Current Status and Evolution of Preclinical Drug Development Models of Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy and the fifth most common cause of female cancer death in the United States. Although important advances in surgical and chemotherapeutic strategies over the last three decades have significantly improved the median survival of EOC patients, the plateau of the survival curve has not changed appreciably. Given that EOC is a genetically and biologically heterogeneous disease, identification of specific molecular abnormalities that can be targeted in each individual ovarian cancer on the basis of predictive biomarkers promises to be an effective strategy to improve outcome in this disease. However, for this promise to materialize, appropriate preclinical experimental platforms that recapitulate the complexity of these neoplasms and reliably predict antitumor activity in the clinic are critically important. In this review, we will present the current status and evolution of preclinical models of EOC, including cell lines, immortalized normal cells, xenograft models, patient-derived xenografts, and animal models, and will discuss their potential for oncology drug development

Safety and efficacy of mirvetuximab soravtansine, a folate receptor alpha (FRα)-targeting antibody-drug conjugate (ADC), in combination with bevacizumab in patients with platinum-resistant ovarian cancer

Bevacizumab; Folate receptor alpha; Platinum-resistant ovarian cancerBevacizumab; Receptor de folato alfa; Cáncer de ovario resistente al platinoBevacizumab; Receptor de folat alfa; Càncer d'ovari resistent al platíPurpose Evaluate the antitumor activity and safety profile of the combination of mirvetuximab soravtansine and bevacizumab in patients with platinum-resistant ovarian cancer. Methods Patients with recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer, whose most recent platinum-free interval was ≤6 months, were administered mirvetuximab soravtansine (6 mg/kg adjusted ideal body weight) and bevacizumab (15 mg/kg), intravenously, once every 3 weeks. Eligibility included FRα expression by immunohistochemistry (IHC; ≥25% of cells with ≥2+ intensity). Prior bevacizumab and/or PARP inhibitor (PARPi) treatment were permitted. The primary endpoint was confirmed objective response rate (ORR). Secondary endpoints included duration of response (DOR), progression-free survival (PFS), and safety. Results Ninety-four patients received combination treatment with mirvetuximab soravtansine and bevacizumab. Median age was 62 years (range, 39–81). Fifty-two percent had ≥3 prior therapies; 59% had prior bevacizumab; and 27% had prior PARPi. ORR was 44% (95% CI 33, 54) with 5 complete responses, median DOR 9.7 months (95% CI 6.9, 14.1), and median PFS 8.2 months (95% CI 6.8, 10.0). Treatment-related adverse events were consistent with the profiles of each agent, with the most common being blurred vision (all grades 57%; grade 3, 1%), diarrhea (54%; grade 3, 1%), and nausea (51%; grade 3, 1%). Conclusion The mirvetuximab soravtansine plus bevacizumab doublet is an active and well-tolerated regimen in patients with FRα-expressing platinum-resistant ovarian cancer. Promising activity was observed for patients regardless of level of FRα expression or prior bevacizumab. These data underscore the potential for mirvetuximab soravtansine as the combination partner of choice for bevacizumab in this setting.This study was supported by ImmunoGen, Inc

Sublethal concentrations of 17-AAG suppress homologous recombination DNA repair and enhance sensitivity to carboplatin and olaparib in HR proficient ovarian cancer cells

