The rationale behind grafting haploidentical hematopoietic stem cells.

The ability to perform hematopoietic cell transplant across major histocompatibility complex barriers can dramatically increase the availability of donors and allow more patients across the world to pursue curative transplant procedures for underlying hematologic disorders. Early attempts at haploidentical transplantation using broadly reactive T-cell depletion approaches were compromised by graft rejection, graft-versus-host disease and prolonged immune deficiency. The evolution of haploidentical transplantation focused on expanding transplanted hematopoietic progenitors as well as using less broadly reactive T-cell depletion. Significant outcome improvements were identified with technology advances allowing selective depletion of donor allospecific T cells, initially ex-vivo with evolution to its current in-vivo approach with the infusion of the highly immunosuppressive chemotherapy agent, cyclophosphamide after transplantation procedure. Current approaches are facile and portable, allowing expansion of allogeneic hematopoietic cell transplantation for patients across the world, including previously underserved populations.

Use of tamibarotene, a potent and selective RARα agonist, in combination with azacitidine in patients with relapsed and refractory AML with RARA gene overexpression.

Tamibarotene-based therapy is a novel targeted approach for the treatment of relapsed/refractory (R/R) acute myeloid leukemia (AML) with retinoic acid receptor alpha (RARA) gene overexpression. Approximately, 50% of higher-risk myelodysplastic syndrome (MDS) patients and approximately 30% of AML patients are positive for RARA overexpression using a blood-based biomarker test that measures RARA expression in peripheral blasts. A phase 2 study investigating the activity of tamibarotene in patients with RARA overexpression was conducted in patients with AML and MDS (NCT02807558). In 28 patients with R/R AML and RARA overexpression treated with tamibarotene in combination with azacitidine, the median overall survival was 5.9 months. In 21 response-evaluable patients, the complete remission/complete remission with incomplete hematologic recovery (CR/CRi) rate was 19%, and median time to initial CR/CRi was 1.2 months. The favorable safety profile and preliminary clinical activity support the development of combination therapies with tamibarotene in myeloid malignancies with RARA overexpression.

Day 4 collection of granulocyte colony-stimulating factor-mobilized HLA-matched sibling donor peripheral blood allografts demonstrates no long-term increase in chronic graft-versus-host disease or relapse rates.

BACKGROUND AIMS: In a previous pilot study of HLA-matched sibling donor hematopoietic cell transplantation (HCT), the authors determined the feasibility of day 4 versus day 5 granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood stem cell (PBSC) collection compared with a historical cohort. Given identified differences in the PBSC product (day 4 cohort with significantly lower infused total nucleated, mononuclear and CD3 cells compared with other collection cohorts), the authors performed a follow-up study to determine long-term post-HCT outcomes, including detailed characterization of chronic graft-versus-host disease (GVHD). METHODS: This was a prospective observational study, and the authors collected data on chronic GVHD, staging, sites of involvement and treatments. Performance status, incidence of relapse, overall survival and duration of immunosuppressive therapy (IST) were also evaluated. Data were examined retrospectively. To account for differences in length of follow-up among cohorts, the authors also determined performance status and chronic GVHD staging, sites and treatment at 2 years post-HCT. RESULTS: At 2 years post-HCT, the overall survival rate was 71.7% in the day 4 cohort compared with 61.5%, 52% and 56% in the day 5, 2-day and historical cohorts, respectively (P = 0.283). The cumulative incidence of chronic GVHD was 65.2% in the day 4 cohort versus 46.4% in the day 5 cohort, 51.1% in the 2-day cohort and 65% in the historical cohort (P = 0.26). There was no significant difference in the maximum overall stage of chronic GVHD (P = 0.513), median number of sites involved (P = 0.401) or cumulative incidence of discontinuation of IST (P = 0.32). Death from chronic GVHD was less common in the day 4 and day 5 cohorts compared with the 2-day and historical cohorts, though this did not reach statistical significance. CONCLUSIONS: The authors' preliminary results demonstrated that collection of allogeneic matched sibling donor PBSCs on day 4 of G-CSF was feasible, reduced donor exposure to growth factor and was associated with an initial cost savings. Importantly, the authors now demonstrate that transplantation of day 4 mobilized PBSCs is not associated with any adverse outcomes post-HCT, including late effects such as chronic GVHD. Further investigation of donor G-CSF collection algorithms is merited in other HCT settings, including unrelated and mismatched related donors.

