Integrated Human and Murine Clinical Study Establishes Clinical Efficacy of Ruxolitinib in Chronic Myelomonocytic Leukemia.

PURPOSE: Chronic myelomonocytic leukemia (CMML) is a rare leukemia characterized by peripheral monocytosis with no disease-modifying therapies. CMML cells are uniquely hypersensitive to granulocyte-macrophage colony-stimulating factor (GM-CSF) and robustly engraft in immunocompromised mice that secrete human cytokines. To leverage these unique biological features, we conducted an integrated human and murine study evaluating ruxolitinib, a JAK1/2 inhibitor that potently downregulates intracellular GM-CSF signaling. PATIENTS AND METHODS: A total of 50 patients with WHO-defined CMML were enrolled in this open-label, multi-institution phase I/II clinical study, with a ruxolitinib dose of 20 mg twice daily studied in phase II. In parallel, 49 patient-derived xenografts (PDX) derived from 13 study participants were generated and randomized to receive ruxolitinib or vehicle control. RESULTS: The most common grade 3/4 treatment-related toxicities observed were anemia (10%) and thrombocytopenia (6%). The clinical overall response rate was 38% by Myelodysplastic Syndrome/Myeloproliferative Neoplasm (MDS/MPN) International Working Group (IWG) criteria and 43% of patients with baseline splenomegaly achieved a spleen response. Profiling of cytokine levels and somatic mutations at baseline failed to identify predictive biomarkers. PDX models derived from screening samples of study participants recapitulated responses seen in humans, particularly spleen responses, and corroborated ruxolitinib's clinical efficacy in a randomized murine study not feasible in human trials. CONCLUSIONS: Ruxolitinib demonstrated clinical efficacy and an acceptable adverse event profile in patients with CMML, identifying a potential novel therapeutic in this rare malignancy. Furthermore, this study demonstrates proof of concept that PDX modeling can recapitulate responses of patients treated on clinical trial and represents a novel correlative study that corroborates clinical efficacy seen in humans.See related commentary by Shastri and Adrianzen-Herrera, p. 6069.

Generalized granuloma annulare as an initial manifestation of chronic myelomonocytic leukemia: a report of 2 cases.

Granuloma annulare is a dermatologic condition of unknown etiology that has been associated with systemic diseases and reported to be a paraneoplastic manifestation. Two patients with generalized granuloma annulare as an initial manifestation of chronic myelomonocytic leukemia are herein described. We suggest that chronic myelomonocytic leukemia should be added to the list of systemic diseases associated with generalized granuloma annulare.

A case of calciphylaxis and chronic myelomonocytic leukemia.

A 70-year-old woman presented for evaluation of symmetric necrotic ulcers of the lower extremities. Biopsy results revealed changes consistent with calciphylaxis. The predisposing factors in this patient included calcium supplementation, obesity, female gender, viscous blood, renal failure, and diabetes mellitus. To our knowledge, this is the first report of calciphylaxis occurring in the setting of chronic myelomonocytic leukemia. We discuss the history, clinical presentation, diagnosis, and treatment of calciphylaxis.