Zanfagnin, Valentina

Abstract PARP inhibitors (PARPi) have activity in homologous recombination (HR) repair-deficient, high-grade serous ovarian cancers (HGSOC). However, even responsive tumors develop PARPi resistance, highlighting the need to delay or prevent the appearance of PARPi resistance. Here, we showed that the ALK kinase inhibitor ceritinib synergizes with PARPis by inhibiting complex I of the mitochondrial electron transport chain, which increases production of reactive oxygen species (ROS) and subsequent induction of oxidative DNA damage that is repaired in a PARP-dependent manner. In addition, combined treatment with ceritinib and PARPi synergized in HGSOC cell lines irrespective of HR status, and a combination of ceritinib with the PARPi olaparib induced tumor regression more effectively than olaparib alone in HGSOC patient-derived xenograft (PDX) models. Notably, the ceritinib and olaparib combination was most effective in PDX models with preexisting PARPi sensitivity and was well tolerated. These findings unveil suppression of mitochondrial respiration, accumulation of ROS, and subsequent induction of DNA damage as novel effects of ceritinib. They also suggest that the ceritinib and PARPi combination warrants further investigation as a means to enhance PARPi activity in HGSOC, particularly in tumors with preexisting HR defects. Significance: The kinase inhibitor ceritinib synergizes with PARPi to induce tumor regression in ovarian cancer models, suggesting that ceritinib combined with PARPi may be an effective strategy for treating ovarian cancer.

Abstract PURPOSE: Ovarian cancer remains the most lethal gynecological malignancy in the United States even though there are a number of treatment options. For the newly diagnosed ovarian cancer patient, treatment is standard with the majority of patients receiving first-line platinum/taxol treatment following surgical debulking or as part of a neo-adjuvant treatment regimen. Standard response assessment to this chemotherapy combination depends on lengthy clinical follow-up of at least 6 months following the conclusion of the chemotherapy. This course is initially effective in 70-80% of patients, but 20-30% will relapse within the 6 months post-chemotherapy or not respond at all. Additionally, most of the initial responders will also relapse. Early prediction of the patients whose cancers do not respond could lead to earlier intervention with more effective therapy. RESULTS: To perform this prediction, we developed a test utilizing live tumor tissue and 3D cell culture to predict the response of ovarian cancer patients to standard platinum and taxol chemotherapy along with the standard agents used for relapse patients. To validate the assay, we performed a prospective trial involving 86 women with newly diagnosed ovarian cancer from whom live tumor tissue was recovered at surgical resection prior to chemotherapy. Of the 79 patients whose tissues yielded a successful assay result, 27 had sufficient clinical follow-up to determine the accuracy of the response predictions made by the assay. Assay response predictions were made within 7 days following surgery while clinical response was not determined until 6 months or more following the conclusion of first-line chemotherapy. Assay results predicted first-line chemotherapy response in 100% of clinical responders (19 of 19) and first-line chemotherapy non-response in 62.5% of clinical non-responders (5 of 8) as defined by CA-125 and radiographic surveillance. This response prediction was statistically significant by Fisher's Exact test, p < 0.001. The sensitivity of the assay was 86% while the specificity was 100%. When the assay results were examined in terms of progression free survival, 19 of 19 patients identified as responders by the assay remained progression free at least 6 months post-chemotherapy with 14 remaining progression free 10 or more months post-chemotherapy. In contrast, of the 8 assay non-responders, 3 were refractory with progression within 3 months of chemotherapy conclusion and 2 progressed less than 6 months post-chemotherapy with a mean progression free survival of 4.5 months. CONCLUSIONS: Our rapid, ex vivo, 3D cellular assay is capable of accurate patient specific response prediction of first-line combination therapy in newly diagnosed ovarian cancer patients and can serve as a prognostic indicator of progression free survival. This preliminary clinical validation shows the significant potential of this assay as a future tool in personalized cancer care for ovarian cancer patients. Citation Format: Stephen Shuford, Jeffrey Elder, Larry Puls, John Weroha, Xiaonan Hou, Valentina Zanfagnin, Alpa Nick, Michael P. Stany, Larry Maxwell, Thomas Conrads, Chris Corless, Anil K. Sood, Matthew Gevaert, Howland E. Crosswell, and Teresa M. DesRochers. PROSPECTIVE CLINICAL VALIDATION OF EX VIVO, PATIENT-SPECIFIC RESPONSE PREDICTION TO FIRST-LINE CHEMOTHERAPY [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 TMIM-069.

