Association of Plasma Nestin With Response to Immune Checkpoint Inhibitors Combined With Chemotherapy in Extensive-stage Small-cell Lung Cancer: A Pilot Study.

Background/aim: Nestin, an intermediate filament protein expressed in stem/progenitor cells of the developing central nervous system, is involved in the progression and poor prognosis of various malignancies. Difficulties in small-cell lung cancer (SCLC) tissue biopsy reduce the accuracy of immunohistochemistry analyses; therefore, evaluating nestin in blood samples is preferred in clinical practice. This study examined the clinical significance of plasma nestin levels in SCLC.

Patients and methods: A single-center observational study of patients with untreated SCLC was conducted from 2019 to 2021. We determined plasma nestin levels before and after two treatment cycles, and the results were analyzed in relation to clinical outcome.

Results: Twenty-five SCLC patients were enrolled. When patients were divided into high-plasma nestin (h-pNES) and low-plasma nestin (l-pNES) groups based on pre-treatment plasma nestin levels, among nine extensive-stage SCLC (ES-SCLC) patients treated with immune checkpoint inhibitor (ICI) combination chemotherapy, h-pNES patients had shorter progression-free survival and overall survival than l-pNES patients (p=0.0150 and p=0.0353, respectively). CD8/FoxP3- and CD8/CD3-positive T-cell ratios in biopsy specimens from h-pNES patients were lower than those of l-pNES patients (p=0.0458 and p=0.0218, respectively).

Conclusion: This pilot study indicated that h-pNES patients exhibited a poorer response to ICI combination chemotherapy than l-pNES patients. Plasma nestin levels are easy to measure in ES-SCLC, in which sufficient tissue is difficult to obtain, and may potentially serve as a predictor of response to ICI combination chemotherapy. A large cohort is needed to investigate the clinical role of plasma nestin.