A phase II trial of ipilimumab, nivolumab, or ipilimumab and nivolumab with or without azacitidine in relapsed or refractory myelodysplastic neoplasms

Patients with myelodysplastic neoplasms (MDS) who progress on hypomethylating agents have poor outcomes [1,2,3]. There are no standard treatment approaches in this setting; while high-dose chemotherapy followed by allogeneic stem cell transplant remains a curative option for higher-risk MDS, advanced age and significant comorbidities preclude this approach for many patients [4]. In these cases, novel therapies are urgently needed.

Programmed cell death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA4) are upregulated in hypomethylating agent failure MDS [5]. PD-L1 on the surface of MDS cells binds to PD-1 on T cells, facilitating immune evasion [6]. Similarly, CTLA4 on T cells binds to B7 on MDS cells, stifling T-cell receptor activation and contributing to immune escape [7]. These findings provide a rationale for assessing PD-1 and CTLA4 blockade in MDS following hypomethylating agent exposure [7]. Ipilimumab and nivolumab are fully human IgG1k monoclonal antibodies that target CTLA4 and PD-1, respectively [8, 9]. Both monotherapy and combination immunotherapy approaches are safe and effective in solid tumors and lymphomas; however, their safety and efficacy in relapsed or refractory MDS remains unclear.