Determining treatment tolerance and fitness for intensive chemotherapy in older adults with AML: a call to action.

ABSTRACT: Determining fitness for intensive chemotherapy in an older adult with acute myeloid leukemia (AML) is an unanswered age-old question. Geriatric assessment captures any variation in multidimensional health, which can influence treatment tolerance. A prospective study is necessary to validate fitness criteria, determine whether geriatric assessment-based fitness performs superiorly to other criteria, and what components of geriatric assessment are associated with treatment tolerance. A validation study should enroll diverse patients from both academic and community centers and patients receiving intensive and lower-intensity chemotherapy. Geriatric assessment should include at minimum measures of comorbidity burden, cognition, physical function, and emotional health, which in previous smaller studies have shown to be associated with mortality in AML. These assessments should be completed before or within a few days of initiation of chemotherapy to reduce the influence of chemotherapy on the assessment results. Treatment tolerance has been measured by rates of toxicities in patients with solid malignancies; however, during the initial treatment of AML, rates of toxicities are very high regardless of treatment intensity. Early mortality, frequently used in previous studies, can provide a highly consequential and easily identifiable measure of treatment tolerance. The key end point to assess treatment tolerance, thus, should include early mortality. Other end points may include decline in function and quality of life and treatment modifications or cessation due to toxicities. Validating fitness criteria can guide treatment selection and supportive care interventions and are crucial to guide fitness-based trial eligibility, inform the interpretation of trial results, and facilitate drug labeling.

Follow-up from the A041202 study shows continued efficacy of ibrutinib regimens for older adults with CLL.

ABSTRACT: A041202 (NCT01886872) is a phase 3 study comparing bendamustine plus rituximab (BR) with ibrutinib and the combination of ibrutinib plus rituximab (IR) in previously untreated older patients with chronic lymphocytic leukemia (CLL). The initial results showed that ibrutinib-containing regimens had superior progression-free survival (PFS) and rituximab did not add additional benefits. Here we present an updated analysis. With a median follow-up of 55 months, the median PFS was 44 months (95% confidence interval [CI], 38-54) for BR and not yet reached in either ibrutinib-containing arm. The 48-month PFS estimates were 47%, 76%, and 76% for BR, ibrutinib, and IR, respectively. The benefit of ibrutinib regimens over chemoimmunotherapy was consistent across subgroups of patients defined by TP53 abnormalities, del(11q), complex karyotype, and immunoglobulin heavy chain variable region (IGHV). No significant interaction effects were observed between the treatment arm and del(11q), the complex karyotype, or IGHV. However, a greater difference in PFS was observed among the patients with TP53 abnormalities. There was no difference in the overall survival. Notable adverse events with ibrutinib included atrial fibrillation (afib) and hypertension. Afib was observed in 11 patients (pts) on BR (3%) and 67 pts on ibrutinib (18%). All-grade hypertension was observed in 95 pts on BR (27%) and 263 pts on ibrutinib (55%). These data show that ibrutinib regimens prolong PFS compared with BR for older patients with treatment-naïve CLL. These benefits were observed across subgroups, including high-risk groups. Strikingly, within the ibrutinib arms, there was no inferior PFS for patients with abnormalities in TP53, the highest risk feature observed in CLL. These data continue to demonstrate the efficacy of ibrutinib in treatment-naïve CLL.

Genome Sequencing as an Alternative to Cytogenetic Analysis in Myeloid Cancers.

