgroups of the ITT population based on baseline disease, median PFS was 8.2 versus 5.3 months (HR, 0.40 [0.28–0.57]) in patients with measurable disease (141 rucaparib vs. 66 placebo), 10.4 versus 4.5 months (HR, 0.31 [0.20–0.48]) in those with nonmeasurable but evaluable disease (104 vs. 56), and 14.1 versus 7.3 months (HR, 0.35 [0.24–0.51]) in those with no residual disease (130 vs. 67). Across subgroups, significantly longer median PFS was observed with rucaparib versus placebo in the BRCA‐mutated and HRD cohorts. Objective responses were reported in patients with measurable disease and in patients with nonmeasurable but evaluable baseline disease. Safety was consistent across subgroups.

Conclusion

Rucaparib maintenance treatment provided clinically meaningful efficacy benefits across subgroups based on response to last platinum‐based chemotherapy or baseline disease.

Lurbinectedin versus pegylated liposomal doxorubicin or topotecan in patients with platinum-resistant ovarian cancer: A multicenter, randomized, controlled, open-label phase 3 study (CORAIL)

OBJECTIVE

The randomized phase 3 CORAIL trial evaluated whether lurbinectedin improved progression-free survival (PFS) compared to pegylated liposomal doxorubicin (PLD) or topotecan in patients with platinum-resistant ovarian cancer.

METHODS

Patients were randomly assigned (1:1) to lurbinectedin 3.2 mg/m² 1-h i.v. infusion q3wk (experimental arm), versus PLD 50 mg/m² 1-h i.v. infusion q4wk or topotecan 1.50 mg/m² 30-min i.v. infusion Days 1-5 q3wk (control arm). Stratification factors were PS (0 vs. ≥1), prior PFI (1-3 months vs. >3 months), and prior chemotherapy lines (1-2 vs. 3). The primary endpoint was PFS by Independent Review Committee in all randomized patients. This study was registered with ClinicalTrials.gov, NCT02421588.

RESULTS

442 patients were randomized: 221 in lurbinectedin arm and 221 in control arm (127 PLD and 94 topotecan). With a median follow-up of 25.6 months, median PFS was 3.5 months (95% CI, 2.1-3.7) in the lurbinectedin arm and 3.6 months (95% CI, 2.7-3.8) in the control arm (stratified log-rank p = 0.6294; HR = 1.057). Grade ≥ 3 treatment-related adverse events (AEs) were most frequent in the control arm: 64.8% vs. 47.9% (p = 0.0005), mainly due to hematological toxicities. The most common grade ≥ 3 AEs were: fatigue (7.3% of patients) and nausea (5.9%) with lurbinectedin; mucosal inflammation (8.5%) and fatigue (8.0%) in the control arm.

CONCLUSIONS

The primary endpoint of improvement in PFS was not met. Lurbinectedin showed similar antitumor efficacy and was better tolerated than current standard of care in patients with platinum-resistant ovarian cancer.

Phase II study of the safety and efficacy of the anti-PD-1 antibody balstilimab in patients with recurrent and/or metastatic cervical cancer

OBJECTIVE

This phase II clinical trial evaluated the safety and antitumor activity of balstilimab, an anti-PD-1 antibody, in patients with previously-treated, recurrent/metastatic cervical cancer.

METHODS

Eligible patients were 18 years or older with recurrent and/or metastatic cervical cancer and who had relapsed after a prior platinum-based treatment regimen for advanced disease. Balstilimab was administered intravenously at 3 mg/kg once every two weeks, for up to 24 months. The primary endpoint was objective response rate (ORR, RECIST v1.1) as assessed by an independent review committee.

