Background:: Immune checkpoint inhibitors are now an approved treatment for patients with extensive-stage small cell lung cancer (SCLC), an aggressive and incurable malignancy. However, the median survival for patients remains around 1 year, and treatment in the second line and beyond is associated with a low likelihood of response. There currently are no data regarding the optimal treatment of patients who progress on upfront chemo-immunotherapy, and biomarkers are needed to aid patient selection. Obtaining sufficient tissue for advanced molecular testing is a challenge in SCLC due to often limited or crushed tissue specimens. Reliable blood based biomarkers may augment tissue based testing and allow for repeated assessments that is often not possible with tumor tissue, and changes in the peripheral blood may provide information regarding the tumor microenvironment. Myeloid-derived suppressor cells (MDSC) exert immunosuppressive function and have been investigated as a potential barrier to response to immune checkpoint inhibitor (ICI) therapy. Here we demonstrate that MDSC level and function can be readily assessed in the peripheral blood at multiple time points during treatment with combination immunotherapy and temozolomide.
This report represents the first case of a patient with refractory SCLC treated with combination nivolumab and temozolomide as part of a clinical trial (
Conclusion:: An assessment of MDSC level and function during treatment, as well as other immune cell subsets, should be included in prospective studies to further evaluate these assays as possible blood-based biomarkers.
Keywords: Biomarker; Chemotherapy; Immune checkpoint inhibitor; Immunomodulation; Immunotherapy.