Prognostic impact of 'multi-hit' versus 'single hit' TP53 alteration in patients with acute myeloid leukemia: results from the Consortium on Myeloid Malignancies and Neoplastic Diseases.

While there is clear evidence to suggest poorer outcome associated with multi-hit (MH) TP53 mutation compared to single-hit (SH) in lower-risk myelodysplastic syndrome (MDS), data are conflicting in both higher-risk MDS and acute myeloid leukemia (AML). We conducted an indepth analysis utilizing data from 10 US academic institutions to study differences in molecular characteristics and outcomes of SH (n= 139) versus MH (n= 243) TP53MTAML. Complex cytogenetics (CG) were more common in MH compared to SH TP53MT AML (p <0.001); whereas ASXL1 (p= <0.001), RAS (p<0.001), splicing factor (p= 0.003), IDH1/2 (p= 0.001), FLT3 ITD (p= <0.001) and NPM1 (p= 0.005) mutations significantly clustered with SH TP53MT AML. Survival after excluding patients who received best supportive care alone was dismal but not significantly different between SH and MH (event free survival [EFS]: 3.0 vs 2.20 months, p= 0.22/ overall survival [OS]: 8.50 vs 7.53 months, respectively, p= 0.13). In multivariable analysis, IDH1 mutation and allogeneic hematopoietic stem cell transplantation (allo-HCT) as a time-dependent covariate were associated with superior EFS (HR; 0.44, 95% CI: 0.19-1.01, p= 0.05/ HR; 0.34, 95% CI: 0.18-0.62, p<0.001) and OS (HR; 0.24, 95% CI: 0.08-0.71, p= 0.01/ HR; 0.28, 95% CI: 0.16-0.47, p<0.001). While complex CG (HR; 1.56, 95% CI: 1.01-2.40, p= 0.04) retained unfavorable significance for OS. Our analysis suggests that unlike in MDS, multihit TP53MT is less relevant in independently predicting outcomes in patients with AML.

Disparities in receiving disease-directed therapy, allogeneic stem cell transplantation in non-Hispanic Black patients with TP53-mutated acute myeloid leukemia.

BACKGROUND: Although the clinical outcomes of patients with TP53-mutated acute myeloid leukemia (AML) are dismal, subsets of patients eligible for curative-intent therapies may fare better. Because racial disparities are known to affect outcome in hematologic malignancies, the authors sought to explore disparities among patients with TP53-mutated AML. METHODS: A multicenter, retrospective study was conducted in a cohort of 340 patients who had TP53-mutated AML (275 non-Hispanic White [NHW] and 65 non-Hispanic Black [NHB]) to analyze differences in treatment and outcome among NHW and NHB patients. RESULTS: The median patient age was comparable between NHW and NHB patients (p = .76). A higher proportion of NHB patients had therapy-related AML (31% vs. 20%; p = .08) and had co-mutations (74% vs. 61%; p = .06). A higher proportion of NHW patients received intensive chemotherapy compared with NHB patients (47% vs. 31%; p = .02). Conversely, a higher proportion of NHB patients received low-intensity chemotherapy (9% vs. 5.5%; p = .02) or best supportive care (22% vs. 7%; p < .001). The complete response rate (including complete responses with or without complete count recovery) was 31% versus 24.5% (p = .39) in NHW and NHB patients, respectively. Only 5% of NHB patients received allogeneic stem cell transplantation compared with 15.5% of NHW patients (p = .02). The proportion of patients who were event-free (18.5% vs. 8.5%; p = .49) or who remained alive (24.9% vs. 8.3%; p = .13) at 18 months was numerically higher in NHW versus NHB patients, respectively, but was not statistically significant. CONCLUSIONS: The current study highlights disparities between NHW and NHB patients with TP53-mutated AML. Efforts are warranted to eliminate treatment disparities in minority populations.

The prognostic impact of cigarette smoking on survival in acute myeloid leukemia with TP53 mutations and/or 17p deletions.

