Effect of tyrosine kinase inhibitors on male fertility in patients with chronic phase chronic myeloid leukemia

Advancements in the management of patients with chronic myeloid leukemia (CML) allowed them to achieve survival comparable with their healthy counterparts. Consequently, their care has widened with growing focus on quality of life, including parenting children. Although tyrosine kinase inhibitors (TKI) are contraindicated in pregnancy given their teratogenic effect, their effect on male fertility is less clear with contradictory results from animal studies and case reports/series. We compared the sperm analysis parameters, as the gold-standard assessment for male fertility, of 11 patients with CP- CML before and after TKI therapy. Median therapy duration was 5.1 years (range: 2.5-16.5). The sperm concentration, % progressive, and total motility before and after therapy were not significantly different (p = 0.376, 0.569, and 0.595, respectively). Our results suggest no impairment in fertility potential in male patients after TKI therapy. A larger sample size is crucial to support/refute our findings.

Mismatched related donor allogeneic haematopoietic cell transplantation compared to other donor types for Ph+ chronic myeloid leukaemia: A retrospective analysis from the Chronic Malignancies Working Party of the EBMT

Allogeneic haematopoietic cell transplantation (allo-HCT) remains an option for tyrosine kinase inhibitor-resistant chronic myeloid leukaemia (CML) in first chronic phase (CP1) and high-risk patients with advanced disease phases. In this European Society for Blood and Marrow Transplantation (EBMT) registry-based study of 1686 CML patients undergoing first allo-HCT between 2012 and 2019, outcomes were evaluated according to donor type, particularly focusing on mismatched related donors (MMRDs). Median age at allo-HCT was 46 years (IQR 36-55). Disease status was CP1 in 43%, second CP (CP2) or later in 27%, accelerated phase in 12% and blast crisis in 18%. Donor type was matched related (MRD) in 39.2%, MMRD in 8.1%, matched unrelated (MUD) in 40.2%, and mismatched unrelated (MMUD) in 12.6%. In 4 years, overall survival (OS) for MRD, MMRD, MUD and MMUD was 61%, 56%, 63% and 59% (p = 0.21); relapse-free survival (RFS) was 48%, 42%, 52% and 46% (p = 0.03); cumulative incidence of relapse (CIR) was 33%, 37%, 27% and 30% (p = 0.07); non-relapse mortality (NRM) was 19%, 21%, 21% and 24% (p = 0.21); and graft-versus-host disease (GvHD)-free/relapse-free survival (GRFS) was 16%, 18%, 22% and 15% (p = 0.05) respectively. On multivariate analysis, MMRD use associated with longer engraftment times and higher risk of graft failure compared to MRD or MUD. There was no statistical evidence that MMRD use associated with different OS, RFS and incidence of GvHD compared to other donor types.

Chronic myeloid leukemia diagnosed in pregnancy: management and outcome of 87 patients reported to the European LeukemiaNet international registry

The management of chronic myeloid leukemia (CML) diagnosed during pregnancy is a rare and challenging situation. We report the treatment and outcome of 87 cases diagnosed in chronic phase from 2001-2022 derived from the largest international observational registry, supported by the European LeukemiaNet (ELN), of 400 pregnancies in 299 CML women. Normal childbirth occurred in 76% without an increased rate of birth abnormalities or life-threatening events, including in patients untreated or treated with interferon-α and/or imatinib in 2nd-3rd trimester. The low birth weight rate of 12% was comparable to that seen in the normal population. Elective and spontaneous abortions occurred in 21% and 3%, respectively. The complete hematologic response rate before labor was 95% with imatinib and 47% with interferon only. No disease progression during pregnancy was observed, 28% of the patients switched their therapy at varying times after delivery. Treatment options balance the efficacy and safety for mother and infant: interferon-α can commence in the 1st trimester and continued throughout in cases of good disease control and tolerability. Because of limited placental crossing, selected tyrosine kinase inhibitors (imatinib and nilotinib) seem to be safe and effective options in 2nd and 3rd trimester while hydroxycarbamide offers few benefits.

Dose modification dynamics of ponatinib in patients with chronic-phase chronic myeloid leukemia (CP-CML) from the PACE and OPTIC trials

Ponatinib, the only approved all known-BCR::ABL1 inhibitor, is a third-generation tyrosine-kinase inhibitor (TKI) designed to inhibit BCR::ABL1 with or without any single resistance mutation, including T315I, and induced robust and durable responses at 45 mg/day in patients with CP-CML resistant to second-generation TKIs in the PACE trial. However, cardiovascular toxicities, including arterial occlusive events (AOEs), have emerged as treatment-related AEs within this class of TKIs. The OPTIC trial evaluated the efficacy and safety of ponatinib using a novel, response-based, dose-reduction strategy in patients with CP-CML whose disease is resistant to ≥2 TKIs or who harbor T315I. To assess the dose-response relationship and the effect on the safety of ponatinib, we examined the outcomes of patients with CP-CML enrolled in PACE and OPTIC who received 45 mg/day of ponatinib. A propensity score analysis was used to evaluate AOEs across both trials. Survival rates and median time to achieve ≤1% BCR::ABL1IS in OPTIC were similar or better than in PACE. The outcomes of patients with T315I mutations were robust in both trials. Patients in OPTIC had a lower exposure-adjusted incidence of AOEs compared with those in PACE. This analysis demonstrates that response-based dosing for ponatinib improves treatment tolerance and mitigates cardiovascular risk.

Allogeneic hematopoietic cell transplantation in patients with chronic phase chronic myeloid leukemia in the era of third generation tyrosine kinase inhibitors: A retrospective study by the chronic malignancies working party of the EBMT

Following the introduction of tyrosine kinase inhibitors (TKI), the number of patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) for chronic phase (CP) chronic myeloid leukemia (CML) has dramatically decreased. Imatinib was the first TKI introduced to the clinical arena, predominantly utilized in the first line setting. In cases of insufficient response, resistance, or intolerance, CML patients can subsequently be treated with either a second or third generation TKI. Between 2006 and 2016, we analyzed the impact of the use of 1, 2, or 3 TKI prior to allo-HCT for CP CML in 904 patients. A total of 323-, 371-, and 210 patients had 1, 2, or 3 TKI prior to transplant, respectively; imatinib (n = 778), dasatinib (n = 508), nilotinib (n = 353), bosutinib (n = 12), and ponatinib (n = 44). The majority had imatinib as first TKI (n = 747, 96%). Transplants were performed in CP1, n = 549, CP2, n = 306, and CP3, n = 49. With a median follow-up of 52 months, 5-year OS for the entire population was 64.4% (95% CI 60.9-67.9%), PFS 50% (95% CI 46.3-53.7%), RI 28.7% (95% CI 25.4-32.0%), and NRM 21.3% (95% CI 18.3-24.2%). No difference in OS, PFS, RI, or NRM was evident related to the number of TKI prior to allo-HCT or to the type of TKI (p = ns). Significant factors influencing OS and PFS were > CP1 versus CP1 and Karnofsky performance (KPS) score > 80 versus ≤80, highlighting CP1 patients undergoing allo-HCT have improved survival compared to >CP1 and the importance of careful allo-HCT candidate selection.

