Dr Nawfal on the Rationale for Assessing Radiological Tumor Burden in mccRCC

Rashad Nawfal, MD, postdoctoral research fellow at Dana-Farber Cancer Institute, discusses the rationale for assessing the independent prognostic value of radiological tumor burden for survival outcomes with first-line immuno-oncology (IO)-based regimens in metastatic clear cell renal cell carcinoma (ccRCC), as well as the potential utility of radiological tumor burden for guiding first-line immunotherapy selection for patients with this disease.

RECIST 1.1 is a widely used method to calculate tumor burden in clinical trials by assessing up to 5 measurable lesions, with a maximum of 2 lesions per organ, Nawfal begins. However, this approach does not provide a comprehensive reflection of the total tumor burden in the body, he says. Limited data have indicated a potential link between radiological tumor burden and survival outcomes in patients treated with VEGF TKIs, Nawfal reports. However, there has been a lack of data on the relationship between radiologic tumor burden for outcomes with first-line immuno-oncology (IO) regimens, he notes. To address this gap, Nawfal and colleagues conducted a study evaluating the prognostic significance of radiological tumor burden, as calculated by RECIST 1.1 criteria, in patients with metastatic ccRCC treated with first-line IO-based therapies.

Results from this investigation were presented at the 2024 Kidney Cancer Research Summit. At a median follow-up period of 44.8 months, the study showed that baseline radiological tumor burden was an independent prognostic factor for overall survival (OS) in this patient population. Specifically, each 1 cm increase in baseline radiological tumor burden was associated with a 5% increase in OS events (hazard ratio [HR], 1.05; 95% confidence interval [CI], 1.03-1.08; P < .0001). This prognostic value persisted even after adjusting for multiple variables, including previous nephrectomy, IMDC risk group, and the presence of metastases in the brain, bone, or liver prior to initiating frontline therapy (HR, 1.04; 95% CI, 1.00-1.08; P = .03).

Given its simplicity and prognostic relevance, baseline radiological tumor burden could become an important factor in initial assessments before starting first-line therapy for metastatic ccRCC, Nawfal states. The next steps involve validating these findings across different clinical trial cohorts and assessing inter-radiologist variability in tumor burden calculations, he details. If these efforts confirm its prognostic utility and reproducibility, radiological tumor burden could be routinely included in the evaluation of patients before beginning IO-based regimens, potentially guiding treatment decisions and improving patient outcomes, Nawfal concludes.