BACKGROUND: Genomic analysis is essential for risk stratification in patients with acute myeloid leukemia (AML) or myelodysplastic syndromes (MDS). Whole-genome sequencing is a potential replacement for conventional cytogenetic and sequencing approaches, but its accuracy, feasibility, and clinical utility have not been demonstrated. METHODS: We used a streamlined whole-genome sequencing approach to obtain genomic profiles for 263 patients with myeloid cancers, including 235 patients who had undergone successful cytogenetic analysis. We adapted sample preparation, sequencing, and analysis to detect mutations for risk stratification using existing European Leukemia Network (ELN) guidelines and to minimize turnaround time. We analyzed the performance of whole-genome sequencing by comparing our results with findings from cytogenetic analysis and targeted sequencing. RESULTS: Whole-genome sequencing detected all 40 recurrent translocations and 91 copy-number alterations that had been identified by cytogenetic analysis. In addition, we identified new clinically reportable genomic events in 40 of 235 patients (17.0%). Prospective sequencing of samples obtained from 117 consecutive patients was performed in a median of 5 days and provided new genetic information in 29 patients (24.8%), which changed the risk category for 19 patients (16.2%). Standard AML risk groups, as defined by sequencing results instead of cytogenetic analysis, correlated with clinical outcomes. Whole-genome sequencing was also used to stratify patients who had inconclusive results by cytogenetic analysis into risk groups in which clinical outcomes were measurably different. CONCLUSIONS: In our study, we found that whole-genome sequencing provided rapid and accurate genomic profiling in patients with AML or MDS. Such sequencing also provided a greater diagnostic yield than conventional cytogenetic analysis and more efficient risk stratification on the basis of standard risk categories. (Funded by the Siteman Cancer Research Fund and others.).

The role of allogeneic transplant for adult Ph+ ALL in CR1 with complete molecular remission: a retrospective analysis.

Historically, Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) has been associated with poor outcomes, and allogeneic hematopoietic cell transplantation (allo-HCT) is recommended in first complete remission (CR1). However, in the tyrosine kinase inhibitor (TKI) era, rapid attainment of a complete molecular remission (CMR) is associated with excellent outcomes without allo-HCT, suggesting transplant may not be required for these patients. To test this hypothesis, we retrospectively identified adult patients with Ph+ ALL treated with induction therapy, including TKIs, and attained CMR within 90 days of diagnosis at 5 transplant centers in the United States. We compared outcomes of those who did and did not receive allo-HCT in first remission. We identified 230 patients (allo-HCT: 98; non-HCT: 132). The allo-HCT cohort was younger with better performance status. On multivariable analysis (MVA), allo-HCT was not associated with improved overall survival (adjusted hazard ratio [aHR]: 1.05; 95% CI, 0.63-1.73) or relapse-free survival (aHR: 0.86; 95% CI, 0.54-1.37) compared with non-HCT treatment. Allo-HCT was associated with a lower cumulative incidence of relapse (aHR: 0.32; 95% CI, 0.17-0.62) but higher non-relapse mortality (aHR: 2.59; 95% CI, 1.37-4.89). Propensity score matching analysis confirmed results of MVA. Comparison of reduced-intensity HCT to non-HCT showed no statistically significant difference in any of the above endpoints. In conclusion, adult patients with Ph+ ALL who achieved CMR within 90 days of starting treatment did not derive a survival benefit from allo-HCT in CR1 in this retrospective study.

Systemic IL-15 promotes allogeneic cell rejection in patients treated with natural killer cell adoptive therapy.

Natural killer (NK) cells are a promising alternative to T cells for cancer immunotherapy. Adoptive therapies with allogeneic, cytokine-activated NK cells are being investigated in clinical trials. However, the optimal cytokine support after adoptive transfer to promote NK cell expansion, and persistence remains unclear. Correlative studies from 2 independent clinical trial cohorts treated with major histocompatibility complex-haploidentical NK cell therapy for relapsed/refractory acute myeloid leukemia revealed that cytokine support by systemic interleukin-15 (IL-15; N-803) resulted in reduced clinical activity, compared with IL-2. We hypothesized that the mechanism responsible was IL-15/N-803 promoting recipient CD8 T-cell activation that in turn accelerated donor NK cell rejection. This idea was supported by increased proliferating CD8+ T-cell numbers in patients treated with IL-15/N-803, compared with IL-2. Moreover, mixed lymphocyte reactions showed that IL-15/N-803 enhanced responder CD8 T-cell activation and proliferation, compared with IL-2 alone. Additionally, IL-15/N-803 accelerated the ability of responding T cells to kill stimulator-derived memory-like NK cells, demonstrating that additional IL-15 can hasten donor NK cell elimination. Thus, systemic IL-15 used to support allogeneic cell therapy may paradoxically limit their therapeutic window of opportunity and clinical activity. This study indicates that stimulating patient CD8 T-cell allo-rejection responses may critically limit allogeneic cellular therapy supported with IL-15. This trial was registered at www.clinicaltrials.gov as #NCT03050216 and #NCT01898793.