Ponatinib after failure of second-generation tyrosine kinase inhibitor in resistant chronic-phase chronic myeloid leukemia

Ponatinib, the only third-generation pan-BCR::ABL1 inhibitor with activity against all known BCR::ABL1 mutations including T315I, has demonstrated deep and durable responses in patients with chronic-phase chronic myeloid leukemia (CP-CML) resistant to prior second-generation (2G) TKI treatment. We present efficacy and safety outcomes from the Ponatinib Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) and CML Evaluation (PACE) and Optimizing Ponatinib Treatment in CP-CML (OPTIC) trials for this patient population. PACE (NCT01207440) evaluated ponatinib 45 mg/day in CML patients with resistance to prior TKI or T315I. In OPTIC (NCT02467270), patients with CP-CML and resistance to ≥2 prior TKIs or T315I receiving 45 or 30 mg/day reduced their doses to 15 mg/day upon achieving ≤1% BCR::ABL1^IS or received 15 mg/day continuously. Efficacy and safety outcomes from patients with CP-CML treated with ≥1 2G TKI (PACE, n = 257) and OPTIC (n = 93), 45-mg starting dose cohort, were analyzed for BCR::ABL1^IS response rates, overall survival (OS), progression-free survival (PFS), and safety. By 24 months, the percentages of patients with ≤1% BCR::ABL1^IS response, PFS, and OS were 46%, 68%, and 85%, respectively, in PACE and 57%, 80%, and 91%, respectively, in OPTIC. Serious treatment-emergent adverse events and serious treatment-emergent arterial occlusive event rates were 63% and 18% in PACE and 34% and 4% in OPTIC. Ponatinib shows high response rates and robust survival outcomes in patients whose disease failed prior to 2G TKIs, including patients with T315I mutation. The response-based dosing in OPTIC led to improved safety and similar efficacy outcomes compared with PACE.

Complications of Autologous Stem Cell Transplantation in Multiple Myeloma: Results from the CALM Study

Background: The main goal of this post hoc analysis of the Collaboration to Collect Autologous Transplant Outcomes in Lymphoma and Myeloma (CALM) study was to evaluate the rate of short- and long-term infectious and non-infectious complications occurring after ASCT in patients with multiple myeloma (MM). Methods: The analysis included all patients with MM from the CALM study who underwent ≥1 ASCT. The primary endpoint of the analysis was to determine the rate of infectious and non-infectious complications after ASCT and to compare them in three time periods: 0−100 days, 101 days−1 year, and >1 year after the first transplant. Results: The analysis included a total of 3552 patients followed up for a median of 56.7 months (range 0.4−108.1). Complication rates decreased with the time from ASCT with 24.85 cases per 100 patient-years from day 0 to 100 days after the transplant, and <2.31 cases per 100 patient-years from the 101st day. At 100 days after ASC T, 45.7% of patients had complications, with infectious events being twice as frequent as non-infectious complications. Bacterial infections (6.5 cases per 100 patient-years, 95% CI: 6.1−7.0) and gastrointestinal complications (4.7 cases per 100 patient-years, 95% CI: 4.3−5.1) were the most common early events. The pattern of complications changed with time from ASCT. The presence of complications after ASCT was not associated with overall survival. Conclusions: Our data provide a solid basis for comparing ASCT-related complications to those caused by emerging treatments in multiple myeloma, such as CAR T-cell therapy and other immunotherapies.

Efficacy and safety results from ASCEMBL, a phase 3 study of asciminib versus bosutinib (BOS) in patients (pts) with chronic myeloid leukemia in chronic phase (CML-CP) after ≥2 prior tyrosine kinase inhibitors (TKIs): Week 96 update

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Background: Asciminib is the first BCR::ABL1 inhibitor to specifically target the ABL Myristoyl Pocket (STAMP). In the ASCEMBL primary analysis, asciminib had superior efficacy and better safety/tolerability than BOS in pts with CML-CP after ≥2 prior TKIs. After a median follow-up of 2.3 years (16.5 months’ additional follow-up since primary analysis), we report efficacy and safety results (cutoff: October 6, 2021). Methods: Eligible pts were adults with CML-CP after ≥2 prior TKIs, with intolerance or lack of efficacy per 2013 European LeukemiaNet. Pts were randomized 2:1 to asciminib 40 mg twice daily or BOS 500 mg once daily, stratified by major cytogenetic response (MCyR) status (Ph+ metaphases ≤35%) at baseline. The key secondary endpoint was major molecular response (MMR) rate at wk 96. Results: 233 pts were randomized to asciminib (n=157) or BOS (n=76). At cutoff, treatment was ongoing in 84 (53.5%) and 15 (19.7%) pts, respectively; the most common reason for discontinuation was lack of efficacy in 38 (24.2%) and 27 (35.5%) pts, respectively. MMR rate at wk 96 (per ITT) was higher on asciminib (37.6%) than BOS (15.8%). The difference, adjusting for baseline MCyR, was 21.7% (95% CI, 10.5%-33.0%; 2-sided P=.001). More pts on asciminib than BOS, respectively, had BCR::ABL1IS ≤1% (45.1% vs 19.4%) at wk 96. The probability of maintaining MMR and BCR::ABL1IS ≤1% for ≥72 wk was 96.7% (95% CI, 87.4%-99.2%) and 94.6% (95% CI, 86.2%-97.9%), respectively, on asciminib and 92.9% (95% CI, 59.1%-99.0%) and 95.0% (95% CI, 69.5%-99.3%), respectively, on BOS. Median duration of exposure was 103.1 (range, 0.1-201.1) wk on asciminib and 30.5 (range, 1.0-188.3) wk on BOS. Despite the longer duration of asciminib exposure, safety/tolerability of asciminib continued to be better than that of BOS (Table). No new on-treatment deaths were reported since the primary analysis. Most frequent (>10%) grade ≥3 adverse events (AEs) on asciminib vs BOS were thrombocytopenia (22.4%, 9.2%), neutropenia (18.6%, 14.5%), diarrhea (0%, 10.5%), and increased alanine aminotransferase (0.6%, 14.5%). Conclusions: After >2 years of follow-up, asciminib continued to show superior efficacy and better safety/tolerability vs BOS. Responses were durable, with more pts on asciminib in MMR. Additionally, more pts on asciminib had BCR::ABL1IS ≤1%, a milestone response in later lines associated with improved survival. These results continue to support the use of asciminib as a new CML therapy, with the potential to transform standard of care. Clinical trial information: NCT03106779. [Table: see text]

