IDH Mutant Myeloid Neoplasms are Associated with Seronegative Rheumatoid Arthritis and Innate Immune Activation

High prevalence of IDH-mutations in seronegative rheumatoid arthritis (RA) with myeloid neoplasm, elevated 2-hydroxyglutarate, dysregulated innate immunity and pro-inflammatory microenvironment, suggests causative association between IDH-mutations and seronegative RA. Our findings merit investigation of IDH-inhibitors as therapeutics for seronegative IDH-mutated RA.

Targeting Molecular Measurable Residual Disease and Low-Blast Relapse in AML With Venetoclax and Low-Dose Cytarabine: A Prospective Phase II Study (VALDAC)

PURPOSE

A prospective phase II study examined the safety and efficacy of venetoclax combined with low-dose cytarabine (LDAC) in AML at first measurable residual disease (MRD) or oligoblastic relapse.

METHODS

Patients with either MRD (≥1 log10 rise) or oligoblastic relapse (blasts 5%-15%) received venetoclax 600 mg once daily D1-28 plus LDAC once daily D1-10 in 28-day cycles. The primary objective was MRD response in the MRD relapse cohort or complete remission (CR/CRh/CRi) in the oligoblastic relapse cohort.

RESULTS

Forty-eight adults with either MRD (n = 26) or oligoblastic (n = 22) relapse were enrolled. Median age was 67 years (range, 18-80) and 94% had received previous intensive chemotherapy. Patients received a median of four cycles of therapy; 17% completed ≥12 cycles. Patients with oligoblastic relapse had more grade ≥3 anemia (32% v 4%; P = .02) and infections (36% v 8%; P = .03), whereas grade 4 neutropenia (32 v 23%) or thrombocytopenia (27 v 15%) were comparable with the MRD relapse cohort. Markers of molecular MRD relapse included mutant NPM1 (77%), CBFB::MYH11 (4%), RUNX1::RUNX1T1 (4%), or KMT2A::MLLT3 (4%). Three patients with a log10 rise in IDH1/2 (12%) were included. By cycle 2 in the MRD relapse cohort, a log10 reduction in MRD was observed in 69%; 46% achieved MRD negative remission. In the oligoblastic relapse cohort, 73% achieved CR/CRh/CRi. Overall, 21 (44%) underwent hematopoietic cell transplantation. Median overall survival (OS) was not reached in either cohort. Estimated 2-year OS rate was 67% (95% CI, 50 to 89) in the MRD and 53% (95% CI, 34 to 84) in the oligoblastic relapse cohorts.

CONCLUSION

For AML in first remission and either MRD or oligoblastic relapse, venetoclax plus LDAC is well tolerated and highly effective.

Special Issue "Advances in Molecular Pathogenesis and Targeted Therapies for Myeloid Neoplasms"

Myeloid neoplasms (MNs) constitute a diverse group of haematological malignancies that includes myelodysplastic neoplasms (MDS), myeloproliferative neoplasms (MPN), MDS/MPN overlap syndrome, and acute myeloid leukaemia (AML) [...].

Efficacy and safety of avatrombopag in combination with immunosuppressive therapy in treatment-naïve and relapsed/refractory severe aplastic anaemia: protocol for the DIAAMOND-Ava-FIRST and DIAAMOND-Ava-NEXT Bayesian Optimal Phase II trials

INTRODUCTION

Immunosuppressive therapy (IST) with antithymocyte globulin (ATG) and ciclosporin is standard of care for patients with severe aplastic anaemia (sAA) not eligible or suitable for allogeneic stem cell transplant. While patients respond to IST, few achieve complete responses and a significant proportion are refractory or relapse. The addition of eltrombopag, a thrombopoietin-receptor agonist (TPO-A), to IST has been shown to improve haematological responses in sAA. Avatrombopag is a second-generation TPO-A with potential advantages over eltrombopag. However, to date avatrombopag has not been studied in sAA.

METHODS AND ANALYSIS

Investigator-initiated, single-arm registry-based Bayesian Optimal Phase II trial of avatrombopag conducted in two cohorts, patients with untreated sAA (FIRST cohort) and in patients with sAA that has relapsed or is refractory to IST (NEXT cohort). In the FIRST cohort, participants receive IST (equine ATG and ciclosporin) plus avatrombopag from day 1 until day 180 at 60 mg oral daily, with dose adjusted according to platelet count. Participants in the NEXT cohort receive avatrombopag at 60 mg oral daily from day 1 until day 180, with or without additional IST at the discretion of the treating clinician.For each cohort, two primary endpoints (haematological response and acquired clonal evolution) are jointly monitored and the trial reviewed at each interim analysis where a 'go/no-go' decision is made by evaluating the posterior probability of the events of interests.