Abstract Introduction: Acquired resistance to platinum remains a major clinical problem in ovarian cancer since systemic therapies have limited efficacy in this setting. There is growing evidence that the tumor microenvironment (TME) contributes to such resistance, as well as the pathogenesis of the disease. The study of the TME is limited by technical challenges of separating the epithelial from the stromal component. To overcome this limitation, we performed RNA sequencing (RNA-Seq) for three pairs of sensitive and induced resistant patient-derived xenograft models since the epithelial transcripts originate from human tissue and the stroma component is murine. Methods: To determine which TME genes might be contributing to chemotherapy resistance, three platinum-sensitive ovarian cancer PDX lines were treated repeatedly with carboplatin/paclitaxel until resistance occurred. Primary platinum-sensitive and induced platinum resistant tumors were characterized histologically by H&E and Masson Trichrome staining. The three pairs of sensitive and resistant PDX models were then subjected to RNA-Seq. Raw sequencing data were processed through Xenome to classify the reads into epithelial carcinoma (human) or TME (mouse) through Mayo Clinic’s internal RNA-Seq pipeline for transcriptome quantification. Differential expression analysis between induced resistant and sensitive models was carried out for both carcinoma and TME components using edgeR paired analysis. Gene set enrichment analysis was used to identify overrepresented biologic functions for differentially expressed genes between the pairs. Top significantly varied, differentially expressed genes between the pairs were validated using species-specific qPCR. Results: Histologic analysis of the matched sensitive/resistant pairs revealed a marked increase of the stromal component in the resistant tumors evident by H&E and Masson trichrome staining. A total number of 95 and 312 genes were differentially expressed in the epithelial and TME component, respectively (FDR<0.05; absolute log2 fold-change >1.5). The stemness marker SOX2 was significantly upregulated in the human component of the resistant tumors as confirmed by qPCR. Genes involved in stroma remodeling were upregulated in the “murine” component of the resistant tumors, and upregulation was confirmed by qPCR (normalized to a murine housekeeper gene). Gene set enrichment analysis showed that the upregulated genes in TME of resistant models were enriched for cytoskeleton related functions, while the downregulated genes were enriched for extracellular matrix-related functions. Conclusion: A bioinformatics strategy able to map human and murine reads separately may identify resistance mechanisms attributed to the two tumor subcompartments and could lead to strategies to potentially target each separately or concurrently. Citation Format: Valentina Zanfagnin, Yuanhang Liu, Pritha Chanana, Xiaonan Pritha, Beverly Long, Joe Pathoulas, Brad Evans, Jaime Davila, Chen Wang, Saravut John Weroha. Transcriptional profiling of tumor stroma using ovarian cancer PDX models with induced platinum-resistance [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr B18.