Managing hematological cancer patients during the COVID-19 pandemic: an ESMO-EHA Interdisciplinary Expert Consensus

BACKGROUND

The COVID-19 pandemic has created enormous challenges for the clinical management of patients with hematological malignancies (HMs), raising questions about the optimal care of this patient group.

METHODS

This consensus manuscript aims at discussing clinical evidence and providing expert advice on statements related to the management of HMs in the COVID-19 pandemic. For this purpose, an international consortium was established including a steering committee, which prepared six working packages addressing significant clinical questions from the COVID-19 diagnosis, treatment, and mitigation strategies to specific HMs management in the pandemic. During a virtual consensus meeting, including global experts and lead by the European Society for Medical Oncology and the European Hematology Association, statements were discussed and voted upon. When a consensus could not be reached, the panel revised statements to develop consensual clinical guidance.

RESULTS AND CONCLUSION

The expert panel agreed on 33 statements, reflecting a consensus, which will guide clinical decision making for patients with hematological neoplasms during the COVID-19 pandemic.

IgD Subtype But Not IgM or Non-Secretory Is a Prognostic Marker for Poor Survival Following Autologous Hematopoietic Cell Transplantation in Multiple Myeloma. Results From the EBMT CALM (Collaboration to Collect Autologous Transplant Outcomes in Lymphomas and Myeloma) Study

BACKGROUND

The Collaboration to Collect Autologous Transplant Outcomes in Lymphoma and Myeloma (CALM) study has provided an opportunity to evaluate the real-world outcomes of patients with myeloma. The aim of this study was to compare the outcome according to the different subtypes of myeloma using CALM data.

PATIENTS

This study compared overall survival (OS), progression-free survival (PFS), and complete remission (CR) and the impact of novel versus non-novel drug containing induction regimens prior to autologous hematopoietic cell transplantation (HCT) of 2802 patients with "usual" and "rare" myelomas.

RESULTS

Our data suggest that IgM and non-secretory myeloma have superior PFS and OS compared with IgD myeloma and outcomes comparable to those for usual myeloma. Patients who received novel agent induction had higher rates of CR prior to transplant. Non-novel induction regimens were associated with inferior PFS but no difference in OS. Although not the primary focus of this study, we show that poor mobilization status is associated with reduced PFS and OS, but these differences disappear in multivariate analysis suggesting that poor mobilization status is a surrogate for other indicators of poor prognosis.

CONCLUSION

We confirm that IgD myeloma is associated with the worst prognosis and inferior outcomes compared with the other isotypes.

OPTIC primary analysis: A dose-optimization study of 3 starting doses of ponatinib (PON)

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Background: PON, a third-generation tyrosine kinase inhibitor (TKI), demonstrated deep and long-lasting responses and survival in patients (pts) with chronic-phase chronic myeloid leukemia (CP-CML) resistant/intolerant to second-generation TKI therapy (PACE; NCT01207440); post hoc analysis suggested a relationship between dose and both adverse events and response. Here we present the primary analysis of OPTIC (NCT02467270), an ongoing, randomized, phase 2 trial with a novel response-based dosing regimen of PON in pts with resistant/intolerant CP-CML. Methods: Pts with CP-CML resistant/intolerant to ≥2 TKIs or with the BCR-ABL1 T315I mutation were randomized to PON starting doses of 45 mg (cohort A; 45 mg → 15 mg), 30 mg (B; 30 mg →15 mg), and 15 mg (C) once daily. Doses were reduced to 15 mg with achievement of ≤1% BCR-ABL1IS in cohorts A and B. The primary endpoint is ≤1% BCR-ABL1IS at 12 mo; secondary endpoints include cytogenetic and molecular responses and safety outcomes. AOEs were adjudicated prospectively by an independent review committee. Results: 283 pts were randomized (A/B/C: n=94/95/94) and had the following baseline characteristics: median age 48 y (18‒81 y); 98% received ≥2 (55% ≥3) TKIs; 99% had resistant disease; 40% had ≥1 baseline mutations (23% T315I). At the primary analysis with 32 mo median follow-up, 134 pts (47%; n=50/41/43) remained on treatment and 204 pts (72%) had PON exposure ≥12 mo. At 12 mo, 44% (41/93) in A, 29% (27/93) in B, and 23% (21/91) in C achieved ≤1% BCR-ABL1IS (Table); primary endpoint was met by cohort A. Dose reductions to 15 mg after achieving response (A/B) were 48/29%. Most common grades ≥3 TEAEs were thrombocytopenia, 27%; neutropenia, 17%; and anemia, 7%. AOEs/serious AOEs were reported in cohorts A (10%/4%), B (5%/4%), and C (3%/3%). Dose reductions or discontinuations for TEAEs (A/B/C) were 46/35/32% and 19/16/14%, respectively. Conclusions: The OPTIC primary analysis demonstrates the optimal benefit:risk profile for PON was achieved with a response-based dosing regimen starting with 45 mg/d, followed by dose reduction to 15 mg/d upon achieving ≤ 1% BCR-ABL1IS; 30 mg→15 mg and 15 mg cohorts may provide benefit, especially in pts without T315I mutation (Table). The observed ≤1% BCR-ABL1IS responses are supported by robust survival outcomes in pts with CP-CML resistant to second-generation BCR-ABL1 TKI therapy, both with and without BCR-ABL1 mutations. Clinical trial information: NCT02467270. [Table: see text]

Proteasome 26S subunit, non-ATPases 1 (PSMD1) and 3 (PSMD3), play an oncogenic role in chronic myeloid leukemia by stabilizing nuclear factor-kappa B

