Phase Ia study of the indoleamine 2,3-dioxygenase 1 (IDO1) inhibitor navoximod (GDC-0919) in patients with recurrent advanced solid tumors.

BACKGROUND: Indoleamine-2,3-dioxygenase 1 (IDO1) catalyzes the oxidation of tryptophan into kynurenine and is partially responsible for acquired immune tolerance associated with cancer. The IDO1 small molecule inhibitor navoximod (GDC-0919, NLG-919) is active as a combination therapy in multiple tumor models. METHODS: This open-label Phase Ia study assessed safety, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary anti-tumor activity of navoximod in patients with recurrent/advanced solid tumors, administered as 50-800 mg BID on a 21/28 day and at 600 mg on a 28/28 day schedule. Plasma kynurenine and tryptophan were longitudinally evaluated and tumor assessments were performed. RESULTS: Patients (n = 22) received a median of 3 cycles of navoximod. No maximum tolerated dose was reached. One dose-limiting toxicity of Grade 4 lower gastrointestinal hemorrhage was reported. Adverse events (AEs) regardless of causality in ≥20% of patients included fatigue (59%), cough, decreased appetite, and pruritus (41% each), nausea (36%), and vomiting (27%). Grade ≥ 3 AEs occurred in 14/22 patients (64%), and were related to navoximod in two patients (9%). Navoximod was rapidly absorbed (Tmax ~ 1 h) and exhibited dose-proportional increases in exposure, with a half-life (t1/2 ~ 11 h) supportive of BID dosing. Navoximod transiently decreased plasma kynurenine from baseline levels with kinetics consistent with its half-life. Of efficacy-evaluable patients, 8 (36%) had stable disease and 10 (46%) had progressive disease. CONCLUSIONS: Navoximod was well-tolerated at doses up to 800 mg BID decreasing plasma kynurenine levels consistent with its half-life. Stable disease responses were observed. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02048709 .

Acute myelogenous leukemia patients are at low risk for invasive fungal infections after high-dose cytarabine consolidations and thus do not require prophylaxis.

We evaluated the frequency of invasive fungal infections (IFI), the frequency of empirical antifungal use (EAFU), and the efficacy of fluconazole prophylaxis on IFI and EAFU after high-dose cytarabine (HiDAC) consolidations. Twenty-seven acute myelogenous leukemia patients in their first complete remission received 76 cycles of HiDAC (median cycle: n = 3). Fluconazole prophylaxis was administered following 44 cycles (fluconazole group) and not given in 32 cycles (control group). IFI (2 episodes) + EAFU (11 episodes) was observed in 13 of 76 cycles (17%); there was no difference between the fluconazole group and the control group (p = 0.469). Neutropenia duration was <13 days in 89% of the 76 cycles and was similar in the fluconazole and control groups (p = 0.845). Neutropenic fever was observed in 34 of the 76 cycles (45%) and was similar in the fluconazole group and the control group (p = 0.43). Although HiDAC cycle 1 was associated with a shorter neutropenia duration, there was no association between HiDAC cycle numbers and neutropenic fever or IFI + EAFU. HiDAC consolidations resulted in a high rate of neutropenic fever, the lack of an appreciable benefit from EAFU, and rare IFI. Most likely because of the low incidence of IFI, use of fluconazole or another antifungal is not warranted in this setting.