RESULTS

At data cutoff, 161 women (median age, 53 years [range 25-81]) were enrolled and treated with balstilimab. Of these, 140 had measurable disease at baseline and one prior line of platinum-based therapy in the metastatic, persistent, or recurrent setting; these patients were included in the efficacy analyses. The ORR was 15% (95% CI, 10.0%-21.8%) and included 5 patients with a complete response and 16 with a partial response. The median duration of response was 15.4 months. In patients with PD-L1-positive tumors the ORR was 20%, however patients with PD-L1-negative tumors also responded to balstilimab (ORR, 7.9%). Responses were not restricted to tumors of squamous cell histology, and an ORR of 12.5% was seen in the subset of patients with cervical adenocarcinoma. The disease control rate was 49.3% (95% CI, 41.1%-57.5%). Immune-mediated enterocolitis (3.1%) and diarrhea (1.9%) were the most common grade 3 or higher treatment-related adverse events.

CONCLUSION

Balstilimab demonstrated meaningful and durable clinical activity, with manageable safety, in patients with previously-treated, recurrent/metastatic cervical cancer.

RaPiDS (GOG-3028): randomized Phase II study of balstilimab alone or in combination with zalifrelimab in cervical cancer

Balstilimab (anti-programmed death 1) and zalifrelimab (anti-CTLA-4) are two new checkpoint inhibitors that have emerged as promising investigational agents for the treatment of cervical cancer, particularly in the setting of previously-treated, recurrent/metastatic disease. Here we describe the rationale and design of RaPiDS (NCT03894215), a two-arm Phase II study evaluating the safety, tolerability and efficacy of balstilimab administered alone or in combination with zalifrelimab in patients with advanced cervical cancer who progressed after first-line, platinum-based chemotherapy. Patients will be randomized in a 1:1 ratio. The primary end point is objective response rate, and key secondary objectives include safety, duration of response, progression-free survival, overall survival and quality of life outcomes.

Characterization and Management of Adverse Reactions in Patients with Advanced Endometrial Carcinoma Treated with Lenvatinib Plus Pembrolizumab

BACKGROUND

The combination of lenvatinib plus pembrolizumab has shown efficacy in treatment of advanced endometrial carcinoma (that is not microsatellite instability-high or mismatch repair deficient) following prior systemic therapy in any setting in the open-label, single-arm, phase Ib/II Study 111/KEYNOTE-146. With the exception of hypothyroidism, the safety profile of the combination was comparable to that of each monotherapy. Given the medical complexity and fragility of patients with endometrial carcinoma, further characterization of adverse reactions (ARs) associated with treatment will help health care professionals to optimize treatment with lenvatinib plus pembrolizumab combination therapy.

PATIENTS AND METHODS

In Study 111/KEYNOTE-146, patients received lenvatinib at a starting dose of 20 mg orally once daily and pembrolizumab 200 mg intravenously every 3 weeks. Selected ARs (hypertension, fatigue, nausea/vomiting, diarrhea, decreased appetite/weight loss, hypothyroidism, palmar-plantar erythrodysesthesia syndrome, musculoskeletal pain, stomatitis, and proteinuria) were chosen for detailed post hoc analyses.

RESULTS

Median times to first onset of the selected ARs in this analysis all occurred within the first 10 weeks of treatment. Of the selected ARs, grade ≥3 severity of fatigue, hypertension, and nausea occurred in ≥5% of patients. Overall incidence of hypothyroidism was 51%, primarily of grade 2 severity (46%). Most of the ARs assessed were managed with a combination of study drug dose modifications and concomitant medications.

CONCLUSION

No new safety signals were identified and the toxicity profile in this study was manageable with supportive medications, dose interruptions, and/or lenvatinib dose reductions. This analysis provides AR management guidance for patients with endometrial cancer receiving lenvatinib plus pembrolizumab combination therapy.

IMPLICATIONS FOR PRACTICE

Lenvatinib plus pembrolizumab has shown efficacy in the treatment of patients with advanced endometrial carcinoma (that is, not microsatellite instability-high or mismatch repair deficient) following at least one prior systemic therapy in any setting. Patients may experience toxicity associated with this combination, including adverse reactions of hypertension, fatigue, nausea/vomiting, diarrhea, decreased appetite/weight loss, hypothyroidism, palmar-plantar erythrodysesthesia syndrome, musculoskeletal pain, stomatitis, and proteinuria. These adverse reactions may be managed with a combination of concomitant supportive care medications and judicious lenvatinib dose modifications. This article provides context and guidance for the recognition and management of adverse reactions in patients receiving lenvatinib plus pembrolizumab.

