e18846 Background: Standard therapy for high-risk HER2+ early breast cancer (EBC) begins with neoadjuvant dual targeted therapy with pertuzumab (P) + trastuzumab (T) + chemotherapy (CTX). After surgery, patients who achieve pathological complete response (pCR) should complete one year of dual targeted therapy, while patients with residual disease should receive ado-trastuzumab emtansine (T-DM1). Recently, a subcutaneously administered formulation of P, T, and hyaluronidase-zzxf (Phesgo) was approved for use in the U.S. This study assesses the value of this new formulation in EBC patients vs. a strategy in which patients initiate standard therapy, but discontinue P following ascertainment of pCR. Methods: We developed a six-state Markov model to assess EBC costs and quality-adjusted life years (QALYs) from a healthcare sector perspective over a lifetime time horizon. Two strategies were modeled: 1) Neoadjuvant therapy with subcutaneous P, T, and hyaluronidase-zzxf + CTX with adjuvant continuation if pCR is achieved, and T-DM1 if not (“intervention”), and 2) neoadjuvant therapy with infused P, T + CTX with adjuvant infused T if pCR is achieved, and T-DM1 if not (“comparator”). Event-free and invasive-disease free survival were derived from the PEONY and KATHERINE/APHINITY trials, respectively. Utility values, drug prices, and procedure costs were derived from KATHERINE EQ-5D data, Wholesale Acquisition Costs, and claims analyses, respectively. We assessed comparator costs using both biosimilar and branded T pricing. The primary outcome was the incremental cost-effectiveness ratio (ICER). Outcomes were discounted at 3%/year and costs are presented in 2020 U.S. dollars. Uncertainty in outcomes was assessed through Monte Carlo simulation (1,000 replicates). Results: The table shows key results. The intervention resulted in a gain of 0.092 QALYs. With biosimilar T pricing in the comparator (base case), the intervention increased costs by $7,575 (ICER = $81,793). With branded T pricing in the comparator (scenario analysis), the intervention increased costs by $982 (ICER = $10,602). In probabilistic analyses, the intervention was favored in 52% and 81% of simulations at a willingness-to-pay of $100,000/QALY with biosimilar and branded T pricing, respectively. Conclusions: This study provides additional evidence to support adjuvant continuation of P+T among patients achieving pCR. Neoadjuvant P, T, and hyaluronidase-zzxf + CTX (with adjuvant continuation of dual targeted therapy) is expected to be cost-effective ( < $100,000/QALY) vs. neoadjuvant P and T + CTX (with adjuvant T continuation) for patients with high-risk HER2+ EBC irrespective of whether the comparator uses biosimilar or branded T.[Table: see text]
Abemaciclib With Endocrine Therapy in the Treatment of High-Risk Early Breast Cancer: ASCO Optimal Adjuvant Chemotherapy and Targeted Therapy Guideline Rapid Recommendation Update