Targeting RARA overexpression with tamibarotene, a potent and selective RARα agonist, is a novel approach in AML.

A superenhancer at the retinoic acid receptor alpha (RARA) gene is associated with RARA mRNA overexpression in ∼30% of non-acute promyelocytic leukemia acute myeloid leukemia (AML) and in ∼50% of myelodysplastic syndromes (MDS). RARA overexpression is an actionable target for treatment with tamibarotene, an oral potent and selective RARα agonist. Sensitivity to the RARα agonist tamibarotene was demonstrated in RARA-high but not RARA-low preclinical AML models. The combination of oral tamibarotene plus azacitidine was evaluated in a phase 2 clinical study in 51 newly diagnosed unfit patients with AML identified as RARA-positive (n = 22) or RARA-negative (n = 29) for RARA mRNA overexpression in peripheral blasts using a blood-based biomarker test. In 18 response-evaluable RARA-positive patients, complete remission (CR)/CR with incomplete hematologic recovery rate was 61%, CR rate was 50%, and time to initial composite CR was rapid at 1.2 months. Transfusion independence was attained by 72% of RARA-positive patients. In contrast, 28 response-evaluable RARA-negative patients had response rates that were consistent with azacitidine monotherapy. Tamibarotene in combination with azacitidine was well tolerated. The majority of nonhematologic adverse events were low grade and hematologic adverse events were comparable to single-agent azacitidine, demonstrating that there was no additional myelosuppression when tamibarotene was combined with azacitidine. These results support further evaluation of tamibarotene-based treatment strategies in patients with AML or MDS with RARA overexpression to provide a targeted approach with the goal of improving patient outcomes. This trial was registered at www.clinicaltrials.gov as #NCT02807558.

Comparison and validation of the 2022 European LeukemiaNet guidelines in acute myeloid leukemia.

Risk stratification in acute myeloid leukemia (AML) remains principle in survival prognostication and treatment selection. The 2022 European LeukemiaNet (ELN) recommendations were recently published, with notable updates to risk group assignment. The complexity of risk stratification and comparative outcomes between the 2022 and 2017 ELN guidelines remains unknown. This comparative analysis evaluated outcomes between the 2017 and 2022 ELN criteria in patients enrolled within the multicenter Beat AML cohort. Five hundred thirteen patients were included. Most patients had 1 or 2 ELN risk-defining abnormalities. In patients with ≥2 ELN risk-defining mutations, 44% (n = 132) had mutations spanning multiple ELN risk categories. Compared with ELN 2017 criteria, the updated ELN 2022 guidelines changed the assigned risk group in 15% of patients, including 10%, 26%, and 6% of patients categorized as being at ELN 2017 favorable-, intermediate-, and adverse-risk, respectively. The median overall survival across ELN 2022 favorable-, intermediate-, and adverse-risk groups was not reached, 16.8, and 9.7 months, respectively. The ELN 2022 guidelines more accurately stratified survival between patients with intermediate- or adverse-risk AML treated with induction chemotherapy compared with ELN 2017 guidelines. The updated ELN 2022 guidelines better stratify survival between patients with intermediate- or adverse-risk AML treated with induction chemotherapy. The increased complexity of risk stratification with inclusion of additional cytogenetic and molecular aberrations necessitates clinical workflows simplifying risk stratification.

Comprehensive molecular characterization of a rare case of Philadelphia chromosome-positive acute myeloid leukemia.

