Need for systematic de-escalation of care in HER2+ breast cancer patients.

Background: Over the last decade, there has been incredible progress in HER2-positive breast cancer patients with the adoption of targeted therapies like Trastuzumab and Pertuzumab to complement existing chemotherapies. Increasingly neoadjuvant therapy is the preferred method of therapy as it is better able to predict prognosis via pCR as well as guide adjuvant therapeutic strategy in cases with residual tumor. There are now a variety of combination therapies recommended for HER2-positive patients. As new therapies are developed, the standard-of-care shifts towards the regimen with highest pCR rate. The latest regimen being TCHP which produced pCR rates over 60% in clinical trials. While the improvement in pCR rates at a population level is encouraging, there is a growing sentiment among physicians that we may be over treating patients impacting both costs and resulting toxicity.

Methods: We performed an analysis of Breast Cancer trials with pCR as the primary end point and stratification available based on HER2+ status. The cost (median insurance reimbursement) was also referenced from a recent ASCO observational study as a proxy for direct costs of drugs. Toxicities were referenced and each regimen scored (TS) from NCCN Evidence Blocks and adverse events from clinical trials. Potential savings were evaluated if a clinician had the ability to individualize regimen choice by patient. We utilized the SimBioSys TumorScope platform to perform in silico simulations to predict response to alternate therapies as it had previously used to analyze potential deescalate between AC-T vs TC in a HER2- cohort.

Results: The following regimens were evaluated HP (pCR:17%,TS:1), TH (pCR: 29%,TS: 2) THP (pCR: 46%, TS: 3), TCH (pCR: 43%, TS: 4), TCHP (pCR: 64%, TS: 5), AC-TH (pCR: 43%, TS: 6), AC-THP(pCR: 55%, TS: 7). Based on an in-silico analysis and selection (where pCR was likely with multiple regimens), the lowest cost & toxicity regimen was selected. The estimated average saving per case of over $100,000 for the overall treatment plan . The calculated toxicity score was also reduced by this method to under 4 from the TCHP(5) standard of care.

Conclusions: While the results above are estimates and perfection in such individualization may not be possible, an in-silico approach provides a promising solution.

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