Higher Than Expected Incidence of Chronic Myeloid Leukemia in Solid Organ Transplant Recipients.

Abstract 2799 Background: Chronic immunosuppression, a known risk factor for many malignancies, has not been identified as a risk factor for chronic myeloid leukemia (CML). Here we report higher than expected incidence of CML in organ transplant recipients observed at a single institution over a 12 year period. Methods: We report all cases of CML diagnosed in adult solid organ transplant recipients at a single institution from 2000–2011. These organ transplant patients were followed at our institution for their transplant related care, which enabled a detailed review of the cases of CML. The observed incidence of CML cases during the 12 year period was compared to the published national CML incidence in the general adult population by the exact binomial test. Results: As reported to the Organ Procurement and Transplant Network, our institution performed 3,223 adult solid organ transplants from 2000–2011. Four of these organ transplant recipients developed CML at various intervals post-transplant ([Table 1][1]). All patients had CML diagnosed in chronic phase after the evaluation of abnormal leukocytosis and splenomegaly. No additional cytogenetic abnormalities besides Philadelphia chromosome t(9;22) were observed in any of these patients. All patients were treated with imatinib and achieved a complete cytogenetic response (CCyR) within 12 months of therapy. Two patients subsequently achieved complete molecular response, one patient remained in CCyR on imatinib and one patient died from septic shock while in CCyR. Conclusion: The observed 12 year incidence of CML was 4 out of 3223 transplant recipients. This incidence significantly exceeds the reported national incidence of 1.6 cases per 100,000 persons per year (p = 0.004, exact binomial test). We hypothesize that the increase in CML incidence in solid organ transplant recipients results from chronic immunosuppression. We also observed that clinical presentation and response of CML to imatinib therapy in solid organ transplant recipients were similar to non-transplant CML patients. | Patient | Age/gender | Transplant Type | Immunosuppressant | Time from transplant to CML diagnosis (years) | CML phase at diagnosis | Best response to imatinib | Time to Best Response (months) | |:-------:| ---------- | -------------------------------- | --------------------------------------- | --------------------------------------------- | ---------------------- | ------------------------- | ------------------------------ | | 1 | 52/male | Liver | Prednisone and tacrolimus | 4 | Chronic | CMR | 18 | | 2 | 48/female | Kidney and pancreatic islet cell | Prednisone and tacrolimus | 6 | Chronic | CCyR | 6 | | 3 | 50/male | Lung transplant | Prednisone, tacroliums and azathioprine | 1.5 | Chronic | CMR | 18 | | 4 | 59/male | Kidney | Sirolimus | 10 | Chronic | CCyR | 6[*][2] | * Abbreviations: CMR- complete molecular response, CCyR- complete cytogenetic response * [↵][3]* - The patient died from septic shock while in CCyR Table 1 Clinical characteristics of solid organ transplant recipients with CML Disclosures: No relevant conflicts of interest to declare. [1]: #T1 [2]: #fn-2 [3]: #xref-fn-2-1