Cigarette smoking has been associated with increased risk of developing acute myeloid leukemia (AML) in adults. There is limited data on the impact of smoking in AML patients with certain cytogenetic abnormalities. The aim of this study is to assess whether cigarette smoking affected the survival outcome of patients with newly diagnosed AML with TP53 alterations. We conducted a retrospective study of patients who were diagnosed with AML at the Thomas Jefferson Hospital with presence of TP53 mutations and/or 17p deletions. Patients' sex, age, race, smoking status (ever vs. never), cytogenetics, mutational profile, induction regimen, and induction response were analyzed. A total of 102 patients were included in the study with a median follow-up of 27.8 months. Among 100 patients who had documentation of smoking status, 59 patients (59%) were ever-smokers and 41 (41%) were never-smokers. Kaplan-Meier survival analysis showed that never-smokers did not differ in overall survival (OS) when compared to ever-smokers (P = 0.34). Univariate analysis revealed that age and cytogenetics had a statistically significant impact on survival. In multivariate analysis incorporating sex, age, race, smoking status, cytogenetics, and induction regimen as covariates, cytogenetics and induction regimen were independent prognostic factors for OS. In summary, no significant difference in OS was found between ever- and never-smokers in AML patients with TP53 alterations. Additional studies are needed to examine the prognostic impact of cigarette smoking in AML with specific cytogenetic abnormalities.

Low Nonrelapse Mortality after HLA-Matched Related 2-Step Hematopoietic Stem Cell Transplantation Using Cyclophosphamide for Graft-versus-Host Disease Prophylaxis and the Potential Impact of Non- Cyclophosphamide-Exposed T Cells on Outcomes.

The use of cyclophosphamide (CY) for bidirectional tolerization of recipient and donor T cells is associated with reduced rates of graft-versus-host disease (GVHD) and nonrelapse mortality (NRM) after HLA-matched hematopoietic stem cell transplantation (HSCT). However, recurrent disease remains the primary barrier to long-term survival. We extended our 2-step approach to HLA-matched related HSCT using a radiation-based myeloablative conditioning regimen combined with a high dose of T cells in an attempt to reduce relapse rates while maintaining the beneficial effects of CY tolerization. After conditioning, patients received their grafts in 2 components: (1) a fixed dose of 2 × 108/kg T cells, followed 2 days later by CY, and (2) a CD34-selected graft containing a small residual amount of non-CY-exposed T cells, at a median dose of 2.98 × 103/kg. Forty-six patients with hematologic malignancies were treated. Despite the myeloablative conditioning regimen and use of high T cell doses, the cumulative incidences of grade II-IV acute GVHD, chronic GVHD, and NRM at 1 year and 5 years were very low, at 13%, 9%, and 4.3%, respectively. This contributed to a high overall survival of 89.1% at 1 year and 65.8% at 5 years. Relapse was the primary cause of mortality, with a cumulative incidence of 23.9% at 1 year and 45.7% at 5 years. In a post hoc analysis, relapse rates were significantly lower in patients receiving greater than versus those receiving less than the group median of non-CY-exposed residual T cells in the CD34 product (19.3% versus 58.1%; P = .009), without a concomitant increase in NRM. In its current form, this 2-step regimen was highly tolerable, but strategies to reduce relapse, potentially the addition of T cells not exposed to CY, are needed.

Acute Myeloid Leukemia: Update on Upfront Therapy in Elderly Patients.

PURPOSE OF REVIEW: Acute myeloid leukemia (AML) disproportionately impacts elderly patients. Treating elderly patients with AML has been a challenge due to the increased prevalence of medical comorbidities and decreased performance status in this population, as well as the different biology of AML in elderly patients. RECENT FINDINGS: The care of elderly patients with AML has advanced significantly over the past few years. Our greater understanding of the biology of AML in elderly patients has led to the development of novel, lower-intensity treatment options. We present here a review of the most recent literature regarding therapeutic options available to older patients, as well as tools to help identify the right treatment for the right patient. As targeted and lower-intensity treatment options become available, developing an approach to "right size" therapy for individual elderly patients is paramount.