The Philadelphia chromosome (Ph) resulting from the t(9;22) translocation generates the oncogenic BCR::ABL1 fusion protein that is most commonly associated with chronic myeloid leukemia (CML) and Ph-positive (Ph+) acute lymphoblastic leukemia (ALL). There are also rare instances of patients (≤1%) with newly diagnosed acute myeloid leukemia (AML) that harbor this translocation (Paietta et al., Leukemia 12: 1881 [1998]; Keung et al., Leuk Res 28: 579 [2004]; Soupir et al., Am J Clin Pathol 127: 642 [2007]). AML with BCR::ABL has only recently been provisionally classified by the World Health Organization as a diagnostically distinct subtype of AML. Discernment from the extremely close differential diagnosis of myeloid blast crisis CML is challenging, largely relying on medical history rather than clinical characteristics (Arber et al., Blood 127: 2391 [2016]). To gain insight into the genomic features underlying the evolution of AML with BCR::ABL, we identified a patient presenting with a high-risk myelodysplastic syndrome that acquired a BCR::ABL alteration after a peripheral blood stem cell transplant. Serial samples were collected and analyzed using whole-exome sequencing, RNA-seq, and ex vivo functional drug screens. Persistent subclones were identified, both at diagnosis and at relapse, including an SF3B1p.Lys700Glu mutation that later cooccurred with an NRASp.Gly12Cys mutation. Functional ex vivo drug screening performed on primary patient cells suggested that combination therapies of ABL1 with RAS or PI3K pathway inhibitors could have augmented the patient's response throughout the course of disease. Together, our findings argue for the importance of genomic profiling and the potential value of ABL1 inhibitor-inclusive combination treatment strategies in patients with this rare disease.

A Phase 1/2 Study of the Oral Janus Kinase 1 Inhibitors INCB052793 and Itacitinib Alone or in Combination With Standard Therapies for Advanced Hematologic Malignancies.

BACKGROUND: The Janus kinase (JAK)/signal transducers and activators of transcription pathway has been implicated in the pathogenesis and progression of various hematologic malignancies. JAK1-regulated cytokines stimulate proliferation and growth of malignant cells and resistance to certain therapies. PATIENTS AND METHODS: This phase 1/2 study evaluated 2 oral, novel JAK1 inhibitors (INCB052793 and itacitinib) in advanced hematologic malignancies. Phase 1a assessed dose escalation and expansion of INCB052793 monotherapy. Phase 1b evaluated INCB052793 plus standard therapy in relapsed/refractory multiple myeloma, acute myeloid leukemia (AML), or myelodysplastic syndrome (MDS). Phase 2 evaluated INCB052793 or itacitinib plus azacitidine in DNA methyltransferase inhibitor (DNMTi)-refractory AML or MDS. Primary endpoints included safety and tolerability for phase 1, and objective response rate for phase 2. RESULTS: Fifty-eight patients were enrolled, all received study treatment and discontinued either treatment or participation in the study. The most common reasons for treatment discontinuation were progressive disease (35.4% and 50.0%) and adverse events (22.9% and 20.0%) for INCB052793 and itacitinib plus azacitidine, respectively. In phase 1, 12 of 39 patients (31%) achieved an objective response; 35 mg once daily was selected as the phase 2 dose. Two patients with DNMTi-refractory disease had an objective response in phase 2. The study was terminated for lack of efficacy. CONCLUSION: Inhibition of JAK1 with INCB052793 (monotherapy or combination therapy) or itacitinib plus azacitidine did not demonstrate clinically meaningful responses in these patients with hematopoietic malignancies.

Advances in acute myeloid leukemia.

Acute myeloid leukemia (AML) is an uncommon but potentially catastrophic diagnosis with historically high mortality rates. The standard of care treatment remained unchanged for decades; however, recent discoveries of molecular drivers of leukemogenesis and disease progression have led to novel therapies for AML. Ongoing research and clinical trials are actively seeking to personalize therapy by identifying molecular targets, discovering patient specific and disease specific risk factors, and identifying effective combinations of modalities and drugs. This review focuses on important updates in diagnostic and disease classifications that reflect new understanding of the biology of AML, its mutational heterogeneity, some important genetic and environmental risk factors, and new treatment options including cytotoxic chemotherapy, novel targeted agents, and cellular therapies.

Graft-versus-host disease after liver transplantation is associated with bone marrow failure, hemophagocytosis, and DNMT3A mutations.

