Oladapo O. Yeku

Normalizing the Tumor Microenvironment: A New Frontier in Ovarian Cancer Therapy

Ovarian cancer is one of the deadliest gynecological malignancies, where most patients become clinically symptomatic at advanced stages of disease due to the lack of effective diagnostic screening. Despite recent advances in surgical resection and chemotherapy, recurrent ovarian cancer remains largely refractory to treatment, resulting in poor prognosis. The ovarian cancer tumor microenvironment (TME) is highly abnormal and presents a significant barrier to successful therapy. A combination of abnormal vasculature, desmoplastic extracellular matrix, and aberrantly activated hypoxic and immune-suppressive pathways culminates in promoting tumor growth, dissemination, chemoresistance, and immunosuppression. Whilst immune checkpoint inhibitors have shown success in other cancers, their application in ovarian cancer, particularly at advanced stages, remains limited. In this review, we discussed the application of tumor extracellular matrix normalizing therapies in preclinical models of advanced ovarian cancer, and their synergistic benefit to chemotherapy and immunotherapy. Collectively, these insights underscore TME normalization as a promising therapeutic strategy with the potential to improve ovarian cancer management.

Hypoxia induced VEGF secretion promotes resistance to bispecific T-cell engagers

Abstract Bispecific T-cell Engagers (BITEs) are a novel form of immunotherapy that overcome a deficiency of immune checkpoint inhibitors (ICI) by targeting a preidentified tumor associated antigen and redirecting a polyclonal population of effector T-cells against the tumor. High grade serous ovarian cancer is a lethal disease in the recurrent setting and has not been amenable to ICI therapy. MUC16/CA125 is overexpressed in high grade serous ovarian cancer. BITEs targeting the tumor-retained portion of MUC16/CA125 have recently been described and are in early-phase clinical trials. To identify mechanisms of resistance to BITEs, we collected serum, peripheral blood mononuclear cells, and ascites samples from patients with disease progression on MUC16-directed bispecific antibodies. Analysis of these samples showed downregulation of MUC16/CA125, elevated secretion of VEGF, and epithelial-to-mesenchymal transition in tumor cells. Interestingly, hypoxia was determined to be a driver of these changes. These findings were prospectively validated in ovarian cancer cell lines with CRISPR/Cas9 knockout of MUC16/CA125 and VEGF. Peripheral blood mononuclear cells from patients with disease progression were capable of effective cytolysis ex vivo, suggesting that resistance to therapy was primarily tumor driven. Restoration of MUC16/CA125 expression did not restore cytotoxicity in the presence of increased VEGF secretion. Combination treatment with a VEGF inhibitor rescued cytotoxicity in hypoxia-conditioned ovarian cancer cell lines with preserved target antigen expression. Collectively, these data outline a link between hypoxia and the development of resistance to BITEs and posits inhibition of VEGF inhibition as a potentially important therapeutic intervention.

Myeloid targeting antibodies PY159 and PY314 for platinum-resistant ovarian cancer

Background Novel treatment options are required in patients with platinum-resistant ovarian cancer (PROC). Myeloid-derived suppressor cells promote a hostile tumor microenvironment and are associated with worse clinical outcomes in PROC. We evaluated the safety and preliminary efficacy of PY159, an agonist antibody to Triggering receptor expressed on myeloid cells-1 (TREM1) that reprograms immunosuppressive intratumoral myeloid cells, and PY314, an antagonist antibody to Triggering receptor expressed on myeloid cells-2 (TREM2) that depletes tumor-associated macrophages, as single agents and in combination with pembrolizumab in subjects with PROC. Methods PY159 and PY314 were individually evaluated in patients with PROC. Patients were treated with monotherapy (PY159 3 mg/kg or PY314 10 mg/kg), based on the recommended dose for expansion derived from the phase 1a studies. At the time of first progression, patients could continue study drug and crossover to combination therapy with pembrolizumab (200 mg) every 3 weeks at the discretion of the investigator. Disease assessment by Response Evaluation Criteria in Solid Tumor version 1.1 was performed every 6 weeks. Results 17 patients were enrolled in the PY159 study (median age 67, range 22–77; median prior therapies 6, range 2–18) and 16 patients in PY314 (median age 65.5, range 49–81; median prior therapies 4, range 2–10). 7 patients in PY159 and 8 patients in PY314 crossed over to combination therapy. Safety events included the following: treatment-related adverse events occurred in 15 patients (88.2%) in PY159 and 9 patients (56.3%) in PY314. Infusion-related reactions occurred in 6 patients (35.3%) in PY159 and 3 patients (18.8%) in PY314. Immune-related adverse events occurred in 13 patients (76.5%) in PY159 (arthralgias) and 1 patient (6.3%) in PY314 (diarrhea). Serious adverse events occurred in 6 patients (36.3%) in PY159 (1 related) and 12 patients (75%) in PY314 (all unrelated). The best radiographic response in PY159 was stable disease in 8/16 patients (50%; median 16 weeks, range 9–33), and in PY314, it was stable disease in 8/16 patients (50%; median 12 weeks, range 6–36). Median PFS was 2.76 months and 2.69 months in PY159 and PY314, respectively. There were no responses in the crossover arm. Conclusions Both PY159 and PY314 were well tolerated, with an acceptable safety profile, as both single agents and in combination with pembrolizumab. Both agents warrant further investigation in heavily pretreated PROC.