Molecular responses in decitabine- and decitabine/venetoclax-treated patients with acute myeloid leukemia and myelodysplastic syndromes.

Not available.

Immunosuppression and outcomes in adult patients with de novo acute myeloid leukemia with normal karyotypes.

Acute myeloid leukemia (AML) patients rarely have long first remissions (LFRs; >5 y) after standard-of-care chemotherapy, unless classified as favorable risk at presentation. Identification of the mechanisms responsible for long vs. more typical, standard remissions may help to define prognostic determinants for chemotherapy responses. Using exome sequencing, RNA-sequencing, and functional immunologic studies, we characterized 28 normal karyotype (NK)-AML patients with >5 y first remissions after chemotherapy (LFRs) and compared them to a well-matched group of 31 NK-AML patients who relapsed within 2 y (standard first remissions [SFRs]). Our combined analyses indicated that genetic-risk profiling at presentation (as defined by European LeukemiaNet [ELN] 2017 criteria) was not sufficient to explain the outcomes of many SFR cases. Single-cell RNA-sequencing studies of 15 AML samples showed that SFR AML cells differentially expressed many genes associated with immune suppression. The bone marrow of SFR cases had significantly fewer CD4+ Th1 cells; these T cells expressed an exhaustion signature and were resistant to activation by T cell receptor stimulation in the presence of autologous AML cells. T cell activation could be restored by removing the AML cells or blocking the inhibitory major histocompatibility complex class II receptor, LAG3. Most LFR cases did not display these features, suggesting that their AML cells were not as immunosuppressive. These findings were confirmed and extended in an independent set of 50 AML cases representing all ELN 2017 risk groups. AML cell-mediated suppression of CD4+ T cell activation at presentation is strongly associated with unfavorable outcomes in AML patients treated with standard chemotherapy.

Flotetuzumab as salvage immunotherapy for refractory acute myeloid leukemia.

Approximately 50% of acute myeloid leukemia (AML) patients do not respond to induction therapy (primary induction failure [PIF]) or relapse after <6 months (early relapse [ER]). We have recently shown an association between an immune-infiltrated tumor microenvironment (TME) and resistance to cytarabine-based chemotherapy but responsiveness to flotetuzumab, a bispecific DART antibody-based molecule to CD3ε and CD123. This paper reports the results of a multicenter, open-label, phase 1/2 study of flotetuzumab in 88 adults with relapsed/refractory AML: 42 in a dose-finding segment and 46 at the recommended phase 2 dose (RP2D) of 500 ng/kg per day. The most frequent adverse events were infusion-related reactions (IRRs)/cytokine release syndrome (CRS), largely grade 1-2. Stepwise dosing during week 1, pretreatment dexamethasone, prompt use of tocilizumab, and temporary dose reductions/interruptions successfully prevented severe IRR/CRS. Clinical benefit accrued to PIF/ER patients showing an immune-infiltrated TME. Among 30 PIF/ER patients treated at the RP2D, the complete remission (CR)/CR with partial hematological recovery (CRh) rate was 26.7%, with an overall response rate (CR/CRh/CR with incomplete hematological recovery) of 30.0%. In PIF/ER patients who achieved CR/CRh, median overall survival was 10.2 months (range, 1.87-27.27), with 6- and 12-month survival rates of 75% (95% confidence interval [CI], 0.450-1.05) and 50% (95% CI, 0.154-0.846). Bone marrow transcriptomic analysis showed that a parsimonious 10-gene signature predicted CRs to flotetuzumab (area under the receiver operating characteristic curve = 0.904 vs 0.672 for the European LeukemiaNet classifier). Flotetuzumab represents an innovative experimental approach associated with acceptable safety and encouraging evidence of activity in PIF/ER patients. This trial was registered at www.clinicaltrials.gov as #NCT02152956.

