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HER2 is an important prognostic and therapeutic target in uterine serous carcinoma (USC). Optimal HER2 testing platforms have not been defined and guidelines for testing have changed over time. Our objective is to assess the concordance of HER2 positivity based on chromogenic in situ hybridization (CISH), immunohistochemistry (IHC), and next generation sequencing (NGS) and to determine the rate of downstream mutations that may affect response to HER2 directed therapy.Utilizing the Caris tumor registry, 2192 USC tumors were identified and analyzed using NGS (NextSeq, 592 Genes and WES, NovaSEQ), IHC, and CISH. PD-L1 expression was tested by IHC. Microsatellite instability was tested by fragment analysis, IHC, and NGS. Tumor mutational burden (TMB) was measured by totaling somatic mutations per tumor. HER2 positivity through IHC and CISH was determined based on 2007 and 2018 ASCO/CAP HER2 breast cancer guidelines.There was a higher rate of HER2 positivity by IHC when using the 2018 guidelines compared to the 2007 guidelines (16.3% vs 12.3%). Concordance between IHC and CISH was 98.9%. ERBB2 amplification was identified by NGS in 10.5% of tumors. Compared to CISH results, this corresponds to a concordance rate of 91.6% and a positive predictive value (PPV) of 60.3%. Single gene alterations in HER2 amplified tumors that may implicate HER2 therapy resistance included PI3K (33.1%), KRAS (2.5%), and PTEN (1.3%).There was high concordance between HER2 positivity based on CISH and IHC. Rate of HER2 positivity is the lowest by NGS. Ultimately these testing platforms need to be validated by response to targeted therapy.

Treatment options for advanced vulvar cancer are limited. We evaluated pembrolizumab monotherapy in patients with advanced vulvar squamous cell carcinoma (SCC) enrolled in the phase 2 multicohort, open-label KEYNOTE-158 study (NCT02628067).Eligible patients had histologically or cytologically documented advanced vulvar SCC with prior treatment failure, measurable disease per RECIST v1.1, ECOG performance status 0-1, and a tumor sample available for biomarker analysis. Pembrolizumab 200 mg was administered intravenously Q3W for up to 35 cycles (approximately 2 years). The primary endpoint was objective response rate (ORR) per RECIST v1.1 by independent central radiologic review in all patients and subgroups based on PD-L1 combined positive score (≥1 [PD-L1-positive] versus1 [PD-L1-negative]).101 patients were enrolled. Median time from first dose to data cutoff was 36.0 months. The ORR (95% CI) was 10.9% (5.6%-18.7%) among all patients, 9.5% (4.2%-17.9%) among the 84 patients with PD-L1-positive tumors, and 28.6% (3.7%-71.0%) among the 7 patients with PD-L1-negative tumors. Among patients with a response, median DOR was 20.4 (range, 2.1+ to 28.0) months. Median (95% CI) PFS and OS were 2.1 (2.0-2.1) and 6.2 (4.9-9.4) months, respectively. Treatment-related AEs occurred in 50.5% of patients (grade 3-5, 11.9%) and led to discontinuation of treatment in 5.0% of patients. Two deaths were considered treatment-related (hepatitis, n = 2).Pembrolizumab monotherapy was associated with durable responses in a subset of patients with vulvar SCC. Responses occurred regardless of tumor PD-L1 status. No new safety signals emerged; overall, pembrolizumab was well tolerated.

BACKGROUND: This report is intended to present a unique patient with acquired vaginal obstruction due to prior radiation therapy and subsequent development of hematocolpos. We present a method of surgical decompression for the hematocolpos as well as this patient’s follow-up and prevention of re-epithelialization. CASE: One patient was recruited and consented for this case study. Pre-operative evaluation, including examination and imaging, intra-operative findings, and post-operative evaluation were reported in this study. After surgical evaluation and drainage of hematocolpos via incision and drainage, a foley balloon was placed to prevent re-epithelialization. Intra-operative fluid cultures yielded no growth. At her follow-up appointment, the foley balloon was removed and the vaginal canal was intact without agglutination or re-accumulation of hematocolpos. CONCLUSIONS: This is a unique case of acquired obstruction from radiation therapy causing significant symptomatic hematocolpos. We offer a minimally invasive approach for decompression, evaluation of malignancy, and prevention of re-obstruction. Her post-operative appointment showed resolution of symptoms and patent vaginal canal. Long-term outcomes are still required, including monitoring for malignant recurrence, re-obstruction and stenosis, and sexual health. If re-epithelialization occurs, more definitive therapy will be required, including excision of the vaginal septum or hysterectomy.