Niraparib, Dostarlimab, and Bevacizumab as Combination Therapy in Pretreated, Advanced Platinum-Resistant Ovarian Cancer: Findings From Cohort A of the OPAL Phase II Trial

PURPOSE To report the results of OPAL (ClinicalTrials.gov identifier: NCT03574779 ) cohort A, a single-arm substudy of niraparib plus dostarlimab and bevacizumab for the treatment of advanced, platinum-resistant ovarian cancer (PROC). METHODS Participants with PROC who received 1-2 previous lines of therapy were treated with niraparib (200 or 300 mg once daily), dostarlimab (500 mg once every 3 weeks for four 21-day cycles, followed by 1,000 mg once every 6 weeks), and bevacizumab (15 mg/kg once every 3 weeks). The primary end point was investigator-assessed objective response rate (ORR) per RECIST v1.1. Safety was also assessed. Exploratory biomarker end points included evaluation of changes in the tumor molecular profile and microenvironment using baseline and on-treatment tumor samples. RESULTS Of 41 enrolled participants (median age, 66.0 years [range, 37-83 years]), 9.8% had tumors that were BRCA-mutated, 19.5% were homologous recombination (HR)–deficient, and 17.1% were HR repair (HRR)–mutated. As of the cutoff date, all participants discontinued treatment. The ORR was 17.1% (80% CI, 9.8 to 27.0), including one complete response (2.4%); the disease control rate was 73.2% (80% CI, 62.3 to 82.2). Two participants withdrew before first postbaseline scan because of adverse events (AEs). Grade ≥3 treatment-emergent AEs were reported in 92.7% of participants, with the most common being hypertension (26.8%). Response was not correlated with BRCA, HRR, HR deficiency (HRD), or PD-L1 status. Changes suggesting immune activation were observed in on-treatment samples after triplet therapy. CONCLUSION Results demonstrated modest activity of niraparib, dostarlimab, and bevacizumab in participants with PROC, many of whom had prognostic factors for poor treatment response. Most participants with response were bevacizumab-naïve. No association was found with HRD, BRCA, or PD-L1 status. AEs were consistent with previous monotherapy reports, except that hypertension was reported more frequently.

A Phase II, Two-Stage Study of Letrozole and Abemaciclib in Estrogen Receptor–Positive Recurrent Endometrial Cancer

PURPOSE Estrogen receptor (ER)–positive endometrial cancers (ECs) are characterized by phosphatidylinositol 3-kinase (PI3K) and receptor tyrosine kinase (RTK)/RAS/β-catenin (CTNNB1) pathway alterations in approximately 90% and 80% of cases, respectively. Extensive cross-talk between ER, PI3K, and RTK/RAS/CTNNB1 pathways leads to both ligand-dependent and ligand-independent ER transcriptional activity as well as upregulation of cyclin D1 which, in complex with cyclin-dependent kinases 4 and 6 (CDK4 and CDK6), is a critical regulator of cell cycle progression and a key mediator of resistance to hormonal therapy. We hypothesized that the combination of the aromatase inhibitor letrozole and CDK4/6 inhibitor abemaciclib would demonstrate promising activity in this setting. METHODS We conducted a phase II, two-stage study of letrozole/abemaciclib in recurrent ER-positive EC. Eligibility criteria included measurable disease, no limit on prior therapies, and all EC histologies; prior hormonal therapy was allowed. Primary end points were objective response rate by RECIST 1.1 and progression-free survival (PFS) rate at 6 months. RESULTS At the data cutoff date (December 03, 2021), 30 patients (28 with endometrioid EC) initiated protocol therapy; 15 (50%) patients had prior hormonal therapy. There were nine total responses (eight confirmed), for an objective response rate of 30% (95% CI, 14.7 to 49.4), all in endometrioid adenocarcinomas. Median PFS was 9.1 months, PFS at 6 months was 55.6% (95% CI, 35.1 to 72), and median duration of response was 7.4 months. Most common ≥ grade 3 treatment-related adverse events were neutropenia (20%) and anemia (17%). Responses were observed regardless of grade, prior hormonal therapy, mismatch repair, and progesterone receptor status. Exploratory tumor profiling revealed several mechanistically relevant candidate predictors of response ( CTNNB1, KRAS, and CDKN2A mutations) or absence of response ( TP53 mutations), which require independent validation. CONCLUSION Letrozole/abemaciclib demonstrated encouraging and durable evidence of activity in recurrent ER positive endometrioid EC.