Graft-versus-host disease after liver transplantation (LT-GVHD) is rare, frequently fatal, and associated with bone marrow failure (BMF), cytopenias, and hyperferritinemia. Given hyperferritinemia and cytopenias are present in hemophagocytic lymphohistiocytosis (HLH), and somatic mutations in hematopoietic cells are associated with hyperinflammatory responses (clonal hematopoiesis of indeterminate potential, CHIP), we identified the frequency of hemophagocytosis and CHIP mutations in LT-GVHD. We reviewed bone marrow aspirates and biopsies, quantified blood/marrow chimerism, and performed next-generation sequencing (NGS) with a targeted panel of genes relevant to myeloid malignancies, CHIP, and BMF. In all, 12 marrows were reviewed from 9 LT-GVHD patients. In all, 10 aspirates were evaluable for hemophagocytosis; 7 had adequate DNA for NGS. NGS was also performed on marrow from an LT cohort (n = 6) without GVHD. Nine of 10 aspirates in LT-GVHD patients showed increased hemophagocytosis. Five (71%) of 7 with LT-GVHD had DNMT3A mutations; only 1 of 6 in the non-GVHD LT cohort demonstrated DNMT3A mutation (p = .04). Only 1 LT-GVHD patient survived. BMF with HLH features was associated with poor hematopoietic recovery, and DNMT3A mutations were over-represented, in LT-GVHD patients. Identification of HLH features may guide prognosis and therapeutics. Further studies are needed to clarify the origin and impact of CHIP mutations on the hyperinflammatory state.

Engrafted Donor-Derived Clonal Hematopoiesis after Allogenic Hematopoietic Cell Transplantation is Associated with Chronic Graft-versus-Host Disease Requiring Immunosuppressive Therapy, but no Adverse Impact on Overall Survival or Relapse.

Clonal hematopoiesis of indeterminate potential (CHIP) is an age-associated condition defined by the presence of a somatic mutation in a leukemia-associated gene in individuals who otherwise have no evidence of a hematologic malignancy. In the allogeneic hematopoietic cell transplantation (HCT) setting, clonal hematopoiesis (CH) mutations present in donor stem cells can be transferred to recipients at the time of HCT. Given that the consequences of donor-derived CH in HCT recipients are not entirely clear, we sought to investigate clinical outcomes in patients with engrafted donor-derived CH using a matched cohort analysis of both related and unrelated donors. Of 209 patients with next-generation sequencing performed before and after HCT, donor-derived CH mutations were detected in 15 (5.2%). DNMT3A was the most commonly mutated gene (9 of 15; 60%); mutations in SF3B1, CSF3R, STAT3, CBLB, TET2, and ASXL1 were also identified. Donor-derived CH was not associated with delayed neutrophil or platelet engraftment, and there was no impact on conversion to full donor chimerism. No patients with donor-derived CH experienced relapse, in contrast to 15.6% (7 of 45) in the matched control cohort without CH (P = .176). Donor-derived CH was not associated with worse overall survival; however, patients with donor-derived CH were more likely to develop chronic graft-versus-host disease (GVHD) necessitating systemic immunosuppressive therapy (IST) (P = .045) and less likely to discontinue IST (P = .03) compared with controls without donor-derived CH. We conclude that donor-derived CH does not have an adverse impact on relapse, survival, or engraftment outcomes but may potentiate a graft-versus-leukemia effect, as reflected by increased chronic GVHD necessitating IST.

Complex confounder-corrected R2* mapping for liver iron quantification with MRI.

OBJECTIVES: MRI-based R2* mapping may enable reliable and rapid quantification of liver iron concentration (LIC). However, the performance and reproducibility of R2* across acquisition protocols remain unknown. Therefore, the objective of this work was to evaluate the performance and reproducibility of complex confounder-corrected R2* across acquisition protocols, at both 1.5 T and 3.0 T. METHODS: In this prospective study, 40 patients with suspected iron overload and 10 healthy controls were recruited with IRB approval and informed written consent and imaged at both 1.5 T and 3.0 T. For each subject, acquisitions included four different R2* mapping protocols at each field strength, and an FDA-approved R2-based method performed at 1.5 T as a reference for LIC. R2* maps were reconstructed from the complex data acquisitions including correction for noise effects and fat signal. For each subject, field strength, and R2* acquisition, R2* measurements were performed in each of the nine liver Couinaud segments and the spleen. R2* measurements were compared across protocols and field strength (1.5 T and 3.0 T), and R2* was calibrated to LIC for each acquisition and field strength. RESULTS: R2* demonstrated high reproducibility across acquisition protocols (p > 0.05 for 96/108 pairwise comparisons across 2 field strengths and 9 liver segments, ICC > 0.91 for each field strength/segment combination) and high predictive ability (AUC > 0.95 for four clinically relevant LIC thresholds). Calibration of R2* to LIC was LIC = - 0.04 + 2.62 × 10-2 R2* at 1.5 T and LIC = 0.00 + 1.41 × 10-2 R2* at 3.0 T. CONCLUSIONS: Complex confounder-corrected R2* mapping enables LIC quantification with high reproducibility across acquisition protocols, at both 1.5 T and 3.0 T. KEY POINTS: • Confounder-corrected R2* of the liver provides reproducible R2* across acquisition protocols, including different spatial resolutions, echo times, and slice orientations, at both 1.5 T and 3.0 T. • For all acquisition protocols, high correlation with R2-based liver iron concentration (LIC) quantification was observed. • The calibration between confounder-corrected R2* and LIC, at both 1.5 T and 3.0 T, is determined in this study.

