Dr Deek on the Investigation of Immune Cell Infiltration in MIBC

Matthew Pierre Deek, MD, radiation oncologist, assistant professor, Division of Clinical Radiation Oncology, Department of Radiation Oncology, Rutgers Robert Wood Johnson Medical School, discusses the significance of pretreatment immune cell infiltration in patients with muscle-invasive bladder cancer (MIBC) who had been treated with definitive chemoradiation.

A retrospective study aimed to evaluate the influence of the tumor immune microenvironment on the outcomes of patients undergoing chemotherapy or radiation therapy for MIBC, Deek begins. To achieve this, investigators retrospectively collected specimens from 2 NRG prospective studies (NRG/RTOG 0712; RTOG 0524) that had been stored in a biobank, he states. Investigators then conducted RNA sequencing on these samples using a novel proprietary method for deconvoluting bulk tumor RNA from tumor samples, Deek emphasizes. Subsequently, investigators performed bioinformatics analyses to assess the immune cell infiltration within the tumor microenvironment of patients who were enrolled in these 2 trials and treated with chemoradiation, he explains.

The investigators’ secondary goal was to comprehend the gene expression patterns that indicated a hot tumor, or a tumor that is predisposed to an active immune response against the cancer, Deek expands. Several noteworthy observations emerged from the analysis. Firstly, when examining the patient population as a whole, a significant variation of immune cell infiltration within the tumor microenvironment was observed, ranging from low levels to high levels of infiltrates, Deek says.

Investigators focused on patients with higher levels of immune cell infiltration, specifically CD8-positive T cells. These patients exhibited significantly better prognoses following chemoradiation than those with lower levels of immune cell infiltration, including improved responses to treatment and enhanced disease control, he continues. Additionally, investigatorsfound that gene expressions associated with a hot tumor, such as interferon gamma, which is indicative of immunological activity, also correlated with improved outcomes after chemoradiation, Deek explains. These findings underscore the significance of immune infiltrates and indicators of immune activation as valuable prognostic factors for predicting a patient's response to chemoradiation therapy for MIBC, he concludes.