ObjectivePreclinical evidence and early clinical trials have demonstrated the activity of SPL-108, a targeted agent that inhibits CD44 mediated induction of multidrug resistance specifically to paclitaxel and platinum agents. We conducted a phase I, open label, dose escalation study of the safety and tolerability of the combination of SPL-108 with weekly paclitaxel in patients with platinum resistant CD44+ ovarian, primary peritoneal, or fallopian tube cancer.MethodsPatients with platinum resistant histologically proven epithelial ovarian, primary peritoneal, or fallopian tube cancers and measurable disease according to RECIST (Response Evaluation Criteria in Solid Tumours) version 1.1 were selected. Tumors were tested for CD44 expression for eligibility, defined as strong (+++) or moderate (++) staining in ≥20% of the tumor tissue or diffuse + staining. Patients were treated with daily and then twice daily SPL-108 subcutaneous injections and weekly intravenous paclitaxel on days 1, 8, and 15 of a 28 day cycle. Endpoints included safety, determination of maximum tolerated dose, and efficacy. Tumors underwent comprehensive genomic profiling, and cell lines and western blotting were used to study markers of response.ResultsWe screened 16 patients, and 14 were enrolled based on CD44+ expression. A total of 86% of patients had high grade serous tumors and all had received multiple prior therapies. There were no grade 4–5 toxicities. One patient had grade 3 peripheral sensory neuropathy attributed to paclitaxel and one patient developed presumed colonic perforation attributed to the study drug. No dose reductions or treatment discontinuations were required. All patients tolerated the maximum planned dose; no maximum tolerated dose was reached. Overall response rate was 36%; 5 (36%) patients had partial response and 5 (36%) patients had stable disease.ConclusionsThe combination of SPL-108 with weekly paclitaxel was safe and well tolerated. Encouraging antitumor activity was observed, with 72% of patients deriving a clinical benefit.Trial registrationNCT03078400.

ObjectivesOur study aimed to determine the publication rates of podium presentations from the 2017 and 2018 Society of Gynecologic Oncology (SGO) Annual Meetings; and to examine rates and predictors of oral presentations that resulted in publication.MethodsWe reviewed podium presentations given at the 2017 and 2018 SGO Annual Meetings. Abstracts were evaluated for publication from January 1, 2017 to March 30, 2020 and January 1, 2018 to June 30, 2021, respectively, to allow for a 3 year period of publication.ResultsIn 2017 and 2018, 43 of 75 (57.3%) and 47 of 83 (56.6%) podium presentations were published within 3 years, respectively. No significant difference was found between the mean time to publication within 3 years (13.0 months vs 14.1 months for 2017 and 2018, respectively; p=0.96). Similarly, the mean difference of journal impact factors between both years did not reach significance (6.57 and 10.7 for 2017 and 2018, respectively; p=0.09). The median impact factor (IF) was 4.54 (range: 40.3) and 4.62 (range: 70.7) in 2017 and 2018, respectively. Of the presentations published, 53.4% (2017) and 38.3% (2018) appeared in the journal Gynecologic Oncology. Significant positive correlations for the likelihood of publication were determined among the following: funding status (r=0.93) including funding involving National Institutes for Health (r=0.91) or pharmaceutical (r=0.95), clinical trial study design (r=0.94), and pre-clinical research (r=0.95) (all pConclusionsAt the 2017 and 2018 SGO Annual Meetings 57% of podium presentations were published in a peer-reviewed journal within 3 years. Publication in peer-reviewed journals is crucial for timely distribution of clinical information to the medical community.