Targeting Galectin 3 illuminates its contributions to the pathology of uterine serous carcinoma

Abstract Background Uterine serous cancer (USC) comprises around 10% of all uterine cancers. However, USC accounts for approximately 40% of uterine cancer deaths, which is attributed to tumor aggressiveness and limited effective treatment. Galectin 3 (Gal3) has been implicated in promoting aggressive features in some malignancies. However, Gal3’s role in promoting USC pathology is lacking. Methods We explored the relationship between LGALS3 levels and prognosis in USC patients using TCGA database, and examined the association between Gal3 levels in primary USC tumors and clinical-pathological features. CRISPR/Cas9-mediated Gal3-knockout (KO) and GB1107, inhibitor of Gal3, were employed to evaluate Gal3’s impact on cell function. Results TCGA analysis revealed a worse prognosis for USC patients with high LGALS3. Patients with no-to-low Gal3 expression in primary tumors exhibited reduced clinical-pathological tumor progression. Gal3-KO and GB1107 reduced cell proliferation, stemness, adhesion, migration, and or invasion properties of USC lines. Furthermore, Gal3-positive conditioned media (CM) stimulated vascular tubal formation and branching and transition of fibroblast to cancer-associated fibroblast compared to Gal3-negative CM. Xenograft models emphasized the significance of Gal3 loss with fewer and smaller tumors compared to controls. Moreover, GB1107 impeded the growth of USC patient-derived organoids. Conclusion These findings suggest inhibiting Gal3 may benefit USC patients.

Dual Fluorescence Isogenic Synthetic Lethal Kinase Screen and High-Content Secondary Screening for MUC16/CA125-Selective Agents

Abstract Significant strides have been made in the development of precision therapeutics for cancer. Aberrantly expressed glycoproteins represent a potential avenue for therapeutic development. The MUC16/CA125 glycoprotein serves as a biomarker of disease and a driver of malignant transformation in epithelial ovarian cancer. Previously, we demonstrated a proof-of-principle approach to selectively targeting MUC16+ cells. In this report, we performed a synthetic lethal kinase screen using a human kinome RNAi library and identified key pathways preferentially targetable in MUC16+ cells using isogenic dual-fluorescence ovarian cancer cell lines. Using a separate approach, we performed high-content small-molecule screening of six different libraries of 356,982 compounds for MUC16/CA125-selective agents and identified lead candidates that showed preferential cytotoxicity in MUC16+ cells. Compounds with differential activity were selected and tested in various other ovarian cell lines or isogenic pairs to identify lead compounds for structure–activity relationship (SAR) selection. Lead siRNA and small-molecule inhibitor candidates preferentially inhibited invasion of MUC16+ cells in vitro and in vivo, and we show that this is due to decreased activation of MAPK, and non–receptor tyrosine kinases. Taken together, we present a comprehensive screening approach to the development of a novel class of MUC16-selective targeted therapeutics and identify candidates suitable for further clinical development.

A phase 2 study of combined chemo-immunotherapy with cisplatin-pembrolizumab and radiation for unresectable vulvar squamous cell carcinoma