Rucaparib maintenance treatment for recurrent ovarian carcinoma: the effects of progression-free interval and prior therapies on efficacy and safety in the randomized phase III trial ARIEL3

INTRODUCTION

In ARIEL3 (NCT01968213), the poly(adenosine diphosphate-ribose) polymerase inhibitor rucaparib significantly improved progression-free survival versus placebo regardless of biomarker status when used as maintenance treatment for recurrent ovarian cancer. The aim of the current analyses was to evaluate the efficacy and safety of rucaparib in subgroups based on progression-free interval following penultimate platinum, number of prior chemotherapies, and prior use of bevacizumab.

METHODS

Patients were randomized 2:1 to rucaparib 600 mg twice daily or placebo. Within subgroups, progression-free survival was assessed in prespecified, nested cohorts: BRCA-mutant, homologous recombination deficient (BRCA-mutant or wild-type BRCA/high genomic loss of heterozygosity), and the intent-to-treat population.

RESULTS

In the intent-to-treat population, median investigator-assessed progression-free survival was 8.2 months with rucaparib versus 4.1 months with placebo (n=151 vs n=76; HR 0.33, 95% CI 0.24 to 0.46, p<0.0001) for patients with progression-free interval 6 to ≤12 months, and 13.6 versus 5.6 months (n=224 vs n=113; HR 0.39, 95% CI 0.30 to 0.52, p<0.0001) for those with progression-free interval >12 months. Median progression-free survival was 10.4 versus 5.4 months (n=231 vs n=124; HR 0.42, 95% CI 0.32 to 0.54, p<0.0001) for patients who had received two prior chemotherapies, and 11.1 versus 5.3 months (n=144 vs n=65; HR 0.28, 95% CI 0.19 to 0.41, p<0.0001) for those who had received ≥3 prior chemotherapies. Median progression-free survival was 10.3 versus 5.4 months (n=83 vs n=43; HR 0.42, 95% CI 0.26 to 0.68, p=0.0004) for patients who had received prior bevacizumab, and 10.9 versus 5.4 months (n=292 vs n=146; HR 0.35, 95% CI 0.28 to 0.45, p<0.0001) for those who had not. Across subgroups, median progression-free survival was also significantly longer with rucaparib versus placebo in the BRCA-mutant and homologous recombination deficient cohorts. Safety was consistent across subgroups.

CONCLUSIONS

Rucaparib maintenance treatment significantly improved progression-free survival versus placebo irrespective of progression-free interval following penultimate platinum, number of lines of prior chemotherapy, and previous use of bevacizumab.

Rationale for combination PARP inhibitor and antiangiogenic treatment in advanced epithelial ovarian cancer: A review