Acute Myeloid Leukemia, Version 3.2023, NCCN Clinical Practice Guidelines in Oncology.

Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy characterized by the clonal expansion of myeloid blasts in the peripheral blood, bone marrow, and/or other tissues. It is the most common form of acute leukemia among adults and accounts for the largest number of annual deaths from leukemias in the United States. Like AML, blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a myeloid malignancy. It is a rare malignancy characterized by the aggressive proliferation of precursors of plasmacytoid dendritic cells that frequently involves the bone marrow, skin, central nervous system, and other organs and tissues. This discussion section focuses on the diagnosis and management of BPDCN as outlined in the NCCN Guidelines for AML.

Ivosidenib induces deep durable remissions in patients with newly diagnosed IDH1-mutant acute myeloid leukemia.

Ivosidenib (AG-120) is an oral, targeted agent that suppresses production of the oncometabolite 2-hydroxyglutarate via inhibition of the mutant isocitrate dehydrogenase 1 (IDH1; mIDH1) enzyme. From a phase 1 study of 258 patients with IDH1-mutant hematologic malignancies, we report results for 34 patients with newly diagnosed acute myeloid leukemia (AML) ineligible for standard therapy who received 500 mg ivosidenib daily. Median age was 76.5 years, 26 patients (76%) had secondary AML, and 16 (47%) had received ≥1 hypomethylating agent for an antecedent hematologic disorder. The most common all-grade adverse events were diarrhea (n = 18; 53%), fatigue (n = 16; 47%), nausea (n = 13; 38%), and decreased appetite (n = 12; 35%). Differentiation syndrome was reported in 6 patients (18%) (grade ≥3 in 3 [9%]) and did not require treatment discontinuation. Complete remission (CR) plus CR with partial hematologic recovery (CRh) rate was 42.4% (95% confidence interval [CI], 25.5% to 60.8%); CR 30.3% (95% CI, 15.6% to 48.7%). Median durations of CR+CRh and CR were not reached, with 95% CI lower bounds of 4.6 and 4.2 months, respectively; 61.5% and 77.8% of patients remained in remission at 1 year. With median follow-up of 23.5 months (range, 0.6-40.9 months), median overall survival was 12.6 months (95% CI, 4.5-25.7). Of 21 transfusion-dependent patients (63.6%) at baseline, 9 (42.9%) became transfusion independent. IDH1 mutation clearance was seen in 9/14 patients achieving CR+CRh (5/10 CR; 4/4 CRh). Ivosidenib monotherapy was well-tolerated and induced durable remissions and transfusion independence in patients with newly diagnosed AML. This trial was registered at www.clinicaltrials.gov as #NCT02074839.

Clinical and molecular relevance of genetic variants in the non-coding transcriptome of patients with cytogenetically normal acute myeloid leukemia.

Expression levels of long non-coding RNA (lncRNA) have been shown to associate with clinical outcome of patients with cytogenetically normal acute myeloid leukemia (CN-AML). However, the frequency and clinical significance of genetic variants in the nucleotide sequences of lncRNA in AML patients is unknown. Herein, we analyzed total RNA sequencing data of 377 younger adults (aged <60 years) with CN-AML, who were comprehensively characterized with regard to clinical outcome. We used available genomic databases and stringent filters to annotate genetic variants unequivocally located in the non-coding transcriptome of AML patients. We detected 981 variants, which are recurrently present in lncRNA that are expressed in leukemic blasts. Among these variants, we identified a cytosine-to-thymidine variant in the lncRNA RP5-1074L1.4 and a cytosine-to-thymidine variant in the lncRNA SNHG15, which independently associated with longer survival of CN-AML patients. The presence of the SNHG15 cytosine-to-thymidine variant was also found to associate with better outcome in an independent dataset of CN-AML patients, despite differences in treatment protocols and RNA sequencing techniques. In order to gain biological insights, we cloned and overexpressed both wild-type and variant versions of the SNHG15 lncRNA. In keeping with its negative prognostic impact, overexpression of the wild-type SNHG15 associated with higher proliferation rate of leukemic blasts when compared with the cytosine-to-thymidine variant. We conclude that recurrent genetic variants of lncRNA that are expressed in the leukemic blasts of CN-AML patients have prognostic and potential biological significance.