Background: Locally advanced cervical cancer accounts for most deaths from disease. Standard of care includes treatment with cisplatin-based chemoradiation with a 70% response rate. The addition of intravenous (IV) triapine to chemoradiation has shown promising clinical activity in phase 1 and 2 studies but comes with a more intensive treatment regimen. An ongoing phase 1 trial has finished the escalation phase, and we report the pharmacokinetics (PK) and pharmacodynamics (PD) of oral (PO) triapine. Methods: This phase 1 study followed a 3+3 design for dose escalation of oral triapine, starting with initial dose of 100 mg five days a week for five weeks combined with external beam pelvic radiation and weekly IV cisplatin. PK was determined by LC-MS/MS, and PD included methemoglobin levels at 4 h post dose. Within patient PK variability after IV and PO dosing and PO bioavailability were calculated. Results: PK data were available for 10 patients at 100 (the MTD) and 150 mg. PO parameter values were Tmax 1.3 h, t1/2 1.4 h, CL/F 104 L/h, and Vz/F 214 L. There was no discernable difference between triapine exposure at 100 vs. 150 mg PO (Cmax 520 (2.5) vs. 344 (1.9) µg/L; AUC 1209 (2.53) vs. 1034 (1.41) µg/L•h), and between patient variability at each dose level was substantial. The correlation of PO Vz/F vs Cl/F was high at R2=0.86, suggesting that the apparent clearance and volume variability is primarily due to variability in the oral bioavailability F. PO within patient variability of Cmax and AUC was also large at 43% and 55%. IV PK was less variable with lower geometric standard deviations across all parameters, including within patients where variability of Cmax and AUC was modest at 10 and 12% coefficient of variation, respectively. Oral bioavailability was estimated at 66%. We found a non-significant trend of smoking almost doubling triapine oral clearance from 68 to 156 L/h (p=0.056). There was no apparent relationship between occurrence of DLT and either IV or PO triapine AUC. Methemoglobin levels directly correlated with triapine exposure expressed as AUC or Cmax. Conclusions: Triapine PK parameter values for PO and IV administration and PO bioavailability values observed in this trial were comparable to previous reports. Correlation of methemoglobin with exposure highlights the importance of optimizing triapine exposure. Additional data may support the exploration of a dose specific to current smokers. Citation Format: Jan H. Beumer, Sarah Behr, Holly Gallion, John Vargo, Frederick Ueland, Haider Mahdi, Brian Orr, Eugenia Girda, Susan Christner, Edward Chu, Charles Kunos, Percy S. Ivy, Sarah Taylor. Pharmacokinetics, bioavailability, and pharmacodynamics of oral triapine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2800.

Cancer care has been greatly impacted during the COVID-19 pandemic. The number of cases and deaths caused by the COVID-19 pandemic continues to escalate throughout the United States and the world. Worldwide, over 150 million people have been diagnosed with the coronavirus and more than 3 million have died. Now that we have gained additional experience with COVID-19, we are starting to learn its full impact on oncology care and its effects on the practice of medicine and clinical research.

TPS277 Background: There is a need to develop novel immunotherapeutic approaches to enhance responses to immune checkpoint blockade. REGN7075 is a human costimulatory bispecific antibody designed to bridge epidermal growth factor receptor (EGFR)-expressing tumor cells with CD28-positive T cells to support further T-cell activation by endogenous tumor antigens. Methods: This is an open-label, Phase 1/2, first-in-human study evaluating the safety, tolerability, pharmacokinetics, and preliminary anti-tumor activity of REGN7075 (EGFRxCD28) alone and in combination with cemiplimab (anti-programmed cell death [PD]-1) in patients with advanced solid tumors (NCT04626635). This study includes a dose-escalation (Bayesian optimal interval design; Part 1) and a dose-expansion phase (Part 2). Patients must have a protocol-defined advanced solid tumor, have an Eastern Cooperative Oncology Group performance status of 0 or 1, and be naive to anti–PD-1/anti–PD-ligand(L)1 therapy in the dose-expansion phase. In Part 1, heavily pre-treated patients with advanced solid tumors receive a lead-in of REGN7075 monotherapy every week for 3 weeks followed by combination therapy with cemiplimab 350 mg every 3 weeks. Planned dose levels (DLs) of REGN7075 are 0.03, 0.1, 0.3, 1, 3, 10, 30, 100, 300, and 900mg. Once the recommended Phase 2 dose is determined in Part 1, five tumor-specific expansion cohorts will be opened in Part 2: colorectal cancer (microsatellite stable [MSS-CRC]), non-small cell lung cancer (NSCLC, PD-L1 ≥50%), triple-negative breast cancer, cutaneous squamous cell carcinoma, and head and neck squamous cell carcinoma (PD-L1 combined positive score ≥1). Patients with MSS-CRC with RAS or BRAF wild type mutations must have received anti-EGFR therapy or anti-vascular endothelial growth factor (VEGF therapy). Primary endpoints are safety and tolerability of REGN7075 alone or in combination with cemiplimab for Part 1, and objective response rate per Response Evaluation Criteria in Solid Tumors version 1.1 for Part 2. For Part 2, a secondary objective is to assess the effect of REGN7075 on patient-reported outcomes as measured by several validated instruments including the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30), and EORTC QLQ-CR29 (CRC patients only). Approximately 400 patients will be enrolled in this phase 1/2 study, including ~80 patients in Part 1 and ~320 patients in Part 2 (including ~70 in the CRC cohort). As of September 13, 2022, 30 patients were treated in the dose-escalation phase, up to the 300 mg DL for REGN7075 in combination with cemiplimab. This study is ongoing and currently open to enrollment. Clinical trial information: NCT04626635 .

