Chromothripsis orchestrates leukemic transformation in blast phase MPN through targetable amplification of DYRK1A

Chromothripsis, the process of catastrophic shattering and haphazard repair of chromosomes, is a common event in cancer. Whether chromothripsis might constitute an actionable molecular event amenable to therapeutic targeting remains an open question. We describe recurrent chromothripsis of chromosome 21 in a subset of patients in blast phase of a myeloproliferative neoplasm (BP-MPN), which alongside other structural variants leads to amplification of a region of chromosome 21 in ∼25% of patients ('chr21amp'). We report that chr21amp BP-MPN has a particularly aggressive and treatment-resistant phenotype. The chr21amp event is highly clonal and present throughout the hematopoietic hierarchy. DYRK1A , a serine threonine kinase and transcription factor, is the only gene in the 2.7Mb minimally amplified region which showed both increased expression and chromatin accessibility compared to non-chr21amp BP-MPN controls. We demonstrate that DYRK1A is a central node at the nexus of multiple cellular functions critical for BP-MPN development, including DNA repair, STAT signalling and BCL2 overexpression. DYRK1A is essential for BP-MPN cell proliferation in vitro and in vivo , and DYRK1A inhibition synergises with BCL2 targeting to induce BP-MPN cell apoptosis. Collectively, these findings define the chr21amp event as a prognostic biomarker in BP-MPN and link chromothripsis to a druggable target.

The effects of monoclonal anti-CD47 on RBCs, compatibility testing, and transfusion requirements in refractory acute myeloid leukemia

BACKGROUND

CD47 is a novel therapeutic target in the treatment of solid-organ and hematologic malignancies. CD47 is also expressed on RBCs. Here, we report our experience of the RBC effects and the impact on blood bank testing and transfusion management in a Phase 1 trial of the humanized anti-CD47 monoclonal antibody Hu5F9-G4 in relapsed or primary refractory acute myeloid leukemia (AML) (NCT02678338).

STUDY DESIGN AND METHODS

Nineteen patients with relapsed or primary refractory AML treated across five UK centers were included for analysis. Patients received escalating doses of Hu5F9-G4. Serial laboratory data were collected to evaluate impact on hemoglobin (Hb), markers of hemolysis (bilirubin, lactate dehydrogenase, reticulocyte count), transfusion requirements, and blood compatibility testing.

RESULTS

A decline in Hb was observed with drug administration (median Hb change, -1.0 g/dL; range, 0.4-1.6) with associated increase in transfusion requirements. Patients responded to transfusion with a median Hb increment per unit of 1.0 g/dL. RBC agglutination was seen in all cases without associated change in Hb, lactate dehydrogenase, bilirubin, or reticulocyte count. Nine of 19 (47%) patients developed a newly positive antibody screen with a pan-agglutinin identified in plasma. Invalid ABO blood grouping occurred in 4 of 12 (33%) non-group O patients due to anomalous reactivity in the reverse ABO-type results.

CONCLUSIONS

Treatment with Hu5F9-G4 in patients with AML resulted in an Hb decline and increased transfusion requirements. Problems with ABO blood typing and compatibility testing were widely observed and should be expected by centers treating recipients of Hu5F9-G4.

Impact of ABO blood group mismatch in alemtuzumab-based reduced-intensity conditioned haematopoietic SCT

The impact of ABO incompatibility on clinical outcomes following haematopoietic SCT (HSCT) remains controversial. This retrospective study assessed the effect of ABO mismatch on transplant outcomes and transfusion requirements in 594 patients undergoing reduced-intensity conditioned (RIC) HSCT with alemtuzumab in three UK transplant centres. We found no significant effects of minor, major or bidirectional ABO mismatch on overall survival, relapse-free survival, nonrelapse mortality or relapse incidence. Although the rate of acute GVHD was unaffected by ABO mismatch, the incidence of extensive chronic GVHD was higher in patients with minor and major mismatch compared with those who were ABO matched (hazard ratio (HR) 1.74, P=0.032 for minor, HR 1.69 P=0.0036 for major mismatch). Red cell and platelet transfusion requirements in the first 100 days post transplant did not differ by ABO mismatch. In this large UK series, ABO mismatch in RIC HSCT has no clinically significant effect on survival outcomes but appears to modify susceptibility to extensive chronic GVHD.