BL-8040 CXCR4 antagonist is safe and demonstrates antileukemic activity in combination with cytarabine for the treatment of relapsed/refractory acute myelogenous leukemia: An open-label safety and efficacy phase 2a study.

BACKGROUND: CXCR4 mediates the retention and survival of acute myelogenous leukemia blasts in bone marrow and contributes to their resistance to chemotherapy. The authors evaluated a combination of the high-affinity CXCR4 antagonist BL-8040 with high-dose cytarabine (HiDAC) chemotherapy in a phase 2a study of patients with relapsed and refractory AML. METHODS: Forty-two patients received treatment with BL-8040 monotherapy for 2 days followed by a combination of BL-8040 with HiDAC for 5 days. Six escalating BL-8040 dose levels were investigated (0.5, 0.75, 1.0, 1.25, 1.5, and 2.0 mg/kg), and 1.5 mg/kg was selected as the dose for the expansion phase (n = 23). RESULTS: BL-8040 in combination with HiDAC was safe and well tolerated at all dose levels. Clinical response was observed with BL-8040 doses ≥1.0 mg/kg. The composite response rate (complete remissions plus complete remissions with incomplete hematologic recovery of platelets or neutrophils) was 29% (12 of 42) in all patients and 39% (9 of 23) in the 1.5-mg/kg phase. The median overall survival was 8.4 months for all patients, 10.8 months in the 1.5-mg/kg phase, and 21.8 months for responding patients in the 1.5-mg/kg cohort. Two days of BL-8040 monotherapy triggered the mobilization of blasts into peripheral blood, with significantly higher mean fold-changes in responders versus nonresponders. This was accompanied by a decrease in bone marrow blasts. CONCLUSIONS: The current results demonstrate the efficacy of CXCR4 targeting with BL-8040 and support continued clinical development in acute myelogenous leukemia.

Mutation Clearance after Transplantation for Myelodysplastic Syndrome.

BACKGROUND: Allogeneic hematopoietic stem-cell transplantation is the only curative treatment for patients with myelodysplastic syndrome (MDS). The molecular predictors of disease progression after transplantation are unclear. METHODS: We sequenced bone marrow and skin samples from 90 adults with MDS who underwent allogeneic hematopoietic stem-cell transplantation after a myeloablative or reduced-intensity conditioning regimen. We detected mutations before transplantation using enhanced exome sequencing, and we evaluated mutation clearance by using error-corrected sequencing to genotype mutations in bone marrow samples obtained 30 days after transplantation. In this exploratory study, we evaluated the association of a mutation detected after transplantation with disease progression and survival. RESULTS: Sequencing identified at least one validated somatic mutation before transplantation in 86 of 90 patients (96%); 32 of these patients (37%) had at least one mutation with a maximum variant allele frequency of at least 0.5% (equivalent to 1 heterozygous mutant cell in 100 cells) 30 days after transplantation. Patients with disease progression had mutations with a higher maximum variant allele frequency at 30 days than those who did not (median maximum variant allele frequency, 0.9% vs. 0%; P<0.001). The presence of at least one mutation with a variant allele frequency of at least 0.5% at day 30 was associated with a higher risk of progression (53.1% vs. 13.0%; conditioning regimen-adjusted hazard ratio, 3.86; 95% confidence interval [CI], 1.96 to 7.62; P<0.001) and a lower 1-year rate of progression-free survival than the absence of such a mutation (31.3% vs. 59.3%; conditioning regimen-adjusted hazard ratio for progression or death, 2.22; 95% CI, 1.32 to 3.73; P=0.005). The rate of progression-free survival was lower among patients who had received a reduced-intensity conditioning regimen and had at least one persistent mutation with a variant allele frequency of at least 0.5% at day 30 than among patients with other combinations of conditioning regimen and mutation status (P≤0.001). Multivariate analysis confirmed that patients who had a mutation with a variant allele frequency of at least 0.5% detected at day 30 had a higher risk of progression (hazard ratio, 4.48; 95% CI, 2.21 to 9.08; P<0.001) and a lower 1-year rate of progression-free survival than those who did not (hazard ratio for progression or death, 2.39; 95% CI, 1.40 to 4.09; P=0.002). CONCLUSIONS: The risk of disease progression was higher among patients with MDS in whom persistent disease-associated mutations were detected in the bone marrow 30 days after transplantation than among those in whom these mutations were not detected. (Funded by the Leukemia and Lymphoma Society and others.).

