A retrospective analysis of first-line PD-1 monoclonal antibodies treatment in patients with leptomeningeal metastasis from solid tumors

Introduction Patients whose solid tumors (ST) show leptomeningeal metastasis (LM) have very poor prognosis and short overall survival. The aim of this study was to evaluate the efficacy of first-line programed death-1(PD-1) monoclonal antibody (mAb) treatment in these patients. Methods We retrospectively evaluated patients diagnosed with LM from ST who were treated with first-line PD-1 mAb at our hospital between April 1 and November 30, 2019. We analyzed their clinicopathological characteristics and response to the treatment. Results We collected and analyzed data from 6 patients with different primary ST. 5 patients received PD-1 mAb combined with chemotherapy and/or anti-angiogenic drugs, while one received only PD-1 mAb. The median (range) number of treatment cycles was 5.5 (1-21). PD-1 mAb treatment did not cause neurotoxicity. The time period of first assessment varied from 21 to 65 days after treatment. Among 5 patients who got obvious symptoms relief, 4 patients persisted for > 3 months and even showed a reduction in the number of tumor cells in cerebrosprinal fluid. Ventriculoperitoneal (VP) shunt was used to treat hydrocephalus observed beneficial in 3 patients: 2 before and 1 after PD-1 mAb treatment. The median (range) follow-up time was 214 (57-460) days. 4 patients died. The overall survival ranged from 57 days to at least 460 days. 1 of the two alive patients continued to show no worsening of symptoms after 457 days. Conclusions Patients with LM from ST can benefit from first-line PD-1 mAb combined treatment without additional neurotoxicity. Further research is required to validate the safety and efficacy.