Abstract Background Unresectable or metastatic vulvar cancer has relatively poor outcomes despite chemotherapy-sensitized radiation therapy and combination cytotoxic therapy. Despite the virus-associated and immunogenic nature of this disease, novel immunotherapy options that exploit this advantage are currently lacking. Platinum agents such as cisplatin have been shown to prime dendritic cells for T-cell costimulation, promote downregulation of inhibitory checkpoint molecules, and sensitize tumor cells to cytotoxic T-cell killing. Radiation therapy has also been shown to promote immunogenetic cell death as monotherapy and in combination with cisplatin. In combination with pembrolizumab, cisplatin-sensitized radiation is hypothesized to increase overall response rates and recurrence-free survival in patients with vulvar cancer, via induction of an anti-tumor inflammatory response. Methods We propose a single-arm phase II clinical trial of pembrolizumab combined with cisplatin-sensitized radiation therapy for women with unresectable, locally advanced, or metastatic vulvar cancer. The first three patients with locally advanced or unresectable disease will receive cycle 1 of pembrolizumab followed by a break and resumption of pembrolizumab at cycle 4 and as part of a safety cohort. All other patients, including the fourth patient with locally advanced/unresectable disease, will receive weekly cisplatin and pembrolizumab every 3 weeks, concurrently with daily radiation therapy. Following the completion of Cis-RT, patients will continue pembrolizumab maintenance for a total of 12 cycles. Archived tissue will be used for HPV status, MSI status, PD-L1, and TIL stratification post hoc. Imaging will be performed at baseline and every 3 cycles (21-day cycles) as per standard-of-care. Laboratory analysis will occur on the first day of each cycle. Discussion The combination of cisplatin-sensitized radiation and immune checkpoint blockade has not been evaluated in the upfront setting for vulvar cancer. In this rare malignancy, there are limited interventional clinical trials. This trial is designed to be as accessible as possible by allowing patients to receive cisplatin and radiation locally according to accepted standard-of-care while receiving pembrolizumab and adverse event monitoring at a centralized site. A robust suite of translational correlative studies has also been built into the trial to evaluate tumor-directed immune activation. Trial registration NCT04430699

Rucaparib maintenance for newly diagnosed advanced ovarian cancer: interim overall survival, progression-free survival, and safety at 5 years of follow-up from the phase III ATHENA-MONO/GOG-3020/ENGOT-ov45 study

We report the long-term efficacy and safety from the multicenter, randomized, double-blind, placebo-controlled, phase III ATHENA-MONO/GOG-3020/ENGOT-ov45 (NCT03522246) study of first-line rucaparib maintenance for advanced ovarian cancer. Patients were randomized 4 : 1 to oral rucaparib + intravenous (i.v.) placebo or oral + i.v. placebo. Stratification factors were homologous recombination deficiency (HRD; BRCA mutation and loss of heterozygosity status) classification, residual disease post-chemotherapy, and surgical timing. The primary endpoint was investigator-assessed progression-free survival (invPFS) in HRD and intent-to-treat (ITT) populations. Overall survival (OS) and safety were secondary endpoints. Second event of progression (PFS2) and time to first subsequent treatment (TFST) were exploratory. Interim OS and final safety analyses data cut-off was 9 March 2023. Updated invPFS, PFS2, and TFST analyses data cut-off was 5 May 2025. Median invPFS follow-up was ∼59 months for both rucaparib (HRD, n = 185; ITT, n = 427) and placebo (HRD, n = 49; ITT, n = 111). invPFS was significantly longer with rucaparib versus placebo in the HRD [31.4 versus 12.0 months; hazard ratio (HR) 0.52, 95% confidence interval (CI) 0.35-0.76] and ITT (20.2 versus 9.2 months; HR 0.53, 95% CI 0.42-0.69) populations. Interim OS was immature (OS maturity: ITT 35%) with the median (95% CI) OS not reached with rucaparib and 46.2 (34.6-not reached) months with placebo for the ITT population (HR 0.83, 95% CI 0.58-1.17). ITT TFST (median 23.6 versus 12.1 months) and PFS2 (35.1 versus 26.9 months) were longer with rucaparib versus placebo. Overall, 34.6% of patients receiving rucaparib completed the 24-month treatment cap versus 17.3% receiving placebo. As of 5 May 2025, 40.0% of patients on rucaparib were still on study and in long-term follow-up. Safety remained consistent with the primary analysis. Rucaparib monotherapy provides significant and durable long-term benefit as first-line maintenance for patients with advanced ovarian cancer with and without HRD.

Serial Circulating Tumor DNA Sequencing to Monitor Response and Define Acquired Resistance to Letrozole/Abemaciclib in Endometrial Cancer