11551 Background: Immune checkpoint inhibitors (ICI) have limited efficacy for most sarcomas. Yet, responses are seen in particular sarcoma subtypes, highlighting the need for better predictive biomarkers. The T cell inflamed score (TIS), a gene expression signature reflective of an active tumor immune microenvironment, is associated with ICI response in multiple solid tumors. We evaluated the TIS across a large database of sarcomas to identify which histologic subtypes may benefit from ICI. Methods: Next generation sequencing of DNA (592 gene or whole exome)/RNA (whole transcriptome) was performed for 3605 sarcoma patient samples, representing 45 histologic subtypes (Caris Life Sciences, Phoenix, AZ). TIS (18 gene weighted coefficient composite value; Cristescu 2018) was calculated and the Microenvironment Cell Populations-counter tool (Becht 2016) was used to quantify immune cell populations. Results were compared to melanoma (n = 1255), a representative immunogenic tumor type. High TIS was defined as a score within the upper quartile of melanoma TIS (> 5.5). Percentage with high TIS are reported with 95% CI. Results: Median TIS was highest in inflammatory myofibroblastic tumor (IMT), epithelioid sarcoma (EPIS), myxofibrosarcoma (MFS), well differentiated liposarcoma, and solitary fibrous tumor (SFT). These did not differ significantly from melanoma (p > 0.06). Median TIS was lowest in embryonal rhabdomyosarcoma, desmoid tumor (DES), synovial sarcoma (SYNS), and Ewing sarcoma (ES). Histologic subtypes where > 10% of samples had a high TIS included IMT (29.9% ± 21.7%), MFS (23.3% ± 12.6%), pleomorphic sarcoma (PLSARC) (21.9% ± 5.8%), cutaneous angiosarcoma (ANGS) (18.4% ± 13.9%), spindle cell sarcoma (17.5% ± 7.6%), liposarcoma (LPS) (17% ± 10.7%), EPIS (15.4% ± 19.6%), visceral ANGS (13.2% ± 10.7%), pleomorphic LPS (13.6% ± 14.3%), fibrosarcoma (12.5% ± 13.2%), leiomyosarcoma (11.6%± 3.4%), malignant peripheral nerve sheath tumor (MPNST) (10.2% ± 7.7%), and perivascular epithelioid cell tumor (PEComa) (10% ± 10.7%). The relative abundance of immune and stromal cell populations was highly variable across sarcoma subtypes, yet a strong positive correlation between TIS and immune cell populations was observed for most subtypes (e.g. T cells, Spearman R range: 0.56 [P = 0.08] - 0.96 [P < 0.0001]). A notable exception was SFT, which had a relatively high median TIS but low abundance of CD8+ T cells and B cells. Conclusions: We found high median TIS and/or significant proportions of samples with a high TIS in sarcoma subtypes with previously demonstrated responsiveness to ICI, including MFS, PLSARC, LPS, and ANGS, while unresponsive tumor types such as RMS, DES, SYNS, and ES had low TIS. We further identified subtypes with high TIS but limited prior clinical data supporting ICI use, such as IMT, EPIS, MPNST, SFT, and PEComa. Our results warrant prospective exploration of TIS as a predictive biomarker for ICI use in sarcoma.

