Antibody-drug conjugates for the treatment of ovarian cancer

INTRODUCTION

Ovarian cancer typically presents at an advanced stage and while initial chemotherapy response rates are favorable, a majority of patients experience recurrence with the subsequent development of chemoresistance. Recurrent, platinum-resistant disease is associated with a very poor prognosis as treatment in this setting is often limited by systemic toxicity. Antibody-drug conjugates (ADCs) are novel therapeutic agents designed to target antigens specific to ovarian tumor cells with direct delivery of cytotoxic agents to combat recurrent, platinum-resistant disease while limiting systemic toxicity.

AREAS COVERED

The basic structure and function of ADCs will be reviewed as well as the current data on ADCs under investigation in ovarian cancer.

EXPERT OPINION

ADCs represent a promising class of targeted therapy in recurrent ovarian cancer with excellent response rates particularly when utilized as combination therapy. While mirvetuximab soravtansine is the only ADC that has been evaluated in a phase 3 trial, many other ADCs and trials are on the horizon. As the field of targeted therapy continues to evolve, continued development of target antigens and ADCs are likely to represent a key development in treatment of recurrent, platinum-resistant disease.

Tamrintamab pamozirine (SC-003) in patients with platinum-resistant/refractory ovarian cancer: Findings of a phase 1 study

OBJECTIVE

Epithelial ovarian carcinoma (EOC) is diagnosed at advanced stage in the majority of women and, despite being initially chemosensitive, eventually recurs and develops resistance to known therapies. SC-003 is a pyrrolobenzodiazepine-based antibody-drug conjugate targeting dipeptidase 3 (DPEP3), a membrane-bound dipeptidase associated with tumor-initiating cells in patient-derived EOC xenograft models. This first-in-human phase 1a/1b study evaluated the safety/tolerability, pharmacokinetics, and preliminary antitumor activity of SC-003 alone or in combination with budigalimab (formerly ABBV-181), an antibody targeting PD-1, in patients with platinum-resistant/refractory EOC (NCT02539719).

METHODS

Patients received SC-003 at 1 of 6 dose levels (0.025-0.4 mg/kg) every 3 weeks (Q3W), utilizing a standard 3 + 3 design (dose-limiting toxicity [DLT] period: 21 days). Patients with DPEP3-positive tumors were enrolled in the dose-expansion phase of the study and treated with SC-003 monotherapy or in combination with budigalimab.

RESULTS

Seventy-four patients (n = 29, dose escalation; n = 45, dose expansion; n = 3 budigalimab combination) were enrolled and received ≥1 dose of study drug. One DLT occurred (grade 3 ileus) but was considered unrelated to study drug. The MTD for the Q3W schedule was 0.3 mg/kg and the SC-003 doses selected for the dose-expansion phase of the study were 0.3 mg/kg and 0.2 mg/kg. The most common treatment-emergent adverse events were fatigue, nausea, decreased appetite, pleural effusion, abdominal pain, and peripheral edema. The overall response rate was low (4%), and responses were not durable. Post-hoc examination of antitumor activity suggested a higher response rate in patients with higher DPEP3 expression.

CONCLUSIONS

SC-003 lacked the requisite safety profile and antitumor activity to warrant further development.

Characterization of patients (pts) with long-term responses to rucaparib in recurrent ovarian cancer (OC)

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Background: Pts who derive durable benefit from PARP inhibitor treatment may provide insights into improving outcomes. Here we describe long-term responders from Study 10 (NCT01482715) and ARIEL2 (NCT01891344), studies of the PARP inhibitor rucaparib for the treatment of high-grade recurrent OC. Methods: This analysis included pts enrolled in Study 10 (Part 2A: BRCA1 or BRCA2 [ BRCA]-mutant OC, platinum sensitive, 2–4 prior chemotherapies; Part 2B: any platinum status, 3–4 prior chemotherapies) and ARIEL2 (Part 1: BRCA-mutant or wild-type OC, platinum sensitive; Part 2: any platinum status, 3–4 prior chemotherapies). Final results from Study 10 (n = 54) and ARIEL2 (n = 491) were pooled. Long-term responders were defined as pts with duration of response (DOR) > 1 y, and short-term responders as pts with DOR ≤ 20 weeks; responses were evaluated using RECIST. Targeted next-generation sequencing was used to detect deleterious mutations and loss of heterozygosity (LOH) in tumors. BRCA1 methylation was quantified by digital droplet PCR. Results: Overall, 25% (138/545) of enrolled pts were responders. Of these, 29% (40/138) had long-term responses, including 16/138 (12%) with DOR > 2 y; 21% (29/138) were short-term responders. Both groups received a median of 3 prior anticancer therapies. Among patients with BRCA mutations, BRCA homozygous deletion or rearrangement was detected in 15% (4/27) of long-term responders vs 0% (0/15) of short-term responders. In an expanded analysis of the 95 pts with BRCA mutations and confirmed response, pts with BRCA homozygous deletion or rearrangement had significantly longer DOR than pts with other mutation types (median 3.5 vs 0.6 y; HR = 0.30; p = 0.024). There was no apparent difference in BRCA gene or mutation location for long- vs short-term responders. Ten of the 13 long-term responders with BRCA wild-type OC had high genome-wide LOH (≥16% LOH), a genomic scar indicative of homologous recombination deficiency, including OC associated with BRCA1 hypermethylation (n = 2) and RAD51C/D mutations (n = 2). Conclusions: Long-term responders to rucaparib include OC with BRCA mutation, particularly homozygous deletion or rearrangements, which would not be susceptible to somatic reversion mutations, as well as BRCA1 hypermethylation, and RAD51C/D mutations. Clinical trial information: NCT01482715; NCT01891344.