Tyrosine kinase inhibitors (TKIs) targeting BCR-ABL1 have revolutionized therapy for chronic myeloid leukemia (CML), paving the way for clinical development in other diseases. Despite success, targeting leukemic stem cells and overcoming drug resistance remain challenges for curative cancer therapy. To identify drivers of kinase-independent TKI resistance in CML, we performed genome-wide expression analyses on TKI-resistant versus sensitive CML cell lines, revealing a nuclear factor-kappa B (NF-κB) expression signature. Nucleocytoplasmic fractionation and luciferase reporter assays confirmed increased NF-κB activity in the nucleus of TKI-resistant versus sensitive CML cell lines and CD34+ patient samples. Two genes that were upregulated in TKI-resistant CML cells were proteasome 26S subunit, non-ATPases 1 (PSMD1) and 3 (PSMD3), both members of the 19S regulatory complex in the 26S proteasome. PSMD1 and PSMD3 were also identified as survival-critical genes in a published small hairpin RNA library screen of TKI resistance. We observed markedly higher levels of PSMD1 and PSMD3 mRNA in CML patients who had progressed to the blast phase compared with the chronic phase of the disease. Knockdown of PSMD1 or PSMD3 protein correlated with reduced survival and increased apoptosis in CML cells, but not in normal cord blood CD34+ progenitors. Luciferase reporter assays and immunoblot analyses demonstrated that PSMD1 and PSMD3 promote NF-κB protein expression in CML, and that signal transducer and activator of transcription 3 (STAT3) further activates NF-κB in scenarios of TKI resistance. Our data identify NF-κB as a transcriptional driver in TKI resistance, and implicate PSMD1 and PSMD3 as plausible therapeutic targets worthy of future investigation in CML and possibly other malignancies.

Evolution of Advanced Chronic Lymphoid Leukemia Unveiled by Single-Cell Transcriptomics: A Case Report

Genetic and transcriptional heterogeneity of Chronic lymphocytic leukaemia (CLL) limits prevention of disease progression. Longitudinal single-cell transcriptomics represents the state-of-the-art method to profile the disease heterogeneity at diagnosis and to inform about disease evolution. Here, we apply single-cell RNA-seq to a CLL case, sampled at diagnosis and relapse, that was treated with FCR (Fludarabine, Cyclophosphamide, Rituximab) and underwent a dramatic decrease in CD19 expression during disease progression. Computational analyses revealed a major switch in clones’ dominance during treatment. The clone that expanded at relapse showed 17p and 3p chromosomal deletions, and up-regulation of pathways related to motility, cytokine signaling and antigen presentation. Single-cell RNA-seq uniquely revealed that this clone was already present at low frequency at diagnosis, and it displays feature of plasma cell differentiation, consistent with a more aggressive phenotype. This study shows the benefit of single-cell profiling of CLL heterogeneity at diagnosis, to identify clones that might otherwise not be recognized and to determine the best treatment options.

Tyrosine kinase inhibitors and pregnancy in chronic myeloid leukemia: opinion, evidence, and recommendations

With survival expectation that of age-matched controls and given excellent response and worldwide access to tyrosine kinase inhibitors (TKI), family planning is increasingly important for a considerable fraction of patients with chronic myeloid leukemia (CML). The potential for therapy discontinuation ("treatment free remission") can afford the opportunity for a CML patient in deep response to plan and carry a pregnancy to full term without any therapeutic interventions. However, the reality of pregnancy desired or occurring when patients are not eligible for treatment-free remission raises the discussion of therapy choices during pregnancy. To date there are no official guidelines available to assist patients and clinicians with these decisions. This first position paper aims to analyze information published and presented surrounding this challenging area, with focus on different scenarios of disease burden and time from CML diagnosis, including CML discovered during pregnancy and pregnancy during CML treatment. An updated review, supported by data and presented together with authors' joint recommendations, is aimed to counsel the practical management of CML patients and pregnancy.

Abstract 647: NF-kB associates with tyrosine kinase inhibitor resistance in chronic myeloid leukemia

Tyrosine kinase inhibitors (TKIs) targeting BCR-ABL1 are effective at eliminating most BCR-ABL1+ cells in chronic myeloid leukemia (CML), but do not target CML leukemic stem cells (LSCs), which are independent of BCR-ABL1 kinase activity. Our previous work showed that BCR-ABL1-independent resistance is largely driven by STAT3 (Eiring et al. Leukemia 2015). To understand how STAT3 contributes to TKI resistance, we performed RNA sequencing on TKI-sensitive K562-S cells versus TKI-resistant K562-R cells, which demonstrate kinase-independent resistance. Surprisingly, gene set enrichment analysis did not reveal STAT3-mediated transcription (p=1.0), but was reminiscent of TNFα signaling via NF-κB (p=0.024). Nucleocytoplasmic fractionation revealed higher levels of phospho-NF-κB in the nucleus of K562-R vs. K562-S controls, and in CD34+ progenitors from TKI-resistant CML patients (n=3) compared to TKI responders (n=2) and normal individuals (n=2). These data suggest NF-κB may be driving the transcriptional signature of TKI resistance, and implicate non-canonical functions for STAT3. To confirm increased NF-κB transcriptional activity in TKI resistance, K562-S and K562-R cells were transduced with an NF-κB luciferase reporter construct or a scrambled control. K562-R cells demonstrated increased NF-κB reporter activity compared to K562-S cells. To assess whether STAT3 activates NF-κB, reporter cells were co-infected with an inducible lentiviral shRNA targeting STAT3 (shSTAT3). STAT3 knockdown decreased NF-κB reporter activity in TKI-resistant cells, but increased reporter activity in TKI-sensitive controls. These data suggest that STAT3 may cooperate with NF-κB in the setting of TKI resistance. NF-κB and STAT3 have been shown to cooperatively bind to gene promoters of cytokines, specifically IL-6. ELISA assays demonstrated that K562-R cells produce autonomous IL-6, but not TNFα. Since IL-6 is a potent activator of STAT3, we treated TKI-resistant cells with the IL-6 receptor inhibitor, tocilizumab (100 and 1000 ng/ml). As expected, tocilizumab treatment reduced STAT3 Y705 phosphorylation as assessed by immunoblot analysis, but surprisingly had no effect on survival or NF-κB reporter activity in K562-R cells. These data suggest that STAT3 phosphorylation is not required for survival or NF-κB activation in TKI resistance. The role of unphosphorylated STAT3 in TKI resistance is currently being explored. We correlated our RNA sequencing data in TKI-resistant cell lines with microarray data in TKI-resistant patient samples (McWeeney et al. Blood 2010), identifying upregulation of the proteasome components, PSMD1 and PSMD3. qRT-PCR confirmed upregulation of PSMD3 but not PSMD1 in TKI resistance, and only the PSMD3 promoter was bound by NF-κB as assessed by ChIP. Lentiviral shRNAs targeting PSMD3 (shPSMD3) reduced colony formation of K562-S and K562-R cells, which correlated with induction of apoptosis, an increase of global protein ubiquitination, and decreased NF-κB activation, with little effects observed in normal cord blood. Altogether, our data implicate a positive feedback loop involving NF-κB and PSMD3 in TKI resistance and suggest that PSMD3 may be a novel target for treatment of TKI-resistant CML.