PURPOSE In a phase II study, letrozole/abemaciclib demonstrated an objective response rate of 30% and a median progression-free survival (PFS) of 9.1 months in recurrent estrogen receptor–positive endometrial cancer (EC). While tissue-based tumor profiling revealed several mechanistically relevant candidate baseline genomic predictors of response, circulating tumor DNA (ctDNA) is a less invasive alternative to monitor therapeutic efficacy and define acquired resistance. METHODS Serial plasma specimens were obtained at baseline, C2D1, C3D1, C8D1, the time of objective response, and the time of progression. Samples were analyzed using the Guardant Reveal assay to assess methylation-based tumor fraction (TF), with the Guardant360 assay providing genotyping of >700 genes in samples with detectable ctDNA. Treatment response was assessed using a measure of the relative change in TF pre- versus on-treatment. RESULTS A total of 99 of 102 (97%) samples from 28 patients were successfully analyzed. Patients with above median baseline TF exhibited worse median PFS (2.0 months v 16.5 months, P < .005, hazard ratio [HR], 24.1) and worse overall survival (OS) (10.7 months v not yet reached, P < .005, HR, 14.8). Patients with molecular response (MR) after the first or second cycle of letrozole/abemaciclib therapy had significantly better median PFS and OS regardless of the cutoff used for definition of MR. ctDNA analysis of postprogression specimens identified several acquired genomic alterations associated with resistance to letrozole/abemaciclib therapy in more than half of the patients, including PI3K pathway, receptor tyrosine kinase ( FGFR1 , 2 and ERBB2 alterations), cell cycle pathway ( RB1 and CCNE1 alterations), and ESR1 and MAPK pathway alterations. Two of the three patients with mismatch repair–deficient ECs acquired ESR1 mutations at the time of progression. CONCLUSION Baseline and on-treatment ctDNA dynamics may provide an early indication of benefit from letrozole/abemaciclib in EC. ctDNA at the time of progression may identify resistance alterations that may inform subsequent therapy.

Phase IIa Study of PLX2853 in Gynecologic Cancers With Known ARID1A Mutation and Phase Ib/IIa Study of PLX2853/Carboplatin in Platinum-Resistant Epithelial Ovarian Cancer

PURPOSE The Bromodomain and Extra-Terminal (BET) domain proteins facilitate the development of many human cancers via epigenetic regulation. BET inhibitors may be effective in reversing platinum resistance in ovarian cancer (OC) and may generate synthetic lethality with ARID1A loss. PLX2853 is an orally active, small-molecule inhibitor of BET bromodomain-mediated interactions that exhibits low nanomolar potency in blocking all four BET family members. METHODS We conducted a multicenter and open-label study with two parallel arms: a phase IIa study of PLX2853 monotherapy in patients with advanced gynecologic malignancies with an ARID1A mutation and a phase Ib/IIa combination study of PLX2853 plus carboplatin in women with platinum-resistant OC. The primary objectives were safety and tolerability for phase Ib and efficacy for both phase IIa portions. Thirty-four of 37 enrolled patients completed at least one post-baseline response assessment. RESULTS Of the 14 evaluable patients on the monotherapy arm, 1 (7.1%) achieved a best overall response of partial response (PR), 5 (35.7%) had stable disease (SD), and 8 (57.1%) had progressive disease (PD). Of the 20 evaluable patients on the combination arm, 1 (5.0%) had PR, 9 (45.0%) had SD, and 10 (50%) had PD. CONCLUSION This study confirmed the safety profile of PLX2853 and demonstrated the feasibility of combination with carboplatin. Although these results did not meet the prespecified response criteria, evidence of clinical activity highlights the rationale for further exploration of BET inhibitors in patients with ARID1A-mutated gynecologic malignancies, possibly in combination with agents targeting potential feedback mechanisms such as the PI3K pathway.

Cisplatin+Pembrolizumab+RT in Vulvar Cancer

This research is being done to see how well the combination of a standard of care drug, investigational drug, and radiation therapy work against unresectable vulvar squamous cell carcinoma. This research study involves the following: * Cisplatin (standard of care drug) * Pembrolizumab (investigational drug) * Radiation Therapy (standard of care intervention)

RESOLVE: Abemaciclib + Letrozole +/- Metformin, Zotatifin, or Gedatolisib in Endometrial or Low-Grade Serous Ovarian Cancer

This research study is studying a combination of targeted therapies as a possible treatment for estrogen-receptor positive (ER+) endometrial cancer and low-grade serous ovarian cancer. The drugs involved in this study are: * Abemaciclib (also known as Verzenio™) * Letrozole (also known as Femara®) * Metformin (also known as Glucophage®) * Zotatifin (also known as eFT226) * Gedatolisib (also known as PF-05212384)

A Study to Evaluate the Efficacy and Safety of Novel Treatment Combinations in Participants With Ovarian Cancer

This study will evaluate the efficacy and safety of niraparib and novel treatment combinations of niraparib as described within each cohort-specific supplement in participants with ovarian, fallopian tube, or primary peritoneal cancer. Cohort A (single arm) includes participants with recurrent ovarian cancer. Cohort B will not be initiated. Cohort C (randomized-2 arms) includes participants with newly diagnosed ovarian cancer.