Mirvetuximab soravtansine, a folate receptor alpha (FRα)-targeting antibody-drug conjugate (ADC), in combination with bevacizumab in patients (pts) with platinum-agnostic ovarian cancer

6004

Background: Mirvetuximab soravtansine (MIRV) is an ADC comprising a FRα-binding antibody, cleavable linker, and the maytansinoid DM4, a potent tubulin-targeting agent. As part of the Phase 1b FORWARD II trial (NCT02606305), the combination of MIRV with bevacizumab (BEV) was evaluated in pts with FRα-positive (medium/high expression; ≥ 50%/ ≥75% of cells with PS2+ staining intensity), platinum agnostic ovarian cancer, defined as pts with either platinum resistant (PR) (recurrence within 6 months after last platinum dose) or platinum sensitive (PS) responded to the last platinum therapy received before study entry and did not progress within 6 months) disease for whom a non-platinum based doublet would be appropriate. Methods: Pts received MIRV (6 mg/kg; adjusted ideal body weight) and BEV (15 mg/kg) on Day 1 of a 21-day cycle. Responses were assessed by investigator according to RECIST 1.1 and adverse events (AEs) evaluated by CTCAE v4.03. Results: In total, 60 pts received the combination, with a median age of 60 years, and a median of 2 prior lines of systemic therapy (range 1-4). Platinum status was determined for 56 pts, with 30 (50%) considered PR and 26 (43%) considered PS; platinum status data were incomplete for 4 pts. The most common treatment related AEs (percent all grade/grade 3+) were diarrhea (65/2), blurred vision (62/3), nausea (55/0), and fatigue (55/5). The most common treatment related grade 3+ AEs were hypertension and neutropenia, (10% each); all other grade 3+ events occurred in ≤ 5% of pts. Serious AEs regardless of relationship to study drug were infrequent, with the most common events being small intestinal obstruction in 3 pts, 5% (grade 3) and pneumonitis in 3 pts, 5% (2 grade 1; 1 grade 2). Objective responses were seen in 26 pts for a confirmed overall response rate (ORR) of 43% (95% CI, 31, 57). In a subset analysis of pts with high FRα expressing tumors (n = 33), the confirmed ORR was 61% (95% CI, 42, 77), with an ORR of at least 50% in each of the PR and PS subsets. With a median follow-up of 5.5 months, the duration of response and progression free survival data are immature. Conclusions: The combination of MIRV with BEV demonstrates an encouraging ORR with a favorable tolerability profile in pts with recurrent ovarian cancer regardless of platinum sensitivity, particularly in those with tumors that express high levels of FRα. Clinical trial information: NCT02606305.

Niraparib exposure-response relationship in patients (pts) with newly diagnosed advanced ovarian cancer (AOC)

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Background: Niraparib improves progression-free survival (PFS) in pts with newly diagnosed AOC after complete or partial response to first-line, platinum-based chemotherapy. In the PRIMA/ENGOT-OV26/GOG-3012 (PRIMA) trial, pts were treated with a fixed starting dose (FSD) of 300 mg QD until a protocol amendment introduced the individualized starting dose (ISD) regimen: 200 mg QD for pts with baseline bodyweight (BW) < 77 kg and/or platelet count (PC) < 150,000/µL, or 300 mg QD for pts with baseline BW ≥77 kg and PC ≥150,000/µL. Here, we developed a population pharmacokinetic (PopPK) model for niraparib and evaluated exposure-response relationships for pts receiving niraparib using safety and efficacy data from PRIMA. Methods: The PopPK model for niraparib was developed based on 7418 plasma samples from 1442 pts from 4 studies: PN001, NOVA, QUADRA, and PRIMA. PRIMA PK samples were collected on cycle 1, day 1 (C1D1), C2D1 pre-dose and 2 h post-dose, C4D1, and C8D1 pre-dose (or EOT if patient discontinued before C8D1). The relationship between PopPK model-based prospective exposure (average concentration [ Cave] until progression/death) and efficacy (PFS) were evaluated in pts receiving niraparib in both the homologous-recombination deficient (HRd) and overall population. The relationship between model-predicted exposure metrics and incidence of clinically relevant adverse events (AEs) was analyzed using univariate logistic regression in pts receiving niraparib. Results: Of 484 pts receiving niraparib in PRIMA, 480 had PK data and were included in the efficacy and safety analysis. The safety exposure-response showed significant associations ( p≤0.0128) between increasing niraparib exposure and increasing probability of experiencing any-grade and grade ≥3 AEs, except grade ≥3 hypertension. The incidence of AEs, including thrombocytopenia, was lower in pts who received a 200-mg ISD. Efficacy was not compromised in these pts. Conclusions: Niraparib exposure was associated with increased risk of select AEs. However, the ISD regimen decreased AE risk without compromising efficacy. Clinical trial information: NCT02655016.

Evaluation of an individualized starting-dose of niraparib in the PRIMA/ENGOT-OV26/GOG-3012 study

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Background: Niraparib is approved at a fixed starting dose (FSD) of 300 mg QD for maintenance treatment of patients (pts) with recurrent ovarian cancer (OC) achieving a complete or partial response to platinum-based chemotherapy based in the ENGOT-OV16/NOVA study. A post-hoc analysis of NOVA showed baseline bodyweight (BW) and platelet count (PC) were predictive for hematologic toxicities and dose reductions. Following this analysis, the PRIMA/ENGOT-OV26/GOG-3012 study was amended to prospectively evaluate the safety and efficacy of an individualized starting dose (ISD) regimen. Methods: This double-blind, placebo-controlled, phase III study randomized 733 pts with newly diagnosed advanced OC with a complete or partial response to first-line (1L) platinum-based chemotherapy. The protocol was amended to change the dose from 300 mg FSD for all patients to an ISD regimen: 200 mg QD in pts with BW <77 kg and/or PC <150,000/µL or 300 mg QD in pts with BW ≥77 kg and PC ≥150,000/µL. Exposure, efficacy, and safety data were compared between patients treated with FSD vs ISD. Results: Efficacy in the ISD subgroup was comparable to the FSD subgroup relative to placebo (Table). An interaction test showed no treatment difference between ISD and FSD at the pre-specified 0.10 significance level ( p=0.30). Medians for dose intensity and relative dose intensity in pts who received niraparib were similar. The overall safety profile among pts in the niraparib arm (n=484), including grade ≥3 hematologic toxicities, improved with the ISD. Conclusions: The ISD in the 1L maintenance setting provides comparable efficacy to the FSD while reducing the risk of hematologic toxicities. No new safety signals were identified. Clinical trial information: NCT02655016. [Table: see text]

Phase Ib/II trial of tisotumab vedotin (TV) ± bevacizumab (BEV), pembrolizumab (PEM), or carboplatin (CBP) in recurrent or metastatic cervical cancer (innovaTV 205/ENGOT-cx8/GOG-3024)

