Allogeneic Hematopoietic Cell Transplantation for Older Patients: Prognosis Determined by Disease Risk Index

Clonal Hematopoiesis of Indeterminate Potential as a Novel Risk Factor for Donor-Derived Leukemia

Hematopoietic stem cell transplantation (HSCT) is a critical treatment modality for many hematological and non-hematological diseases that is being extended to treat older individuals. However, recent studies show that clonal hematopoiesis of indeterminate potential (CHIP), a common, asymptomatic condition characterized by the expansion of age-acquired somatic mutations in blood cell lineages, may be a risk factor for the development of donor-derived leukemia (DDL), unexplained cytopenias, and chronic graft-versus-host disease. CHIP may contribute to the pathogenesis of these significant transplant complications via various cell-autonomous and non-cell-autonomous mechanisms, and the clinical presentation of DDL may be broader than anticipated. A more comprehensive understanding of the contributions of CHIP to DDL may have important implications for the screening of donors and will improve the safety of HSCT. The objective of this review is to discuss studies linking DDL and CHIP and to explore potential mechanisms by which CHIP may contribute to DDL.

How old is too old for a transplant?

Allogeneic transplantation remains the most definitive curative option for patients with acute myeloid leukemia (AML). However, given the median age of diagnosis of AML in the late 60s, patients and clinicians have been reluctant to offer transplant to many in the older population. In this age group, AML presents with higher risk molecular and cytogenetic phenotype and patients' comorbidities, performance status, frailty and life views all impact the decision-making about whether to proceed with transplantation. Recent analyses suggest promising outcomes and thus acknowledgement of chronological age should be tempered with assessments of performance status, frailty, donor availability and careful balancing of a patient's wishes, life goals and understanding of the risks before restricting access of older patients to the curative potential of allotransplantation.

Feasibility of an intensified myeloablative conditioning regimen consisting of busulfan, fludarabine, cytarabine, and total body irradiation before single cord blood transplantation in elderly patients

The optimal conditioning regimen for stem cell transplantation in elderly patients remains to be established. We developed a novel preparative regimen using fludarabine 180 mg/m², intravenous busulfan 12.8 mg/m², cytarabine 8 g/m², and 4-Gy total body irradiation before cord blood transplantation (CBT) in patients older than 55 years with various hematological malignancies. All but one patient received graft-versus-host disease (GVHD) prophylaxis consisting of cyclosporine (CsA) and short-term methotrexate (sMTX). Thirty-three patients were included in this study, with a median age of 64 years (range 56-70). The disease risk index was high or very high in 67% of patients, and 73% had a disease status other than complete remission. The probabilities of overall survival and disease-free survival at 3 years were 60 and 57%, respectively. The cumulative incidences of relapse and non-relapse mortality at 3 years were 18 and 25%, respectively. Regimen-related toxicities were generally tolerable. Disease-free survivors (n = 20) stopped immunosuppressants at a median of 7.4 months (range 2.6-25.0), in all cases by the time of the last follow-up. In conclusion, this highly myeloablative conditioning regimen resulted in a high probability of disease-free, GVHD-free, immunosuppressant-free survival after single CBT.(190 words).

A real-world study of clofarabine and cytarabine combination therapy for patients with acute myeloid leukemia

Clofarabine and cytarabine (Clo + Ara-C) combinations have efficacy in treatment of acute myeloid leukemia (AML). We retrospectively analyzed clinical outcomes of 71 AML patients receiving Clo + Ara-C regimens at the University of Minnesota from 2011 to 2016: 44 patients (62%) had newly diagnosed AML and 27 patients (38%) had relapsed/refractory AML. The median age of patients was 69 years (interquartile range [IQR], 63-75 years). Nearly 60% of the patients had secondary AML, and about half of patients had adverse risk cytogenetics. Objective response rate (ORR) was 42% in all patients with complete remission (CR) rate of 20%. Progression-free survival (PFS) at 2 years was 16% (95% CI 8-27%) and overall survival (OS) at 2 years was 21% (95% CI 11-33%) for all patients. The 30-day mortality rate was 18%. Clo + Ara-C- containing regimens are an acceptable upfront therapy option for patients who are not candidates for "7 + 3" induction, but do not induce durable remissions.