ETHICS AND DISSEMINATION

The trial has received ethics approval (Monash Health RES-18-0000707A). The trial conduct will comply with ICH-GCP and all applicable regulatory requirements. The results of the trial will be submitted to a peer-review journal for publication.

TRIAL REGISTRATION NUMBER

ACTRN12619001042134, ACTRN12619001043123.

Sorafenib plus intensive chemotherapy in newly diagnosed FLT3-ITD AML: a randomized, placebo-controlled study by the ALLG

Sorafenib maintenance improves outcomes after hematopoietic cell transplant (HCT) for patients with FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) acute myeloid leukemia (AML). Although promising outcomes have been reported for sorafenib plus intensive chemotherapy, randomized data are limited. This placebo-controlled, phase 2 study (ACTRN12611001112954) randomized 102 patients (aged 18-65 years) 2:1 to sorafenib vs placebo (days 4-10) combined with intensive induction: idarubicin 12 mg/m2 on days 1 to 3 plus either cytarabine 1.5 g/m2 twice daily on days 1, 3, 5, and 7 (18-55 years) or 100 mg/m2 on days 1 to 7 (56-65 years), followed by consolidation and maintenance therapy for 12 months (post-HCT excluded) in newly diagnosed patients with FLT3-ITD AML. Four patients were excluded in a modified intention-to-treat final analysis (3 not commencing therapy and 1 was FLT3-ITD negative). Rates of complete remission (CR)/CR with incomplete hematologic recovery were high in both arms (sorafenib, 78%/9%; placebo, 70%/24%). With 49.1-months median follow-up, the primary end point of event-free survival (EFS) was not improved by sorafenib (2-year EFS 47.9% vs 45.4%; hazard ratio [HR], 0.87; 95% confidence interval [CI], 0.51-1.51; P = .61). Two-year overall survival (OS) was 67% in the sorafenib arm and 58% in the placebo arm (HR, 0.76; 95% CI, 0.42-1.39). For patients who received HCT in first remission, the 2-year OS rates were 84% and 67% in the sorafenib and placebo arms, respectively (HR, 0.45; 95% CI, 0.18-1.12; P = .08). In exploratory analyses, FLT3-ITD measurable residual disease (MRD) negative status (<0.001%) after induction was associated with improved 2-year OS (83% vs 60%; HR, 0.4; 95% CI, 0.17-0.93; P = .028). In conclusion, routine use of pretransplant sorafenib plus chemotherapy in unselected patients with FLT3-ITD AML is not supported by this study.

The Australian Aplastic Anaemia and other Bone Marrow Failure Syndromes Registry

The bone marrow failure syndromes (BMFS) are a diverse group of acquired and inherited diseases which may manifest in cytopenias, haematological malignancy and/or syndromic multisystem disease. Patients with BMFS frequently experience poor outcomes, and improved treatment strategies are needed. Collation of clinical characteristics and patient outcomes in a national disease-specific registry represents a powerful tool to identify areas of need and support clinical and research collaboration. Novel treatment strategies such as gene therapy, particularly in rare diseases, will depend on the ability to identify eligible patients alongside the molecular genetic features of their disease that may be amenable to novel therapy. The Australian Aplastic Anaemia and other Bone Marrow Failure Syndromes Registry (AAR) aims to improve outcomes for all paediatric and adult patients with BMFS in Australia by describing the demographics, treatments (including supportive care) and outcomes, and serving as a resource for research and practice improvement.

Case report: Rare case of donor cell-derived T-cell acute lymphoblastic leukaemia in a female patient after receiving an allo-transplant from her male sibling

Donor-derived haematological neoplasms, in which recipients present with haematological malignancies that have evolved from transplant donor stem cells, have previously been described for myelodysplastic syndrome, myeloproliferative neoplasms, acute myeloid leukaemia and less often, leukaemias of lymphoid origin. Here we describe a rare and complex case of donor-derived T-cell acute lymphoblastic leukaemia with a relatively short disease latency of less than 4 years. Through genomic and in vitro analyses, we identified novel mutations in NOTCH1 as well as a novel activating mutation in STAT5B; the latter targetable with the clinically available drugs, venetoclax and ruxolitinib.