Feasibility and cost analysis of day 4 granulocyte colony-stimulating factor mobilized peripheral blood progenitor cell collection from HLA-matched sibling donors.

BACKGROUND: Guidelines recommend treatment with 4-5 days of granulocyte colony-stimulating factor (G-CSF) for optimal donor peripheral blood progenitor cell (PBPC) mobilization followed by day 5 collection. Given that some autologous transplant recipients achieve adequate collection by day 4 and the possibility that some allogeneic donors may maximally mobilize PBPC before day 5, a feasibility study was performed evaluating day 4 allogeneic PBPC collection. METHODS: HLA-matched sibling donors underwent collection on day 4 of G-CSF for peripheral blood (PB) CD34+ counts ≥0.04 × 106/mL, otherwise they underwent collection on day 5. Those with inadequate collected CD34+ cells/kg recipient weight underwent repeat collection over 2 days. Transplant and PBPC characteristics and cost analysis were compared with a historical cohort collected on day 5 per our prior institutional algorithm. RESULTS: Of the 101 patient/donor pairs, 50 (49.5%) had adequate PBPC collection on day 4, with a median PB CD34+ cell count of 0.06 × 106/mL. Day 4 donors were more likely to develop bone pain and require analgesics. Median collected CD34+ count was significantly greater, whereas total nucleated, mononuclear and CD3+ cell counts were significantly lower, at time of transplant infusion for day 4 versus other collection cohorts. There were no significant differences in engraftment or graft-versus-host disease. Cost analysis revealed 6.7% direct cost savings for day 4 versus historical day 5 collection. DISCUSSION: Day 4 PB CD34+ threshold of ≥0.04 × 106/mL identified donors with high likelihood of adequate PBPC collection. Day 4 may be the optimal day of collection for healthy donors, without adverse effect on recipient transplant outcomes and with expected cost savings.

Next-generation sequencing-defined minimal residual disease before stem cell transplantation predicts acute myeloid leukemia relapse.

In acute myeloid leukemia (AML), the assessment of post-treatment minimal residual disease (MRD) may inform a more effective management approach. We investigated the prognostic utility of next-generation sequencing (NGS)-based MRD detection undertaken before hematopoietic stem cell transplantation (HSCT). Forty-two AML subjects underwent serial disease monitoring both by standard methods, and a targeted 42-gene NGS assay, able to detect leukemia-specific mutant alleles (with >0.5% VAF) (mean 5.1 samples per subject). The prognostic relevance of any persisting diagnostic mutation before transplant (≤27 days) was assessed during 22.1 months (median) of post-transplant follow-up. The sensitivity of the NGS assay (27 MRD-positive subjects) exceeded that of the non-molecular methods (morphology, FISH, and flow cytometry) (11 positive subjects). Only one of the 13 subjects who relapsed after HSCT was NGS MRD-negative (92% assay sensitivity). The cumulative incidence of post-transplant leukemic relapse was significantly higher in the pre-transplant NGS MRD-positive (vs MRD-negative) subjects (P = .014). After adjusting for TP53 mutation and transplant conditioning regimen, NGS MRD-positivity retained independent prognostic significance for leukemic relapse (subdistribution hazard ratio = 7.3; P = .05). The pre-transplant NGS MRD-positive subjects also had significantly shortened progression-free survival (P = .038), and marginally shortened overall survival (P = .068). In patients with AML undergoing HSCT, the pre-transplant persistence of NGS-defined MRD imparts a significant, sensitive, strong, and independent increased risk for subsequent leukemic relapse and death. Given that NGS can simultaneously detect multiple leukemia-associated mutations, it can be used in the majority of AML patients to monitor disease burdens and inform treatment decisions.

