A phase Ib study of the Akt inhibitor GDC-0068 with docetaxel (D) or mFOLFOX-6 (F) in patients (pts) with advanced solid tumors.

Abstract

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Background: Activation of the Akt pathway is observed in multiple tumors and may contribute to chemoresistance. GDC-0068 is an ATP-competitive small molecule inhibitor of all three isoforms of Akt; in a phase Ia study, it was well tolerated with maximum tolerated dose (MTD) of 600 mg daily (21 days on/7days off) and pharmacodynamic down-regulation of Akt signaling in tumors at doses ≥100 mg. In vitro, GDC-0068 shows synergism with cytotoxic agents. This phase Ib study defines the dose limiting toxicities (DLT), MTD, safety and pharmacokinetics (PK) of GDC0068 in combination with D and F. Methods: Using a 3+3 designeligible patients (pt) with advanced/metastatic solid tumors were treated with either D, 75 mg/m ² day 1 and GDC-0068 daily on days 2-15 of a 21 day cycle (Arm A); or F, bolus 5FU 400mg/m ², leucovorin 400 mg/m ², oxaliplatin 85 mg/m ² all day 1, and infusional 5FU 2400mg/m ² for 46 hours and GDC-0068 daily on days 1-7 of a 14 day cycle (Arm B). PK sampling was performed in Cycles 1 and 2. Results: 23 pts have enrolled; Arm A (GDC-0068, mg): 100 (n=3), 200 (n=4), and 400 (n=5); Arm B:100 (n=6) and 200 (n=5). Median prior therapies = 3. GDC-0068-related adverse events in ≥ 10% of pts were diarrhea, nausea, vomiting, fatigue, and decreased appetite. All GDC-0068-related AEs were grade 1 or 2, except one grade 4 neutropenia in Arm A. No DLTs have been reported to date. Preliminary data show no alteration in the PK of GDC-0068, D or F compared to phase Ia or historical data. Two heavily pretreated pts with cervical and PTEN-loss colon cancers treated in Arm B demonstrated both RECIST partial response and tumor marker decrease by first CT evaluation. Conclusions: The combination of GDC-0068 with D or F is well-tolerated and shows early signs of anti-tumor activity. Dose-escalations continue.