A Two-Step Haploidentical Versus a Two-Step Matched Related Allogeneic Myeloablative Peripheral Blood Stem Cell Transplantation.

Haploidentical stem cell transplantation (SCT) offers a transplantation option to patients who lack an HLA-matched donor. We developed a 2-step approach to myeloablative allogeneic hematopoietic stem cell transplantation for patients with haploidentical or matched related (MR) donors. In this approach, the lymphoid and myeloid portions of the graft are administered in 2 separate steps to allow fixed T cell dosing. Cyclophosphamide is used for T cell tolerization. Given a uniform conditioning regimen, graft T cell dose, and graft-versus-host disease (GVHD) prophylaxis strategy, we compared immune reconstitution and clinical outcomes in patients undergoing 2-step haploidentical versus 2-step MR SCT. We retrospectively compared data on patients undergoing a 2-step haploidentical (n = 50) or MR (n = 27) peripheral blood SCT for high-risk hematological malignancies and aplastic anemia. Both groups received myeloablative total body irradiation conditioning. Immune reconstitution data included flow cytometric assessment of T cell subsets at day 28 and 90 after SCT. Both groups showed comparable early immune recovery in all assessed T cell subsets except for the median CD3/CD8 cell count, which was higher in the MR group at day 28 compared with that in the haploidentical group. The 3-year probability of overall survival was 70% in the haploidentical group and 71% in the MR group (P = .81), while the 3-year progression-free survival was 68% in the haploidentical group and 70% in the MR group (P = .97). The 3-year cumulative incidence of nonrelapse mortality was 10% in the haploidentical group and 4% in the MR group (P = .34). The 3-year cumulative incidence of relapse was 21% in the haploidentical group and 27% in the MR group (P = .93). The 100-day cumulative incidence of overall grades II to IV acute GVHD was higher in the haploidentical group compared with that in the MR group (40% versus 8%, P < .001), whereas the grades III and IV acute GVHD was not statistically different between both groups (haploidentical, 6%; MR, 4%; P = .49). The cumulative incidence of cytomegalovirus reactivation was also higher in the haploidentical group compared to the MR group (haploidentical, 68%; MR, 19%; P < .001). There were no deaths from GVHD in either group. Using an identical conditioning regimen, graft T cell dose, and GVHD prophylaxis strategy, comparable early immune recovery and clinical outcomes were observed in the 2-step haploidentical and MR SCT recipients.

Polo-like kinase and its inhibitors: Ready for the match to start?

Polo-like kinases (Plks) plays a central role in the normal cell cycle and their upregulation has been shown to play a role in the pathogenesis of multiple human cancers. Preclinical work demonstrates that targeting Plk has a significant impact on the treatment of both solid and hematologic malignancies in vitro and in vivo. We review here the basic science and clinical work to date with the Plks as well as future directions with this novel class of mitotic inhibitors.

PRT543, a protein arginine methyltransferase 5 inhibitor, in patients with advanced adenoid cystic carcinoma: An open-label, phase I dose-expansion study.

OBJECTIVES: Currently, no systemic treatments are approved for patients with recurrent and/or metastatic (R/M) adenoid cystic carcinoma (ACC). PRT543, a protein arginine methyltransferase 5 inhibitor that downregulates NOTCH1 and MYB signalling in tumours, is a potential candidate for R/M ACC treatment. We report the safety, tolerability and preliminary efficacy of PRT543 in a dose-expansion cohort of patients with R/M ACC. MATERIALS AND METHODS: This phase I multicentre, open-label, sequential-cohort, dose-escalation and dose-expansion study (NCT03886831) enrolled patients with advanced solid tumours and select haematologic malignancies. Dose-escalation study design and results were reported previously. In the dose expansion, patients with R/M ACC received recommended phase II doses of 35 or 45 mg PRT543 orally on days 1-5 of each week. Primary objectives were to establish the safety and tolerability of PRT543. Secondary objectives included efficacy. RESULTS: Between February 2019 and May 2022, 56 patients with ACC were enrolled across 23 US sites and received either 35 mg (n = 28) or 45 mg (n = 28) of PRT543. Overall, 23% of patients experienced a grade 3 treatment-related adverse event, most commonly anaemia (16%) and thrombocytopaenia (9%). No grade 4/5 treatment-emergent adverse events were reported. Median progression-free survival was 5.9 months (95% CI: 3.8-8.3). The clinical benefit rate was 57% (95% CI: 43-70). Overall response rate (per Response Evaluation Criteria in Solid Tumours v1.1) was 2%, with 70% of patients having stable disease. CONCLUSION: In this analysis, PRT543 was tolerable, and the observed efficacy was limited in patients with R/M ACC.