5510 Background: Single agent aromatase inhibitor (AI) therapy is associated with limited clinical activity in ovarian cancer (OC) and endometrial cancers (EC). AI therapy was associated with a progression free survival (PFS) at 12 weeks of only 20% in relapsed OC (Bowman et al, 2002) and a median PFS of 1 month in relapsed EC (Rose et al, 2000). In Estrogen Receptor (ER) positive metastatic breast cancer, clinical studies had shown a significant prolongation of PFS with the addition of the cyclin kinase 4/6 inhibitor ribociclib to AI (Hortobagyi et al, 2016). Here, we report the results of a phase 2 clinical trial of the combination of ribociclib and letrozole in patients with relapsed ER positive OC or EC. Objectives: Primary endpoint was the proportion of patients with relapsed ER positive OC or EC alive and progression-free after 12 weeks of therapy (PFS12) with the combination of ribociclib given at a dose of 400 mg orally daily and letrozole 2.5 mg orally daily. A PFS of 45% was considered a favorable result based on the data referenced above from Bowman et al. Methods: Eligibility criteria included patients with relapsed ER positive OC or EC, with measurable disease, not previously treated with ribociclib or AIs. Xenografts were created from CT guided tumor biopsies at baseline to assess feasibility. Results: A total of 40 patients were enrolled (20 with OC and 20 with EC) ) with a median age of 61 years (range: 30-82) and 64.5 (range: 52-75) in the OC and EC groups respectively. Among the OC patients, 17 had high grade serous carcinomas and 3 had low grade serous carcinomas. 11 EC patients had endometrioid cancers (3 with grade 1 tumors) and 9 had high grade serous tumors. Ten out of 20 OC patients and 11/20 EC patients were alive and progression-free at 12 weeks (PFS12 of 50 and 55%, respectively). The most common grade 3 or higher adverse events (occurring in at least 5 pts) were leukopenia (18%), lymphopenia (18%), neutropenia (13%), and fatigue (13%). 34 tumor biopsies were suitable for injection into mice and 44% engrafted. ER expression persisted through multiple passages in mice. Two of three EC PDX models exhibited improved PFS with letrozole/ribociclib compared to letrozole alone. Conclusions: The combination of ribociclib and letrozole is associated with a promising 50% and 55% PFS12 in patients with ER positive relapsed OC or EC respectively. Creation of xenograft tumor models from CT guided biopsies of OC and EC tumors was feasible. Clinical trial information: NCT02657928.

Abstract Malignant ascites is one of the most common causes of morbidity in end stage ovarian cancer patients with negative impact on quality of life. Novel non-invasive palliative therapeutic options are lacking for such patients. The zinc metalloprotease, pregnancy-associated plasma protein-A (PAPP-A), plays a key role in the insulin-like growth factor (IGF) pathway, promoting ovarian cancer cellular transformation, growth and invasiveness. Furthermore, patient primary malignant ascites is known to contain high levels of PAPP-A by ELISA. Preliminary data shows that inhibition of PAPP-A through a neutralizing monoclonal PAPP-A antibody (mAb-PA) inhibits the accumulation and promote the regression of ascites in an ovarian cancer patient-derived xenograft (PDX) models. In the current study, we investigated whether mAb-PA can promote ascites regression in an additional ovarian PDX model with measurable ascites. Patient derived ascites xenograft (PDAX) models were defined as SCID mice that developed ascites after intraperitoneal heterotransplantation of patient solid tumor collected at the time of primary cytoreduction. Ascites from these models (n=51) was screened for human PAPP-A protein by ELISA and models were divided into two groups by the relative concentration of PAPPA-A: high (n=18) and low (n=33). PAPP-A High PDAX model PH438 was re-established intraperitoneal in 20 SCID mice by ascites injection (0.1 ml per mouse). When ascites area reached a threshold of >0.60 cm2 by ultrasound, mice were treated with 60mg/Kg of mAb-PA (n=10) or IgG2a control (n=10) on day one and three. On day four, a second ultrasound measurement was obtained and the mice were euthanized. Ascites burden was measured at necropsy. Personnel involved with the acquisition of ultrasounds measurements, subsequent ascites harvests, and post hoc analyses were blinded to the treatments. The ratio of mean ascites (mAb-PA/IgG2a in grams) collected at necropsy was 2.04/2.51, indicating that the mAb-PA arm had less ascites compared to control. These data were consistent with pre- and post-treatment ultrasound measurements of ascites burden; a statistically significant (p=0.0283 by paired t test) reduction of ascites burden of 52.3% was observed, compared to the starting baseline, indicating that mAb-PA treatment causes ascites regression. Ascites weight at necropsy was compared to the area of greatest fluid echogenicity by ultrasound and the Pearson correlation R value achieved was of 0.859 (p<0.0001). These PDAX data implicate PAPP-A attenuation as a potential strategy to treat malignant ascites in OC. Additional PDAX models are under examination to confirm these findings and support the translational development of PAPP-A as a new therapeutic target for women with refractory ascites. Citation Format: Valentina Zanfagnin, Laurie K. Bale, Marc A. Becker, Xiaonan Hou, Diogo Torres, Cheryl A. Conover, Saravut J. Weroha. Regression of malignant ascites via PAPP-A inhibition in ovarian cancer patient-derived xenograft model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4817. doi:10.1158/1538-7445.AM2017-4817