5548 Background: Clear cell carcinomas (CCC) are rare histologies outside of the kidney and are typically less sensitive to standard treatments. Genomic alterations in chromatin remodeling pathways involving ARID1A or the intracellular PI3K-mTOR signaling pathway are found in both renal and ovarian CCC. It is unclear whether CCCs originating from different anatomic sites share a common genomic landscape. This CARIS Precision Oncology Alliance project sought to determine whether CCC of different organs shared similar genomic signatures and to identify potential pathways that could be targeted in a tumor-agnostic clinical trial. Methods: CCCs (N = 861) from multiple primary tumor sites, including kidney (30.5%), ovary (39%), endometrium (23.9%), other gynecologic sites (e.g., cervix, fallopian tube, 3.3%), and miscellaneous (non-kidney or gynecologic sites, 3.3%) were analyzed at the Caris Life Sciences Laboratory (Phoenix, AZ). Using hierarchical clustering (HC) and principal component analysis (PCA), the samples were compared across 648 total genes from five metabolic gene sets consisting of angiogenesis, glycolysis, hypoxia, oxidative phosphorylation, and fatty acid metabolism. Gene Set Enrichment Analysis (GSEA) was further conducted on the samples across fifty hallmark gene sets representing specific biologic processes and expression. Samples were also analyzed for individual genomic alterations and immune-oncology associated biomarkers. PD-L1 (SP142) expression was evaluated by immunohistochemistry (positive threshold: 2+ stain intensity and ≥ 5% tumor cells). Results: HC and PCA demonstrated that renal CCC formed distinct clusters compared to non-renal CCC. Tumors from gynecologic sites could not be separated into distinct clusters. GSEA showed that the hypoxia gene set was significantly upregulated in the renal but not in non-renal CCCs. Mutations involving TP53, ARID1A, PIK3CA were found to be the most altered genes in endometrial (62%, 26%, 31%), ovarian (13%, 55%, 48%), other gynecological sites (33%, 38%, 44%), and non-gynecologic CCC (13%, 17%, 12%) respectively. PD-L1 expression, high tumor mutational burden (≥10 mutations/Mb), and deficient mismatch repair/microsatellite instability rates across sites were: kidney (11%, 2%, 2%), endometrium (13%, 12%, 7%), ovary (9%, 4%, 3%), other gynecological sites (31%, 11%, 11%), and miscellaneous sites (11%, 19%, 4%). Conclusions: Initial metabolic gene expression clustering analysis shows that CCCs do not separate by organ of origin beyond renal versus extra-renal. TP53, ARID1A, and PIK3CA were the most frequently altered genes in non-renal CCC. Out of fifty hallmark gene sets, only two were statistically significantly different among gynecological CCCs. This similarity between gynecological CCC can be leveraged by targeting pathways such as PI3K-AKT-mTOR, DNA repair, and MYC targets in a site agnostic manner. Furthermore, high PD-L1 expression is found in other gynecological sites.

TPS5602 Background: Tumor-infiltrating lymphocytes (TIL) are a heterogeneous population of T cells that recognize multiple endogenous tumor antigens but may have developed an exhausted phenotype due to the tumor microenvironment. While existing TIL therapies produce durable responses in patients with melanoma, cervical, and head and neck cancers, poor in vitro cell expansion, limited short-lived in vivo persistence, and diminishing potency restrict this approach’s broader application. DeTIL-0255 (drug-enhanced TIL [DeTIL]) is an autologous adoptive cell therapy (ACT) derived from a patient’s tumor and expanded ex vivo with NX-0255, a small-molecule inhibitor of the E3 ligase, Casitas B-lineage lymphoma proto-oncogene B (CBL-B). CBL-B is expressed in T cells, where it functions as a regulator of immune cell activation, in part by requiring CD28 co-stimulation in addition to T-cell receptor activation. Desirable properties enhanced by DeTIL-0255 when compared with TIL include increased number of stem-like CD39-/CD69-, and CD8+ T cells associated with persistence, as well as enhanced cytolytic function. ACT with T cells expanded ex vivo using NX-0255 demonstrated increased anti-tumor activity, longer survival, increased stem-like phenotype, and persistence of tumor antigen-specific T cells in mouse tumor models. Adoptive cell transfer of DeTIL-0255, therefore, may exhibit broader functional activity than conventional TIL, potentially conferring improved anti-tumor activity and response. Methods: NX-DeTIL-0255-201 is a Phase 1 multicenter, open-label study of DeTIL-0255 administered with systemic high-dose IL-2 following nonmyeloablative lymphodepleting chemotherapy in patients with advanced gynecological malignancies for whom standard therapy with proven clinical benefit does not exist, is no longer effective, or is inappropriate. The primary objectives are to evaluate the safety, tolerability, and preliminary antitumor activity of DeTIL-0255. A safety run-in will consist of 3 to 6 patients treated with DeTIL-0255 and evaluated for dose-limiting toxicity (DLT). The DLT period starts with DeTIL-0255 infusion and ends after a total of 28 days. The safety run-in will investigate DeTIL-0255 at a dose range of 1 to 150 x 109 CD3+ T cells (exact dose varying based on expansion potential of DeTIL-0255 from tumor biopsies). Following the safety run-in, cohort expansion will further evaluate the safety and antitumor activity of DeTIL-0255 in patients with recurrent/persistent platinum-resistant epithelial ovarian cancer, cervical carcinoma, and endometrial cancer. Key eligibility criteria include measurable disease, a resectable lesion for TIL harvest, ≥2 prior lines of therapy, and an Eastern Cooperative Oncology Group performance status 0 or 1. The study is expected to enroll ̃54 patients in ̃10 sites across the United States. Clinical trial information: NCT05107739.

