Assessment of current approaches of starting dose selection and dose escalation for oncology biologics in first-in-patient trials.

Abstract

e14093 Background: Current approaches for starting dose selection for first-in-patient (FIP) trials of oncology biologics vary according to pharmacological properties and modality of the investigational agent. For biologics with immune agonistic properties, the FIP starting dose is typically based on the minimal anticipated biological effect level (MABEL). For non-immune activating biologics, the starting dose is typically based on allometric scaling of a threshold toxic dose determined in the most appropriate animal species. The aim of this work is to assess the performance of current approaches of FIP starting dose selection and dose escalation for oncology biologics. Methods: FIP clinical trials for oncology biologics licensed by the US FDA from 2010 to 2019 were analyzed to extract information related to starting dose and dose escalation. Source materials for the relevant FIP trials included the Drugs@FDA database, PubMed, and conference proceedings. The data were further analyzed to evaluate parameters related to appropriateness of the starting dose and dose escalation efficiency, which include the number of cohorts to reach the maximum tolerated dose [MTD] (or, when MTD was not identified, the highest human dose [HHD]) and the ratio of MTD/HHD to starting dose. Results: The 26 oncology biologics licensed by the US FDA between 2010 and 2019 included 8 ADCs/immunotoxins, 7 checkpoint inhibitors and 11 other biologics (monoclonal antibody, fusion protein or CD3 bispecific construct). The majority (69%) of these biologics were well tolerated without MTD identified in the FIP trials. All 26 FIP trials with biologics appeared to follow ICH S9 Guidance for starting dose selection, and the dose increment ranged from 1.2- to 10-fold. These FIP trials had a median of 6 cohorts (range: 3-10) to reach MTD (or HHD) from the starting dose. About 50% of these trials involved ≥ 6 cohorts to reach MTD (or HHD). The MTD/HHD to starting dose ratio was > 100 for 4 of the biologics. The median label dose to starting dose ratio was 10 (range: 1-3200), suggesting that a large number of patients in these FIP trials received subtherapeutic dose levels. Conclusions: Current approaches of starting dose selection and dose escalation led to a very low starting dose and many dose escalation cohorts for the FIP trials of a large portion of recently licensed oncology biologics. There exist opportunities to improve current approaches to increase FIP trial efficiency and reduce the number of patients receiving subtherapeutic dose levels in these trials.