Olutasidenib (FT-2102) induces durable complete remissions in patients with relapsed or refractory IDH1-mutated AML

Olutasidenib (FT-2102) is a potent, selective, oral, small-molecule inhibitor of mutant isocitrate dehydrogenase 1 (mIDH1). Overall, 153 IDH1 inhibitor-naive patients with mIDH1R132 relapsed/refractory (R/R) acute myeloid leukemia (AML) received olutasidenib monotherapy 150 mg twice daily in the pivotal cohort of this study. The median age of participants was 71 years (range, 32-87 years) and the median number of prior regimens received by patients was 2 (1-7). The rate of complete remission (CR) plus CR with partial hematologic recovery (CRh) was 35%, and the overall response rate was 48%. Response rates were similar in patients who had, and who had not, received prior venetoclax. With 55% of patients censored at the time of data cut-off, the median duration of CR/CRh was 25.9 months. The median duration of overall response was 11.7 months, and the median overall survival was 11.6 months. Of 86 patients who were transfusion dependent at baseline, a 56-day transfusion independence was achieved in 29 (34%), which included patients in all response groups. Grade 3 or 4 treatment-emergent adverse events (≥10%) were febrile neutropenia and anemia (n = 31; 20% each), thrombocytopenia (n = 25; 16%), and neutropenia (n = 20; 13%). Differentiation syndrome adverse events of special interest occurred in 22 (14%) patients, with 14 (9%) grade ≥3 and 1 fatal case reported. Overall, olutasidenib induced durable remissions and transfusion independence with a well-characterized and manageable side effect profile. The observed efficacy represents a therapeutic advance in this molecularly defined, poor-prognostic population of patients with mIDH1 R/R AML. This trial was registered at www.clinicaltrials.gov as #NCT02719574.

Factors predicting survival following alloSCT in patients with therapy-related AML and MDS: a multicenter study

Therapy-related myeloid neoplasms (t-MN) are aggressive myeloid neoplasms. Factors predicting post-allogeneic stem cell transplant (alloSCT) survival are not well-known. We studied the prognostic utility of factors at: t-MN diagnosis, pre-alloSCT, and post-alloSCT. Primary endpoints were 3-year overall survival (OS), relapse incidence (RI), and non-relapse mortality (NRM). Post-alloSCT OS did not differ between t-MDS and t-AML (20.1 vs. 19.6 months, P = 1), though t-MDS had a significantly higher 3-year RI compared to t-AML (45.1% vs. 26.9%, P = 0.03). In t-MDS, the presence of monosomy 5 (HR 3.63, P = 0.006) or monosomy 17 (HR 11.81, P = 0.01) pre-alloSCT were associated with higher RI. Complex karyotype was the only factor adversely influencing survival at all the timepoints. The inclusion of genetic information yielded 2 risk-categories: high-risk defined by the presence of pathogenic variants (PV) in (TP53/BCOR/IDH1/GATA2/BCORL1) and standard-risk (remainder of the patients) with 3-year post-alloSCT OS of 0% and 64.6%, respectively (P = 0.001). We concluded that while alloSCT was curative in a subset of t-MN patients, outcomes remained poor, specifically in the high-risk category. t-MDS patients, especially those with persistent disease pre-alloSCT were at increased risk of relapse. Disease-related factors at t-MN diagnosis were the most prognostic of post-alloSCT survival; utility of factors available later in the course, was incremental.

TP53 mutation variant allele frequency of ≥10% is associated with poor prognosis in therapy-related myeloid neoplasms

Revised diagnostic criteria for myeloid neoplasms (MN) issued by the International Consensus Classification (ICC) and the World Health Organization (WHO) recommended major change pertaining to TP53-mutated (TP53mut) MN. However, these assertions have not been specifically examined in therapy-related myeloid neoplasm (t-MN), a subset enriched with TP53mut. We analyzed 488 t-MN patients for TP53mut. At least one TP53mut with variant allele frequency (VAF) ≥ 2% with or without loss of TP53 locus was noted in 182 (37.3%) patients and 88.2% of TP53mut t-MN had a VAF ≥10%. TP53mut t-MN with VAF ≥ 10% had a distinct clinical and biological profile compared to both TP53mut VAF < 10% and wild-type TP53 (TP53wt) cases. Notably, TP53mut VAF ≥ 10% had a significantly shorter survival compared to TP53wt (8.3 vs. 21.6 months; P < 0.001), while the survival of TP53mut VAF < 10% was comparable to TP53wt. Within TP53mut VAF ≥ 10% cohort, the inferior outcomes persisted irrespective of the single- or multi-hit status, co-mutation pattern, or treatments received. Finally, survival of TP53mut patients was poor across all the blast categories and MDS patients with >10% blasts had inferior survival compared to <5%. In summary, TP53mut VAF ≥10% signified a clinically and molecularly homogenous cohort regardless of the allelic status.

Role of Germline Predisposition to Therapy-Related Myeloid Neoplasms

PURPOSE OF REVIEW

Therapy-related myeloid neoplasms (t-MNs) are aggressive leukemias that develop following exposure to DNA-damaging agents. A subset of patients developing t-MN may have an inherited susceptibility to develop myeloid neoplasia. Herein, we review studies reporting t-MN and their association with a germline or inherited predisposition.