Controversies in antiepidermal growth factor receptor therapy in metastatic colorectal cancer.

The randomized first-line trials, including the CRYSTAL trial, the OPUS trial, and the PRIME trial, have demonstrated the significant efficacy of cetuximab or panitumumab in patients with v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) wild-type tumors. The addition of an antiepidermal growth factor receptor (anti-EGFR)-directed monoclonal antibody to chemotherapy for these patients significantly improved progression-free survival, response rates, and R0 resection rates to a greater extent than overall survival compared with patients who received chemotherapy alone. However, 2 recent randomized phase 3 trials, the MRC COIN trial and the Nordic VII trial, reported an unexpected lack of benefit from the addition of cetuximab to chemotherapy in the first-line setting. In addition, recent retrospective analyses performed on a pooled data set from major clinical trials added more complexity, reporting an unexpected association of KRAS G13D mutation with a better clinical outcome compared with patients who had other KRAS mutations in the first-line and salvage settings, whereas the other independent analysis failed to demonstrate a benefit from panitumumab in patients with the same KRAS G13D mutation. The anti-EGFR monoclonal antibody-associated skin toxicity and the controversial strategies of management also are discussed. In this review, the authors analyze the previous randomized clinical trials and more critically re-evaluate recent trials and subgroup analyses to derive 3 factors that need to be taken into consideration regarding the addition of EGFR-directed monoclonal antibodies to chemotherapy: the preclinical data on mechanisms of action between chemotherapy and anti-EGFR antibodies along with mechanisms of resistance to anti-EGFR antibodies, the role of cross-over events in overall survival data, and the significant dose reductions of chemotherapeutic agents when combined with anti-EGFR agents.

A phase I study of the combination of palbociclib and dexamethasone for the treatment of relapsed or refractory B-cell acute lymphoblastic leukemia.

PURPOSE: Despite advances in the treatment of B-cell acute lymphoblastic leukemia (B-ALL), outcomes for relapsed/refractory (R/R) disease remain poor. Preclinical studies suggest that the combination of the CDK4/6 inhibitor palbociclib and dexamethasone may be effective in targeting leukemic cell growth. We conducted a phase I study of escalating doses of palbociclib in combination with dexamethasone in adults with R/R B-ALL. METHODS: Cycle 1 consisted of single agent palbociclib given for 7 days and continued for 28 additional days in combination with dexamethasone 20 mg daily. Palbociclib dosing began at 100 mg daily. Patients with a response were eligible for maintenance consisting of 1 week of palbociclib plus dexamethasone (20 mg daily × 2 days, 16 mg daily × 2 days, 12 mg daily × 2 days, 6 mg daily × 1 day), followed by 3 weeks of palbociclib alone. Safety, efficacy, and the expression of phospho-RB and c-MYB/BCL-2 were measured. CONCLUSIONS: Seven patients were treated on study before it was closed early due to slow accrual. No dose limiting toxicities were identified. One patient had a complete response with incomplete hematologic recovery, suggesting possible efficacy of the treatment. Reduction in CD34+ cells, p-RB, c-MYB, and BCL-2 expression also suggested on-target therapy effects.

A Phase I Trial of Sirolimus with "7&3" Induction Chemotherapy in Patients with Newly Diagnosed Acute Myeloid Leukemia.