The promise of PARP-inhibitors(PARPis) in the management of epithelial ovarian cancer(EOC) is tempered by the fact that approximately 50% of patients with homologous recombination (HR)-proficient tumors do not respond well to these agents. Combination of PARPis with agents that inhibit HR may represent an effective strategy to enhance their activity in HR-proficient tumors. Using a bioinformatics approach, we identified that heat shock protein 90 inhibitors(HSP90i) may suppress HR and thus revert HR-proficient to HR-deficient tumors. Analysis of publicly available gene expression data showed that exposure of HR-proficient breast cancer cell lines to HSP90i 17-AAG(17-allylamino-17-demethoxygeldanamycin) downregulated HR, ATM and Fanconi Anemia pathways. In HR-proficient EOC cells, 17-AAG suppressed HR as assessed using the RAD51 foci formation assay and this was further confirmed using the Direct Repeat-GFP reporter assay. Furthermore, 17-AAG downregulated BRCA1 and/or RAD51 protein levels, and induced significantly more γH2AX activation in combination with olaparib compared to olaparib alone. Finally, sublethal concentrations of 17-AAG sensitized HR-proficient EOC lines to olaparib and carboplatin but did not affect sensitivity of the HR-deficient OVCAR8 line arguing that the 17-AAG mediated sensitization is dependent on suppression of HR. These results provide a preclinical rationale for using a combination of olaparib/17-AAG in HR-proficient EOC

NRG Oncology/RTOG 0921: A phase 2 study of postoperative intensity-modulated radiotherapy with concurrent cisplatin and bevacizumab followed by carboplatin and paclitaxel for patients with endometrial cancer.

BACKGROUND: The current study was conducted to assess acute and late adverse events (AEs), overall survival (OS), pelvic failure, regional failure, distant failure, and disease-free survival in a prospective phase 2 clinical trial of bevacizumab and pelvic intensity-modulated radiotherapy (IMRT) with chemotherapy in patients with high-risk endometrial cancer. METHODS: Patients underwent a hysterectomy and lymph node removal, and had ≥1 of the following high-risk factors: grade 3 carcinoma with \u3e50% myometrial invasion, grade 2 or 3 disease with any cervical stromal invasion, or known extrauterine extension confined to the pelvis. Treatment included pelvic IMRT and concurrent cisplatin on days 1 and 29 of radiation and bevacizumab (at a dose of 5 mg/kg on days 1, 15, and 29 of radiation) followed by adjuvant carboplatin and paclitaxel for 4 cycles. The primary endpoint was grade ≥3 AEs occurring within the first 90 days (toxicity was graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.0]). RESULTS: A total of 34 patients were accrued from November 2009 through December 2011, 30 of whom were eligible and received study treatment. Seven of 30 patients (23.3%; 1-sided 95% confidence interval, 10.6%-36.0%) developed grade ≥3 treatment-related nonhematologic toxicities within 90 days; an additional 6 patients experienced grade ≥3 toxicities between 90 and 365 days after treatment. The 2-year OS rate was 96.7% and the disease-free survival rate was 79.1%. No patient developed a within-field pelvic failure and no patients with International Federation of Gynecology and Obstetrics stage I to IIIA disease developed disease recurrence after a median follow-up of 26 months. CONCLUSIONS: Postoperative bevacizumab added to chemotherapy and pelvic IMRT appears to be well tolerated and results in high OS rates at 2 years for patients with high-risk endometrial carcinoma

Tumor Mutation Burden Forecasts Outcome in Ovarian Cancer with BRCA1 or BRCA2 Mutations

Background: Increased number of single nucleotide substitutions is seen in breast and ovarian cancer genomes carrying disease-associated mutations in BRCA1 or BRCA2. The significance of these genome-wide mutations is unknown. We hypothesize genome-wide mutation burden mirrors deficiencies in DNA repair and is associated with treatment outcome in ovarian cancer. Methods and Results: The total number of synonymous and non-synonymous exome mutations (Nmut), and the presence of germline or somatic mutation in BRCA1 or BRCA2 (mBRCA) were extracted from whole-exome sequences of high-grade serous ovarian cancers from The Cancer Genome Atlas (TCGA). Cox regression and Kaplan-Meier methods were used to correlate Nmut with chemotherapy response and outcome. Higher Nmut correlated with a better response to chemotherapy after surgery. In patients with mBRCA-associated cancer, low Nmut was associated with shorter progression-free survival (PFS) and overall survival (OS), independent of other prognostic factors in multivariate analysis. Patients with mBRCA-associated cancers and a high Nmut had remarkably favorable PFS and OS. The association with survival was similar in cancers with either BRCA1 or BRCA2 mutations. In cancers with wild-type BRCA, tumor Nmut was associated with treatment response in patients with no residual disease after surgery. Conclusions: Tumor Nmut was associated with treatment response and with both PFS and OS in patients with high-grade serous ovarian cancer carrying BRCA1 or BRCA2 mutations. In the TCGA cohort, low Nmut predicted resistance to chemotherapy, and for shorter PFS and OS, while high Nmut forecasts a remarkably favorable outcome in mBRCA-associated ovarian cancer. Our observations suggest that the total mutation burden coupled with BRCA1 or BRCA2 mutations in ovarian cancer is a genomic marker of prognosis and predictor of treatment response. This marker may reflect the degree of deficiency in BRCA-mediated pathways, or the extent of compensation for the deficiency by alternative mechanisms

