Targeting the epigenome has demonstrated efficacy in hematological malignancies, and results of recent phase 1 (P1) trials have shown promising activity in solid tumors. The number of novel epidrugs is increasing exponentially, with several first-in-class, first-in-human selective compounds now evaluated in P1 trials. Accurate knowledge of their safety profile and toxicity management beyond cycle 1 is essential to appropriate P2 dose recommendation.
All patients (pts) with hematologic or solid tumors enrolled in at least one epidrug P1 trial at Gustave Roussy Drug Development Department were retrospectively analysed. Baseline pts characteristics, treatment-related adverse events (AEs) – type, grade, date of occurrence, duration, resolution - toxicity management (medication, dose modification) and outcome were collected.
A total of 243 pts (43,6% hematologic, 23,1% non-Hodgkin lymphoma (NHL), 33,3% solid tumors excluding NHL) were included in 15 epidrug monotherapy P1 trials between Jan 2010 and March 2017; 62% were male; median age was 65 yo and median treatment duration was 119 days; 1980 treatment cycles and 335 AEs were analysed: 118 (35%) (64 G1-2; 54 G3-4) and 217 (65%) (114 G1-2; 103 G3-4) AEs occurred during and after cycle 1 (C1; DLT period), respectively; 58% of AEs were hematological toxicities. The risk of G3-4 toxicity for hematologic pts was 15% and 11% during and after C1 respectively, and was 12% and 18% for solid tumors excluding NHL, and was 29% and 24% for pts with NHL. DLT occurred in 10 pts (4%). Dose reduction occurred in 15% of pts, after a median duration of 21 treatment days. Temporary and definitive treatment interruption for toxicity occurred in 21% and 9% of pts, respectively; 87% of these occurred after C1.
In P1 trials of epidrugs, 65% of high-grade AEs occur after cycle 1 and 42% are non-haematological toxicities. More pts with NHL than pts with solid tumors (excluding NHL) or hematological malignancies present their first severe AE during C1. The dose recommendation process may require fine-tuning according to each pt population. Like molecularly targeted or immune therapies, epidrugs have distinct toxicity profile requiring specific attention in their development process.
Gustave Roussy Institut.
Has not received any funding.
All authors have declared no conflicts of interest.