Chemotherapy remains a primary treatment for younger AML patients, though many relapse. Data from our group have shown that highly phosphorylated S6 in blasts may predict response to sirolimus given with chemotherapy. We report the results of a phase I study of this combination in newly diagnosed AML and the pharmacodynamic analysis of pS6 before and after treatment. Subjects received sirolimus (12 mg on day 1, 4 mg daily, days 2-10), then idarubicin and cytarabine (days 4-10). Response was assessed at hematologic recovery or by day 42 using a modified IWG criteria. Fifty-five patients received sirolimus. Toxicity was similar to published 7 + 3 data, and 53% had high-, 27% intermediate-, and 20% favorable-risk disease. Forty-four percent of the high-risk patients entered into CR/CRp. Seventy-nine percent of the intermediate-risk subjects had a CR/CRp. All favorable-risk patients had a CR by day 42; 9/11 remained alive and in remission with a median follow-up of 660 days. Additionally, 41/55 patients had adequate samples for pharmacodynamic analysis. All patients demonstrated activation of S6 prior to therapy, in contrast to 67% seen in previous studies of relapsed AML. mTORC1 inhibition was observed in 66% of patients without enrichment among patients who achieved remission. We conclude that sirolimus and 7 + 3 is a well-tolerated and safe regimen. mTORC1 appears to be activated in almost all patients at diagnosis of AML. Inhibition of mTORC1 did not differ based on response, suggesting that AML cells may have redundant signaling pathways that regulate chemosensitivity in the presence of mTORC1 inhibition.

Survival of TP53-mutated acute myeloid leukemia patients receiving allogeneic stem cell transplantation after first induction or salvage therapy: results from the Consortium on Myeloid Malignancies and Neoplastic Diseases (COMMAND).

We conducted a multi-center study to analyze factors predicting survival among patients with TP53-mutated (m) AML receiving allogeneic hematopoietic stem cell transplant (allo-HSCT) in the recent era. Out of 370 TP53m AML patients, 68 (18%) patients were bridged to allo-HSCT. The median age of the patients was 63 years (range, 33-75), 82% of patients had complex cytogenetics and 66% of patients had multi-hit TP53m. Forty three percent received myeloablative conditioning and 57% received reduced intensity conditioning. The incidence of acute graft versus host disease (GVHD) was 37% and chronic GVHD was 44%. The median event-free survival (EFS) from the time of allo-HSCT was 12.4 months (95% CI: 6.24-18.55) and median overall survival (OS) was 24.5 months (95% CI: 21.80-27.25). In multivariate analysis utilizing variables that showed significance in univariate analysis, complete remission at day 100 post allo-HSCT retained significance for EFS (HR: 0.24, 95% CI: 0.10-0.57, p = 0.001) and OS (HR: 0.22, 95% CI: 0.10-0.50, p ≤ 0.001). Similarly, occurrence of chronic GVHD retained significance for EFS (HR: 0.21, 95% CI: 0.09-0.46, p ≤ 0.001) and OS (HR: 0.34, 95% CI: 0.15-0.75, p = 0.007). Our report suggests that allo-HSCT offers the best opportunity to improve long-term outcome among patients with TP53m AML.