Overall survival in patients with platinum-sensitive recurrent serous ovarian cancer receiving olaparib maintenance monotherapy: an updated analysis from a randomised, placebo-controlled, double-blind, phase 2 trial

Background: In patients with platinum-sensitive recurrent serous ovarian cancer, maintenance monotherapy with the PARP inhibitor olaparib significantly improves progression-free survival versus placebo. We assessed the effect of maintenance olaparib on overall survival in patients with platinum-sensitive recurrent serous ovarian cancer, including those with BRCA1 and BRCA2 mutations (BRCAm). / Methods: In this randomised, placebo-controlled, double-blind, phase 2 trial involving 82 sites across 16 countries, patients with platinum-sensitive recurrent serous ovarian cancer who had received two or more courses of platinum-based chemotherapy and had responded to their latest regimen were randomly assigned (1:1) using a computer-generated sequence to receive oral maintenance olaparib (as capsules; 400 mg twice a day) or a matching placebo by an interactive voice response system. Patients were stratified by ancestry, time to progression on penultimate platinum, and response to most recent platinum. Patients and investigators were masked to treatment assignment by the use of unique identifiers generated during randomisation. The primary endpoint of the trial was progression-free survival. In this updated analysis, we present data for overall survival, a secondary endpoint, from the third data analysis after more than 5 years’ follow-up (intention-to-treat population). We did the updated overall survival analysis, described in this Article at 77% data maturity, using a two-sided α of 0·95%. As the study was not powered to assess overall survival, this analysis should be regarded as descriptive and the p values are nominal. We analysed randomly assigned patients for overall survival and all patients who received at least one dose of treatment for safety. This trial is ongoing and is registered with ClinicalTrials.gov, number NCT00753545. / Findings: Between Aug 28, 2008, and Feb 9, 2010, 265 patients were randomly assigned to olaparib (n=136) or placebo (n=129). 136 patients had deleterious BRCAm. The data cutoff for this analysis was Sept 30, 2015. An overall survival advantage was seen with maintenance olaparib versus placebo in all patients (hazard ratio [HR] 0·73 [95% CI 0·55–0·96]; nominal p=0·025, which did not meet the required threshold for statistical significance [p<0·0095]; median overall survival was 29·8 months [95% CI 26·9–35·7] for those treated with olaparib vs 27·8 months [24·9–33·7] for those treated with placebo), and in patients with BRCAm (HR 0·62 [95% CI 0·41–0·94] nominal p=0·025; 34·9 months [95% CI 29·2–54·6] vs 30·2 months [23·1–40·7]). The overall survival data in patients with BRCA wild-type were HR 0·83 (95% CI 0·55–1·24, nominal p=0·37; 24·5 months [19·8–35·0] for those treated with olaparib vs 26·6 months [23·1–32·5] for those treated with placebo). 11 (15%) of 74 patients with BRCAm received maintenance olaparib for 5 years or more. Overall, common grade 3 or worse adverse events in the olaparib and placebo groups were fatigue (11 [8%] of 136 patients vs four [3%] of 128) and anaemia (eight [6%] vs one [1%]). 30 (22%) of 136 patients in the olaparib group and 11 (9%) of 128 patients in the placebo group reported serious adverse events. In patients treated for 2 years or more, adverse events in the olaparib and placebo groups included low-grade nausea (24 [75%] of 32 patients vs two [40%] of five), fatigue (18 [56%] of 32 vs two [40%] of five), vomiting (12 [38%] of 32 vs zero), and anaemia (eight [25%] of 32 vs one [20%] of five); generally, events were initially reported during the first 2 years of treatment. / Interpretation: Despite not reaching statistical significance, patients with BRCA-mutated platinum-sensitive recurrent serous ovarian cancer receiving olaparib maintenance monotherapy after platinum-based chemotherapy appeared to have longer overall survival, supporting the reported progression-free survival benefit. Clinically useful long-term exposure to olaparib was seen with no new safety signals. Taken together, these data support both the long-term clinical benefit and tolerability of maintenance olaparib in patients with BRCA-mutated platinum-sensitive recurrent serous ovarian cancer. / Funding: AstraZeneca

