Refractory Thrombocytopenia in TP53-Aberrant Chronic Lymphocytic Leukemia: A Multimechanistic Case with Response to...

Background/Objectives: Thrombocytopenia in chronic lymphocytic leukemia (CLL) is a heterogeneous and multifactorial complication that often reflects the combined effects of immune dysregulation, impaired megakaryopoiesis, bone marrow microenvironmental disruption, and disease-related factors. In patients with high-risk molecular features, particularly TP53 abnormalities, management becomes increasingly challenging and frequently refractory to conventional therapies. Methods: We report a 57-year-old male with long-standing CLL characterized by a highly aggressive and treatment-refractory course. The patient developed persistent severe thrombocytopenia despite multiple lines of therapy, including corticosteroids, intravenous immunoglobulin, rituximab, splenectomy, and thrombopoietin receptor agonists. Subsequent treatments with ibrutinib and a venetoclax-based regimen failed to improve platelet counts and were discontinued due to worsening cytopenia. Bone marrow evaluation, molecular/cytogenetic analyses, and subsequent treatment responses were thoroughly evaluated. Results: Bone marrow evaluation revealed hypercellularity with significant CLL infiltration, dysplastic megakaryopoiesis, and reticulin fibrosis, indicating impaired platelet production in addition to immune-mediated destruction. Molecular and cytogenetic analyses demonstrated high-risk disease with deletion of 17p and dual TP53 mutations (p.His179Tyr and p.Arg282Trp), consistent with biallelic TP53 disruption. Romiplostim monotherapy did not result in a meaningful hematologic response. However, following the addition of idelalisib, a rapid and sustained increase in platelet counts was observed, allowing tapering of romiplostim and stabilization of hematologic parameters. Conclusions: This case highlights the complex and dynamic pathophysiology of thrombocytopenia in CLL, where immune-mediated destruction and defective thrombopoiesis coexist within a profoundly altered marrow microenvironment. TP53 disruption appears to play a central role not only in driving treatment resistance but also in promoting immune dysregulation and disease aggressiveness. Although a delayed therapeutic effect of romiplostim cannot be entirely excluded, the distinct temporal association following idelalisib initiation suggests a potential collaborative interaction or disease-directed clearance that may facilitate platelet recovery in this setting. Refractory thrombocytopenia in CLL should be approached as a manifestation of complex disease biology rather than an isolated complication. This single observation indicates that in TP53 aberrant cases with multi-mechanism thrombocytopenia, disease-directed targeted therapy may contribute significantly to platelet recovery.