Allogeneic hematopoietic cell transplantation for blastic plasmacytoid dendritic cell neoplasm: a CIBMTR analysis.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematological malignancy with a poor prognosis and considered incurable with conventional chemotherapy. Small observational studies reported allogeneic hematopoietic cell transplantation (allo-HCT) offers durable remissions in patients with BPDCN. We report an analysis of patients with BPDCN who received an allo-HCT, using data reported to the Center for International Blood and Marrow Transplant Research (CIBMTR). We identified 164 patients with BPDCN from 78 centers who underwent allo-HCT between 2007 and 2018. The 5-year overall survival (OS), disease-free survival (DFS), relapse, and nonrelapse mortality (NRM) rates were 51.2% (95% confidence interval [CI], 42.5-59.8), 44.4% (95% CI, 36.2-52.8), 32.2% (95% CI, 24.7-40.3), and 23.3% (95% CI, 16.9-30.4), respectively. Disease relapse was the most common cause of death. On multivariate analyses, age of ≥60 years was predictive for inferior OS (hazard ratio [HR], 2.16; 95% CI, 1.35-3.46; P = .001), and higher NRM (HR, 2.19; 95% CI, 1.13-4.22; P = .02). Remission status at time of allo-HCT (CR2/primary induction failure/relapse vs CR1) was predictive of inferior OS (HR, 1.87; 95% CI, 1.14-3.06; P = .01) and DFS (HR, 1.75; 95% CI, 1.11-2.76; P = .02). Use of myeloablative conditioning with total body irradiation (MAC-TBI) was predictive of improved DFS and reduced relapse risk. Allo-HCT is effective in providing durable remissions and long-term survival in BPDCN. Younger age and allo-HCT in CR1 predicted for improved survival, whereas MAC-TBI predicted for less relapse and improved DFS. Novel strategies incorporating allo-HCT are needed to further improve outcomes.

Novel Mechanisms for Post-Transplant Maintenance Therapy in Acute Myeloid Leukemia.

Allogeneic stem cell transplantation has improved survival for patients with acute myeloid leukemia (AML), especially for patients with disease at high risk of relapse. However, relapse remains the most common cause of treatment failure and death in the post-transplant period. Maintenance therapy, an extended course of treatment after achieving remission to reduce the rate of relapse, is an important component of the treatment of various hematologic malignancies; however, its role in the treatment of AML is far less well-defined. Recently, there has been significant interest in the use of novel therapeutic agents as maintenance therapy after allogeneic stem cell transplant, utilizing new mechanisms of treatment and more favorable toxicity profiles. In this review, we will discuss the mechanistic and clinical data for post-transplant maintenance therapies in AML. Then, we will review several emergent and current clinical trials which aim to incorporate novel agents into maintenance therapy regimens.

miR-196b-TLR7/8 Signaling Axis Regulates Innate Immune Signaling and Myeloid Maturation in DNMT3A-Mutant AML.

PURPOSE: DNMT3A mutations confer a poor prognosis in acute myeloid leukemia (AML), but the molecular mechanisms downstream of DNMT3A mutations in disease pathogenesis are not completely understood, limiting targeted therapeutic options. The role of miRNA in DNMT3A-mutant AML pathogenesis is understudied. EXPERIMENTAL DESIGN: DNA methylation and miRNA expression was evaluated in human AML patient samples and in Dnmt3a/Flt3-mutant AML mice. The treatment efficacy and molecular mechanisms of TLR7/8-directed therapies on DNMT3A-mutant AML were evaluated in vitro on human AML patient samples and in Dnmt3a/Flt3-mutant AML mice. RESULTS: miR-196b is hypomethylated and overexpressed in DNMT3A-mutant AML and is associated with poor patient outcome. miR-196b overexpression in DNMT3A-mutant AML is important to maintain an immature state and leukemic cell survival through repression of TLR signaling. The TLR7/8 agonist resiquimod induces dendritic cell-like differentiation with costimulatory molecule expression in DNMT3A-mutant AML cells and provides a survival benefit to Dnmt3a/Flt3-mutant AML mice. The small molecule bryostatin-1 augments resiquimod-mediated AML growth inhibition and differentiation. CONCLUSIONS: DNMT3A loss-of-function mutations cause miRNA locus-specific hypomethylation and overexpression important for mutant DNMT3A-mediated pathogenesis and clinical outcomes. Specifically, the overexpression of miR-196b in DNMT3A-mutant AML creates a novel therapeutic vulnerability by controlling sensitivity to TLR7/8-directed therapies.

Targeting Chemotherapy to Decondensed H3K27me3-Marked Chromatin of AML Cells Enhances Leukemia Suppression.

