The development of biosimilar medicines has provided an opportunity for patient utilization of oncology treatments at a lower cost, particularly in individuals for whom biologicals play a predominant role in providing effective therapeutic and supportive care. Although there has been an increase in the use of biosimilars in recent years, challenges to mass adoption remain. According to data presented at the virtual 2021 American Society of Clinical Oncology Quality Care Symposium, however, utilization of the biosimilar trastuzumab-anns (Kanjinti) is trending in the right direction.
Preliminary findings of an analysis of commercial insurance claims suggest an increasing number of incident users of the biosimilar trastuzumab-anns, while use of the trastuzumab (Herceptin) originator decreased over time. Although complete data were not available for 2019 to 2020 for all health plans, lead study investigator Catherine M. Lockhart, PharmD, PhD, Executive Director, Biologics and Biosimilars Collective Intelligence Consortium, Asheville, NC, called the data “encouraging.”
“The trastuzumab biosimilars are turning out to be a bigger success story than we’ve seen with all the other biosimilar classes in the US,” said Dr Lockhart. “When trastuzumab-anns was first available in 2019, utilization was only 3%. Now, 30% of total utilization is with the biosimilar. That’s a big jump.”
According to Dr Lockhart, biosimilars for trastuzumab, an HER2 inhibitor, have been available in the United States since 2019, but information on their utilization and patient characteristics are limited. Using the FDA’s Sentinel distributed analysis tools, Dr Lockhart and colleagues analyzed healthcare claims between October 2016 and February 2020 from the Biologics and Biosimilars Collective Intelligence Consortium’s Distributed Research Network, which has access to more than 95 million patients.
The researchers conducted descriptive analyses on the number of incident users and patients’ characteristics for each HER2 inhibitor. Adults continuously enrolled in their health plan with medical and drug coverage for more than 1 year prior to their incident HER2 inhibitor use were eligible for analysis.
Of the incident HER2 inhibitor users identified, 6631 used trastuzumab, 122 used trastuzumab-anns, 116 used ado-trastuzumab emtansine (Kadcyla), and 54 used neratinib (Nerlynx) and lapatinib (Tykerb), respectively. However, the overwhelming majority of biosimilar utilization began in 2019.
As Dr Lockhart reported, the number of incident users per 100,000 person-years decreased for the trastuzumab originator from 13.5 in 2016 to 9.4 in 2020 and increased for trastuzumab-anns from 0.4 in 2019 to 4.9 in 2020. Based on the 2020 first quarter sample, 30% of total utilization of HER2 inhibitors was with the biosimilar trastuzumab-anns.
According to Dr Lockhart, findings also showed that the Charlson/Elixhauser Comorbidity Index Score was the highest for lapatinib and similar between the trastuzumab originator and trastuzumab-anns. Although there were variations in patient characteristics between HER2 inhibitors and by metastatic status, said Dr Lockhart, the characteristics were generally similar between the trastuzumab originator and trastuzumab-anns.
The proportion of patients who received any chemotherapy during the baseline period was 38.9% for lapatinib, 18.5% for the trastuzumab originator, and 14.8% for trastuzumab-anns. The proportion of endocrine therapy users was the highest for neratinib (63%) and similar between the trastuzumab originator (11.1%) and trastuzumab-anns (10.7%). Among incident users with metastatic breast cancer, endocrine therapy receivers during the baseline period accounted for 19.3% for the trastuzumab originator and 69.6% for lapatinib.
Dr Lockhart and colleagues are planning to conduct ongoing assessment of HER2 inhibitor utilization as more data become available to help inform clinical practices and health policies.
“This is just the first step for us in terms of studying trastuzumab and other biosimilar products,” said Dr Lockhart. “We have a unique approach, and as an organization, we’re the only ones who are dedicated specifically to looking at real-world evidence around biologic products in the US.”
“I’m hopeful that we’ll continue to see more biosimilars being actively used in the market, especially now that we have more than one biosimilar of trastuzumab,” Dr Lockhart added. “These results are very positive, and we should be very optimistic.”
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