Dr. Emily Jackson
The current funding policy in British Columbia restricts patients to two lines of HER2-directed therapy for metastatic breast cancer, but accessing continued HER2 suppression has become more complex as novel agents have emerged, Emily Jackson, MD, and colleagues explained (in poster PD8-09) at the San Antonio Breast Cancer Symposium.
Continuing HER2 suppression has improved progression free survival (PFS) and overall survival (OS), but the financial implications of adapting funding policies to “reflect increasing lines of proven HER2 treatment” are unclear, they noted.
Drug funding is provided through the provincial government, but it can take months – and sometimes years – from when a drug is approved by Health Canada and when provincial protocols are approved and funding is made available, Dr. Jackson, co-chief resident (PGY5) at BC Cancer, Vancouver, said in an interview.
During that “lag time,” the province is negotiating drug prices with pharmaceutical companies and determining “which patients are eligible and under which circumstances,” she said.
To assess the potential costs, the investigators analyzed data from the BC Cancer outcomes unit, which collects clinical and outcome information on 85% of all patients diagnosed with breast cancer in the province. Information on therapy use was obtained from the BC Cancer pharmacy database.
Of 230 patients who received any HER2 treatment for metastatic breast cancer dispensed by BC Cancer between 2013 and 2018, 112 (49%) were eligible to continue beyond their second line of therapy.
“Of these, 86 patients accessed continued HER2-directed therapy, while 26 were eligible but unable to access continued HER2Rx,” they reported, noting that “the remaining 51% (n = 118) were not eligible for consideration of further HER2Rx due to either stable disease (n = 61) or deterioration precluding treatment (n = 57).”
At median follow-up of 42.2 months, the median number of lines of therapy in the entire study population was three. The median number of cycles in those who received HER2-directed therapy beyond second-line therapy was 33.
The median overall survival was 37.5 months for those who were eligible but did not continue HER2, compared with 57.9 months for those who did continue, they found.
The overall survival difference was not statistically significant (P = .13), but this was likely due to the small number of patients included in the initial analysis, Dr. Jackson said, noting that the finding is “hypothesis generating,” and should be further assessed.
Notably, most patients who continued HER2 therapy did so through pharmaceutical company compassionate access programs or clinical trials, she said.
The “conservative estimated cost per cycle of HER2Rx” was based on currently available trastuzumab biosimilars, and the potential financial implications were calculated based on the current cost of commonly used third-line therapies.
The findings demonstrate that most patients access continued treatment despite prohibitive funding policies, and suggest that significant increases in cost per patient can be expected if funding policies don’t evolve to meet treatment needs, they concluded, noting that “if these trends in survival continue we would expect an additional cost of $68,000 per patient over current costs.
“As the cost of novel therapies are likely to be higher than currently available biosimilars, there will be significant implications for both private payer and public payer healthcare systems,” they added.
A larger, more comprehensive analysis of the data is planned, said Dr. Jackson, who did not disclose any funding or other conflicts of interest associated with this study.