5514 Background: Mesothelin and its binder, antigen-CA125, are highly expressed in high grade serous and endometrioid ovarian cancers (HGOC) and, can inhibit paclitaxel-induced cell death. Anetumab ravtansine (AR) is a fully-human antibody directed at the mesothelin antigen, conjugated to a tubulin polymerization inhibitor. We assessed the safety and activity of the combination AR/bevacizumab (ARB) versus weekly paclitaxel/bevacizumab (PB) in patients (pts) with platinum resistant HGOC. Methods: An initial run-in phase I assessed the safety of ARB. After determination of the recommended phase 2 dose (RP2D), a multicenter 1:1 randomized phase 2 trial was designed to evaluate the progression free survival (PFS) in pts with platinum resistant/refractory HGOC. Pts were stratified by platinum resistant or refractory and prior bevacizumab (bev). Eligibility required measurable disease and mesothelin tested positive centrally on archival tissue by IHC. No limitation on the number of prior lines of therapy. A futility analysis was planned at 35 PFS events. The control arm was weekly intravenous paclitaxel 80mg/m2 with bev 10mg/kg every 2 weeks. A CT was performed every 8 weeks for RECIST1.1 assessment. The toxicities were reported according to CTCAE version 5.1. NCT03587311. Results: 7 pts were enrolled in the run-in phase 1 and the RP2D determined as bev (10mg/kg) biweekly with AR (2.2mg/kg) weekly on a 28 day-cycle. In the phase 2, 57 pts were enrolled, 28 pts in the ARB and 29 pts in the control group. The positivity rate for mesothelin screening was 88%. Pts were heavily pre-treated, median prior lines of 3 (range (1-9) with 24 pts received prior bev (42%) and 13 pts were platinum refractory (7 in ARB and 6 in PB). At the time of 35 PFS events, one CR and 4 PR were observed (ORR = 18%) in the ARB arm, versus no CR and 16 PR in the weekly PB (ORR = 55%). The estimated median PFS was 5.3 (95% CI: 3.7-7.4) months for ARB and 9.6 (95% CI: 7.4-17.4) months for PB (HR = 1.7(95% CI: 0.9-3.4)). The median number of cycles were 4 (1, 29) and 8 (1, 19) respectively. The most common treatment-related AEs in the ARB arm were mostly grade 1/2 increase AST (71%) and ALT (64%), thrombocytopenia (61%), fatigue (57%), and peripheral neuropathy (46%). In the PB arm, the most common treatment-related AE were anemia (66%), neutropenia (59%), epistaxis (48%), fatigue (45%) and peripheral neuropathy (45%). Conclusions: At the time of futility analysis, weekly PB had better outcome than weekly ARB leading to the study termination. Molecular and blood analyses are on-going to assess potential biomarkers of response. This study highlights the importance of randomization in assessment of novel therapies and potential for re-challenge with bevacizumab. These data show that weekly PB is an effective regimen and can be considered as the control arm in platinum resistant HGOC. Clinical trial information: NCT03587311.