Inhibitors of poly(ADP-ribose) polymerase (PARP) and angiogenesis have demonstrated single-agent activity in women with advanced ovarian cancer. Recent studies have aimed to establish whether combination therapy can augment the response seen with PARP inhibitors or antiangiogenic agents alone. This review provides an overview of PARP inhibitors and antiangiogenics as monotherapy in women with advanced ovarian cancer, explores potential mechanisms of action of PARP inhibitor and antiangiogenic combination treatments, reviews efficacy and safety data from trials evaluating this combination, and outlines ongoing and future trials evaluating this combination, discussing these in the context of the current and future treatment landscape for women with advanced ovarian cancer. Sentinel studies evaluating PARP inhibitor (n = 8), antiangiogenic (n = 4), and combination (n = 7) therapy were identified in women with newly diagnosed (n = 7) and recurrent (n = 12) ovarian cancer. PARP inhibitors included olaparib (n = 9), niraparib (n = 4), rucaparib (n = 1), and veliparib (n = 1). Antiangiogenic agents included bevacizumab (n = 7) and cediranib (n = 4). PARP inhibitors combined with antiangiogenics demonstrated efficacy based on objective response rates and progression-free survival (PFS) in the relapsed disease setting. Maintenance therapy with the PARP inhibitor, olaparib, plus antiangiogenic therapy offered a significant PFS benefit versus the antiangiogenic alone in women with newly diagnosed advanced ovarian cancer who tested positive for homologous recombination deficiency. Combination therapy was tolerated, with no new safety signals reported compared with monotherapy trials. PARP inhibitors and antiangiogenics have changed the landscape of ovarian cancer treatment. The PARP inhibitor plus antiangiogenic combination is a novel treatment option that appears promising in the first-line advanced and recurrent ovarian cancer settings, although the role of this combination in recurrent disease requires further elucidation. Defining which patients are candidates for monotherapy or combination therapy is critical, taking into consideration safety profiles of therapies alone or in combination, and how these treatments should be sequenced in clinical practice.

Population exposure-efficacy and exposure-safety analyses for rucaparib in patients with recurrent ovarian carcinoma from Study 10 and ARIEL2

OBJECTIVE

To evaluate correlations between rucaparib exposure and selected efficacy and safety endpoints in patients with recurrent ovarian carcinoma using pooled data from Study 10 and ARIEL2.

METHODS

Efficacy analyses were limited to patients with carcinomas harboring a deleterious BRCA1 or BRCA2 mutation who had received ≥2 prior lines of chemotherapy. Safety was evaluated in all patients who received ≥1 rucaparib dose. Steady-state daily area under the concentration-time curve (AUCss) and maximum concentration (Cmax,ss) for rucaparib were calculated for each patient and averaged by actual dose received over time (AUCavg,ss and Cmax,avg,ss) using a previously developed population pharmacokinetic model.

RESULTS

Rucaparib exposure was dose-proportional and not associated with baseline patient weight. In the exposure-efficacy analyses (n = 121), AUCavg,ss was positively associated with independent radiology review-assessed RECIST response in the subgroup of patients with platinum-sensitive recurrent disease (n = 75, p = 0.017). In the exposure-safety analyses (n = 393, 40 mg once daily to 840 mg twice daily [BID] starting doses), most patients received a 600 mg BID rucaparib starting dose, with 27% and 21% receiving 1 or ≥2 dose reductions, respectively. Cmax,ss was significantly correlated with grade ≥2 serum creatinine increase, grade ≥3 alanine transaminase/aspartate transaminase increase, platelet decrease, fatigue/asthenia, and maximal hemoglobin decrease (p < 0.05).

CONCLUSION

The exposure-response analyses provide support for the approved starting dose of rucaparib 600 mg BID for maximum clinical benefit with subsequent dose modification only following the occurrence of a treatment-emergent adverse event in patients with BRCA-mutated recurrent ovarian carcinoma.

Use of Khorana score to predict VTE in patients undergoing chemotherapy for uterine cancer