TPS6095

Background: Patients (pts) with recurrent/metastatic cervical cancer (r/mCC) receive paclitaxel/platinum or paclitaxel/topotecan ± BEV as first-line standard-of-care therapy. Tissue factor (TF) expression has been associated with poor prognosis in solid tumors, and TF is highly expressed in r/mCC. TV is an investigational antibody-drug conjugate composed of a fully human, TF-directed monoclonal antibody covalently attached to the microtubule-disrupting agent monomethyl auristatin E (MMAE) via a protease-cleavable linker. Upon internalization, MMAE is released resulting in cell cycle arrest and apoptotic cell death. In pts with previously treated r/mCC, TV monotherapy (IV 2.0 mg/kg Q3W) demonstrated a manageable safety profile and encouraging antitumor activity (investigator-assessed confirmed ORR, 24%; median DOR, 4.2 mo) [Hong DS et al. Clin Cancer Res. 2019. doi: 10.1158/1078-0432.CCR-19-2962]. The preliminary safety and efficacy data for TV monotherapy suggest a positive benefit/risk profile and warrant further investigation of TV in combination with therapies commonly administered to pts with r/mCC. The global, open-label, phase Ib/II trial innovaTV 205/ENGOT-cx8/GOG-3024 (NCT03786081) evaluates the safety and antitumor activity of TV monotherapy and TV in combination with BEV, PEM, or CBP in pts with untreated or previously treated r/mCC. This abstract presents the new TV monotherapy weekly dosing schedule. Results from this study will inform the further clinical development of TV in the treatment of r/mCC. Methods: Approximately 170 adult pts with recurrent or stage IVB squamous, adenosquamous, or adenocarcinoma of the cervix; measurable disease; and ECOG PS 0-1 will be enrolled. The phase I part of the study will consist of 3 dose-escalation arms for identification of the recommended phase II dose (RP2D) of TV administered Q3W with BEV, PEM, or CBP. In this part, previously treated pts will receive escalating doses of TV (IV Q3W) in combination with escalating doses of BEV (IV Q3W), a fixed dose of PEM (IV Q3W), or a fixed dose of CBP (IV Q3W). The phase II part will include 4 expansion arms. In this phase, pts who have not received prior systemic therapy for r/mCC will receive 1) TV RP2D + PEM or 2) TV RP2D + CBP; pts who received 1-2 prior treatments for r/mCC will receive 3) TV RP2D + PEM or 4) TV monotherapy with weekly dosing (IV 3Q4W). The primary endpoint of phase II is ORR by RECIST v1.1. Secondary endpoints include DOR, time to response, PFS, OS, and safety. Clinical trial information: NCT03786081.

Rucaparib for patients with platinum-sensitive, recurrent ovarian carcinoma (ARIEL3): post-progression outcomes and updated safety results from a randomised, placebo-controlled, phase 3 trial

BACKGROUND

In ARIEL3, rucaparib maintenance treatment significantly improved progression-free survival versus placebo. Here, we report prespecified, investigator-assessed, exploratory post-progression endpoints and updated safety data.

METHODS

In this ongoing (enrolment complete) randomised, placebo-controlled, phase 3 trial, patients aged 18 years or older who had platinum-sensitive, high-grade serous or endometrioid ovarian, primary peritoneal, or fallopian tube carcinoma and an Eastern Cooperative Oncology Group performance status of 0 or 1 who had received at least two previous platinum-based chemotherapy regimens and responded to their last platinum-based regimen were randomly assigned (2:1) to oral rucaparib (600 mg twice daily) or placebo in 28-day cycles using a computer-generated sequence (block size of six with stratification based on homologous recombination repair gene mutation status, progression-free interval following penultimate platinum-based regimen, and best response to most recent platinum-based regimen). Patients, investigators, site staff, assessors, and the funder were masked to assignments. The primary endpoint of investigator-assessed progression-free survival has been previously reported. Prespecified, exploratory outcomes of chemotherapy-free interval (CFI), time to start of first subsequent therapy (TFST), time to disease progression on subsequent therapy or death (PFS2), and time to start of second subsequent therapy (TSST) and updated safety were analysed (visit cutoff Dec 31, 2017). Efficacy analyses were done in all patients randomised to three nested cohorts: patients with BRCA mutations, patients with homologous recombination deficiencies, and the intention-to-treat population. Safety analyses included all patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, NCT01968213.

FINDINGS

Between April 7, 2014, and July 19, 2016, 564 patients were enrolled and randomly assigned to rucaparib (n=375) or placebo (n=189). Median follow-up was 28·1 months (IQR 22·0-33·6). In the intention-to-treat population, median CFI was 14·3 months (95% CI 13·0-17·4) in the rucaparib group versus 8·8 months (8·0-10·3) in the placebo group (hazard ratio [HR] 0·43 [95% CI 0·35-0·53]; p<0·0001), median TFST was 12·4 months (11·1-15·2) versus 7·2 months (6·4-8·6; HR 0·43 [0·35-0·52]; p<0·0001), median PFS2 was 21·0 months (18·9-23·6) versus 16·5 months (15·2-18·4; HR 0·66 [0·53-0·82]; p=0·0002), and median TSST was 22·4 months (19·1-24·5) versus 17·3 months (14·9-19·4; HR 0·68 [0·54-0·85]; p=0·0007). CFI, TFST, PFS2, and TSST were also significantly longer with rucaparib than placebo in the BRCA-mutant and homologous recombination-deficient cohorts. The most frequent treatment-emergent adverse event of grade 3 or higher was anaemia or decreased haemoglobin (80 [22%] patients in the rucaparib group vs one [1%] patient in the placebo group). Serious treatment-emergent adverse events were reported in 83 (22%) patients in the rucaparib group and 20 (11%) patients in the placebo group. Two treatment-related deaths have been previously reported in this trial; there were no new treatment-related deaths.

INTERPRETATION

In these exploratory analyses over a median follow-up of more than 2 years, rucaparib maintenance treatment led to a clinically meaningful delay in starting subsequent therapy and provided lasting clinical benefits versus placebo in all three analysis cohorts. Updated safety data were consistent with previous reports.

FUNDING

Clovis Oncology.

COVID-19 and ovarian cancer: Exploring alternatives to intravenous (IV) therapies

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The pandemic COVID-19 requires alternative methods and thinking to keep healthcare professionals and patients safe.

