Phase I Trial of a Tablet Formulation of Pilaralisib, a Pan-Class I PI3K Inhibitor, in Patients with Advanced Solid Tumors

Background. A phase I trial of pilaralisib, an oral pan-class I phosphoinositide 3-kinase (PI3K) inhibitor, established the maximum tolerated dose (MTD) of the capsule formulation in patients with advanced solid tumors as 600 mg once daily. This phase I study investigated pilaralisib in tablet formulation. Materials and Methods. Patients with advanced solid tumors received pilaralisib tablets (100-600 mg once daily). Primary endpoints were MTD and safety; secondary and exploratory endpoints included pharmacokinetics (PK), pharmacodynamics, and efficacy. Results. Twenty-two patients were enrolled. No dose-limiting toxicities (DLTs) were reported. The most common treatment-related adverse events were diarrhea (40.9%), fatigue (40.9%), decreased appetite (22.7%), and hyperglycemia (22.7%). Pilaralisib plasma exposure did not appear to increase dose-proportionally. Steady-state exposure was higher with pilaralisib tablet formulation at 400 mg than with pilaralisib capsule formulation at 400 or 600 mg (mean area under the curve [AUC(0-24)] 2,820,000 ng x h/mL vs. 2,653,000 and 1,930,000 ng 3 h/mL, respectively). Of 18 evaluable patients, 2 (11.1%) had a partial response (PR). Conclusion. Pilaralisib tablets were associated with a favorable safety profile and preliminary antitumor activity. MTD was not determined. The recommended phase II dose for pilaralisib tablets, based on PK data, was 400 mg once daily.