Citation Format: Andres J. Rubio, Idaly M. Olivas, Alfonso E. Bencomo, Mayra A. Gonzalez, Joshua J. Lara, Rebecca Ellwood, Carme Ripoll-Fiol, Georgios Nteliopoulos, Alistair Reid, Dragana Milojkovic, Jane Apperley, Jamshid Sorouri-Khorashad, Anna M. Eiring. NF-kB associates with tyrosine kinase inhibitor resistance in chronic myeloid leukemia [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 647.

Expert opinion-management of chronic myeloid leukemia after resistance to second-generation tyrosine kinase inhibitors

Regardless of line of therapy, treatment goals in chronic phase chronic myeloid leukemia (CML) are: avoid progression to accelerated phase or blast crisis CML such that patients achieve a life expectancy comparable with that of the general population; avoid adverse events (AEs); and restore and maintain quality of life. The most important prognostic factor for achieving these goals is response to tyrosine kinase inhibitors (TKIs) at key milestones. For patients failing a TKI, a treatment change is mandatory to limit the risk of progression and death. There is currently no precise guideline for patients that fail a second-generation TKI, and there is a paucity of data to guide clinical decision making in this setting. There is, therefore, an unmet need for practical and actionable guidance on how to manage patients who fail a second-generation TKI. Although the term 'failure' includes patients failing for resistance or intolerance, the focus of this paper is failure of a second-generation TKI because of resistance. CML patients who fail their first second-generation TKI for true resistance need a more potent therapy. In these patients, the key issues to consider are the relative appropriateness of early allogeneic hematopoietic stem cell transplantation or the use of a further TKI. Selection of the next line of treatment after second-generation TKI resistance should be individualized and must be based on patient-specific factors including cytogenetics, mutation profile, comorbidities, age, previous history of AEs with prior TKI therapy, and risk profile for AEs on specific TKIs. This expert opinion paper is not in conflict with existing recommendations, but instead represents an evolution of previous notions, based on new data, insights, and clinical experience. We review the treatment options for patients resistant to second-generation TKI therapy and provide our clinical opinions and guidance on key considerations for treatment decision making.

Interim analysis (IA) of OPTIC: A dose-ranging study of three ponatinib (PON) starting doses

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Background: In PACE (NCT01207440) heavily pretreated patients (pts) with chronic-phase CML (CP-CML) had deep, lasting responses to PON; long-term follow-up showed increasing rates of arterial occlusive events (AOEs). We present IA results from OPTIC (NCT02467270), evaluating the association between PON exposure, efficacy, and safety, and response-based dose reduction in pts with CP-CML. Methods: This ongoing, multicenter, randomized phase 2 trial enrolled pts with CP-CML resistant or intolerant to ≥2 TKIs or with a T315I mutation to receive PON at a starting dose of 45 mg (cohort A), 30 mg (B), and 15 mg (C) qd. Doses were reduced to 15 mg qd on achievement of ≤1% BCR-ABL1IS in A/B. Primary endpoint: 12 mo ≤1% BCR-ABL1IS; secondary endpoints include cytogenetic and molecular response and AOE, VTE, and TEAE rates. Results are descriptive at this IA and will be inferential by adjusting multiplicity across 3 cohorts at final analysis. Results: 283 pts were randomized (A/B/C: n = 94/95/94); median age 48 y (18‒81 y). 26% had hypertension history; 2/43/55% received 1/2/≥3 TKIs; 40% had ≥1 baseline (BL) mutations, with 23% T315I. At IA data cutoff (20 Jul 2019), 162 pts (57%; n = 57/51/54) remained on study treatment. Among 282 pts in the safety population, median duration of exposure was ≈1 y (A/B/C, 12.9/11.2/11.0 mo). At 12 mo, 39% (95% CI, 27.6, 50.6), 27% (17.6, 39.1), and 26% (16.5, 38.6) in A, B, and C, respectively, achieved ≤1% BCR-ABL1IS. Additional efficacy in Table. Dose reductions due to efficacy (A/B): 35/21%. Most common TEAEs (any grade/≥3): thrombocytopenia 39/27%, neutropenia 25/17%. AOEs/serious AOEs were reported by (A, B, C) 5%/2%, 4%/3%, and 1%/0%. Dose reductions due to TEAEs: (A/B/C): 44/31/28%; discontinuations due to TEAEs: 18/15/14%. There were 4 (1.4%) on-study deaths; A, sudden death, n = 2; C, pneumonia, n = 2; no deaths were due to AOEs. Clinical trial information: NCT01207440 . Conclusions: OPTIC IA shows a trend toward dose-dependent efficacy and safety and may provide a refined understanding of the PON benefit:risk profile and its relation to dose. Data from longer follow-up may support an alternate dosing regimen for pts with CP-CML. [Table: see text]

Pre-transplantation Risks and Transplant-Techniques in Haematopoietic Stem Cell Transplantation for Acute Leukaemia

BACKGROUND

The role of conditioning intensity and stem cell source on modifying pre-transplantation risk in allogeneic haematopoietic stem cell transplantation (HSCT) is a matter of debate, but crucial when benchmarking centres.

METHODS

This Retrospective, multicenter exploratory-validation analysis of 9103 patients, (55.5% male, median age 50 years; 1-75 years range) with an allogeneic HSCT between 2010 and 2016 from a matched sibling (N = 8641; 95%) or matched unrelated donor (N = 462; 5%) for acute myeloid (N = 6432; 71%) or acute lymphoblastic (N = 2671; 29%) leukaemia in first complete remission, and reported by 240 centres in 30 countries to the benchmark database of the European Society for Blood and Marrow Transplantation (EBMT) searched for factors associated with use of transplant techniques (standard N = 6375;70% or reduced intensity conditioning N = 2728;30%, respectively bone marrow N = 1945;21% or peripheral blood N = 7158;79% as stem cell source), and their impact on outcome.