Durable Remissions with Ivosidenib in IDH1-Mutated Relapsed or Refractory AML.

BACKGROUND: Mutations in the gene encoding isocitrate dehydrogenase 1 ( IDH1) occur in 6 to 10% of patients with acute myeloid leukemia (AML). Ivosidenib (AG-120) is an oral, targeted, small-molecule inhibitor of mutant IDH1. METHODS: We conducted a phase 1 dose-escalation and dose-expansion study of ivosidenib monotherapy in IDH1-mutated AML. Safety and efficacy were assessed in all treated patients. The primary efficacy population included patients with relapsed or refractory AML receiving 500 mg of ivosidenib daily with at least 6 months of follow-up. RESULTS: Overall, 258 patients received ivosidenib and had safety outcomes assessed. Among patients with relapsed or refractory AML (179 patients), treatment-related adverse events of grade 3 or higher that occurred in at least 3 patients were prolongation of the QT interval (in 7.8% of the patients), the IDH differentiation syndrome (in 3.9%), anemia (in 2.2%), thrombocytopenia or a decrease in the platelet count (in 3.4%), and leukocytosis (in 1.7%). In the primary efficacy population (125 patients), the rate of complete remission or complete remission with partial hematologic recovery was 30.4% (95% confidence interval [CI], 22.5 to 39.3), the rate of complete remission was 21.6% (95% CI, 14.7 to 29.8), and the overall response rate was 41.6% (95% CI, 32.9 to 50.8). The median durations of these responses were 8.2 months (95% CI, 5.5 to 12.0), 9.3 months (95% CI, 5.6 to 18.3), and 6.5 months (95% CI, 4.6 to 9.3), respectively. Transfusion independence was attained in 29 of 84 patients (35%), and patients who had a response had fewer infections and febrile neutropenia episodes than those who did not have a response. Among 34 patients who had a complete remission or complete remission with partial hematologic recovery, 7 (21%) had no residual detectable IDH1 mutations on digital polymerase-chain-reaction assay. No preexisting co-occurring single gene mutation predicted clinical response or resistance to treatment. CONCLUSIONS: In patients with advanced IDH1-mutated relapsed or refractory AML, ivosidenib at a dose of 500 mg daily was associated with a low frequency of grade 3 or higher treatment-related adverse events and with transfusion independence, durable remissions, and molecular remissions in some patients with complete remission. (Funded by Agios Pharmaceuticals; ClinicalTrials.gov number, NCT02074839 .).

Acute Lymphoblastic Leukemia, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology.

The NCCN Guidelines for Acute Lymphoblastic Leukemia (ALL) focus on the classification of ALL subtypes based on immunophenotype and cytogenetic/molecular markers; risk assessment and stratification for risk-adapted therapy; treatment strategies for Philadelphia chromosome (Ph)-positive and Ph-negative ALL for both adolescent and young adult and adult patients; and supportive care considerations. Given the complexity of ALL treatment regimens and the required supportive care measures, the NCCN ALL Panel recommends that patients be treated at a specialized cancer center with expertise in the management of ALL This portion of the Guidelines focuses on the management of Ph-positive and Ph-negative ALL in adolescents and young adults, and management in relapsed settings.

A phase 1 study of the MDM2 antagonist RO6839921, a pegylated prodrug of idasanutlin, in patients with advanced solid tumors.

