Abstract P5-13-08: Association of tumor infiltrating lymphocytes and chemotherapy regimen in response to preoperative chemotherapy in underserved patients
Authors: Komenaka IK , Cocco D , Huliyar R , Hsu C-H , Martinez ME , Gago M , Nodora J , Mehta D , Caruso DM 
Published: May 2019

Introduction

Preoperative chemotherapy can demonstrate an individual's response to the chemotherapeutic regimen by comparing the amount of cancer at presentation to the amount remaining after treatment. Multiple previous studies have demonstrated that the amount of residual cancer, or final pathologic stage, is a better indicator of prognosis than the initial stage at presentation.

Tumor infiltrating lymphocytes have been recognized in breast cancer, and when found concentrated in breast cancer specimens, have been associated with a good prognosis. Breast cancer is not only a heterogeneous disease, but also displays varied presentation and behavior in patients of different race/ethnicities.

This study was performed to evaluate factors which predict response to chemotherapy. The effectiveness of different chemotherapeutic regimens, the effect of breast cancer subtype, and tumor infiltrating lymphocytes (TILs) were evaluated in our racial/ethnic minority population.

Methods

All patients at the safety net institution in Phoenix, AZ who underwent preoperative chemotherapy from 2002 to 2017 and had tissue available for evaluation were included in the study. Response to chemotherapy regimen was recorded. Pathologic complete response (pCR) was defined as no invasive cancer in the breast and lymph nodes in the final pathologic specimen. Breast cancer subtypes were divided based on IHC and FISH testing. Luminal subtypes were classified based on Ki67 (&gt;15%) and/or PR (&lt;20%) for Luminal B. Her2 subtype was defined as Her2 IHC 3+ or Her2 FISH amplified. Triple negative breast cancer (TNBC) was defined as ER and PR (&lt;5%) and Her2 negative. TILs concentration was determined from fixed formalin paraffin embedded (FFPE) core needle biopsy specimens.

Results

A total of 259 patients were included in the study. The mean age was 45 years. 80% of the population were racial/ethnic minorities. The vast majority (94%) were underinsured or uninsured, with 75% uninsured. The mean clinical tumor size at presentation was 6cm. 52% presented at clinical stage 2 while 48% presented at clinical stage 3. The overall pCR rate was 32%. pCR rate was impacted by breast cancer subtype with TNBC 52% and Her2 38% showing a better response to chemotherapy, while Luminal B was 16% and Luminal A 2% (p &lt; 0.05). In TNBC, chemotherapy regimens with anthracycline and docetaxel may have improved efficacy with pCR of 56% (p = 0.05). In the subgroup available for TIL evaluation, breast cancer subtype appeared to show similar importance with pathologic complete response rates of TNBC 50%, Her2 44%, Luminal B 12%, and Luminal A 0%. TIL appeared to affect the likelihood of pCR. When TIL were less than 5% the pCR rate was 16% compared to when there were TIL of at least 5% or more the pCR rate was 41% (p &lt; 0.05).

Conclusions

In our racial/ethnic minority population, breast cancer subtype and chemotherapy regimen did affect likelihood of pathologic complete response. Tumor infiltrating lymphocyte concentration as low as 5% may indicate a higher likelihood of pathologic complete response and could be used as an additional factor in the evaluation of patients for preoperative therapy.

Citation Format: Komenaka IK, Cocco D, Huliyar R, Hsu C-H, Martinez ME, Gago M, Nodora J, Mehta D, Caruso DM. Association of tumor infiltrating lymphocytes and chemotherapy regimen in response to preoperative chemotherapy in underserved patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-13-08.