Use of single-arm trials to support malignant hematology and oncology drug and biologic approvals: A 20-year FDA experience.

Abstract

e13572 Background: Improved understanding of the underlying biology of cancer has led to a paradigm shift in cancer drug development and has paved the way for many products to receive accelerated or regular approval based on non-randomized/single arm trials (SATs). Given the high unmet medical need of cancer patients, challenges with lengthy and confounded survival endpoints, and difficulty enrolling rare biomarker-defined subsets of disease, SATs have been used to evaluate a variety of cancer therapies. Unlike time to event endpoints, the objective and clinically relevant endpoint of response rate (RR) and duration of response is interpretable in SATs, as spontaneous tumor shrinkage is not expected. Methods: A search of FDA databases identified all drugs and biologics approved for malignant hematology and oncology indications from January 1, 2001, to December 31, 2020 based on SATs. Data sources included approval letters, U.S. prescribing information, and clinical review documents. The definition of response varied by setting and time period (e.g. RECIST, WHO, IWG, etc.). Results: Between January 1, 2001 and December 31, 2020, FDA granted 153 new indications based on SATs, including 102 accelerated approvals (AAs) and 51 regular approvals (RAs). Overall, 69 approvals (45%) were for new molecular entities and 84 (55%) were expanded indications. Response rate was the most common endpoint used in the trial providing substantial evidence of efficacy to support approval [120/153, (78%)]. The durability of response was also considered to support evidence of clinical benefit. Of the 102 AAs, 38 (37%) have fulfilled their post-marketing requirement (PMR) to verify clinical benefit, 59 (58%) are pending verification of benefit, and 5 (5%) have been withdrawn from the market. Of note, 88% (52/59) of AAs pending verification of benefit occurred in the last 5 years alone (22 AAs in 2020, 8 in 2019, 8 in 2018, 12 in 2017, and 2 in 2016). Between 2001-2020, 58 (38%) new indications were granted for kinase inhibitors, 34 (22%) for immune checkpoint inhibitors (CPIs), and 61 (40%) for drugs with other mechanisms of action including but not limited to antibody-drug conjugates, cytotoxic drugs, and non-CPI monoclonal antibodies. Conclusions: In the last two decades, SATs have been effectively used to study anti-cancer therapies in well-defined patient populations using durable RR as an objective and interpretable clinical endpoint. Although randomized clinical trials remain the gold standard in clinical research, SATs have allowed for rapid advancements in oncology drug development and will continue to serve an important role in bringing new therapies to patients with unmet need.