5589

Background: Gynecologic cancers are associated with a high risk of venous thromboembolism (VTE). The Khorana score is a clinically-validated tool to assess risk of VTE in cancer patients (using disease site, BMI and blood counts). Recent ASCO clinical practice guidelines have recommended patients with a Khorana score of 2 or greater be offered pharmacologic thromboprophylaxis during systemic chemotherapy. For women with uterine cancer, the utility of the Khorana score is still unknown. Methods: A retrospective cohort study was performed from January 2016 to January 2020. All patients with uterine cancer were screened. Patients receiving chemotherapy, both neoadjuvant (NACT) and adjuvant (ACT), were included. VTE was evaluated for 12 months following the first cycle of chemotherapy. The Khorana score was calculated for each patient using both a high risk score of ≥2 and ≥3 and the patients were stratified based on NACT vs ACT. Logistic regression and chi-square were used to evaluate the prognostic utility of the Khorana score as well as other clinico-pathologic criteria on development of VTE. Results: A total of 265 patients were included. The majority of patients were obese (160, 60.4%) and 60 years or older (188, 70.9%). The most common histology was endometrioid (107, 40.4%) followed by serous (71, 26.8%) and the majority were advanced-stage (169, 63.8%). Most women underwent hysterectomy during treatment (243, 91.7%) followed by ACT (228, 86.0%). 14% (37) had NACT. 24 patients developed VTE (9.1%), which was higher, but not statistically different, with NACT vs ACT (13.5% vs 8.3%, p = 0.35). Demographics including age, race and BMI nor pathologic data including histology, grade or stage significantly correlated with development of VTE. Similarly, treatment factors including undergoing hysterectomy and radiation treatment were not statistically significant in regards to VTE. The proportion of patients with high Khorana score (both ≥2 and ≥3) was similar between groups. In the whole cohort, high Khorana score (defined either as ≥2 or ≥3) did not significantly predict VTE; however, the model using ≥3 was more predictive (OR 1.154, 95%CI 0.402-2.907, p = 0.7326). In the NACT cohort, neither model was predictive of VTE (both with OR < 1). In the ACT group, Khorana ≥3 was a better prediction model, but was still not statistically significant (OR 1.557, 95%CI 0.480-4.343, p = 0.4213). Conclusions: Although validated in other cancer types, the Khorana score was found to be a poor predictor of VTE in this population. A defined high risk Khorana score of ≥3 (per the original validation study) better predicted VTE than a score of ≥2 (per guidelines). Independent of the Khorana score, demographic and pathologic data were poor predictors of VTE. At this time, use of the Khorana score to guide routine thromboprophylaxis in patients undergoing chemotherapy for uterine cancer should be used with caution.

SGNTUC-019: Phase 2 basket study of tucatinib and trastuzumab in previously treated solid tumors with HER2 alterations (trial in progress)

TPS3151

Background: Tucatinib (TUC) is a highly selective HER2-directed TKI approved in combination with trastuzumab (Tras) and capecitabine (Cape) for HER2 overexpressed/amplified (HER2+) metastatic breast cancer (BC), based on a statistically significant and clinically meaningful PFS, OS, and ORR benefit over Tras and Cape. In xenograft models of HER2+ and HER2-mutated (HER2-mut) tumors, dual targeting of HER2 with TUC and Tras showed superior activity to either agent alone. While various HER2-directed agents have been evaluated in HER2+ and HER2-mut tumors, there are no approved HER2 therapies outside of breast and gastric cancers. The SGNTUC-019 basket study is evaluating TUC combined with Tras in patients (pts) with HER2+ or HER2-mut locally-advanced unresectable or metastatic solid tumors. Methods: SGNTUC-019 (NCT04579380) is a multi-cohort, open-label, international phase 2 study. Eligible pts must have progressed on or after the last systemic therapy for advanced disease. Metastatic cervical cancer: must have received platinum-based chemotherapy ± bevacizumab; hormone receptor positive (HR+) HER2-mut BC: must have received a prior CDK4/6 inhibitor. Pts must be ≥18 years old, with ECOG PS ≤1, adequate hepatic, hematological, renal, coagulation, and cardiac function, and no prior HER2-directed therapy (except Tras for uterine serous carcinoma). For eligibility, HER2 alterations can be demonstrated by HER2+ in tumor tissue by prior IHC/ISH (IHC 3+/signal ratio ≥2.0 or gene copy number >6), or by HER2 amplification/mutation in a prior or on-study NGS assay of ctDNA or prior tissue NGS assay. Pts with HER2+ disease will be enrolled in cohorts for cervical, uterine, biliary tract, and urothelial cancers, non-squamous NSCLC, and other solid tumors (except GEC, BC, and CRC). Pts with HER2-mut disease will be enrolled in cohorts for non-squamous NSCLC, BC, and other solid tumors. Except for solid tumor and BC cohorts, 12 RECIST 1.1 evaluable pts will be enrolled in each cohort. If ≥2 responses are observed, the cohort will be expanded to a total of 30 pts. Other solid tumor and BC cohorts will enroll 30 pts in a single stage. If justified, additional HER2+ or HER2-mut disease-specific cohorts may be opened. Approximately 162-270 pts are planned. The primary objective is antitumor activity in each cohort, with confirmed ORR per investigator as primary endpoint, and disease control rate, duration of response, PFS, and OS as secondary endpoints. Pts will receive TUC 300 mg orally twice daily and Tras 8 mg/kg IV on Cycle 1 Day 1 and 6 mg/kg q21 days from Cycle 2 Day 1. HR+ BC pts will also receive fulvestrant 500 mg IM every 4 weeks and C1 D15. Disease assessments per RECIST 1.1 will occur q6 weeks for 24 weeks, then q12 weeks. TUC PK will be evaluated in all pts in Cycles 2-6. QoL is evaluated q2 cycle using EQ-5D-5L. Sites are open in the US; EU and Asia will be opened. Enrollment began in Dec 2020. Clinical trial information: NCT04579380.

