A Phase Ib, Open-label Study Evaluating the Safety and Efficacy of Ipatasertib plus Rucaparib in Patients with Metastatic Castration-resistant Prostate Cancer.

PURPOSE: To report the safety and efficacy of ipatasertib (AKT inhibitor) combined with rucaparib (PARP inhibitor) in patients with metastatic castration-resistant prostate cancer (mCRPC) previously treated with second-generation androgen receptor inhibitors. PATIENTS AND METHODS: In this two-part phase Ib trial (NCT03840200), patients with advanced prostate, breast, or ovarian cancer received ipatasertib (300 or 400 mg daily) plus rucaparib (400 or 600 mg twice daily) to assess safety and identify a recommended phase II dose (RP2D). A part 1 dose-escalation phase was followed by a part 2 dose-expansion phase in which only patients with mCRPC received the RP2D. The primary efficacy endpoint was prostate-specific antigen (PSA) response (≥50% reduction) in patients with mCRPC. Patients were not selected on the basis of tumor mutational status. RESULTS: Fifty-one patients were enrolled (part 1 = 21; part 2 = 30). Ipatasertib 400 mg daily plus rucaparib 400 mg twice daily was the selected RP2D, received by 37 patients with mCRPC. Grade 3/4 adverse events occurred in 46% (17/37) of patients, with one grade 4 adverse event (anemia, deemed related to rucaparib) and no deaths. Adverse events leading to treatment modification occurred in 70% (26/37). The PSA response rate was 26% (9/35), and the objective response rate per Response Criteria in Solid Tumors (RECIST) 1.1 was 10% (2/21). Median radiographic progression-free survival per Prostate Cancer Working Group 3 criteria was 5.8 months [95% confidence interval (CI), 4.0-8.1], and median overall survival was 13.3 months (95% CI, 10.9-not evaluable). CONCLUSIONS: Ipatasertib plus rucaparib was manageable with dose modification but did not demonstrate synergistic or additive antitumor activity in previously treated patients with mCRPC.

Mitigating ipatasertib-induced glucose increase through dose and meal timing modifications.

Ipatasertib, an AKT inhibitor, in combination with prednisone and abiraterone, is under evaluation for the treatment of metastatic castration-resistant prostate cancer (mCRPC). Hyperglycemia is an on-target effect of ipatasertib. An open-label, single-arm, single-sequence, signal-seeking study (n = 25 mCRPC patients) was conducted to evaluate the glucose changes across four different treatment periods: ipatasertib alone, ipatasertib-prednisone combination, ipatasertib-prednisone-abiraterone combination (morning dose), and ipatasertib-prednisone-abiraterone combination (evening dose). Continuous glucose monitoring (CGM) was used in this study to compare the dynamic glucose changes across the different treatment periods. Four key parameters: average glucose, peak glucose and % time in range (70-180 and >180 mg/dl) were evaluated for this comparison. Ipatasertib-prednisone-abiraterone combination when administered in the morning after an overnight fast significantly increased average glucose, peak glucose and % time in range >180 mg/dl compared to ipatasertib monotherapy. Ipatasertib, when co-administered with abiraterone, increased ipatasertib and M1 (G-037720) metabolite exposures by approximately 1.5- and 2.2-fold, respectively. Exposure-response analysis results show that increased exposures of ipatasertib in combination with abiraterone are associated with increased glucose levels. When ipatasertib-prednisone-abiraterone combination was administered as an evening dose compared to a morning dose, lowered peak glucose and improved % time in range was observed. The results from this study suggest that dosing ipatasertib after an evening meal followed by overnight fasting can be an effective strategy for managing increased glucose levels.

Drug-Drug Interaction Study to Evaluate the Pharmacokinetics, Safety, and Tolerability of Ipatasertib in Combination with Darolutamide in Patients with Advanced Prostate Cancer.

Ipatasertib is a selective, small molecule Akt inhibitor that is currently being developed for the treatment of metastatic castration-resistant prostate cancer. Darolutamide is an androgen receptor (AR) inhibitor that is approved for the treatment of non-metastatic castration-resistant prostate cancer. Ipatasertib is metabolized by CYP3A4 to form a less active metabolite M1 (G-037720). Ipatasertib is also a weak time-dependent CYP3A4 inhibitor. Darolutamide is a mild CYP3A4 inducer and is metabolized into an active keto-darolutamide metabolite via CYP3A4. In this Phase 1b open-label, single sequence crossover study, ipatasertib pharmacokinetics safety and tolerability were evaluated in combination with darolutamide in metastatic castration-resistant prostate cancer (n = 15 patients). Specifically, the effect of 600 mg BID of darolutamide on 400 mg QD ipatasertib was evaluated in this study. Based on pharmacokinetic analysis, a mild reduction in ipatasertib AUC0-24 h,ss and Cmax,ss exposures was observed (~8% and ~21%, respectively) when administered in combination with darolutamide, which is considered not clinically meaningful. M1 exposures were similar with and without darolutamide administration. Darolutamide and keto-darolutamide exposures in combination with ipatasertib were similar to previously reported exposures for single agent darolutamide. Overall, the combination appears to be well-tolerated in the metastatic castration-resistant prostate cancer indication with very few AEs.