Paraneoplastic Neurological Syndrome in a Patient with Limited-stage Small-cell Lung Cancer Receiving Durvalumab Maintenance after Concurrent Chemoradiotherapy: A Case Report.

Paraneoplastic neurological syndromes (PNSs) are immune-mediated disorders associated with small-cell lung cancer (SCLC). Durvalumab following concurrent chemoradiotherapy (cCRT) improves outcomes in patients with limited-stage SCLC (LS-SCLC); however, its safety in patients with pre-existing PNS and residual neurological deficits is uncertain. A 63-year-old woman with LS-SCLC and definite PNS (anti-Hu/anti-SOX1-positive subacute cerebellar syndrome, PNS-Care score 10) received cCRT followed by durvalumab maintenance therapy. No neurological worsening or severe immune-related adverse events occurred during approximately one year of durvalumab maintenance therapy, and the tumor response was sustained. Durvalumab maintenance after cCRT may be feasible in carefully selected patients with LS-SCLC and clinically stable pre-existing PNS and residual neurological deficits, under close multidisciplinary monitoring.