FINDINGS

Treatment groups differed significantly from baseline population (p < 0.001), and within groups regarding patient-, disease-, donor-, and centre-related pre-transplantation risk factors (p < 0.001); choice of technique did depend on pre-transplantation risk factors and centre (p < 0.001). Probability of overall survival at 5 years decreased systematically and significantly with increasing pre-transplantation risk score (score 2 vs 0/1 HR: 1·2, 95% c.i. [1·1-1·.3], p = 0.002; score 3 vs 0/1 HR: 1·5, 95% c.i. [1·3-1·7], p < 0.001; score 4/5/6 vs 0/1 HR: 1·9, 95% c.i. [1·6-2·2], p < 0.001) with no significant differences between treatment groups (likelihood ratio test on interaction: p = 0.40). Overall survival was significantly associated with selection steps and completeness of information (p < 0.001).

INTERPRETATION

Patients' pre-transplantation risk factors determine survival, independent of transplant techniques. Transplant techniques should be regarded as centre policy, not stratification factor in benchmarking. Selection criteria and completeness of data bias outcome. Outcomes may be improved more effectively through better identifying pre-transplantation factors as opposed to refinement of transplant techniques.

FUNDING

The study was funded by EBMT.

Worldwide Network for Blood and Marrow Transplantation (WBMT) recommendations for establishing a hematopoietic cell transplantation program (Part I): Minimum requirements and beyond

Hematopoietic cell transplantation (HCT) is a highly complex procedure that requires a dedicated multidisciplinary team to optimize its safety. In addition, institutions may have different needs regarding indications based on regional disease prevalence or may have an interest in developing specialized services. Yet, structured recommendations are not commonly available. Here, the Transplant Center and Recipient Issues Standing Committee for the Worldwide Network for Blood and Marrow Transplantation (WBMT) organized a structured review of all pertinent elements to establish a transplant program. First, we solicited components from committee members and grouped them in domains (infrastructure, staff, cell processing laboratory, blood banking, laboratory, radiology, pharmacy, HLA testing, ancillary services and quality). Subsequently, reviewers scored all elements on a 7-point scale, from an absolute requirement (score of 1) to not required (score of 7). An independent group of five experienced transplant physicians reviewed the rankings. Minimum requirements to establish any HCT program were identified among elements with mean score of ≤2.0, and specific elements for allogeneic and autologous HCT were identified. Mean scores >2.0-4.0 were classified as preferred recommendation, and mean scores of >4.0 to ≤7.0 were considered ideal recommendations for advanced and complex types of transplantation. This structured set of recommendations guides the prioritization of minimum requirements to establish a transplant program and to set the path for expansion and further development.

Abstract 3018: Mechanisms of tyrosine kinase inhibitor resistance in chronic myeloid leukemia

Tyrosine kinase inhibitors (TKIs) targeting BCR-ABL1 have turned chronic myeloid leukemia (CML) from a fatal to a chronic disease. Despite improved survival, resistance is a clinical problem, and TKIs do not target the quiescent CML leukemic stem cell (LSC), meaning that patients must be treated for life at a high economic burden and sometimes with significant side effects. TKI resistance is frequently characterized by mutations in the BCR-ABL1 kinase domain, but they explain only ~50% of clinical TKI failure. The remaining patients have BCR-ABL1-independent resistance, defined as survival despite BCR-ABL1 inhibition. We have previously reported a gene expression signature predictive of TKI failure in CD34+ cells from chronic phase CML patients (McWeeney et al. 2010). This gene expression signature demonstrated significant overlap with signatures of blast phase CML (Zheng et al. 2006), suggesting that similar biological processes may be driving TKI resistance and disease progression. We expanded our analysis, and also found significant overlap between the expression profiles of TKI resistance and quiescent CML LSCs reported by Graham et al. (p=4x10-14) and Cramer Morales et al. (p=7x10-6). These data suggest that there is a core of genes whose expression is consistently associated with multiple scenarios of BCR-ABL1-independent resistance. Our previous work has shown that BCR-ABL1-independent resistance is largely driven by STAT3, and that targeting STAT3 in combination with TKIs restores sensitivity in TKI-resistant CML stem and progenitor cells (Eiring et al. Leukemia 2015). Unexpectedly, gene set enrichment analysis revealed that our gene expression signature predictive of TKI failure (McWeeney et al. 2010) does not reveal a STAT3 transcriptional signature. Similarly, RNA sequencing data on TKI-resistant K562-R cells, which are resistant to TKIs but lack BCR-ABL1 kinase domain mutations, revealed that, while TKI resistance was not associated with a STAT3 transcriptional signature (p=1.0), it was correlated with a signature reminiscent of TNFα signaling via NFκB (p=0.024). Nucleocytoplasmic fractionation revealed higher levels of total- and phospho-NFκB in the nucleus of K562-R versus K562-S cells, and in CD34+progenitors from TKI-resistant CML patients (n=3) compared to TKI responders (n=2) and normal individuals (n=2). These data indicate that NFκB may be driving the gene expression signature associated with BCR-ABL1-independent resistance, and suggest non-canonical functions for STAT3 that go beyond its traditional role as a transcription factor.

Citation Format: Anna M. Eiring, Rebecca Ellwood, Carme Ripoll Fiol, Robert K. Hills, Georgios Nteliopoulos, Alistair Reid, Dragana Milojkovic, Jane Apperley, Jamshid Sorouri-Khorashad. Mechanisms of tyrosine kinase inhibitor resistance in chronic myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3018.

Manufacturing Mesenchymal Stromal Cells for the Treatment of Graft-versus-Host Disease: A Survey among Centers Affiliated with the European Society for Blood and Marrow Transplantation

The immunosuppressive properties of mesenchymal stromal cells (MSC) have been successfully tested to control clinical severe graft-versus host disease and improve survival. However, clinical studies have not yet provided conclusive evidence of their efficacy largely because of lack of patients' stratification criteria. The heterogeneity of MSC preparations is also a major contributing factor, as manufacturing of therapeutic MSC is performed according to different protocols among different centers. Understanding the variability of the manufacturing protocol would allow a better comparison of the results obtained in the clinical setting among different centers. In order to acquire information on MSC manufacturing we sent a questionnaire to the European Society for Blood and Marrow Transplantation centers registered as producing MSC. Data from 17 centers were obtained and analyzed by means of a 2-phase questionnaire specifically focused on product manufacturing. Gathered information included MSC tissue sources, MSC donor matching, medium additives for ex vivo expansion, and data on MSC product specification for clinical release. The majority of centers manufactured MSC from bone marrow (88%), whilst only 2 centers produced MSC from umbilical cord blood or cord tissue. One of the major changes in the manufacturing process has been the replacement of fetal bovine serum with human platelet lysate as medium supplement. 59% of centers used only third-party MSC, whilst only 1 center manufactured exclusively autologous MSC. The large majority of these facilities (71%) administered MSC exclusively from frozen batches. Aside from variations in the culture method, we found large heterogeneity also regarding product specification, particularly in the markers used for phenotypical characterization and their threshold of expression, use of potency assays to test MSC functionality, and karyotyping. The initial data collected from this survey highlight the variability in MSC manufacturing as clinical products and the need for harmonization. Until more informative potency assays become available, a more homogeneous approach to cell production may at least reduce variability in clinical trials and improve interpretation of results.

