In little over 1 year of use in patients with breast cancer, trastuzumab biosimilars have seen rapid growth in uptake.
Investigators studying trastuzumab biosimilar savings and use rates across different disease settings in human epidermal growth factor receptor 2 (HER2)-positive breast cancer observed dramatically increased usage of biosimilars and said payer policy appears to have contributed to higher biosimilar utilization.
They looked at treatment plans submitted for patients to determine usage rates for originator vs biosimilar trastuzumab and trastuzumab in combination with hyaluronidase-oysk. The average costs of originator and biosimilar trastuzumab per patient cycle were $4502 and $3618, respectively, with an average savings per biosimilar dose (440 mg, trastuzumab; 600 mg trastuzumab hyaluronidase) of $884. Total savings for 4502 patients with stage I to III disease was $24.4 million, according to the poster presentation at the 2020 San Antonio Breast Cancer Symposium (SABCS).
Of 6657 treatment plans submitted for 4505 patients with stage 0 to III disease, the biosimilar usage rate was 34% (n = 2271 treatment plans). Investigators said that for 3312 plans submitted for 1933 patients with stage IV/recurrent disease, the biosimilar usage rate was 27% (n = 904 treatment plans).
The treatment plan submissions were tracked from June 2019 to October 2020 and showed a dramatic increase in biosimilar adoption. For patients with stage I to III disease, trastuzumab biosimilar use was 1.4% in the third quarter of 2019 vs 65.9 % in the fourth quarter of 2020. For patients with stage IV/recurrent disease, usage climbed from 1.6% to 49.3%, respectively.
Some patients had multiple treatment plans based on receipt of adjuvant or neoadjuvant therapy, treatment for local or recurrent disease, or metastatic/recurrent therapy. Patients with stage I to III disease were assumed to receive 1 year (18 doses) of trastuzumab therapy. Those with stage IV/recurrent disease were assumed to receive 11 months (16 cycles) of treatment.
The investigators said there was evidence that biosimilar use increased based on payer policies that favored biosimilars. Biosimilar use was 41.5% where payer policies were favorable vs 30.9% when that was not the case.
”As biosimilars were being introduced at different times during this time period and payer policy would likely lag behind these introductions, it is likely that the observed difference in biosimilar use by payer policy is underestimated,” the authors of the study wrote.
They concluded that the potential savings from biosimilar trastuzumab in breast cancer are “significant. Future estimates should use more rigorous models with stratification by use with hormonal therapy, chemotherapy, combinations with pertuzumab, or single agent, and the corresponding durations of therapy,” the authors recommended.
Flood WA, Avery T, Kozlovsky V, Margolis N, Reddy SK. Real world data on the adoption of trastuzumab biosimilars in the treatment of HER2-positive breast cancer. Poster presented at: SABCS; December 8-11, 2020. PS9-63. https://sabcs.onlineeventpro.freeman.com/single-file-viewer/25582299