A Study of ELA026 in Participants With Relapsed/Refractory (R/R) T/NK Cell Malignancies (TCMs)

Inclusion Criteria: * Age ≥18 years Participants with a confirmed histologic diagnosis of a TCM who are R/R following any line of prior therapy (participants with CTCLs should have received at least 2 prior lines of systemic therapy for R/R CTCL) and eligible for investigational therapies * Presence of measurable disease by clinical examination, radiologic imaging (computed tomography, magnetic resonance imaging, or whole body FDG-PET scans), and/or in bone marrow aspirate/biopsy * Eastern Cooperative Oncology Group performance score of ≤2 * Anticipated life expectancy \>6 months per investigator judgment Exclusion Criteria: * Participants who are eligible for standard of care or approved therapeutic options for R/R TCMs with established clinical benefit * Organ dysfunction as defined in the protocol * Participants with hemophagocytic lymphohistiocytosis (HLH) based on HLH2004 diagnostic criteria * Participants receiving or planning to start immunotherapy or immune effector cell therapy (such as chimeric antigen receptor \[CAR\] T-cell therapy, T-cell engagers, or programmed cell death protein 1 \[PD1\]/programmed cell death ligand 1 \[PD-L1\] inhibitors) * Allogeneic hemopoietic stem cell transplant within 100 days prior to the first dose of ELA026 and currently receiving systemic immunosuppressive therapy * Women of childbearing potential who are planning to become pregnant or are breastfeeding during the conduct of the study, including 60 days after last dose of study drug * Male participants whose partners are women of childbearing potential and who are planning to become pregnant during the conduct of this trial by the male partner, including within 60 days after the last dose of study drug