Dr. Blum on Potential of CA-125 as a Biomarker for Renal Medullary Carcinoma

Kyle A. Blum, MD, MS, is a urologic surgery resident at The University of Kyle A. Blum, MD, MS, a urologic surgery resident at The University of Texas MD Anderson Cancer Center. Blum and his colleagues have discovered a correlation between CA-125 levels, an established biomarker for ovarian cancer, increased tumor burden, and treatment response in patients with renal medullary carcinoma (RMC).

Blum presented findings at the 2022 International Kidney Cancer Symposium from an analysis of CA-125 levels and other serum tumor biomarkers in 32 patients with RMC to see if these markers could be used to monitor disease severity. Only CA-125 and lactate dehydrogenase (LDH) appeared to be elevated in metastatic RMC. Blum notes that LDH tends to be elevated across a broad range of cancers and is considered a nonspecific marker of disease severity.

Blum and his research team cast a wide net, evaluating a range of serum biomarkers known to be related to tumor malignancy in order to elucidate any marker that may yield a high fidelity to treatment response. The signal for CA-125 was very strong, he says, even in a small patient population.

CA-125 appeared to be more sensitive to fluctuations in a patient’s treatment clinical course than LDH. In one representative patient, CA-125 levels dipped with remission or disease convalescence and spiked during adverse events. Furthermore, the patient’s CA-125 level increased shortly before the patient died of their disease.

CA-125 levels were elevated in 82% of patients with metastatic RMC, and CA-125 was above the 100 ng/mL threshold in 58% of patients. This threshold of 100 ng/mL is important, as physicians and researchers treating patients with ovarian cancer have published that a threshold of that level can be suggested as a therapeutic target.

Investigators observed positive clinical correlations between CA-125 levels above the 100 ng/mL threshold and therapies and convalescence in RMC for this biomarker. He says it is exciting to postulate that perhaps this cutoff may be usable in RMC as well. Blum suspects that these results will prompt a several other preclinical studies to further explore the value of CA-125 as a biomarker and potential therapeutic target.