STING agonism overcomes STAT3-mediated immunosuppression and adaptive resistance to PARP inhibition in ovarian cancer

BackgroundPoly (ADP-ribose) polymerase (PARP) inhibition (PARPi) has demonstrated potent therapeutic efficacy in patients with BRCA-mutant ovarian cancer. However, acquired resistance to PARPi remains a major challenge in the clinic.MethodsPARPi-resistant ovarian cancer mouse models were generated by long-term treatment of olaparib in syngeneic Brca1-deficient ovarian tumors. Signal transducer and activator of transcription 3 (STAT3)-mediated immunosuppression was investigated in vitro by co-culture experiments and in vivo by analysis of immune cells in the tumor microenvironment (TME) of human and mouse PARPi-resistant tumors. Whole genome transcriptome analysis was performed to assess the antitumor immunomodulatory effect of STING (stimulator of interferon genes) agonists on myeloid cells in the TME of PARPi-resistant ovarian tumors. A STING agonist was used to overcome STAT3-mediated immunosuppression and acquired PARPi resistance in syngeneic and patient-derived xenografts models of ovarian cancer.ResultsIn this study, we uncover an adaptive resistance mechanism to PARP inhibition mediated by tumor-associated macrophages (TAMs) in the TME. Markedly increased populations of protumor macrophages are found in BRCA-deficient ovarian tumors that rendered resistance to PARPi in both murine models and patients. Mechanistically, PARP inhibition elevates the STAT3 signaling pathway in tumor cells, which in turn promotes protumor polarization of TAMs. STAT3 ablation in tumor cells mitigates polarization of protumor macrophages and increases tumor-infiltrating T cells on PARP inhibition. These findings are corroborated in patient-derived, PARPi-resistant BRCA1-mutant ovarian tumors. Importantly, STING agonists reshape the immunosuppressive TME by reprogramming myeloid cells and overcome the TME-dependent adaptive resistance to PARPi in ovarian cancer. This effect is further enhanced by addition of the programmed cell death protein-1 blockade.ConclusionsWe elucidate an adaptive immunosuppression mechanism rendering resistance to PARPi in BRCA1-mutant ovarian tumors. This is mediated by enrichment of protumor TAMs propelled by PARPi-induced STAT3 activation in tumor cells. We also provide a new strategy to reshape the immunosuppressive TME with STING agonists and overcome PARPi resistance in ovarian cancer.Peer reviewe

Niraparib maintenance treatment improves time without symptoms or toxicity (TWiST) versus routine surveillance in recurrent ovarian cancer: a TWiST analysis of the ENGOT-OV16/NOVA trial