Allogeneic transplantation outcomes amongst a contemporary cohort of high-risk myelodysplastic syndrome and acute myeloid leukemia patients aged ≥70 years.

Allogeneic hematopoietic stem cell transplantation (HSCT) is an integral therapy for patients with hematological malignancies, myelodysplasia, and bone marrow failure. Its use has been increasing over the past decade, as understanding of the treatment and its related toxicities has led to changes in patient selection, conditioning regimens, and post-transplant care. Older (age ≥65 years) patients are often considered unfit for transplantation; however, more recent data suggest that older patients, when selected appropriately, tolerate transplantation well. We report our institutional experience with HSCT in patients aged ≥70 years. A cohort of 22 patients underwent HSCT. Median overall survival was 5.16 years [95% confidence interval (CI): 1.5-8.7 years], and median post-transplant survival was 2.2 years (myelodysplastic syndrome: median 1.3 years, 95% CI: 4.7 months-2.2 years; acute myeloid leukemia: median not reached). Thirty-day mortality following HSCT was 9.5% (n = 2). These data provide further support for the use of HSCT in selected older patients, and highlight the impact of HSCT on overall survival among a patient cohort primarily of acute myeloid leukemia and myelodysplasia.

The Difficulties of Informed Consent in Stem Cell Transplant.

Informed consent is the process by which a competent patient is provided with a sufficient amount of relevant information to make an educated decision about a procedure. The process of informed consent is designed to prioritize patients' autonomy. Stem cell transplant (SCT) is a complicated process with many possible results and requirements for on-going decision-making depending on outcomes and complications. While understanding basic theories of decision science will help the physician provide improved information at the time of consent, experiential learning by the patients as they proceed through SCT may have the strongest influence in continued patient decision-making that may or may not align with their initial informed consent.

Magnetic susceptibility as a B0 field strength independent MRI biomarker of liver iron overload.

PURPOSE: MR-based quantification of liver magnetic susceptibility may enable field strength-independent measurement of liver iron concentration (LIC). However, susceptibility quantification is challenging, due to nonlocal effects of susceptibility on the B0 field. The purpose of this work is to demonstrate feasibility of susceptibility-based LIC quantification using a fat-referenced approach. METHODS: Phantoms consisting of vials with increasing iron concentrations immersed between oil/water layers, and 27 subjects (9 controls/18 subjects with liver iron overload) were scanned. Ferriscan (1.5 T) provided R2-based reference LIC. Multiecho three-dimensional-SPGR (1.5 T/3 T) enabled fat-water, B0- and R2*-mapping. Phantom iron concentration (mg Fe L(-1)) was estimated from B0 differences (ΔB0) between vials and neighboring oil. Liver susceptibility and LIC (mg Fe g(-1) dry tissue) was estimated from ΔB0 between the lateral right lobe of the liver and adjacent subcutaneous adipose tissue. RESULTS: Estimated phantom iron concentrations had good correlation with true iron concentrations (1.5 T:slope = 0.86, intercept = 0.72, r(2) = 0.98; 3 T:slope = 0.85, intercept = 1.73, r(2) = 0.98). In liver, ΔB0 correlated strongly with R2* (1.5 T:r(2) = 0.86; 3 T:r(2) = 0.93) and B0-LIC had good agreement with Ferriscan-LIC (slopes/intercepts nearly 1.0/0.0, 1.5 T:r(2) = 0.67, slope = 0.93 ± 0.13, P ≈ 0.50, intercept = 1.93 ± 0.78, P ≈ 0.02; 3 T:r(2) = 0.84, slope = 1.01 ± 0.09, P ≈ 0.90, intercept = 0.23 ± 0.52, P ≈ 0.68). DISCUSSION: Fat-referenced, susceptibility-based LIC estimation is feasible at both field strengths. This approach may enable improved susceptibility mapping in the abdomen.