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In COVID-19 hot spots, oral therapies may be viable alternatives to intravenous therapies for treatment of ovarian cancer.

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Minimizing patient visits to hospitals and cancer clinics may help mitigate the spread of SARS-CoV-2.

Predictive Blood-Based Biomarkers in Patients with Epithelial Ovarian Cancer Treated with Carboplatin and Paclitaxel with or without Bevacizumab: Results from GOG-0218

PURPOSE

GOG-0218, a double-blind placebo-controlled phase III trial, compared carboplatin and paclitaxel with placebo, bevacizumab followed by placebo, or bevacizumab followed by bevacizumab in advanced epithelial ovarian cancer (EOC). Results demonstrated significantly improved progression-free survival (PFS), but no overall survival (OS) benefit with bevacizumab. Blood samples were collected for biomarker analyses.

EXPERIMENTAL DESIGN

Plasma samples were analyzed via multiplex ELISA technology for seven prespecified biomarkers [IL6, Ang-2, osteopontin (OPN), stromal cell-derived factor-1 (SDF-1), VEGF-D, IL6 receptor (IL6R), and GP130]. The predictive value of each biomarker with respect to PFS and OS was assessed using a protein marker by treatment interaction term within the framework of a Cox proportional hazards model. Prognostic markers were identified using Cox models adjusted for baseline covariates.

RESULTS

Baseline samples were available from 751 patients. According to our prespecified analysis plan, IL6 was predictive of a therapeutic advantage with bevacizumab for PFS (P = 0.007) and OS (P = 0.003). IL6 and OPN were found to be negative prognostic markers for both PFS and OS (P < 0.001). Patients with high median IL6 levels (dichotomized at the median) treated with bevacizumab had longer PFS (14.2 vs. 8.7 months) and OS (39.6 vs. 33.1 months) compared with placebo.

CONCLUSIONS

The inflammatory cytokine IL6 may be predictive of therapeutic benefit from bevacizumab when combined with carboplatin and paclitaxel. Aligning with results observed in patients with renal cancer treated with antiangiogenic therapies, it appears plasma IL6 may also define those patients with EOC more or less likely to benefit from the addition of bevacizumab to standard chemotherapy.

Low-grade serous ovarian cancer: State of the science

In January 2019, a group of basic, translational, and clinical investigators and patient advocates assembled in Miami, Florida, to discuss the current state of the science of low-grade serous carcinoma of the ovary or peritoneum-a rare ovarian cancer subtype that may arise de novo or following a diagnosis of serous borderline tumor. The purpose of the conference was to review current knowledge, discuss ongoing research by established researchers, and frame critical questions or issues for future directions. Following presentations and discussions, the primary objective was to initiate future collaborations, uniform database platforms, laboratory studies, and clinical trials to better understand this disease and to advance clinical care outside the boundaries of single academic institutions. This review summarizes the state of the science in five principal categories: epidemiology and patient outcomes, pathology, translational research, patient care and clinical trials, and patients' perspective.

Intraperitoneal chemotherapy following neoadjuvant chemotherapy and optimal interval tumor reductive surgery for advanced ovarian cancer

OBJECTIVES

Intraperitoneal (IP) chemotherapy following neoadjuvant chemotherapy (NACT) and interval tumor reductive surgery (TRS) for advanced ovarian cancer is feasible, however, the impact on disease outcomes remains unclear. We compare outcomes of patients treated with IP chemotherapy versus intravenous (IV) chemotherapy following NACT and interval TRS.

METHODS

In this retrospective review, patients with advanced ovarian cancer were included if they received NACT followed by optimal interval TRS between 1/2004 and 4/2017. Patients were excluded if they had an ECOG PS >1, received >6 cycles of NACT or postoperative chemotherapy, and/or received bevacizumab during primary therapy. Primary outcomes were progression free survival (PFS) and overall survival (OS).

RESULTS

There were 134 patients included in this study, 37 (28%) received IP and 97 (72%) received IV chemotherapy postoperatively. Patients in the IV group were older (median 66.3 vs 59.7 years, p = 0.0039) though there were no differences in BMI, race, BRCA status, stage, or histology. Median PFS was 3 months longer in the IP group (14.5 versus 11.5 months, p = 0.028) however there was no significant difference in OS. On univariate analysis, increasing number of NACT cycles (HR 1.914, 95% CI 1.024-3.497) and residual disease at completion of TRS (HR 1.541, 95% CI 1.042-2.248) were associated with decreased PFS; IP chemotherapy was associated with increased PFS (HR 0.633, 95% CI 0.414-0.944). These associations remained on multivariate analysis. Toxicity was comparable between the groups.

CONCLUSIONS

IP after NACT and optimal interval TRS was associated with in improved PFS compared to IV chemotherapy without significant differences in toxicity.

Outcomes of secondary cytoreductive surgery for patients with platinum-sensitive recurrent ovarian cancer

BACKGROUND

Most women with advanced epithelial ovarian cancer develop recurrent disease, despite maximal surgical cytoreduction and adjuvant platinum-based chemotherapy. In observational studies, secondary cytoreductive surgery has been associated with improved survival; however its use is controversial, because there are concerns that the improved outcomes may reflect selection bias rather than the superiority of secondary surgery.

OBJECTIVE

To compare the overall survival of women with platinum-sensitive recurrent ovarian cancer treated at National Cancer Institute-designated cancer centers who receive secondary surgery vs chemotherapy.

STUDY DESIGN

This retrospective cohort study included women from 6 National Cancer Institute-designated cancer centers diagnosed with platinum-sensitive recurrent ovarian cancer between January 1, 2004, and December 31, 2011. The primary outcome was overall survival. Propensity score matching was used to compare similar women who received secondary surgery vs chemotherapy. Additional analyses examined how these findings may be influenced by the prevalence of unobserved confounders at the time of recurrence.

RESULTS

Among 626 women, 146 (23%) received secondary surgery and 480 (77%) received chemotherapy. In adjusted analyses, patients who received secondary surgery were younger (P = 0.001), had earlier-stage disease at diagnosis (P = 0.002), and had longer disease-free intervals (P < 0.001) compared with those receiving chemotherapy. In the propensity score-matched groups (n = 244 patients), the median overall survival was 54 months in patients who received secondary surgery and 33 months in those treated with chemotherapy (P < 0.001). Among patients who received secondary surgery, 102 (70%) achieved optimal secondary cytoreduction. There were no significant differences in complication rates between the 2 groups. In sensitivity analyses, the survival advantage associated with secondary surgery could be explained by the presence of more multifocal recurrences (if 4.3 times more common), ascites (if 2.7 times more common), or carcinomatosis (if 2.1 times more common) among patients who received chemotherapy instead of secondary surgery.