Abstract 1134: The tumor suppressor activity of miR-300 is detrimental for leukemia development but required for leukemia stem cell maintenance

Inhibition of protein phosphatase 2A (PP2A) tumor suppressor is essential for chronic myelogenous leukemia (CML) stem cell (LSC) maintenance and disease development. Persistence of drug-resistant quiescent LSCs depends on cell-autonomous and bone marrow (BM) signals. Herein, we identified miR-300 as an miRNA inhibited in CD34+ CML progenitors and during blastic transformation (BC) through the BCR-ABL1-dependent inhibition of C/EBPβ-induced miR-300 transcription. In CML progenitors, ectopic mir-300 expression directly targets the PP2A inhibitory pathway (i.e., Jak2, hnRNPA1, SET) and other factors essential for LSC maintenance and disease progression (e.g., CCND1/2, b-catenin, Myc, Twist-1). In leukemic but not normal CD34+ cells, miR-300 acts as a potent tumor suppressor by inducing cell cycle exit and promoting apoptosis. Conversely, hypoxia-induced BCR-ABL1 inhibition and induction of C/EBPβ were found essential for increased miR-300 levels in quiescent LSCs, although mesenchymal stromal cells (MSC)-derived exosomal miR-300 also contributed to it. Moreover, low O2 levels and MSC-derived exosomes induced quiescence of CD34+ CML cells. Notably, expression of an anti-miR-300 in MSCs prevented exosome-induced CD34+ CML growth arrest. LSCs escaped miR-300-induced apoptosis through the autocrine/paracrine TGFβ1-induced expression of TUG1, a lncRNA acting as an miR-300 sponge. In fact, TUG1 or TGFβ1 inhibition decreased quiescent (CFSEMAX) LSC number. By contrast, miR-300 inhibition did not alter LSC survival/self-renewal, further supporting a role for TUG1 as an miR-300 sponge. Accordingly, TUG1 was markedly induced in CFSEMAX but not dividing CD34+ CML cells. In fact, low levels of ectopic miR-300 induced growth arrest (decreased LTC-IC and CFC/replating activity) without affecting quiescent LSC number. By contrast, high doses of miR-300 but not scramble CpG-ODN impaired LSC survival (LTC-IC) and self-renewal (CFC/replating), induced marked killing of quiescent LSCs and dividing progenitors, and impaired CML engraftment in NRG-SGM3 mice. Such effects were further enhanced when CPG-miR-300 and CPG-anti-TUG1 were combined. By contrast, high CpG-miR-300 levels did not affect normal CD34+ cell survival/self-renewal likely because of high TUG1 expression. Altogether our results indicate that while miR-300 loss is essential for survival/proliferation of leukemic progenitors, increased miR-300 levels are required for LSC maintenance. Thus, induction of TUG1 may occur to preserve LSC survival in the BM endosteal niche where quiescence is induced by MSCs and low O2 levels through abnormal miR-300 induction. Thus, disrupting the miR-300/TUG1 balance may represent a potential therapeutic approach for treatment/eradication of LSC-derived leukemias.

This work is supported in part by NIH-NCI R01CA163800.

Citation Format: Giovannino Silvestri, Lorenzo Stramucci, Justin Ellis, Jason Harb, Paolo Neviani, Bin Zhang, Klara Srutova, Gabriel Pineda, Catriona Jamieson, Bruno Calabretta, Fabio Stagno, Paolo Vigneri, Georgios Nteliopoulos, Philippa May, Alistar Reid, Ramiro Garzon, Denis-Claude Roy, Martin Guimond, Peter Hokland, Michael Deininger, Garrett Fitzgerald, Chris Harman, Francesco Dazzi, Dragana Milojkovic, Jane Apperley, Guido Marcucci, Jianfei Qi, Katerina Machova-Polakova, Xiaoxuan Fan, Maria Baer, Rossana Trotta, Danilo Perrotti. The tumor suppressor activity of miR-300 is detrimental for leukemia development but required for leukemia stem cell maintenance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1134.

Cyclophosphamide versus etoposide in combination with total body irradiation as conditioning regimen for adult patients with Ph-negative acute lymphoblastic leukemia undergoing allogeneic stem cell transplant: On behalf of the ALWP of the European Society for Blood and Marrow Transplantation

Allogeneic hematopoietic cell transplantation (alloHCT) with myeloablative conditioning based on total body irradiation (TBI) is widely used for the treatment of adults with acute lymphoblastic leukemia (ALL). TBI is most frequently administered in combination with either cyclophosphamide (Cy/TBI) or etoposide (Vp/TBI). The goal of this study was to retrospectively compare these two regimens. Adult patients with Ph-negative ALL treated with alloHCT in first or second complete remission who received Cy/TBI (n = 1346) or Vp/TBI (n = 152) conditioning were included in the analysis. In a univariate analysis, as compared to Cy/TBI, the use of Vp/TBI was associated with reduced incidence of relapse (17% vs. 30% at 5 years, P = .007), increased rate of leukemia-free survival (60% vs. 50%, P = .04), and improved "graft versus host disease (GVHD) and relapse-free survival" (GRFS, 43% vs. 33%, P = .04). No significant effect could be observed in terms of the incidence of nonrelapse mortality or acute or chronic GVHD. In a multivariate model, the use of Vp/TBI was associated with reduced risk of relapse (HR = 0.62, P = .04) while the effect on other study end-points was not significant. In conclusion, conditioning regimen based on Vp combined with TBI appears more effective for disease control than the combination of Cy with TBI for adult patients with Ph-negative ALL treated with alloHCT.