Despite treatment with intensive chemotherapy, acute myelogenous leukemia (AML) remains an aggressive malignancy with a dismal outcome in most patients. We found that AML cells exhibit an unusually rapid accumulation of the repressive histone mark H3K27me3 on nascent DNA. In cell lines, primary cells and xenograft mouse models, inhibition of the H3K27 histone methyltransferase EZH2 to decondense the H3K27me3-marked chromatin of AML cells enhanced chromatin accessibility and chemotherapy-induced DNA damage, apoptosis, and leukemia suppression. These effects were further promoted when chromatin decondensation of AML cells was induced upon S-phase entry after release from a transient G1 arrest mediated by CDK4/6 inhibition. In the p53-null KG-1 and THP-1 AML cell lines, EZH2 inhibitor and doxorubicin cotreatment induced transcriptional reprogramming that was, in part, dependent on derepression of H3K27me3-marked gene promoters and led to increased expression of cell death-promoting and growth-inhibitory genes.In conclusion, decondensing H3K27me3-marked chromatin by EZH2 inhibition represents a promising approach to improve the efficacy of DNA-damaging cytotoxic agents in patients with AML. This strategy might allow for a lowering of chemotherapy doses, with a consequent reduction of treatment-related side effects in elderly patients with AML or those with significant comorbidities. SIGNIFICANCE: Pharmacological inhibition of EZH2 renders DNA of AML cells more accessible to cytotoxic agents, facilitating leukemia suppression with reduced doses of chemotherapy.See related commentary by Adema and Colla, p. 359.

A Prospective, Randomized Trial Examining the Use of G-CSF Versus No G-CSF in Patients Post-Autologous Transplantation.

Contemporary, prospective data regarding the impact of granulocyte-colony stimulating factor (G-CSF) on outcomes after autologous hematopoietic stem cell transplantation (Auto-HSCT) in an era when stem cell grafts are more qualitatively robust are limited. Recent retrospective analyses have not supported a beneficial effect of post-transplantation G-CSF use on major outcomes after Auto-HSCT leading to strategies to delay or eliminate the use of G-CSF altogether in this context. To test the hypothesis that the infusion of consistently higher doses of stem cells (defined as ≥4 × 106/kg) in Auto-HSCT will obviate the need for post-transplantation G-CSF. If so, the impact of withholding G-CSF will be noninferior to the use of G-CSF in terms of length of stay (LOS). The specific objectives were to conduct a prospective, randomized clinical trial primarily examining the impact of post-transplantation G-CSF on LOS, and secondarily on engraftment, infectious complications, antibiotic usage, and incidence of engraftment syndrome after Auto-HSCT in patients receiving versus not receiving G-CSF after Auto-HSCT. Patients with multiple myeloma or non-Hodgkin lymphoma (NHL) who underwent Pegfilgrastim plus Plerixafor-primed stem cell collection followed by Auto-HSCT were randomized to the G-CSF group (receive G-CSF starting at day 3 after Auto-HSCT) or the no G-CSF group (G-CSF withheld after Auto-HSCT). Seventy patients per arm were planned to demonstrate the primary endpoint of noninferiority in LOS between the G-CSF and the no G-CSF groups. Patient outcomes in the two groups were followed up and compared after Auto-HSCT, and an interim analysis for futility was planned when accrual reached 50%.The primary finding of this study was that despite only a 2-day longer median absolute neutrophil count (ANC) recovery in the no G-CSF arm (median 11 versus 13 days; P = .001), LOS was 4 days longer in patients not treated with G-CSF (median 11 days versus 15 days; P = .001). G-CSF use was associated with more robust incremental daily increases in ANC once recovered (P = .001), fewer days of febrile neutropenia (P = .001), and fewer days on antibiotics (P = .001), potentially contributing to this disproportionate finding. Inferiority in LOS in the no G-CSF group was demonstrated on the interim analysis, and the study was closed at the half-way point. There were no significant group differences in platelet recovery, documented infections, hospital readmissions, or overall survival at 1 year. Engraftment syndrome occurred in 54.3% of patients and was not related to G-CSF use. These results suggest that the increased LOS associated with the omission of G-CSF is largely due to concerns regarding the potential for infection in patients without a stable, recovered ANC in a hospital setting. Engraftment syndrome represented a significant source of febrile neutropenia further contributing to patient safety concerns and requires strategies to decrease its incidence. Infectious complications and death were not affected by the omission of G-CSF supporting a carefully monitored outpatient approach to Auto-HSCT in which white blood cell growth factor is eliminated or given as needed for documented infection. © 2023 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

