Cross-activity analyses of standard chemotherapy regimens for primary breast cancer using the ATP-based tumor chemosensitivity assay: Pharmacoeconomic implications.

Abstract

e11033 Background: Chemotherapy (Ctx) for primary breast cancer (PBC) now utilizes expensive drugs, thus emerging important pharmacoecomic implications. This study was initiated to analyze the cross-activity of standard Ctx regimens (Ctx-R) in PBC using the ex vivo ATP-based tumor chemosensitivity assay (ATP-TCA). Methods: Eight Ctx-R were studied in a total of 96 native PBCs: epirubicin (EPI); mitoxantrone (MX); paclitaxel (PCT); docetaxel (DCT); CMF, 4-OH-cyclophosphamide (4-HC) + methotrexate (MTX) + 5-fluorouracil (5-FU); EC, EPI+4-HC; ET, EPI+PCT; NT, MX+PCT. Each Ctx-R was tested at a 1.5 log dose range. Using a semi-quantitative score, individual chemosensitivity score was classified as complete, incomplete, or resistance. Eight head-to-head comparisons were made: CMF versus EC, n = 56; CMF versus PCT, n = 49; CMF versus DCT, n = 34; EC versus PCT, n = 51; EC versus DCT, n = 35; EC versus ET, n = 45; ET versus NT, n = 24; PCT versus DCT, n = 34. For every comparison, the assumed cost reduction if using ATP-TCA directed Ctx was calculated for the tested population regarding the current German prices for both Ctx and supportive drugs and the costs for the ATP-TCA. Results: CMF was at least equal to EC in 47 (84%), to PCT in 37 (76%), and to DCT in 29 PBCs (86%). EC was at least equal to PCT in 41 (80%), to DCT in 28 (80%), and to ET in 28 PBCs (62%). NT was at least equal to ET in 47 PBCs (79%), and PCT was at least equal to DCT in 27 PBCs (80%). The calculated potential cost reduction by ATP-TCA directed Ctx ranged between € 457 (PCT vs. DCT) and € 18.847 (CMF vs. DCT) per treatment. Regarding the whole study population, the potential cost reduction ranged between € 2.550 (PCT vs. DCT) and € 611.819 (CMF vs. DCT). Conclusions: These results are in good agreement to clinical studies showing that novel Ctx-R will benefit only a limited proportion of PBC patients. Systematic analyses using biological methods like the ATP-TCA could help to identify individual patients who are likely to benefit from these Ctx-R whereas the remainder could be equally subjected to less toxic or less costly regimens. Depending on the particular comparison made in this study, the use of the ATP-TCA could lead to a considerable cost reduction in Ctx for PBC. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration L.a.n.c.e. mbH L.a.n.c.e. mbH