Immune Checkpoint Inhibitors in Relapsed/Refractory Anaplastic Large Cell Lymphoma (ALCL): A Case Report and Review of the Literature.

BACKGROUND: While immune checkpoint inhibitors (ICI) have transformed the landscape of clinical oncology, their application in rare malignancies such as anaplastic large cell lymphoma (ALCL) remains limited. CASE: We report a patient with relapsed/refractory (r/r) ALCL treated at the University Hospital Krems who achieved sustained complete remission under PD-1 blockade after multiple prior lines of therapy. In addition, we performed a literature review and identified three previously published cases. Across the four reported patients, all achieved complete remission and remained progression-free throughout their respective observation periods, ranging from 4 to 33 months. Where patient-level safety data were available, reported adverse events were manageable and consistent with known immune-related toxicities. CONCLUSION: Although based on very limited data, these observations suggest potential clinical activity of PD-1/PD-L1 inhibition in r/r ALCL. They also underscore the urgent need for prospective studies to validate efficacy and safety in larger cohorts. Future research should incorporate biomarker analyses to refine patient selection and explore rational treatment combinations, such as ICI with Brentuximab Vedotin, in order to broaden therapeutic opportunities for this challenging disease.