KAT6A and ENL Form an Epigenetic Transcriptional Control Module to Drive Critical Leukemogenic Gene-Expression Programs.

Epigenetic programs are dysregulated in acute myeloid leukemia (AML) and help enforce an oncogenic state of differentiation arrest. To identify key epigenetic regulators of AML cell fate, we performed a differentiation-focused CRISPR screen in AML cells. This screen identified the histone acetyltransferase KAT6A as a novel regulator of myeloid differentiation that drives critical leukemogenic gene-expression programs. We show that KAT6A is the initiator of a newly described transcriptional control module in which KAT6A-catalyzed promoter H3K9ac is bound by the acetyl-lysine reader ENL, which in turn cooperates with a network of chromatin factors to induce transcriptional elongation. Inhibition of KAT6A has strong anti-AML phenotypes in vitro and in vivo, suggesting that KAT6A small-molecule inhibitors could be of high therapeutic interest for mono-therapy or combinatorial differentiation-based treatment of AML. SIGNIFICANCE: AML is a poor-prognosis disease characterized by differentiation blockade. Through a cell-fate CRISPR screen, we identified KAT6A as a novel regulator of AML cell differentiation. Mechanistically, KAT6A cooperates with ENL in a "writer-reader" epigenetic transcriptional control module. These results uncover a new epigenetic dependency and therapeutic opportunity in AML. This article is highlighted in the In This Issue feature, p. 587.

Haploidentical vs sibling, unrelated, or cord blood hematopoietic cell transplantation for acute lymphoblastic leukemia.

The role of haploidentical hematopoietic cell transplantation (HCT) using posttransplant cyclophosphamide (PTCy) for acute lymphoblastic leukemia (ALL) is being defined. We performed a retrospective, multivariable analysis comparing outcomes of HCT approaches by donor for adults with ALL in remission. The primary objective was to compare overall survival (OS) among haploidentical HCTs using PTCy and HLA-matched sibling donor (MSD), 8/8 HLA-matched unrelated donor (MUD), 7 /8 HLA-MUD, or umbilical cord blood (UCB) HCT. Comparing haploidentical HCT to MSD HCT, we found that OS, leukemia-free survival (LFS), nonrelapse mortality (NRM), relapse, and acute graft-versus-host disease (aGVHD) were not different but chronic GVHD (cGVHD) was higher in MSD HCT. Compared with MUD HCT, OS, LFS, and relapse were not different, but MUD HCT had increased NRM (hazard ratio [HR], 1.42; P = .02), grade 3 to 4 aGVHD (HR, 1.59; P = .005), and cGVHD. Compared with 7/8 UD HCT, LFS and relapse were not different, but 7/8 UD HCT had worse OS (HR, 1.38; P = .01) and increased NRM (HR, 2.13; P ≤ .001), grade 3 to 4 aGVHD (HR, 1.86; P = .003), and cGVHD (HR, 1.72; P ≤ .001). Compared with UCB HCT, late OS, late LFS, relapse, and cGVHD were not different but UCB HCT had worse early OS (≤18 months; HR, 1.93; P < .001), worse early LFS (HR, 1.40; P = .007) and increased incidences of NRM (HR, 2.08; P < .001) and grade 3 to 4 aGVHD (HR, 1.97; P < .001). Haploidentical HCT using PTCy showed no difference in survival but less GVHD compared with traditional MSD and MUD HCT and is the preferred alternative donor HCT option for adults with ALL in complete remission.