CONCLUSION

Patients with platinum-sensitive recurrent ovarian cancer who received secondary surgery had favorable surgical characteristics and were likely to have minimal residual disease following secondary surgery. These patients had a superior median overall survival compared with patients who received chemotherapy, although unmeasured confounders may explain this observed difference.

Abstract GMM-048: CTDNA RESPONSE TO THE PARP INHIBITOR RUCAPARIB PREDICTS PROGRESSION-FREE SURVIVAL AND BEST OVERALL RESPONSE ON THE ARIEL2 TRIAL

BACKGROUND: High grade serous ovarian carcinoma (HGSOC) is characterized by ubiquitous TP53 mutation and has the highest genomic complexity of all epithelial neoplasms. Sensitivity to PARP inhibitor therapy is strongly associated with homologous recombination deficiency (HRD). Genomic biomarkers of HRD such as genome-wide loss of heterozygosity (LOH) scores predict HRD and response to rucaparib. We hypothesized that functional testing of response during PARP inhibitor treatment using changes in circulating tumour DNA (ctDNA) could improve prediction of patient outcome. We tested whether the change in ctDNA TP53 mutant allele fraction (MAF) after one cycle of rucaparib treatment was predictive of progression free survival (PFS) and response in patients from the phase 2 ARIEL2 trial in women with platinum-sensitive recurrent high grade ovarian cancer (NCT01891344).

METHODS: We analyzed serial plasma samples (n = 636) from 142 HGSOC patients during screening, on day 1 of each treatment cycle, and at the end of rucaparib treatment. Targeted amplicon deep sequencing (TADS) of TP53 was performed on DNA extracted from plasma (median depth 6916×). Somatic TP53 mutation and loss of heterozygosity score (LOH) were available from archival and biopsy specimens. Statistical analyses were pre-specified and ctDNA analysis was carried out blinded to visit and response data. TP53 MAF changes after one cycle of treatment were compared with PFS and best overall response assessed by RECIST v1.1 and GCIG CA-125 criteria. Optimal cut points for ctDNA response were determined using a cross-validation analysis. In cases with &gt;1 TP53 mutation, response assessment was performed using the mutation with highest MAF.

RESULTS: We detected TP53 mutations in plasma from 134 patients; all cases were concordant between tumour and plasma except for one patient (present in plasma but not tumour). In 18 patients (13%), 2 or more TP53 mutations were detected in ctDNA. The median TP53 MAF prior to cycle 1 was 2.6% (IQR 0.3–8.6). Reduction of &gt;70% of TP53 MAF in ctDNA between cycle 1 and 2 was significantly predictive of improved PFS (n = 97; HR = 0.53, 95% CI 0.34-0.85, p = 0.008, median 273 vs 158 days, sensitivity 76%, specificity 62%) and best overall response (n = 97; OR = 7.04, 95% CI 2.69–21.06, p &lt; 0.001). Combining ctDNA and LOH scores did not improve prediction of response.

CONCLUSIONS

Response measured by &gt;70% fall in TP53 ctDNA between pre-cycle 1 and pre-cycle 2 of rucaparib therapy was significantly associated with best overall response and improved PFS. Similar findings were observed in a retrospective study of recurrent HGSOC treated with standard of care chemotherapy. The pathological or genomic factors causing multiple TP53 mutations in ctDNA are unknown.

The association between early fall in ctDNA and validated RECIST and CA-125 response markers provides strong evidence that ctDNA may have utility for detecting early response to targeted therapy. Further analyses in randomized studies should be performed to confirm that ctDNA response has strong predictive value.

Citation Format: Anna Piskorz, David Robertson, Kevin K. Lin, James Morris, Elaina Mann, Amit Oza, Robert L. Coleman, David M. O'Malley, Michael Friedlander, Janiel M. Cragun, Ling Ma, Heidi Giordano, Iain A. McNeish, Elizabeth Swisher, James Wason, James D. Brenton. CTDNA RESPONSE TO THE PARP INHIBITOR RUCAPARIB PREDICTS PROGRESSION-FREE SURVIVAL AND BEST OVERALL RESPONSE ON THE ARIEL2 TRIAL [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr GMM-048.

Adjuvant Chemotherapy plus Radiation for Locally Advanced Endometrial Cancer

BACKGROUND

Stage III or IVA endometrial cancer carries a significant risk of systemic and locoregional recurrence.

METHODS

In this randomized phase 3 trial, we tested whether 6 months of platinum-based chemotherapy plus radiation therapy (chemoradiotherapy) is associated with longer relapse-free survival (primary end point) than six cycles of combination chemotherapy alone in patients with stage III or IVA endometrial carcinoma. Secondary end points included overall survival, acute and chronic toxic effects, and quality of life.

RESULTS

Of the 813 patients enrolled, 736 were eligible and were included in the analysis of relapse-free survival; of those patients, 707 received the randomly assigned intervention (346 received chemoradiotherapy and 361 received chemotherapy only). The median follow-up period was 47 months. At 60 months, the Kaplan-Meier estimate of the percentage of patients alive and relapse-free was 59% (95% confidence interval [CI], 53 to 65) in the chemoradiotherapy group and 58% (95% CI, 53 to 64) in the chemotherapy-only group (hazard ratio, 0.90; 90% CI, 0.74 to 1.10). Chemoradiotherapy was associated with a lower 5-year incidence of vaginal recurrence (2% vs. 7%; hazard ratio, 0.36; 95% CI, 0.16 to 0.82) and pelvic and paraaortic lymph-node recurrence (11% vs. 20%; hazard ratio, 0.43; 95% CI, 0.28 to 0.66) than chemotherapy alone, but distant recurrence was more common in association with chemoradiotherapy (27% vs. 21%; hazard ratio, 1.36; 95% CI, 1.00 to 1.86). Grade 3, 4, or 5 adverse events were reported in 202 patients (58%) in the chemoradiotherapy group and 227 patients (63%) in the chemotherapy-only group.