RECENT FINDINGS

Emerging evidence suggests that development of t-MN is the result of complex interactions including generation of somatic variants in hematopoietic stem cells and/or clonal selection pressure exerted by the DNA-damaging agents, and immune evasion on top of any inherited genetic susceptibility. Conventionally, alkylating agents, topoisomerase inhibitors, and radiation have been associated with t-MN. Recently, newer modalities including poly (ADP-ribose) polymerase inhibitors (PARPi) and peptide receptor radionucleotide therapy (PRRT) are associated with t-MN. At the same time, the role of pathogenic germline variants (PGVs) in genes such as BRCA1/2, BARD1, or TP53 on the risk of t-MN is being explored. Moreover, studies have shown that while cytotoxic therapy increases the risk of developing myeloid neoplasia, it may be exposing the vulnerability of an underlying germline predisposition. t-MN remains a disease with poor prognosis. Studies are needed to better define an individual's inherited neoplastic susceptibility which will help predict the risk of myeloid neoplasia in the future. Understanding the genes driving the inherited neoplastic susceptibility will lead to better patient- and cancer-specific management including choice of therapeutic regimen to prevent, or at least delay, development of myeloid neoplasia after treatment of a prior malignancy.

Clinical impact of NPM1-mutant molecular persistence after chemotherapy for acute myeloid leukemia

Monitoring of NPM1 mutant (NPM1mut) measurable residual disease (MRD) in acute myeloid leukemia (AML) has an established role in patients who are treated with intensive chemotherapy. The European LeukemiaNet has defined molecular persistence at low copy number (MP-LCN) as an MRD transcript level <1% to 2% with a <1-log change between any 2 positive samples collected after the end of treatment (EOT). Because the clinical impact of MP-LCN is unknown, we sought to characterize outcomes in patients with persistent NPM1mut MRD after EOT and identify factors associated with disease progression. Consecutive patients with newly diagnosed NPM1mut AML who received ≥2 cycles of intensive chemotherapy were included if bone marrow was NPM1mut MRD positive at the EOT, and they were not transplanted in first complete remission. One hundred patients were followed for a median of 23.5 months; 42% remained free of progression at 1 year, either spontaneously achieving complete molecular remission (CRMRD-; 30%) or retaining a low-level NPM1mut transcript (12% for ≥12 months and 9% at last follow-up). Forty percent met the criteria for MP-LCN. Preemptive salvage therapy significantly prolonged relapse-free survival. Risk factors associated with disease progression were concurrent FLT3-internal tandem duplication at diagnosis and suboptimal MRD response (NPM1mut reduction <4.4-log) at EOT.

Outcomes and health care utilization of older patients with acute myeloid leukemia

BACKGROUND

The incidence of acute myeloid leukemia (AML) in older patients is increasing, but practice guidelines balancing quality-of-life, time outside of hospital and overall survival (OS) are not established.

METHODS

We conducted a retrospective analysis comparing time outside hospital, OS and end-of-life care in AML patients ≥60 years treated with intensive chemotherapy (IC), hypomethylating agents (HMA) and best supportive care (BSC) in a tertiary hospital.

RESULTS

Of 201 patients diagnosed between 2005 and 2015, 54% received IC while 14% and 32% were treated with HMA and BSC respectively. Median OS was significantly higher in patients treated with IC and HMA compared with BSC (11.5 versus 16.2 versus 1.3 months; p < .0001). Median number of hospital admissions for the entire cohort was 3 (1-17) and patients spent <50% of their life after the diagnosis in the hospital setting. Compared to BSC, IC (HR 0.27, p < .0001) and HMA therapy (HR 0.16, p < .0001) were associated with the lower likelihood of spending at least 25% of survival time in hospital. Although 66% patients were referred to palliative care, the interval between referral to death was 24 (1-971) days and 46% patients died in the hospital.

CONCLUSION

Older patients with AML, irrespective of treatment, require intensive health care resources, are more likely to die in hospital and less likely to use hospice services. Older AML patients treated with disease modifying therapy survive longer than those receiving BSC, and spend >50% of survival time outside the hospital. These data are informative for counselling older patients with AML.

