Using Real-World Data and Biomarkers to Optimize Immunotherapy Use in Oncology Practice

At the San Antonio Breast Cancer Symposium (SABCS) in San Antonio, Justin Balko, PharmD, PhD, discussed how molecular testing and real-world evidence can help refine the use of immunotherapy in breast cancer care and highlighted key roles for pharmacists in clinical oncology settings. He emphasized that incorporating emerging biomarkers into approved assays or laboratory-developed tests could provide clinicians with reliable tools to guide treatment decisions and create meaningful opportunities for pharmacists to ensure appropriate test utilization.

Pharmacy Times: Given the substantial toxicity burden of immune checkpoint inhibitors, how could biomarker-driven patient selection—particularly using tsMHC-II or spatial immune profiling—help pharmacists better assess risk–benefit and counsel patients?

Justin Balko, PharmD, BCOP: So I think that this is a very good point that, ultimately, if we’re able to incorporate these into approved assays or laboratory-developed tests, LDTs, that clinicians can order and rely on those results, these will be excellent recommendations for pharmacists working in clinical oncology settings. Pharmacists can remind patients’ care providers and staff about the availability of these tests and the benefits to clinical decision-making, especially for patients who do move forward with immunotherapy.

I think one of the key areas for pharmacists would be understanding treatment algorithms and the signs and symptoms of severe immune-related adverse events in order to catch them early and provide steroids or other recommended treatment guidelines.

Pharmacy Times: There is no chemotherapy-only comparator arm in this study. What next steps are needed to determine whether these biomarkers truly predict immunotherapy-specific benefit rather than general chemotherapy response?

Balko: One of the challenges with real-world studies such as the one we’ve done is that all patients within our cohort receive both chemotherapy and immunotherapy, because that is the standard of care. One area that we can explore to determine immunotherapy-specific benefit is the use of historical data sets of patients who were treated only with chemotherapy before immunotherapy became the standard of care. However, those analyses are subject to retrospective biases, including differences in how chemotherapy was administered, and they would likely represent a very different patient cohort, which creates challenges.

Ultimately, what we want to use are both of those mechanisms—the data that we’ve generated and historical controls—to identify the best molecular markers. We can then evaluate those markers in existing phase III studies that were randomized and controlled with a chemotherapy-alone cohort, such as NSABP B-59, which was reported last year at San Antonio, or other randomized controlled trials that include chemotherapy alone as well as chemotherapy plus immunotherapy.