CONCLUSIONS

Chemotherapy plus radiation was not associated with longer relapse-free survival than chemotherapy alone in patients with stage III or IVA endometrial carcinoma. (Funded by the National Cancer Institute; ClinicalTrials.gov number, NCT00942357.).

A phase I study of veliparib incorporated into front-line platinum based cheotherpy and bevacizumab in epithelial ovarian cancer (NCT00989651): A GOG/nrg trial

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Background: Veliparib, a poly-(ADP-ribose)-polymerase inhibitor, increases anti-tumor activity when combined with platinum chemotherapy and has monotherapy activity in BRCA deficient tumors. This study was done to determine the recommended phase II dose (RP2D) of veliparib in combination with front line treatment for epithelial ovarian cancer (EOC). Methods: Eligible patients had newly diagnosed, stage II-IV EOC. Six regimens were evaluated, 3 variations of chemo delivery with either continuous (D1-21) or intermittent (days-2-5) veliparib BID. Chemo included 1: IV q3week carboplatin (C) (AUC 6) and paclitaxel(T) (175mg/m2); 2, IV q3week C (AUC 6) and weekly T(80mg/m2); and 3, IV T (135mg/m2, day 1), IP cisplatin (75mg/m2, day 1 or 2) and IP T (60mg/m2, day 8). Bevacizumab 15mg/kg started cycle 2 and continued as monotherapy cycles 7-22. A 3+3 dose escalation design evaluated dose-limiting toxicities (DLTs) in cycles 1 and 2. Once < 2/6 patients experienced a DLT, that dose level was expanded to evaluate feasibility over 4 cycles. Results: The study accrued 424 treated patients. For regimen 1, continuous (Reg1c) the maximum tolerated dose (MTD) was 250mg veliparib BID but the feasible dose was found to be 150mg BID. For regimen 1, intermittent (Reg1i) the MTD and feasible dose were 400 and 250mg BID respectively. For Reg2c the MTD and feasible dose were the same at 150mg BID. For Reg2i the MTD and feasible dose were 250 and 150mg BID respectively. For Reg3c the MTD and feasible dose are both 150mg BID and for Reg3i, the MTD was 400mg BID and the feasible dose felt to be 300mg BID. Median PFS by residual disease and BRCA status is: (Positive residual disease) 14.6, 19.1 and 16.9 months for BRCA+, BRCAwt and BRCA ukn respectively. For no gross residual disease the PFS is NR, 34.2 and 24.5 months respectively. Conclusions: Given the difficulty with toxicity not defined as a DLT, the RP2D for all regimens is veliparib 150mg BID. This data informed the dose that moved into the phase III trial GOG 3005/Velia: NCT02470585. Velia also incorporated maintenance veliparib instead of maintenance bevacizumab among all high grade serous patients (BRCA+ and wt). These results will determine utilization of veliparib in this space. Clinical trial information: NCT00989651.

Sex hormone, insulin, and insulin-like growth factor signaling in recurrence of high stage endometrial cancer: Results from the NRG Oncology/Gynecologic Oncology Group 210 trial

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Background: Sex hormone and insulin/insulin-like growth factor (IGF) axis signaling pathways play an important role in endometrial cancer development but their role in endometrial cancer recurrence is unknown. In this study GOG-8015 we evaluated these pathways in a prospective cohort of patients diagnosed with the most common type of endometrial cancer, endometrioid adenocarcinoma. Methods: Stage II-IV endometrioid endometrial adenocarcinoma patients (N = 816) enrolled in the GOG-210 study with pre-treatment specimens were tested for tumor mRNA and protein expression levels of IGF1, IGF2, IGF binding proteins ( IGFBP) -1and -3, the insulin (IR) and IGF-I receptors (IGF1R), and phosphorylated (activated) IR/IGF1R as well as estrogen (ER) and progesterone receptors (PR) using quantitative PCR and immunohistochemistry (IHC). Serum concentrations of insulin, IGF-I, IGFBP-3, estradiol, estrone and sex hormone binding globulin were measured using ELISAs. Hazard ratios (HR) and 95% confidence intervals (CI) for risk of recurrence were obtained from multivariable Cox proportional hazard’s models with adjustment for age, stage and grade. Results: Recurrence occurred in 280 (34%) cases during a mean of 5.4 years of follow-up. ER-positivity (HR 0.67, 95% CI 0.47-0.95), IR-positivity (HR 0.53, 95% CI 0.29-0.98) and serum IGF-I levels (highest versus lowest quartile, HR 0.66, 95% CI 0.47-0.92) were inversely associated with recurrence risk. Conversely, circulating estradiol (highest versus lowest tertile, HR 1.55, 95% CI 1.02-2.36) and insulin (per 10 uU/ml, HR 1.52, 95% CI 1.12-2.06) and phosphorylated IGF1R/pIR expression (HR 1.40, 95% CI 1.02-1.92) were associated with increased risk of recurrence. Conclusions: We identified novel sex hormone and insulin/IGF axis tissue and circulating biomarkers of recurrence in a prospective study of high stage endometrioid endometrial cancer. Circulating insulin and estradiol, and tissue phosphorylated (activated) IGR1R/IR were independently associated with recurrence. These findings support prioritizing studies to establish their clinical utility as prognostic biomarkers and to investigate new strategies that target these pathways for prevention and treatment of endometrial cancer recurrence.

