Response to systemic therapies in patient-derived cell lines from primary and recurrent adult granulosa cell tumors

In patients with the rare adult-type granulosa cell tumors (aGCT), surgery is the primary treatment for both primary and recurrent disease. In cases of inoperable disease, systematic therapy is administered, but variable response rates and drug resistance complicate predicting the most effective therapy. Drug screen testing on patient-derived cell lines may offer a solution. In a national prospective study on aGCT, fresh tissue was cultured into 2D cell lines, testing 27 clinically and experimental drugs. Dose-response curves and synergy were calculated using GraphPad Prism and Compusyn software. We established 34 patient-derived cell lines from tissue of 20 adult granulosa cell tumor patients. Of these, seven patients had a primary diagnosis of adult granulosa cell tumor and 13 patients had recurrent disease. In eight patients multiple tumor locations were cultured. On each cell line 10 monotherapies and 17 combinations of drugs were tested. Carboplatin/gemcitabine showed efficacy and synergy in almost all patient-derived cell lines. Synergy could not be detected in the regular carboplatin/paclitaxel and carboplatin/etoposide combinations. Experimental combinations alpelisib/fulvestrant and alpelisib/gemcitabine showed efficacy of more than 75%. Drug screens on patient-derived tumor cell lines reflects the reality of the variable response of systemic therapy in aGCT patients. In future research, this technique may be used to personalize the systemic treatment of aGCT patients in a clinical study. The good response to carboplatin/gemcitabine in our patient-derived cell lines can then be confirmed in a clinical setting.