Abstracts Highlight Growing Comfortability With Trastuzumab Biosimilars in Breast Cancer

Abstracts presented at the annual meeting of the American Society of Clinical Oncology (ASCO 2023) emphasized the safety and efficacy of a trastuzumab biosimilar in treating HER2-postive breast cancer and growing utilization of trastuzumab biosimilars over time.

Clinical Analysis of Zedora in Brazil

A study from Brazil noted that the nature and severity of adverse events (AEs) associated with administration of Zedora, a trastuzumab biosimilar, were consistent with the safety profile of the reference product (Herceptin).

The analysis was a national, multicentric, observational, and prospective real-world study of patients with early-stage HER2-positive breast cancer who received at least 1 dose of trastuzumab as adjuvant therapy. Overall, 162 of 170 planned patients were recruited. The researchers presented preliminary data for the first 59 patients.

The primary endpoints were the occurrence of AEs until the end of adjuvant therapy, which were collected after patients signed a consent form. Among the 59 patients, the mean (SD) age was 51.7 (12.9) years and 79.7% of them had node-negative disease. Most patients had hormone­–receptor-positive tumors (estrogen–receptor-positive, 67.8%; progesterone–receptor-positive, 55.9%), and the rate of patients who underwent conservative surgery was higher than mastectomy (67.8% vs 32.2%, respectively).

The most frequent histological breast cancer subtype was invasive ductal carcinoma (98.3%). All participants received adjuvant anti-HER2 therapy, which included administration of Zedora plus perztuzumab (22.0%); however, 2 patients began therapy with the reference product and were switched to the biosimilar upon entry into the study. The mean duration of adjuvant therapy was 10.2 (2.2) months, ranging from 5.8 to 13.9 months and corresponded to 14 (3.2) cycles of 21 days on average.

Overall, 78.0% of patients experienced at least 1 AE, 4 of which were considered serious AEs (6.8%). Three of the serious AEs were of severe intensity and 1 was deemed life-threatening. However, these results were consistent with the known AE profiles associated with the reference product.

Survey Results on Physician Confidence in India

An analysis sales data on trastuzumab products coincided with the results of a physician perception survey, showing increased utilization of trastuzumab biosimilars over the last 7 years.

The original survey was concentrated on physician perceptions on using trastuzumab biosimilars in HER2-positive breast cancer and changes in trends from before trastuzumab biosimilars were present on the Indian market and after they launched, the first of which entered the market in 2014.

In the present analysis, the researchers gathered sales data from the Ipsos India Oncology Sales Audit from January 2014 to December 2020. The audit contained reports for Net Realized Value of all brands marketed by over 60 oncology companies across India. The data were collected using open-source intelligence and telephone interviews with sales/marketing personnel from pharmaceutical companies and distributors. The number of patients treataed with trastuzumab was determined using body weight and whether they completed 6 months of therapy and received 1 vial of 440 mg/cycle of the drug.

About 68,000 patients with HER2-positive breast cancer received trastuzumab from 2014-2020, out of which 46,000 received biosimilars and 22,000 innovators. Only 18% of patients were treated with biosimilars in 2014, compared with 88% in 2020. There was a 17% decline in patients treated with the reference product between 2017 and 2018, and the number of patients treated with biosimilars grew by 229% during the same period.

In 2020, there was a 15% overall decline in trastuzumab administration (biosimilars, -13%; originator, -30%), which was caused by the COVID-19 pandemic.

“Biosimilars are preferred option amongst oncologists in India because of affordability and accessibility. The availability of quality biosimilars has the potential to reduce health care expenditure, and an effective supply also increase patient’s adherence to treatment,” the researchers wrote.

Reference

1. Cardoso ACF, Gagliato DEM, Brito NM, et al. A prospective real-world study to assess the effectiveness and safety of trastuzumab biosimilar in the adjuvant treatment of HER2-positive breast cancer: Preliminary safety results. Presented at: 2023 ASCO Annual Meeting; June 3-5, 2023; Chicago, IL. Abstract e12532. doi:10.1200/JCO.2023.41.16_suppl.e12532
2. Ramanjinappa N, Upveja KH, Agarwal J. Shifting trends in the usage of trastuzumab with its biosimilar inception in India. Presented at: 2023 ASCO Annual Meeting; June 3-5, 2023; Chicago, IL. Abstract e13037. doi:10.1200/JCO.2023.41.16_suppl.e13037