Exploratory analysis of the effect of maintenance rucaparib on postprogression outcomes in patients (pts) with platinum-sensitive recurrent ovarian carcinoma (OC) and updated safety data from the phase 3 study ARIEL3

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Background: In ARIEL3, rucaparib maintenance treatment significantly improved progression-free survival (PFS) vs placebo in all predefined, nested cohorts: BRCA mutation; BRCA mutation + wild-type BRCA/high loss of heterozygosity (LOH); and intent-to-treat (ITT) population. Methods: Pts were randomized 2:1 to receive oral rucaparib 600 mg BID or placebo. Exploratory endpoints of time to first subsequent therapy (TFST), time to investigator-assessed PFS on the subsequent line of treatment or death (PFS2), and time to second subsequent therapy (TSST) were assessed in the predefined cohorts. Results: Exploratory efficacy endpoint data are given in the Table. As of Dec 31, 2017, the most common treatment-emergent adverse events (TEAEs) of any grade (rucaparib vs placebo) were nausea (75.8% vs 36.5%), asthenia/fatigue (70.7% vs 44.4%), dysgeusia (39.8% vs 6.9%), and anemia/decreased hemoglobin (39.0% vs 5.3%). The most common grade ≥3 TEAEs were anemia/decreased hemoglobin (21.5% vs 0.5%) and alanine/aspartate aminotransferase increase (10.2% vs 0.0%). Conclusions: Rucaparib significantly improved the clinically meaningful endpoints TFST, PFS2, and TSST vs placebo in all predefined cohorts of pts with platinum-sensitive, recurrent OC. The updated safety profile was consistent with prior reports. Clinical trial information: NCT01968213. [Table: see text]

Mirvetuximab soravtansine, a folate receptor alpha (FRα)-targeting antibody-drug conjugate (ADC), in combination with bevacizumab in patients (pts) with platinum-resistant ovarian cancer: Final findings from the FORWARD II study

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Background: Mirvetuximab soravtansine is an ADC comprising a FRα-binding antibody, cleavable linker, and the maytansinoid DM4, a potent tubulin-targeting agent. As part of the Phase 1b FORWARD II trial (NCT02606305), the combination of mirvetuximab soravtansine with bevacizumab (BEV) was evaluated in pts with FRα-positive, platinum-resistant ovarian cancer (recurrence within 6 months after last platinum). Methods: Pts received mirvetuximab soravtansine (6 mg/kg; adjusted ideal body weight) and BEV (15 mg/kg) on Day 1 of a 21-day cycle. Responses were assessed according to RECIST 1.1 and adverse events (AEs) evaluated by CTCAE v4.03. Results: In total, 66 pts received combination dosing at this level: 11 during escalation and 55 in expansion. The median age was 63 years, pts received a median of 3 prior lines of systemic therapy (range 1-8), and 62% had received prior therapy with BEV. The most common AEs were diarrhea (58%), nausea (50%), and blurred vision (48%), and were primarily low grade (≤ grade 2). Serious AEs were largely gastrointestinal in nature, with small intestinal obstruction the most frequent individual event (4 pts, 6%). Objective responses were seen in 27 pts for a confirmed overall response rate (ORR) of 41% (95% CI, 29, 54), median progression-free survival (mPFS) interval of 7.1 months (95% CI, 4.9, 9.5), and median duration of response (mDOR) of 8.6 months (95% CI, 4.9, 14.9). In a subset analysis of pts (n = 16) who were bevacizumab-naïve, had 1-2 prior therapies, and medium/high FRα levels (i.e., ≥ 50% of cells with at least moderate staining intensity) the ORR was 56% (95% CI, 30, 80), mPFS 9.9 months (95% CI, 4.1, 15.9), and mDOR 12 months (95% CI, 6.0, 14.9). Conclusions: The combination of mirvetuximab soravtansine with BEV exhibits favorable tolerability in pts with platinum-resistant ovarian cancer, characterized by a manageable side-effect profile. The encouraging efficacy compares favorably to reported outcomes for BEV and chemotherapy seen in similar patient populations. These data support continued exploration of the combination in ovarian cancer. Clinical trial information: NCT02606305.

Feasibility of text-based symptom monitoring of ovarian and endometrial patients during treatment

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Background: Unreported symptoms during cancer treatment can lead to poorer patient care and quality of life. Newer technology enables effective means to track patients’ health in real time. We evaluated the feasibility of implementing systematic patient symptom monitoring during the first 12 months after diagnosis. Methods: Newly diagnosed endometrial and ovarian cancer patients were enrolled post-surgically to respond to monthly text message symptom surveys. Patients’ fatigue, sleep quality, pain, and quality of life during the past 7 days were rated on a 0 (worst) -10 (best) scale, and depressive symptoms were assessed using the Patient Health Questionnaire (PHQ-9). Patients’ responses were captured in REDCap and monitored by program staff, with patients’ oncologists receiving monthly feedback. Patient navigators were also engaged for patients needing assistance during treatment. We provide the results of the first 6 months of this program. Results: 134 patients were approached, and 120 patients (ovarian [n = 70] and endometrial [n = 50]) were enrolled among 5 physicians. The mean participant age was 63 (range: 35-87), 85% were non-Hispanic White, and 66% had education beyond high school. The most commonly reported monthly symptoms for both cancer types were moderate levels (scores of ≥ 4-7) of fatigue and sleep disturbance. 35 patients with PHQ-9 scores ≥ 10 and/or with suicidal ideation were reported to their oncologists for appropriate follow-up. At the 6 month survey, patients were asked to evaluate the text messaging program: 97% found the symptom surveys easy to complete on their smart phone or computer; 77% believed reporting their symptoms monthly was useful all or most of the time; 78% liked being monitored for symptoms all or most of the time; and 89% liked being asked if they needed any assistance prior to their next clinic visit. Patient navigators were used by 13 patients, and 17 patients dropped from the program over the 6 months due to death (n = 9) or lack of need/interest (n = 8). Average monthly compliance was 81%. Conclusions: We established the feasibility of enrolling patients in a monthly text-based monitoring program to facilitate symptom management during treatment. Patient follow-up is continuing.

Phase 2 trial of tisotumab vedotin in platinum-resistant ovarian cancer (innovaTV 208)