Respiratory Viruses Cause Late Morbidity in Recipients of Hematopoietic Stem Cell Transplantation

Common respiratory viral infections (CRVIs) frequently complicate hematopoietic stem cell transplantation (HSCT). We conducted a retrospective, single-center, observational cohort study to determine the incidence of CRVI in patients who received an allogeneic (allo) or autologous (auto) HSCT at the Royal Adelaide Hospital between 2009 and 2017. The median follow-up was 8.9 and 4.5 years for auto- and allo-HSCT recipients, respectively. There were 149 CRVI episodes in 74 patients, with rhinovirus being the most commonly isolated virus (n = 81, 47%). The majority of CRVIs (113/149, 75.8%) occurred more than 100 days post-HSCT and 67% were diagnosed in the outpatient setting. There was evidence of lower respiratory tract infection (LRTI) in 45.6% (68/149) of CRVIs. On multivariate logistic regression analysis, coviral infections and cytomegalovirus viremia were independent risk factors for progression of CRVI to LRTI. Ten (6.7%) CRVI episodes resulted in admission to intensive care for ventilatory support and 8 (5.4%) patients died within 30 days of CRVI diagnosis. In our study, 10.4% of HSCT recipients experienced a CRVI post-transplant, primarily causing late morbidity and potentially mortality. Prevention with strict infection control practices, vaccination, and patient education is essential.

Clinical Effectiveness of Conjugate Pneumococcal Vaccination in Hematopoietic Stem Cell Transplantation Recipients

Hematopoietic stem cell transplantation (HSCT) recipients are vulnerable to invasive pneumococcal disease (IPD), with reported IPD rates ranging from 3.81 to 22.5/1000 HSCT. This IPD risk could relate to immunodeficiency, low vaccination uptake, and poor immunogenicity of pneumococcal polysaccharide vaccine (PPV). Literature comparing the clinical effectiveness of pneumococcal conjugate vaccination (PCV) and PPV after HSCT is limited. In this retrospective analysis of HSCT recipients at our center from 2004 to 2015, we evaluated vaccination uptake and compared IPD rates in patients receiving PPV (pre-2010 group) and PCV (post-2010 group). IPD was determined from microbiological results for all HSCT recipients from January 2004 to June 30, 2019. Eight hundred patients had a total of 842 HSCT events, including autologous HSCT (auto-HSCT; n = 562) and allogeneic HSCT (allo-HSCT; n = 280). More than 90% of the HSCT recipients were enrolled, and >93% of surviving HSCT recipients completed the vaccination protocol. Fifteen IPD episodes occurred in 13 patients between 2004 and June 30, 2019. Thirteen episodes occurred in the pre-2010 group, even though 9 of 13 (69%) serotyped isolates were covered by PPV. Two episodes occurred in the post-2010 group; neither serotype was covered by PCV. Thus, with PCV introduction, IPD rate was significantly reduced from 38.5/1000 unique HSCTs pre-2010 to 4.0/1000 unique HSCTs post-2010 (P < .001). A significant reduction was seen in both auto-HSCTs (from 29.4 to 3.1 /1000 unique auto-HSCTs; P = .011) and allo-HSCTs (from 58.3 to 5.6/1000 unique allo-HSCTs; P = .011). PCV demonstrated superior clinical effectiveness over PPV, highlighting its importance in preventing infectious complications after HSCT. Robust vaccination programs at transplantation centers are needed to optimize vaccination uptake and completion.

1572. Conjugate Pneumococcal Vaccination Reduces Invasive Pneumococcal Disease Post Haemotopoietic Stem Cell Transplant

Background

Immunosuppressed patients, especially haematopoietic stem cell transplant (HSCT) recipients, are particularly vulnerable to invasive pneumococcal disease (IPD). However, uptake of pneumococcal vaccination tends to be lower in the immunosuppressed, partly due to concerns of vaccine effectiveness. Our institution introduced protocolised 10- or 13-valent conjugate pneumococcal vaccination (PCV) to all allogeneic and autologous HSCT recipients in 2010 to replace routine 23-valent polysaccharide vaccine (PPV23).

Methods

We conducted a retrospective single-centre observational study of all HSCT recipients from 2004 to 2015 to assess the impact of PCV introduction on IPD incidence. All HSCT recipients were reviewed for microbiological evidence of IPD following HSCT. The pre-2010 group of HSCT recipients who did not receive PCV, were compared with the post-2010 group of HSCT recipients who did receive PCV. Enrolment and compliance with the post-HSCT vaccination protocol was assessed.

Results

Of the 917 HSCT screened for IPD, 14 episodes of IPD occurred in 12 patients between 2004 and 2016. Twelve episodes occurred in the pre-2010 group, 40% of serotyped isolates would have been covered by PCV. Two episodes occurred in the post-2010 group, neither isolate serotype was covered by PCV. There was >90% enrolment and vaccination protocol completion for surviving HSCT recipients. Overall IPD rate reduced significantly from 31.9/1,000 transplants pre-2010, to 3.7/1,000 transplants post-2010 group (P < 0.05). Specific reductions occurred in the autologous transplant group from 26.2 to 2.8/1,000 transplants (P < 0.05) and the allogeneic transplant group from 45.5 to 5.3/1,000 transplants (P < 0.05).

