Phase I study of the investigational oral mTORC1/2 inhibitor sapanisertib (TAK-228): tolerability and food effects of a milled formulation in patients with advanced solid tumours

Background Sapanisertib (TAK-228) is an investigational, orally available, potent and highly selective mTORC1/2 inhibitor demonstrating promise in numerous malignancies. This phase I study (NCT02412722) evaluated the safety, tolerability, pharmacokinetics and antitumour activity of single-agent TAK-228 (milled capsules), administered daily (QD) or weekly (QW) and in combination with paclitaxel in patients with advanced solid tumours. Pharmacokinetic comparisons of milled versus unmilled TAK-228 and the impact of food were also investigated. Methods Patients were enrolled to receive: TAK-228 QD, TAK-228 3 days/week plus paclitaxel 80 mg/m 2 days 1, 8, 15 (TAK-228+P) or TAK-228 QW (all 28-day cycles); starting TAK‑228 doses were 4, 6 and 20 mg, respectively. Results Sixty-one adults were enrolled. Maximum tolerated doses for milled TAK-228 were 3 mg (TAK-228 QD), 6 mg (TAK-228+P) and 30 mg (TAK-228 QW). Most patients reported ≥1 adverse event (AE); there were no meaningful differences in drug-related AEs across regimens or doses. Three on-study deaths occurred, all considered unrelated to study drugs. TAK-228 pharmacokinetics did not differ between unmilled/milled capsules or with/without paclitaxel. However, TAK-228 C max decreased by ~40% in fed versus fasted patients. Objective response rates were 12% (TAK-228 QD), 18% (TAK-228+P) and 0% (TAK-228 QW). One patient receiving TAK-228+P had a complete response; three patients receiving TAK-228+P and two patients receiving TAK-228 QD had partial responses. Conclusions Milled TAK-228 was well tolerated with signs of antitumour activity; administration did not reduce overall exposure (area under the plasma concentration–time curve) but reduced C max , which is expected when dosed in the fed state. These promising findings warrant further investigation. Trial registration number NCT02412722.