Phase 1 dose-escalation study of STRO-002, an antifolate receptor alpha (FRα) antibody drug conjugate (ADC), in patients with advanced, progressive platinum-resistant/refractory epithelial ovarian cancer (EOC)

5550

Background: STRO-002-GM1 is a Phase 1, open-label study in patients (pts) with advanced, platinum resistant or refractory EOC. STRO-002 is a novel FRα-targeting ADC with a precise DAR of 4 using site-specific conjugation technology to circumvent limitations of current ADCs. STRO-002 induces immunogenic cell death and contains the tubulin-targeting 3-aminophenyl hemiasterlin warhead SC209, a potent cytotoxin that is a weak substrate for P-gp. Methods: STRO-002 is given IV on Day 1 of each 21-day cycle until disease progression. Ocular exams are performed at baseline and every other cycle. Prophylactic corticosteroid eyedrops are not administered. FRα expression was not required for eligibility and retrospective analysis of FRα expression in archival tumor tissue is ongoing. Results: Enrollment has been completed with 39 pts treated at 9 dose levels (0.5 to 6.4 mg/kg). Data cut-off is Jan 30, 2021. Median age was 61 years (range 48-79). Median number of prior systemic therapies was 6 (range 2-11). 86% of treatment emergent adverse events (AEs) were Grade 1-2. The most common treatment related Grade 3 and 4 AEs were reversible neutrophil count decreased (36%) and neutropenia (33%), Grade 3 arthralgia (12.8%) and neuropathy (7.7%). Two pts developed neutropenic fever that resolved with antibiotic therapy. 34 pts were treated at clinically active doses (≥ 2.9 mg/kg) and 31/34 are evaluable for RECIST 1.1 response. Objective responses were seen in 10/31 pts - 1 CR, 4 confirmed PR, and 5 unconfirmed PR (imaging studies under review in 1 pt with uPR). Disease control rate (CR+PR+SD) is 74% at ≥ 12 weeks and 61% at ≥ 16 weeks. 5 pts remain on treatment with 3 ongoing at > 74 weeks. FRα-expression results are available in 14 pts treated at ≥ 2.9 mg/kg with 50% low, 21% medium and 29% high FRα-expressing tumors per PS2+ scoring algorithm. 12/13 pts with H-scores of ≥ 105 achieved disease control with PR or SD. Maximum plasma concentrations of STRO-002 were achieved at the end of the 1 hour infusion and exposure increased in an apparent dose proportionate/linear manner. Conclusions: STRO-002 is a novel FRα-targeting ADC with an encouraging emerging safety and efficacy profile in heavily pretreated relapsed/refractory EOC. No ocular toxicity signals have been observed. Durable responses and anti-tumor activity have been demonstrated across a broad range of FRα expression levels in evaluable pts treated at ≥ 2.9 mg/kg. 48% (15/31) of pts were on treatment without disease progression for ≥ 24 weeks and 13% (4/31) remain on treatment for over a year, suggesting that STRO-002 is well tolerated in long-term responding patients. A randomized expansion cohort comparing STRO-002 at 4.3 mg/kg vs 5.2 mg/kg dose levels in less heavily pretreated EOC pts is ongoing. Clinical trial information: NCT03748186.