Conclusion

Introduction of PCV resulted in a significant reduction in IPD among our high-risk cohort, demonstrating clinical effectiveness of PCV in HSCT recipients and confirming immunogenicity data. To our knowledge, this is the first study to demonstrate the clinical effectiveness of PCV in this group, highlighting the importance of this vaccination to prevent infectious complications following allogeneic and autologous HSCT. The clinical effectiveness of PCV vaccine is enhanced by the high quality of our post-HSCT vaccination program.

Disclosures

All authors: No reported disclosures.

Red cell alloimmunization is associated with development of autoantibodies and increased red cell transfusion requirements in myelodysplastic syndrome

Up to 90% of patients with a myelodysplastic syndrome require red blood cell transfusion; nevertheless, comprehensive data on red cell alloimmunization in such patients are limited. This study evaluates the incidence and clinical impact of red cell alloimmunization in a large cohort of patients with myelodysplastic syndrome registered in the statewide South Australian-MDS registry. The median age of the 817 patients studied was 73 years, and 66% were male. The cumulative incidence of alloimmunization was 11%. Disease-modifying therapy was associated with a lower risk of alloimmunization while alloimmunization was significantly higher in patients with a revised International Prognostic Scoring System classification of Very Low, Low or Intermediate risk compared to those with a High or Very High risk (P=0.03). Alloantibodies were most commonly directed against antigens in the Rh (54%) and Kell (24%) systems. Multiple alloantibodies were present in 49% of alloimmunized patients. Although 73% of alloimmunized patients developed alloantibodies during the period in which they received their first 20 red cell units, the total number of units transfused was significantly higher in alloimmunized patients than in non-alloimmunized patients (90±100 versus 30±52; P<0.0001). In individual patients, red cell transfusion intensity increased significantly following alloimmunization (2.8±1.3 versus 4.1±2.0; P<0.0001). A significantly higher proportion of alloimmunized patients than non-alloimmunized patients had detectable autoantibodies (65% versus 18%; P<0.0001) and the majority of autoantibodies were detected within a short period of alloimmunization. In conclusion, this study characterizes alloimmunization in a large cohort of patients with myelodysplastic syndrome and demonstrates a signficant increase in red cell transfusion requirements following alloimmunization, most probably due to development of additional alloantibodies and autoantibodies, resulting in subclinical/clinical hemolysis. Strategies to mitigate alloimmunization risk are critical for optimizing red cell transfusion support.

Dynamic assessment of RBC-transfusion dependency improves the prognostic value of the revised-IPSS in MDS patients

RBC-transfusion dependency (RBC-TD) is an independent prognostic factor for poor overall survival (OS) in the WHO classification-based prognostic scoring system (WPSS) for MDS patients. However, WPSS did not include cytopenia, whereas revised International Prognostic Scoring System (IPSS-R) did not include RBC-TD. Thus, neither of these prognostic scoring systems incorporates both cytopenia and RBC-TD. We aimed to test whether RBC-TD adds prognostic value to the IPSS-R. We analyzed MDS patients not treated with disease-modifying therapy, and enrolled in SA-MDS Registry (derivation cohort; n = 295) and Dusseldorf registry (Germany; validation cohort; n = 113) using time-dependent Cox proportional regression and serial landmark analyses. In the derivation cohort, RBC-TD patients had inferior OS compared to RBC transfusion-independent (RBC-TI) patients (P < 0.0001) at 6- (18 vs. 64 months), 12- (24 vs. 71 months), and 24-months (40 vs. 87 months). In a Cox proportional regression analysis, RBC-TD was an independent adverse prognostic marker in addition to age, sex, and IPSS-R variables (P < 0.0001). A prognostic index (PI) was derived using these Cox-proportional regression model variables. In the validation cohort, this PI classified patients into four prognostic groups with significantly different OS (P < 0.001) as in the derivation cohort. In conclusion, multivariate analysis by Cox proportional hazards regression and serial landmark analyses clearly demonstrates that development of RBC-TD at any time during the course of MDS is associated with poor OS, independent of IPSS-R. This study demonstrates that dynamic assessment of RBC-TD provides additional prognostic value to IPSS-R and should be included in treatment decision algorithms for MDS patients.

Splice factor mutations and alternative splicing as drivers of hematopoietic malignancy

Differential splicing contributes to the vast complexity of mRNA transcripts and protein isoforms that are necessary for cellular homeostasis and response to developmental cues and external signals. The hematopoietic system provides an exquisite example of this. Recently, discovery of mutations in components of the spliceosome in various hematopoietic malignancies (HMs) has led to an explosion in knowledge of the role of splicing and splice factors in HMs and other cancers. A better understanding of the mechanisms by which alternative splicing and aberrant splicing contributes to the leukemogenic process will enable more efficacious targeted approaches to tackle these often difficult to treat diseases. The clinical implications are only just starting to be realized with novel drug targets and therapeutic strategies open to exploitation for patient benefit.

