Many advances have been made in therapies for patients having breast cancer driven by the estrogen receptor, the progesterone receptor, or the human epidermal growth factor 2 receptor (HER2). However, for patients with breast cancer not driven by any of these mechanisms, the disease, termed triple-negative, is characterized by an aggressive clinical course with poor patient outcomes.
In a recent poster presented at the AACR Annual Meeting 2023, Saurabh K. Garg, PhD, a research scientist in the Czerniecki Lab at Moffitt Cancer Center, presented data from a retrospective study of triple-negative breast cancer patients who had undergone surgery at the Moffitt Cancer Center between January 2010 and February 2019 (Abstract 962).
"Our team at the Czerniecki Lab and Moffitt Breast Clinic utilizes the power of dendritic cells, the primary antigen-presenting cells of the body, to present major histocompatibility complex Class II antigens from tumor-associated oncodrivers to prime the immune response against breast cancer," Garg noted. "In our clinical trials, we are seeing a robust targeted response with dendritic cell-based therapies in HER2-positive breast cancer. This prompted us to identify immunogenic oncodrivers to develop targeted immunotherapies for triple-negative breast cancer, which accounts for 15-20 percent of breast cancer cases and presents as a more aggressive disease, with poor outcomes from current standard-of-care treatment options."
Regarding their study, Garg noted, "This is an institutional review board-approved, single institution retrospective study of 90 patients with triple-negative breast cancer who have undergone standard of care at Moffitt Cancer Center between January 2010 and February 2019.
"Surgical biopsy tissue blocks of various stages, along with patient outcome data, were available to perform this downstream analysis," he stated.
"We utilized multiplex tissue microarray analyses, where multiple tissue core biopsies are arranged on a single slide for this immunofluorescence assay," Garg explained. The tissue microarray analyses were divided into two panels: one for the oncodrivers and the other for tumor-infiltrating lymphocytes.
In the first panel, "the expression of three oncodrivers: MET (MET proto-oncogene, receptor tyrosine kinase), EGFR (epidermal growth factor receptor), and HER3 (erb-b2 receptor tyrosine kinase 3) on surgical tissue blocks was scored by tumor microarray analysis," Garg explained.
"We also performed a second tissue microarray analysis to examine tumor-infiltrating lymphocytes expressing CD4, CD8, CD20, CD45, and CD56," Garg noted about the second panel. "Subsequently, we correlated the expression of oncodrivers with patient outcome data and lymphocyte infiltration to catalog the immunogenicity of MET, EGFR, and HER-3 expression in triple-negative breast cancer settings."
Research Results
When queried as to their findings, Dr. Garg answered, "The main finding of this study is that high expression of MET, EGFR, and HER3 correlated with higher occurrence of CD4, CD8, and CD45, respectively. This provided us invaluable information, indicating that these tumor-driving proteins have immunogenic potential to recruit lymphocytes to the tumor site, which could be harnessed to design targeted immunotherapies."
In addition, the elevated expression of HER3 was observed in the samples obtained from chemotherapy-treated patients, possibly implying a role in disease resistance. Interestingly, there was no correlation of prognoses with increased expression levels of the oncodrivers explored in this study. Another relevant observation was that better survival was observed in patients who had intermediate expression levels for EGFR with higher numbers of activated tumor-infiltrating lymphocytes.
Future Directions
"The present study provided a perfect segue for future targeted therapies that will be further developed and utilized in the clinic for triple-negative breast cancer patients," Garg noted. "The identification of these immunogenic oncodrivers for triple-negative breast cancer will assist researchers at Moffitt and all over the world to target them with innovative therapies.
"The next step in this study will be to identify the immunogenic regions of MET and EGFR proteins using our in-house peptide screening pipeline," he stated. "This pipeline utilizes pre-clinical investigative tools to screen immunogenic major histocompatibility complex class II peptides to design dendritic cell-based cancer immunotherapies. Once identified and produced, we will test the efficacy of these treatments utilizing murine models of triple-negative breast cancer.
"Furthermore, we have already performed peptide screening for the HER3 protein and have validated it in murine models of triple-negative breast cancer," Garg said. "This HER3-based dendritic cell immunotherapy has been translated to a clinical trial, which is now underway at Moffitt for triple-negative breast cancer patients. Overall, successful completion of the pre-clinical translational research on all three triple-negative breast cancer oncodrivers will open the door for them to be incorporated in future dendritic cell immunotherapy clinical trials at the Moffitt Cancer Center with the potential of making significant improvements to the current triple-negative breast cancer standard of care and patient outcomes."
Richard Simoneaux is a contributing writer.