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Dr. Bunn on TMB as a Biomarker in Small Cell Lung Cancer

Paul A. Bunn Jr, MD
Published: Wednesday, Aug 15, 2018



Paul A. Bunn Jr, MD, distinguished professor, Division of Medical Oncology, James Dudley Chair in Lung Cancer Research, University of Colorado Denver, 2014 Giant of Cancer Care® in Lung Cancer, discusses tumor mutational burden (TMB) as a biomarker in small cell lung cancer (SCLC).

Patients with SCLC typically have low PD-L1 expression, so using that as a biomarker won’t be very effective. Since SCLC is a diagnosis specific to smokers, these patients usually have high TMB. There is some evidence that TMB is a good biomarker, particularly with the addition of CTLA-4 inhibitors.

Bunn mentions a study of single-agent pembrolizumab (Keytruda), which demonstrated a 30% response rate in patients. The impressive thing about the responses was the durability—patients lived up to 2 years on pembrolizumab, which is much longer than chemotherapy.


Paul A. Bunn Jr, MD, distinguished professor, Division of Medical Oncology, James Dudley Chair in Lung Cancer Research, University of Colorado Denver, 2014 Giant of Cancer Care® in Lung Cancer, discusses tumor mutational burden (TMB) as a biomarker in small cell lung cancer (SCLC).

Patients with SCLC typically have low PD-L1 expression, so using that as a biomarker won’t be very effective. Since SCLC is a diagnosis specific to smokers, these patients usually have high TMB. There is some evidence that TMB is a good biomarker, particularly with the addition of CTLA-4 inhibitors.

Bunn mentions a study of single-agent pembrolizumab (Keytruda), which demonstrated a 30% response rate in patients. The impressive thing about the responses was the durability—patients lived up to 2 years on pembrolizumab, which is much longer than chemotherapy.

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