Dasatinib targets chronic myeloid leukemia-CD34+ progenitors as effectively as it targets mature cells

Dasatinib is effective in most chronic phase chronic myeloid leukemia patients both in first-line therapy and following imatinib failure. While imatinib uptake into CD34(+) cells is low compared to mononuclear cells, few data evaluate how well dasatinib targets primitive CML cells. This study compares intracellular concentration of dasatinib and Bcr-Abl kinase inhibition in CML-CD34(+) progenitors and mononuclear cells induced by dasatinib. The intracellular concentrations of dasatinib were similar between CML-CD34(+) and mononuclear cells (P=0.8). Similarly, there was no significant difference in the degree of dasatinib-mediated Bcr-Abl kinase inhibition. ABCB1 (MDR1) and ABCG2 inhibitors neither increased dasatinib intracellular concentration nor enhanced dasatinib-mediated Bcr-Abl kinase inhibition. In contrast to nilotinib, we show that dasatinib is not an ABCB1 inhibitor. Thus, dasatinib targets CML-CD34(+) progenitors as effectively as it targets mononuclear cells. ABCB1 and ABCG2 efflux pumps do not appear to influence the intracellular dasatinib concentration in CML-CD34(+) progenitors.

Blocking cytokine signaling along with intense Bcr-Abl kinase inhibition induces apoptosis in primary CML progenitors

In chronic myeloid leukemia (CML) cell lines, brief exposure to pharmacologically relevant dasatinib concentrations results in apoptosis. In this study, we assess the impact of intensity and duration of Bcr-Abl kinase inhibition on primary CD34(+) progenitors of chronic phase CML patients. As CML cells exposed to dasatinib in vivo are in a cytokine-rich environment, we also assessed the effect of cytokines (six growth factors cocktail or granulocyte-macrophage colony-stimulating factor (CSF) or granulocyte-CSF) in combination with dasatinib. In the presence of cytokines, short-term intense Bcr-Abl kinase inhibition (>or=90% p-Crkl inhibition) with 100 nM dasatinib did not reduce CD34(+) colony-forming cells (CFCs). In contrast, without cytokines, short-term exposure to dasatinib reduced CML-CD34(+) CFCs by 70-80%. When cytokines were added immediately after short-term exposure to dasatinib, CML-CD34(+) cells remained viable, suggesting that oncogene dependence of these cells can be overcome by concomitant or subsequent exposure to cytokines. Additional inhibition of Janus tyrosine kinase (Jak) activity re-established the sensitivity of CML progenitors to intense Bcr-Abl kinase inhibition despite the presence of cytokines. These findings support the contention that therapeutic strategies combining intense Bcr-Abl kinase inhibition and blockade of cytokine signaling pathways can be effective for eradication of CML progenitors.

Dasatinib cellular uptake and efflux in chronic myeloid leukemia cells: therapeutic implications

PURPOSE

The organic cation transporter OCT-1 mediates active transport of imatinib. We recently showed that low OCT-1 activity is a major contributor to suboptimal response in chronic myeloid leukemia (CML) patients treated with imatinib. The relevance of OCT-1 activity and efflux pumps in determining intracellular uptake and retention (IUR) of dasatinib was assessed.

EXPERIMENTAL DESIGN

The effect of OCT inhibitors on [14C]dasatinib and [14C]imatinib IUR was compared using peripheral blood mononuclear cells from newly diagnosed CML patients. The role of efflux transporters was studied using ABCB1- and ABCG2-overexpressing cell lines and relevant inhibitors.

RESULTS

Unlike imatinib, there was no significant difference in the dasatinib IUR at 37 degrees C and 4 degrees C (P = 0.8), and OCT-1 inhibitors including prazosin did not reduce dasatinib IUR significantly. In CML mononuclear cells, prazosin inhibitable IUR was significantly higher for imatinib than dasatinib (6.38 versus 1.48 ng/200,000 cells; P = 0.002; n = 11). Patients with high OCT-1 activity based on their imatinib uptake had IC50(dasatinib) values equivalent to patients with low OCT-1 activity. Dasatinib IUR was significantly lower in ABCB1-overexpressing cell lines compared with parental cell lines (P < 0.05). PSC833 (ABCB1 inhibitor) significantly increased the dasatinib IUR (P < 0.05) and reduced IC50(dasatinib) (from 100 to 8 nmol/L) in K562-DOX cell line. The ABCG2 inhibitor Ko143 significantly increased dasatinib IUR in ABCG2-overexpressing cell lines and reduced IC(50)(dasatinib).