Purpose MDM2 is a negative regulator of the tumor suppressor p53. RO6839921 is an inactive pegylated prodrug of idasanutlin, an MDM2 antagonist, developed for intravenous administration. On cleavage by plasma esterases, the active principle (AP = idasanutlin) is released. This phase 1 study investigated the safety, pharmacokinetics, and pharmacodynamics of RO6839921 in patients with advanced solid tumors (NCT02098967). Methods Patients were evaluated on a 5-day dosing schedule every 28 days. Dose escalation used the Bayesian new continual reassessment model. Accelerated dose titration was permitted until grade ≥2 drug-related AEs were observed. The target DLT rate to define the MTD was 16-25%. p53 activation was assessed by measuring macrophage inhibitory cytokine-1 (MIC-1). Results Forty-one patients received 14-120 mg AP; 39 were DLT evaluable. The MTD was 110-mg AP (8% DLT rate), whereas 120-mg AP had a 44% DLT rate. DLTs were neutropenia, thrombocytopenia, and stridor. The most common treatment-related AEs (≥30%) were nausea, fatigue, vomiting, and thrombocytopenia. Pharmacokinetic analyses indicated rapid conversion of prodrug to AP and an approximately linear and dose-proportional dose-exposure relationship, with a 2-fold increase in exposure between Days 1 and 5 of AP. MIC-1 increases were exposure dependent. Stable disease was observed in 14 patients (34%). Conclusions RO6839921 showed reduced pharmacokinetic exposure variability and a safety profile comparable with that of oral idasanutlin. Although this study indicated that RO6839921 could be administered to patients, the results did not provide sufficient differentiation or improvement in the biologic or safety profile compared with oral idasanutlin to support continued development.

Phase 1 study of the MDM2 antagonist RO6839921 in patients with acute myeloid leukemia.

In acute myeloid leukemia (AML), TP53 mutations and dysregulation of wild-type p53 is common and supports an MDM2 antagonist as a therapy. RO6839921 is an inactive pegylated prodrug of the oral MDM2 antagonist idasanutlin (active principle [AP]) that allows for IV administration. This phase 1 monotherapy study evaluated the safety, pharmacokinetics, and pharmacodynamics of RO6839921 in patients with AML. Primary objectives identified dose-limiting toxicities (DLTs) and maximum tolerated dose (MTD). Secondary objectives assessed pharmacokinetic, pharmacodynamic, and antileukemic activity. A total of 26 patients received 120-300 mg AP of idasanutlin. The MTD was 200 mg, with DLTs at 250 (2/8 patients) and 300 mg (2/5). Treatment-related adverse events in >20% of patients were diarrhea, nausea, vomiting, decreased appetite, and fatigue. Six deaths (23.1%) occurred, all unrelated to treatment. Pharmacokinetics showed rapid and near-complete conversion of the prodrug to AP and dose-proportional exposure across doses. Variability ranged from 30%-47% (22%-54% for idasanutlin). TP53 was 21 (87.5%) wild-type and 3 mutant (12.5%). The composite response rate (complete remission [CR], CR with incomplete hematologic recovery/morphological leukemia-free state [CRi/MLFS], or CR without platelet recovery [CRp]) was 7.7%. Antileukemic activity (CR, CRi/MLFS, partial response, hematologic improvement/stable disease) was observed in 11 patients (disease control rate, 42%): 10/11 were TP53 wild-type; 1 had no sample. p53 activation was demonstrated by MIC-1 induction and was associated with AP exposure. There was not sufficient differentiation or improvement in the biologic or safety profile compared with oral idasanutlin to support continued development of RO6839921. NCT02098967.

The effect of donor type on outcomes in adults with acute myeloid leukemia after reduced-intensity hematopoietic peripheral blood cell transplant - a retrospective study.