Maintenance vigil immunotherapy in newly diagnosed advanced ovarian cancer: Efficacy assessment of homologous recombination proficient (HRP) patients in the phase IIb VITAL trial

5502

Background: In the VITAL (NCT02346747) trial, maintenance therapy with Vigil, an autologous tumor cell vaccine transfected with a DNA plasmid encoding GMCSF and bi-shRNA-furin for TGFβ expression control, following frontline platinum-based chemotherapy led to a recurrence-free survival (RFS) benefit in patients with advanced high-grade ovarian cancer (HR=0.69, 90% CI 0.44–1.07, p=0.078) and significantly in BRCA-wt patients (HR=0.51, 90% CI 0.30-0.88, p=0.020) ( Rocconi et al. Lancet Oncol. 2020). Here we report post-hoc HR deficiency (HRD) subgroup analysis and identification of an additional molecular subgroup sensitive to Vigil therapy involving STRING analysis. Methods: This double-blind, placebo-controlled, Phase 2b study randomized 92 patients with newly diagnosed stage III/IV ovarian cancer with a complete clinical response (CR) to frontline surgery and chemotherapy. Patients received 1 x 10e7 cells/ml of Vigil or placebo intradermally once a month for up to 12 doses or disease progression. RFS was the primary endpoint assessed by blinded independent central review. HRD status was determined according to the Myriad Genetics myChoice CDx assay (HRD score < 42 for proficient). Using tumor annotated DNA polymorphism data, a protein-protein interaction network was constructed using the STRING database. Properties of this network including topological distance and the identification of hub genes were used to predict a target molecular population sensitive to Vigil. Results: In the per-protocol population (PP, n=91), 62 BRCA-wt patients were tested for HRD status. Forty-five patients were HR proficient (HRP) and 17 patients were HR deficient (HRD). No HRP patients in the Vigil group reported treatment related Grade 3 or higher adverse events. From the time of study randomization median RFS was improved with Vigil (n=25) in HRP patients compared to placebo (n=20) (Table 1). Similarly, overall survival (OS) benefit was observed in the Vigil group compared to placebo (Table 1). Improved RFS was demonstrated for a subset of patients with STRING predicted molecular profile. Conclusions: Vigil immunotherapy as frontline maintenance in Stage III/IV ovarian cancer is well tolerated and showed clinical benefit in both BRCA-wt and HRP molecular profile patients. Results suggest a unique molecular network that enhances sensitivity to Vigil therapy. Clinical trial information: NCT02346747. [Table: see text]

Molecular results and potential biomarkers identified from MILO/ENGOT-ov11 phase 3 study of binimetinib versus physicians choice of chemotherapy (PCC) in recurrent low-grade serous ovarian cancer (LGSOC)