Purpose: this study estimated time without symptoms or toxicity (TWiST) with niraparib compared with routine surveillance (RS) in the maintenance treatment of patients with recurrent ovarian cancer. Patients and methods: mean progression-free survival (PFS) was estimated for niraparib and RS by fitting parametric survival distributions to Kaplan-Meier data for 553 patients with recurrent ovarian cancer who were enrolled in the phase III ENGOT-OV16/NOVA trial. Patients were categorized according to the presence or absence of a germline BRCA mutation-gBRCAmut and non-gBRCAmut cohorts. Mean time with toxicity was estimated based on the area under the Kaplan-Meier curve for symptomatic grade 2 or greater fatigue, nausea, and vomiting adverse events (AEs). Time with toxicity was the number of days a patient experienced an AE post-random assignment and before disease progression. TWiST was estimated as the difference between mean PFS and time with toxicity. Uncertainty was explored using alternative PFS estimates and considering all symptomatic grade 2 or greater AEs. Results: in the gBRCAmut and non-gBRCAmut cohorts, niraparib treatment resulted in a mean PFS benefit of 3.23 years and 1.44 years, respectively, and a mean time with toxicity of 0.28 years and 0.10 years, respectively, compared with RS. Hence, niraparib treatment resulted in a mean TWiST benefit of 2.95 years and 1.34 years, respectively, compared with RS, which is equivalent to more than four-fold and two-fold increases in mean TWiST between niraparib and RS in the gBRCAmut and non-gBRCAmut cohorts, respectively. This TWiST benefit was consistent across all sensitivity analyses, including modeling PFS over 5-, 10-, and 15-year time horizons. Conclusion: patients who were treated with niraparib compared with RS experienced increased mean TWiST. Thus, patients who were treated with niraparib in the ENGOT-OV16/NOVA trial experienced more time without symptoms or symptomatic toxicities compared with control

Enhanced Efficacy of Aurora Kinase Inhibitors in G2/M Checkpoint Deficient TP53 Mutant Uterine Carcinomas Is Linked to the Summation of LKB1-AKT-p53 Interactions.

Uterine carcinoma (UC) is the most common gynecologic malignancy in the United States. TP53 mutant UCs cause a disproportionate number of deaths due to limited therapies for these tumors and the lack of mechanistic understanding of their fundamental vulnerabilities. Here we sought to understand the functional and therapeutic relevance of TP53 mutations in UC. We functionally profiled targetable TP53 dependent DNA damage repair and cell cycle control pathways in a panel of TP53 mutant UC cell lines and patient-derived organoids. There were no consistent defects in DNA damage repair pathways. Rather, most models demonstrated dependence on defective G2/M cell cycle checkpoints and subsequent upregulation of Aurora kinase-LKB1-p53-AKT signaling in the setting of baseline mitotic defects. This combination makes them sensitive to Aurora kinase inhibition. Resistant lines demonstrated an intact G2/M checkpoint, and combining Aurora kinase and WEE1 inhibitors, which then push these cells through mitosis with Aurora kinase inhibitor-induced spindle defects, led to apoptosis in these cases. Overall, this work presents Aurora kinase inhibitors alone or in combination with WEE1 inhibitors as relevant mechanism driven therapies for TP53 mutant UCs. Context specific functional assessment of the G2/M checkpoint may serve as a biomarker in identifying Aurora kinase inhibitor sensitive tumors

EPIK-O/ENGOT-OV61: alpelisib plus olaparib vs cytotoxic chemotherapy in high-grade serous ovarian cancer (phase III study)

Patients with platinum-resistant or -refractory high-grade serous ovarian cancer (HGSOC) have a poor prognosis, and their management represents a substantial unmet medical need. Preclinical data and results from a phase Ib trial demonstrated the efficacy and tolerability of the combination of the α-specific phosphatidylinositol-3-kinase (PI3K) inhibitor alpelisib plus the poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitor olaparib in platinum-resistant, non-BRCA-mutated ovarian cancer. Here, we describe the study design and rationale for the phase III, multicenter, open-label, randomized, active-controlled EPIK-O/ENGOT-OV61 trial investigating alpelisib in combination with olaparib compared with standard-of-care chemotherapy in patients with platinum-resistant or -refractory HGSOC with no germline BRCA mutation. Progression-free survival (blinded independent review committee) is the primary end point. Overall survival is a key secondary end point