Programmed cell death-1 inhibitor combination treatment for recurrent proficient mismatch repair/ miscrosatellite-stable type endometrial cancer: A case report

BACKGROUND: Endometrial cancer (EC) is one of the most common cancers of the female reproductive tract, and the incidence is increasing rapidly. Immunotherapy using programmed cell death-1 (PD-1) inhibitors is an emerging research topic and treatment strategy for refractory gynecological malignancies. However, clinical management of EC with checkpoint inhibitors requires improvement. Herein, we discuss a case of refractory proficient mismatch repair (pMMR)/miscrosatellite-stable (MSS) EC treated with a combination of PD-1 and angiogenesis inhibitors and offer a review of the pathophysiology and clinical outcomes based on previous studies. CASE SUMMARY: A 62-year-old woman diagnosed with invasive or metastatic EC in 2015 was treated with six courses of chemotherapy and refused further radiotherapy. Four years later, she developed chest pain, and lung biopsy indicated thyroid transcription factor-1 (-), Napsin A (-), estrogen receptor (+), progesterone receptor (+), anaplastic lymphoma kinase (D5F3) (-), and receptor tyrosine kinase (D4D6) (-) metastatic EC. Genetic testing results showed low tumor mutation burden, pMMR, PD ligand 1 (-), MSS, and HLA-class 1 heterogeneous disease. The patient was started on toripalimab combined with nab-paclitaxel for seven cycles (every 3 wk), but this regimen was terminated because of an intolerable chemotherapy adverse event. The disease progressed in 2020, and the patient’s treatment was switched from nab-paclitaxel to anlotinib, while immunotherapy using toripalimab was continued. The patient achieved a major partial response with well-tolerated toxicities, and treatment is ongoing. CONCLUSION: Molecular testing is advised for clinical classifications of EC owing to its high heterogeneity. In this case, the patient had pMMR/MSS EC and achieved a positive outcome with combination PD-1 inhibitor treatment. These results warrant further clinical exploration.