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Background: Ovarian cancer (OC) is the most lethal gynecologic cancer, accounting for ≈185,000 deaths worldwide in 2018. Most patients (pts) initially respond to platinum-based chemotherapy (chemo), but more than 50% of pts recur. Pts who recur in ≤6 months have platinum-resistant OC (PROC), which is associated with poor prognosis. Standard therapy for PROC includes chemo ± bevacizumab (bev). However, many pts receive single-agent chemo, which demonstrates limited response and survival (≈12% ORR, 3-4 mo PFS, ≈12 mo OS). Therefore, there is an urgent need for novel therapeutic strategies. Tissue factor (TF) is a novel oncogenic target expressed in OC. Tisotumab vedotin (TV) is a first-in-class antibody drug conjugate comprising a TF-targeted fully human monoclonal antibody conjugated to the microtubule-disrupting agent monomethyl auristatin E. TV has shown encouraging antitumor activity and a manageable safety profile in PROC in the multicohort phase 1/2 innovaTV 201 study. innovaTV 208 is a multicenter, open-label, phase 2 trial with a safety run-in phase for a dose-dense regimen (DDR) evaluating the efficacy and safety of TV in pts with PROC. Methods: innovaTV 208 will enroll ≈142 adult pts with platinum-resistant epithelial ovarian, primary peritoneal, or fallopian tube cancer; measurable disease by RECIST v1.1; and ECOG score 0-1. Eligible pts must have received bev-containing treatment for OC. Pts with platinum-refractory disease, increased risk of bleeding, active ocular surface disease, or grade > 1 peripheral neuropathy will be excluded. A safety run-in phase for the DDR will be performed in up to 12 pts who received ≤5 prior treatment regimens for PROC. In the DDR, TV will be given at previously decided lower doses IV 3Q4W for the same dose intensity as the standard 1Q3W dose; the primary endpoint is incidence of DLTs. In phase 2, pts who received ≤1 prior cytotoxic chemo regimen for PROC will be randomized to receive TV administered as IV 1Q3W or as IV 3Q4W, if shown to be tolerable. The primary endpoint for phase 2 is confirmed ORR by RECIST v1.1. Secondary endpoints include DOR, time to response, DCR, CA-125 response rate by GCIG criteria, PFS, OS, pharmacokinetics, and safety. Clinical trial information: NCT03657043.

Trebananib or placebo plus carboplatin and paclitaxel as first-line treatment for advanced ovarian cancer (TRINOVA-3/ENGOT-ov2/GOG-3001): a randomised, double-blind, phase 3 trial

BACKGROUND

Angiopoietin 1 and 2 regulate angiogenesis and vascular remodelling by interacting with the tyrosine kinase receptor Tie2, and inhibition of angiogenesis has shown promise in the treatment of ovarian cancer. We aimed to assess whether trebananib, a peptibody that inhibits binding of angiopoietin 1 and 2 to Tie2, improved progression-free survival when added to carboplatin and paclitaxel as first-line therapy in advanced epithelial ovarian, primary fallopian tube, or peritoneal cancer in a phase 3 clinical trial.

METHODS

TRINOVA-3, a multicentre, multinational, phase 3, double-blind study, was done at 206 investigational sites (hospitals and cancer centres) in 14 countries. Eligible patients were aged 18 years or older with biopsy-confirmed International Federation of Gynecology and Obstetrics (FIGO) stage III to IV epithelial ovarian, primary peritoneal, or fallopian tube cancers, and an ECOG performance status of 0 or 1. Eligible patients were randomly assigned (2:1) using a permuted block method (block size of six patients) to receive six cycles of paclitaxel (175 mg/m²) and carboplatin (area under the serum concentration-time curve 5 or 6) every 3 weeks, plus weekly intravenous trebananib 15 mg/kg or placebo. Maintenance therapy with trebananib or placebo continued for up to 18 additional months. The primary endpoint was progression-free survival, as assessed by the investigators, in the intention-to-treat population. Safety analyses included patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, number NCT01493505, and is complete.

FINDINGS

Between Jan 30, 2012, and Feb 25, 2014, 1164 patients were screened and 1015 eligible patients were randomly allocated to treatment (678 to trebananib and 337 to placebo). After a median follow-up of 27·4 months (IQR 17·7-34·2), 626 patients had progression-free survival events (405 [60%] of 678 in the trebananib group and 221 [66%] of 337 in the placebo group). Median progression-free survival did not differ between the trebananib group (15·9 months [15·0-17·6]) and the placebo group (15·0 months [12·6-16·1]) groups (hazard ratio 0·93 [95% CI 0·79-1·09]; p=0·36). 512 (76%) of 675 patients in the trebananib group and 237 (71%) of 336 in the placebo group had grade 3 or worse treatment-emergent adverse events; of which the most common events were neutropenia (trebananib 238 [35%] vs placebo 126 [38%]) anaemia (76 [11%] vs 40 [12%]), and leucopenia (81 [12%] vs 35 [10%]). 269 (40%) patients in the trebananib group and 104 (31%) in the placebo group had serious adverse events. Two fatal adverse events in the trebananib group were considered related to trebananib, paclitaxel, and carboplatin (lung infection and neutropenic colitis); two were considered to be related to paclitaxel and carboplatin (general physical health deterioration and platelet count decreased). No treatment-related fatal adverse events occurred in the placebo group.

INTERPRETATION

Trebananib plus carboplatin and paclitaxel did not improve progression-free survival as first-line treatment for advanced ovarian cancer. The combination of trebananib plus carboplatin and paclitaxel did not produce new safety signals. These results show that trebananib in combination with carboplatin and paclitaxel is minimally effective in this patient population.

FUNDING

Amgen.

BRCA Reversion Mutations in Circulating Tumor DNA Predict Primary and Acquired Resistance to the PARP Inhibitor Rucaparib in High-Grade Ovarian Carcinoma

A key resistance mechanism to platinum-based chemotherapies and PARP inhibitors in BRCA-mutant cancers is the acquisition of BRCA reversion mutations that restore protein function. To estimate the prevalence of BRCA reversion mutations in high-grade ovarian carcinoma (HGOC), we performed targeted next-generation sequencing of circulating cell-free DNA (cfDNA) extracted from pretreatment and postprogression plasma in patients with deleterious germline or somatic BRCA mutations treated with the PARP inhibitor rucaparib. BRCA reversion mutations were identified in pretreatment cfDNA from 18% (2/11) of platinum-refractory and 13% (5/38) of platinum-resistant cancers, compared with 2% (1/48) of platinum-sensitive cancers (P = 0.049). Patients without BRCA reversion mutations detected in pretreatment cfDNA had significantly longer rucaparib progression-free survival than those with reversion mutations (median, 9.0 vs. 1.8 months; HR, 0.12; P < 0.0001). To study acquired resistance, we sequenced 78 postprogression cfDNA, identifying eight additional patients with BRCA reversion mutations not found in pretreatment cfDNA. SIGNIFICANCE: BRCA reversion mutations are detected in cfDNA from platinum-resistant or platinum-refractory HGOC and are associated with decreased clinical benefit from rucaparib treatment. Sequencing of cfDNA can detect multiple BRCA reversion mutations, highlighting the ability to capture multiclonal heterogeneity.This article is highlighted in the In This Issue feature, p. 151.