Recognizing and addressing challenges to the adoption of trastuzumab biosimilars and HER2-targeted therapies.

Oncology biologics are one of the fastest-growing segments of pharmaceutical development, bringing more options to patients, including those with human epidermal growth factor receptor 2 (HER2)-positive breast cancer. The advent of multiple oncology biosimilars is affecting this patient population, as 5 trastuzumab biosimilars had been FDA approved as of the end of 2019; only 2, however, have been commercially marketed. Trastuzumab serves as the foundation for treatment for patients with HER2-positive breast cancer. HER2-targeted antibody-drug conjugates have been developed to enhance efficacy, improve safety, and/or create more convenient administration. Three biologic drug entities have been approved using trastuzumab, including 2 antibody-drug conjugates and a subcutaneous trastuzumab formulation that includes hyaluronidase. More products are being developed, so biosimilars and other HER2-targeted therapies may further disrupt the biologic market. Many challenging questions surround the adoption of oncology biosimilars, including regulatory pathways, efficacy, safety, cost-benefit, and comparability. The Biologics Price Competition and Innovation Act established an abbreviated regulatory approval pathway for biosimilars to create a catalyst for innovation and competition in the biologics market and to lower the costs of biologics. Challenges to adoption of therapeutic oncology biosimilars continue in the United States and include a lack of directed education to providers and patients, residual concerns regarding efficacy and safety, and practices including "pay-for-delay." The uptake of oncology biosimilars is also affected by multiple issues stemming mainly from cost of care, including drug cost, patient access, formulary inclusion, and treatment management algorithms. Managed care organizations and payers need to be familiar with the biosimilar approval process, the concerns of stakeholders (eg, providers and patients), and factors influencing HER2-directed therapies, including the use of biosimilars and antibody-drug conjugates in today's market.