We retrospectively analyzed outcomes in patients with acute myeloid leukemia (AML) receiving reduced-intensity conditioning (RIC) hematopoietic stem cell transplants (HCT) from a peripheral blood (PB) source. We identified 46 haploidentical HCT (haplo), 59 matched unrelated donor HCT (MUD), and 40 matched related donor HCT (SIB) patients at a single institution. Haplo had improved overall survival (OS) when compared to MUD, HR 2.03 (P = 0.01) but not SIB, HR 1.17 (P = 0.61). There were no differences in relapse rates or treatment-related mortality (TRM). Haplo had higher rates of acute graft-versus-host disease (GVHD) grade II-IV at day 180 than MUD (44% vs. 25%, P = 0.03) and SIB (44% vs. 13% P < 0.01). Rates of acute GVHD III-IV and chronic GVHD were similar among the groups. Haplo had slower engraftment rates compared to MUD with neutrophil engraftment at 87% vs. 93%, (P < 0.01) and platelet engraftment at 59% vs. 86%, (P < 0.01) at 28 days. Although patients receiving haplo had higher acute GVHD II-IV and slower engraftment, they did not have increased TRM. These data may suggest that patients receiving haplo have improved OS compared to MUD for AML patients receiving RIC transplants. This should be confirmed using a larger cohort.

TP53 and Decitabine in Acute Myeloid Leukemia and Myelodysplastic Syndromes.

BACKGROUND: The molecular determinants of clinical responses to decitabine therapy in patients with acute myeloid leukemia (AML) or myelodysplastic syndromes (MDS) are unclear. METHODS: We enrolled 84 adult patients with AML or MDS in a single-institution trial of decitabine to identify somatic mutations and their relationships to clinical responses. Decitabine was administered at a dose of 20 mg per square meter of body-surface area per day for 10 consecutive days in monthly cycles. We performed enhanced exome or gene-panel sequencing in 67 of these patients and serial sequencing at multiple time points to evaluate patterns of mutation clearance in 54 patients. An extension cohort included 32 additional patients who received decitabine in different protocols. RESULTS: Of the 116 patients, 53 (46%) had bone marrow blast clearance (<5% blasts). Response rates were higher among patients with an unfavorable-risk cytogenetic profile than among patients with an intermediate-risk or favorable-risk cytogenetic profile (29 of 43 patients [67%] vs. 24 of 71 patients [34%], P<0.001) and among patients with TP53 mutations than among patients with wild-type TP53 (21 of 21 [100%] vs. 32 of 78 [41%], P<0.001). Previous studies have consistently shown that patients with an unfavorable-risk cytogenetic profile and TP53 mutations who receive conventional chemotherapy have poor outcomes. However, in this study of 10-day courses of decitabine, neither of these risk factors was associated with a lower rate of overall survival than the rate of survival among study patients with intermediate-risk cytogenetic profiles. CONCLUSIONS: Patients with AML and MDS who had cytogenetic abnormalities associated with unfavorable risk, TP53 mutations, or both had favorable clinical responses and robust (but incomplete) mutation clearance after receiving serial 10-day courses of decitabine. Although these responses were not durable, they resulted in rates of overall survival that were similar to those among patients with AML who had an intermediate-risk cytogenetic profile and who also received serial 10-day courses of decitabine. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT01687400 .).

Mobilization of allogeneic peripheral blood stem cell donors with intravenous plerixafor mobilizes a unique graft.

A single subcutaneous (SC) injection of plerixafor results in rapid mobilization of hematopoietic progenitors, but fails to mobilize 33% of normal allogeneic sibling donors in 1 apheresis. We hypothesized that changing the route of administration of plerixafor from SC to IV may overcome the low stem cell yields and allow collection in 1 day. A phase 1 trial followed by a phase 2 efficacy trial was conducted in allogeneic sibling donors. The optimal dose of IV plerixafor was determined to be 0.32 mg/kg. The primary outcome of reducing the failure to collect ≥2 × 106 CD34+/kg recipient weight in 1 apheresis collection to ≤10% was not reached. The failure rate was 34%. Studies evaluating the stem cell phenotype and gene expression revealed a novel plasmacytoid dendritic cell precursor preferentially mobilized by plerixafor with high interferon-α producing ability. The observed cytomegalovirus (CMV) viremia rate for patients at risk was low (15%), as were the rates of acute grade 2-4 graft-versus-host disease (GVHD) (21%). Day 100 treatment related mortality was low (3%). In conclusion, plerixafor results in rapid stem cell mobilization regardless of route of administration and resulted in novel cellular composition of the graft and favorable recipient outcomes. These trials were registered at clinicaltrials.gov as #NCT00241358 and #NCT00914849.