First-in-human study of PM14 in patients with advanced solid tumors

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Background: PM14 is a new chemical entity that forms DNA adducts which specifically inhibit RNA synthesis and block active transcription of protein-coding genes. Antitumor activity has been demonstrated in vitro in several cell lines (e.g. lung, kidney, prostate), and in vivo in mice bearing xenografted human-derived tumors (soft tissue sarcoma, small cell lung cancer, ovarian, gastric, breast and renal cancer). Methods: Open-label, dose-escalating, phase I trial of PM14 administered as a 3-hour infusion i.v. every 3 weeks (q3wk) in patients (pts) with advanced solid tumors, adequate organ function and ECOG PS score of 0-1. Two schedules were explored: Schedule A (Day 1 [D1], Day 8 [D8]) and Schedule B (D1). Results: 37 pts were treated (Schedule A/B: 28/9 pts). Baseline characteristics of pts (A/B): median age 56/47 years; male 57%/56%; ECOG PS 0: 57%/56%; median of prior lines (range): 3 (1-8)/4 (1-10). Most common tumor types (A + B): STS (n=7 pts), ovarian (n=6), pancreatic (n=4), prostate cancer (n=3). The maximum tolerated dose was 4.5 mg/m2 for A (dose-limiting toxicities [DLTs]: D8 omission due to lack of recovery of lab parameters for re-treatment [n=2 pts]) and 5.6 mg/m2 (DLTs: G4 febrile neutropenia [n=1], G4 transaminase increase [n=1]) for B. The recommended dose (RD) was 3.0 mg/m2 on D1,D8 (A), and 4.5 mg/m2 on D1 (B). No DLTs were present at the RDs. Most common toxicities were hematological abnormalities and transaminase increase. Main toxicities at the RDs are shown below. Antitumor activity comprised stable disease ≥4 months in 7 heavily pretreated pts (6 in A; 1 in B) at all dose levels. Linear pharmacokinetics were observed for PM14 at tested doses (0.25-5.6 mg/m²), with geometric mean (CV%) total plasma clearance 5.9 L/h (88%), volume of distribution 128 L (81%) and median (range) terminal half-life 15.9 h (7.5-34.3 h). Less than 1.6% of administered dose was recovered in urine. Conclusions: RDs were determined for two PM14 schedules in pts with advanced solid tumors. At the RDs, PM14 is well tolerated and has a manageable safety profile. An expansion phase in specific tumor types, with an optional Bayesian continual reassessment method for RD fine-tuning, is ongoing with both schedules.[Table: see text]