A phase 1/2a trial of docetaxel plus ribavirin for reprogramming efficacy in patients with progressive metastatic castration resistant prostate cancer who have previously received docetaxel alone: DRREEM trial.

Abstract

329 Background: We previously reported a novel cell reprogramming approach, termed drug efficacy reprogramming, as a new model for identifying candidate antitumor drugs targeting the cancer stemness-related gene network, and identified ribavirin as a candidate drug for overcoming docetaxel-resistant castration-resistant prostate cancer (CRPC). We conducted this phase 1/2a trial of docetaxel plus ribavirin for reprogramming efficacy in patients with progressive metastatic castration resistant prostate cancer who have previously received docetaxel alone. (DRREEM trial) Methods: In this clinical study, patients received intravenous docetaxel at 60-75 mg/m2is intravenously administered on Cycle1-Day1 in combination with the investigational drug (ribavirin). Docetaxel is administered at 3-week intervals (1 cycle) (total: 3 cycles). During administration, the dose may be reduced based on the subject’s condition if necessary. The primary endpoint was safety. Accessory evaluation items included prostate-specific antigen (PSA) response, objective response rate, health-related quality of lifel. Exploratory items included changes in CTC count, cfDNA, and exosome. Patients with progressive CRPC based on PSA and/or radiographic criteria, performance status (PS) 0–1, and normal renal and hepatic function were eligible. Results: Six patients were enrolled in this study; average age was 71.7±4.2. Average serum PSA concentration was 100.1±128.0 ng/ml (range: 3.0-336.8). The median cycle of docetaxel received before the study was 6 cycles. Safety: Grade 3/4 adverse events requiring dose modification were not observed. Two patients showed PSA reduction. Three patients showed stable disease. Changes in the blood concentrations of ribavirin, docetaxel, and prednisolone were within normal range. Conclusions: This combination of ribavirin with docetaxel was well tolerated with a promising response rate that justifies further investigations in docetaxel-resistant CRPC. This clinical study provides a useful drug re-positioning model in the area of translational medicine. Clinical trial information: UMIN000021107.