5519

Background: Lower responses to chemotherapy and the unique molecular profile of LGSO led to the adoption of MEK-inhibitors for this disease. Updated analysis from the MILO/ENGOT-ov11 phase III study of binimetinib vs PCC in recurrent LGSOC showed response rate of 24% in those treated with binimetinib (JCO, 2020; NCT01849874). Here we present results of the post-hoc tumor tissue biomarker analysis performed with MILO/ENGOT-ov11. Methods: Mutational/copy number analysis was performed via Foundation Medicine on archival tissue obtained prior to randomization. Unbiased univariate analysis was used to test association between mutation status and outcomes in binimetinib and PCC treated patients. Outcomes examined were progression free survival (PFS), binary response by local RECIST 1.1 (complete or partial response [CR/PR] vs. stable [SD] or progressive disease [PD]), and ordinal response. Kaplan-Meier was used to estimate PFS. Cox regression, binary logistic regression, and ordinal logistic regression were used to examine relationship between mutation status and outcomes. Results: MILO/ENGOT-OV11 enrolled 341 patients from June, 2013 to April, 2016. Patients were randomized 2:1 to binimetinib or PCC. Based on January 1, 2020 data cut-off the data is as-is, amongst those patients treated with binimetinib with molecular results available, PFS data is available for 144 and response rate (RR) data for 135. There were 47 mutations detected in ≥5% of patients, most commonly KRAS (33%). Patients harboring a KRAS mutation had 3.4 times the odds of responding to treatment with binimetinib as patients without KRAS mutation (95% CI 1.57,7.67; p-value 0.002). There was no difference in effect of KRAS G12V mutation vs other KRAS mutation on PFS (PFS HR 1.06; 95% CI:0.53, 2.12; p value 0.9). In the 135 patients with binimetinib RR data, other MAPK mutations were identified as follows; NRAS in 11(8.1%), BRAFV600E in 8(5.9%), RAF1 in 2 (1.5%), NF1 in 7 (5.2%). In patients with MAPK mutation (as defined above) the RR was 41% vs 13% in those without MAPK mutation. PFS was significantly better in patients treated with binimetinib harboring MAPK mutation vs those without (HR 0.5; 95% CI 0.31, 0.79; p = 0.003). In patients treated with PCC there was a nonsignificant trend towards improved PFS in those with MAPK mutation vs those without (HR 0.82; 95% CI 0.43,1.59; p = 0.6). A test for interaction between treatment and MAPK pathway was not significant by Cox regression model (p = 0.32). Conclusions: While this hypothesis generating analysis is limited by multiple testing, higher response rates and longer PFS were seen in those patients with LGSOC treated with binimetinib who harbored MAPK mutations, most commonly in KRAS. Somatic tumor testing should be routinely performed in patients with recurrent LGSOC to aid in clinical decision making. Clinical trial information: NCT01849874.

Clinical and molecular characteristics of ARIEL3 patients who derived exceptional benefit from rucaparib maintenance treatment for high-grade ovarian cancer (HGOC)

5537

Background: ARIEL3 is a placebo-controlled randomized trial of the PARP inhibitor (PARPi) rucaparib as maintenance treatment in HGOC patients (pts) who responded to the latest line of platinum therapy (NCT01968213). Rucaparib improved progression-free survival (PFS) across all predefined subgroups. Here, we present an exploratory analysis of clinical and molecular characteristics associated with exceptional benefit from rucaparib. Methods: Pts were randomized 2:1 to receive rucaparib 600 mg BID or placebo. At the data cutoff of Dec 31, 2019, 33/375 (9%) and 1/189 (0.5%) pts were still ongoing and receiving rucaparib or placebo, respectively. Molecular features (genomic alterations, BRCA1 promoter methylation) and baseline clinical characteristics were compared between pts who derived exceptional benefit (PFS ≥2 yrs), and those with disease progression on first scan (≈12 wks; the short-term [ST] subgroup) within each treatment arm. Results: Of 564 pts, 83 (15%) showed exceptional benefit: 79/375 (21%) in the rucaparib arm and 4/189 (2%) in the placebo arm. Within the rucaparib arm, exceptional benefit pts had more favorable clinical prognostic factors at baseline compared with the ST subgroup (Table). While BRCA mutations were enriched in the rucaparib exceptional benefit subgroup, 34/79 (43%) of these pts were BRCA wild type. Among other biomarkers, RAD51C/D mutations were associated with exceptional benefit; low genome-wide loss of heterozygosity was enriched within the ST subgroup; and high BRCA1 methylation was present at similar fractions. Trends were similar in the placebo arm (Table). Conclusions: Exceptional benefit in ARIEL3 was more common in, but not exclusive to, pts with favorable clinical characteristics and known mechanisms of PARPi sensitivity. Our results suggest that rucaparib can deliver exceptional benefit to a diverse set of HGOC pts. Clinical trial information: NCT01968213. [Table: see text]