Chemosensitivity (CS) of patient (pt) breast cancer (BrCa) cells in vitro: Correlation with prior chemotherapy (CT) and implications for personalized treatment planning
Authors: Whitworth P. W. , Presant C. A. , Rutledge J. , Hallquist A. , Perree M. , Agapitos D. 
Published: August 2020

e11563^ Background: A predictive BrCa chemosensitivity assay will facilitate individualized treatment. Unlike older assays, the Microculture Kinetic (MiCK) assay measures active apoptosis. In order to determine the in vitro CS of pt BrCa cells, we tested pt tumor cells (tc) in vitro using the MiCK assay. Methods: Tumor excisions or biopsies were sent to a central laboratory, prepared using our previously described MiCK technology (Lab Invest 74: 557, 1996) and tc apoptosis was measured over 48 hours with various drugs. In vitro results were compared to clinical status. CS was measured in kinetic units of apoptosis (KU) with inactive <1.0, low CS 1.0–2.59, moderate CS 2.6–4.2, and high CS >4.2. Physicians (MDs) decided on CT without knowledge of MiCK results. Results: 57 pts were evaluable for MiCK results. CS to drugs for tc from pts with no prior CT was: paclitaxel (P) mean 1.2 KU, cyclophosphamide as 4-hydroxycyclophosphamide (4HC) 2.7, doxorubicin (Dox) 1.8, epirubicin (Epi) 2.1, docetaxel (Doc) 2.0, vinorelbine 0.9, gemcitabine (Gem) 0.7, liposomal D 1.4, carboplatin (Carbo) 1.7, cisplatin (Cis) 2.0, and topotecan 1.2. Combinations tested in some pts showed Carbo-P 2.6 KU and Cis-Gem 2.7. These results were compared to CS of tc from pts with prior CT. CS for pts with prior CT were P 1.8 KU, Doc 1.7, Dox 1.9, Epi 2.9, 4HC 1.1, and Vin 1.2. Although there was no difference between the CS of BrCa cells with or without prior CT for Dox or Epi, CS for 4HC was statistically significantly reduced after prior CT (p<0.0003). Overall, Doc had higher CS than P (p<0.004), Epi higher than Dox (p<0.0001), and 4HC higher than P (p<0.0001) or Carbo (p=0.03). However, in individual pts, P was higher or equal to Doc in 5/18 (28%), Dox higher or equal to Epi in 9/36 (25%), and P higher or equal to 4HC in 5/32 (16%). Conclusions: This indicates that the MiCK assay may be used to evaluate CS of BrCa cells from individual pts. After prior CT, BrCa cells show altered CS profiles, with persistent CS to Dox or Epi but reduced CS to 4HC. These data may be useful to MDs in selecting CT for individual pts. MiCK may also be useful in developing new drugs and new combination therapies. ASCO Conflict of Interest Policy and Exceptions In compliance with the guidelines established by the ASCO Conflict of Interest Policy (J Clin Oncol. 2006 Jan 20;24[3]:519–521) and the Accreditation Council for Continuing Medical Education (ACCME), ASCO strives to promote balance, independence, objectivity, and scientific rigor through disclosure of financial and other interests, and identification and management of potential conflicts. According to the ASCO Conflict of Interest Policy, the following financial and other relationships must be disclosed: employment or leadership position, consultant or advisory role, stock ownership, honoraria, research funding, expert testimony, and other remuneration (J Clin Oncol. 2006 Jan 20;24[3]:520). The ASCO Conflict of Interest Policy disclosure requirements apply to all authors who submit abstracts to the Annual Meeting. For clinical trials that began accrual on or after April 29, 2004, ASCO's Policy places some restrictions on the financial relationships of principal investigators (J Clin Oncol. 2006 Jan 20;24[3]:521). If a principal investigator holds any restricted relationships, his or her abstract will be ineligible for placement in the 2009 Annual Meeting unless the ASCO Ethics Committee grants an exception. Among the circumstances that might justify an exception are that the principal investigator (1) is a widely acknowledged expert in a particular therapeutic area; (2) is the inventor of a unique technology or treatment being evaluated in the clinical trial; or (3) is involved in international clinical oncology research and has acted consistently with recognized international standards of ethics in the conduct of clinical research. NIH-sponsored trials are exempt from the Policy restrictions. Abstracts for which authors requested and have been granted an exception in accordance with ASCO's Policy are designated with a caret symbol (^) in the Annual Meeting Proceedings. For more information about the ASCO Conflict of Interest Policy and the exceptions process, please visit www.asco.org/conflictofinterest .