Abstract 235: Application of high-grade serous ovarian cancer organoids in functional precision medicine

Abstract High-grade serous ovarian cancer (HGSC) is the most frequent and lethal ovarian cancer type. Despite responding favorably to first-line therapy, most HGSC patients eventually relapse. HGSC is characterized by high interpatient genomic heterogeneity and few recurrent mutations that could be used as therapeutic biomarkers. Thus, except the introduction of PARP inhibitors for BRCA1/2-mutated patients, there has been little progress with personalizing HGSC treatment. Functional precision medicine - tailoring personalized therapies based on functional assays on patient-derived cells - has been applied in cancer clinical trials to address this issue. Organoids - three-dimensional cell cultures, recapitulating aspects of original tumors’ structure and function - have often been used as models in these efforts. However, inefficient and time-consuming organoid derivation protocols have been hindering the application of HGSC organoids in functional precision medicine clinical trials, due to the short time during which the therapy must be selected. To address this, we here aimed to establish whether we could predict second-line therapy drug sensitivities in relapsed HGSC using organoids from tumor material from first-line therapy. We have previously derived a collection of 23 organoid models from 16 patients, sampled sequentially at different times of their treatment (1). Here, for several organoid primary-relapse pairs, we performed drug screens using a library of 370 compounds (approved, in clinical development or tool compounds). We found that 90% of the hit compounds in the primary organoids also were hits in the matched relapse-derived organoid models. In several patients, we observed a pronounced cytotoxicity of several cyclin-dependent kinase (CDK) inhibitors, all of which potently inhibit CDK9, including two selective inhibitors (AZD4573 and VIP152) in clinical development. Screening of CDK9 inhibitors in an extended panel of organoid models revealed that most organoids are sensitive to CDK9 inhibition in nanomolar range. CDK9 inhibitors also prevented organoid outgrowth in long-term culture (>1.5 month) in drug-free medium. Taken together, we demonstrate that HGSC organoids from material sampled during first-line treatment predict most drug sensitivities of relapse-derived organoids. This suggests a feasibility of functional precision approach for selection of second-line therapy using only primary tumor material, circumventing the problem of limited time available for the therapy choice after tumor sampling. This work also highlights that CDK9 inhibitors, currently in clinical development for hematological malignancies, are worthwhile to be explored in HGSC. 1. Senkowski et al. A platform for efficient establishment and drug-response profiling of high-grade serous ovarian cancer organoids. Developmental Cell (2023) Citation Format: Wojciech Senkowski, Laura Gall-Mas, Matias M. Falco, Yilin Li, Kari Lavikka, Aura Crispino, Jaana Oikkonen, Daria Bulanova, Yan-Jun Chen, Elena M. Doncel, Karolin Voßgröne, Erdogan P. Erkan, Jun Dai, Anastasia Lundgren, Jutta Huvila, Kaisa Huhtinen, Johanna Hynninen, Sampsa Hautaniemi, Anna Vähärautio, Krister Wennerberg. Application of high-grade serous ovarian cancer organoids in functional precision medicine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 235.