CONCLUSION

Unlike imatinib, dasatinib cellular uptake is not significantly affected by OCT-1 activity, so that expression and function of OCT-1 is unlikely to affect response to dasatinib. Dasatinib is a substrate of both efflux proteins, ABCB1 and ABCG2.

Higher infused lymphocyte dose predicts higher lymphocyte recovery, which in turn, predicts superior overall survival following autologous hematopoietic stem cell transplantation for multiple myeloma

Autologous stem cell transplantation (ASCT) is the standard of care for patients with multiple myeloma (MM) younger than 70 years. However, despite this aggressive therapy most patients will still die of progressive disease. Recent reports have suggested that lymphocyte recovery is an important predictor of relapse or progressive disease in a number of hematologic malignancies including MM. We have conducted retrospective analysis of factors that could predict overall (OS) and progression free survival (PFS) in patients with MM who had ASCT. One hundred nineteen patients with multiple myeloma underwent ASCT. The median OS and PFS were 64 and 32 months, respectively. Univariate and multivariate analysis using Cox proportional hazards regression model showed that absolute lymphocyte count on day 30 following ASCT (ALC-30), international staging system (ISS) stage at diagnosis, and age at diagnosis significantly influenced OS and PFS following ASCT. OS (96 versus 48 months, P = .04) and PFS (43 versus 29 months, P = .03) following ASCT were higher in patients with ALC-30 >or=1.0 x 10(9)/L compared to patients ALC-30 <1.0 x 10(9)/L. Higher ALC-60, ALC-100, ALC-180, and ALC-365 did not predict superior OS and PFS. Patients with early-stage disease had significantly higher OS (ISS stages I, II, and III: 96, 53, and 29 months, respectively; P = .0023) and PFS (ISS stages I, II, and III: 55.5, 31, and 12 months, respectively; P = .027) compared to patients with advanced-stage disease at diagnosis. On univariate analysis, the type of initial chemotherapy (melphalan, VAD, PCAB), lymphocyte count on day of leukapheresis, and the lymphocyte dose infused (LY-DO) significantly influenced lymphocyte recovery following ASCT. Patients who received higher lymphocyte dose (LY-DO) >or=0.2 x 10(9)/kg had higher median ALC-15 (0.25 versus 0.19 x 10(9)/L; P = .3), ALC-30 (1.20 versus 0.99 x 10(9)/L; P = .08), ALC-60 (1.90 versus 1.01 x 10(9)/L; P = .013), ALC-100 (1.58 versus 1.03 x 10(9)/L; P = .016), and ALC-180 (1.33 versus 1.01 x 10(9)/L; P = .1), compared to patients who received LY-DO <0.2 x 10(9)/kg. In summary, our data suggest that infusing large numbers of lymphocytes improves lymphocyte recovery post-ASCT, and that higher ALC-30 is associated with better PFS and OS. These data suggest that a threshold number of CD34(+) cells should not be the only parameter considered for an adequate PBSC collection--perhaps a certain number of lymphocytes should be aimed for as well.

Intermediate-dose CY and G-CSF more efficiently mobilize adequate numbers of PBSC for tandem autologous PBSC transplantation compared with low-dose CY in patients with multiple myeloma

BACKGROUND

Autologous PBSC transplantation is the standard care for patients with multiple myeloma. The most common regimen used to mobilize PBSC consists of CY and G-CSF.

METHODS

We retrospectively analyzed the efficacy and toxicity of two regimens of CY for PBSC mobilization: low-dose CY (1-2 g/m(2), LD-CY, n=61) plus G-CSF, and intermediate-dose CY (3-4 g/m(2), ID-CY, n=26) plus G-CSF.

RESULTS

In the LD-CY group, 5.17 (0.23-17.3)x10(6) CD34(+) cells/kg, and in the ID-CY group 7.71 (0.08-26.4)x10(6) CD34(+) cells/kg (P=0.018), were collected. Although >/=2x10(6)/kg CD34(+) cells were collected in 89% of the LD-CY group and 92% of the ID-CY group, this was achieved after a single leukapheresis in 54% of the LD-CY group and 92% of the ID-CY group (P=0.0001). Patients who are to have tandem autologous PBSC transplants require >/=4x10(6)/kg CD34(+) cells. This was achieved in only 65% patients in the LD-CY group but 88% in the ID-CY group (P=0.05). Among patients who had not had prior melphalan and/or >12 months of prior treatment, 74% in the LD-CY group and 100% in ID-CY group mobilized >/=4x10(6)/kg CD34(+) cells. Febrile neutropenia was more frequent in the ID-CY group (38% vs. 13%).

DISCUSSION

In conclusion, compared with LD-CY, patients receiving ID-CY were more likely to collect a total CD34(+) cell number adequate for tandem autologous PBSC transplantation. The increased toxicity was manageable and considered acceptable.