Incidence of Second Primary Malignancies after Autologous Transplantation for Multiple Myeloma in the Era of Novel Agents

The advent of novel agents for multiple myeloma (MM) is cause for a re-examination of the incidence of second primary malignancies (SPMs). We examined the SPM rate in MM patients who were enrolled in the prospective observational CALM (Collaboration to Collect Autologous Transplant outcome in Lymphoma and Myeloma) study. Between 2008 and 2012, 3204 patients with MM underwent a first autologous hematopoietic stem cell transplantation. Plerixafor was used as a mobilizing agent for patients with poor (or potentially poor) stem cell mobilization as defined by the respective centers. A total of 135 patients developed SPMs, with a cumulative incidence of 5.3% (95% confidence interval, 4.4 to 6.3) at 72 months. Ninety-four patients developed solid tumors, 30 developed hematologic malignancies, and 11 developed an SPM of an unknown type. The cumulative incidence of known hematologic and solid malignancies were 1.4% and 3.6%, respectively, at 72 months. In a univariate analysis, use of radiotherapy, type of induction regimen, hematopoietic stem cell dose, poor mobilizer status, plerixafor use, and sex did not influence the cumulative incidence of SPMs. Only age over 65 years was statistically associated with an increased incidence. Overall, the incidence of SPMs was comparable to earlier estimations of SPMs in MM.

Apoptosis in mesenchymal stromal cells induces in vivo recipient-mediated immunomodulation

The immunosuppressive activity of mesenchymal stromal cells (MSCs) is well documented. However, the therapeutic benefit is completely unpredictable, thus raising concerns about MSC efficacy. One of the affecting factors is the unresolved conundrum that, despite being immunosuppressive, MSCs are undetectable after administration. Therefore, understanding the fate of infused MSCs could help predict clinical responses. Using a murine model of graft-versus-host disease (GvHD), we demonstrate that MSCs are actively induced to undergo perforin-dependent apoptosis by recipient cytotoxic cells and that this process is essential to initiate MSC-induced immunosuppression. When examining patients with GvHD who received MSCs, we found a striking parallel, whereby only those with high cytotoxic activity against MSCs responded to MSC infusion, whereas those with low activity did not. The need for recipient cytotoxic cell activity could be replaced by the infusion of apoptotic MSCs generated ex vivo. After infusion, recipient phagocytes engulf apoptotic MSCs and produce indoleamine 2,3-dioxygenase, which is ultimately necessary for effecting immunosuppression. Therefore, we propose the innovative concept that patients should be stratified for MSC treatment according to their ability to kill MSCs or that all patients could be treated with ex vivo apoptotic MSCs.

Five-year results of the ponatinib phase II PACE trial in heavily pretreated CP-CML patients (pts)

7012

Background: The tyrosine kinase inhibitor (TKI) ponatinib has potent activity against native and mutant BCR-ABL1 and is approved for use in pts with relapsed/intolerant CML or Ph+ ALL, or with BCR-ABL1/T315I. Methods: In the pivotal PACE study (NCT01207440), ponatinib (starting dose 45 mg/d) was assessed in pts with CML or Ph+ ALL resistant/intolerant to dasatinib or nilotinib, or with T315I. In Oct ’13, dose reductions were implemented due to observed arterial occlusive events (AOEs). Efficacy and safety at 5 yrs (data as of 3 Oct ’16) for CP-CML pts are reported. Results: Of 270 CP-CML pts in the safety population, 60% received ≥3 prior TKIs. At initiation of study closure, 99 pts were ongoing; among these pts, minimum follow-up was 52 months, and most (78%) had 15 mg/d as their last dose. In all CP-CML pts (n = 267, efficacy evaluable), cumulative response rates were: MCyR, 60%; CCyR, 54%; MMR, 40%; and MR4.5, 24%. Among pts who achieved MCyR (n = 148) or MMR (n = 108), the Kaplan-Meier (KM) estimated probability of remaining in response at 5 yrs was 74% (95% CI, 62 – 83) and 61% (95% CI, 51 – 70), respectively. Regardless of dose reduction in Oct ’13, maintenance of response was high (Table). KM estimated 5-yr rate for PFS/OS was 49%/77%. TEAEs in ≥45% of CP-CML pts were rash 47%, abdominal pain 46%, and thrombocytopenia 46%. Most newly occurring AEs were observed within the first year. The incidence of any AOEs/serious AOEs for CP-CML pts was 29%/23%. Among CP-CML pts with no prior AOEs who had a prospective dose reduction, 17% (11/63) had a first AOE occurring after Oct ‘13. Conclusions: Long-term (5-yr) results from PACE demonstrate that ponatinib continues to show clinical benefit, irrespective of dose reductions, with deep and lasting responses in heavily pretreated CP-CML pts. Safety results were consistent with the safety profile across the ponatinib clinical program. Clinical trial information: NCT01207440. [Table: see text]

Sickle cell disease: an international survey of results of HLA-identical sibling hematopoietic stem cell transplantation

Despite advances in supportive therapy to prevent complications of sickle cell disease (SCD), access to care is not universal. Hematopoietic cell transplantation is, to date, the only curative therapy for SCD, but its application is limited by availability of a suitable HLA-matched donor and lack of awareness of the benefits of transplant. Included in this study are 1000 recipients of HLA-identical sibling transplants performed between 1986 and 2013 and reported to the European Society for Blood and Marrow Transplantation, Eurocord, and the Center for International Blood and Marrow Transplant Research. The primary endpoint was event-free survival, defined as being alive without graft failure; risk factors were studied using a Cox regression models. The median age at transplantation was 9 years, and the median follow-up was longer than 5 years. Most patients received a myeloablative conditioning regimen (n = 873; 87%); the remainder received reduced-intensity conditioning regimens (n = 125; 13%). Bone marrow was the predominant stem cell source (n = 839; 84%); peripheral blood and cord blood progenitors were used in 73 (7%) and 88 (9%) patients, respectively. The 5-year event-free survival and overall survival were 91.4% (95% confidence interval, 89.6%-93.3%) and 92.9% (95% confidence interval, 91.1%-94.6%), respectively. Event-free survival was lower with increasing age at transplantation (hazard ratio [HR], 1.09; P < .001) and higher for transplantations performed after 2006 (HR, 0.95; P = .013). Twenty-three patients experienced graft failure, and 70 patients (7%) died, with the most common cause of death being infection. The excellent outcome of a cohort transplanted over the course of 3 decades confirms the role of HLA-identical sibling transplantation for children and adults with SCD.

RT-qPCR and RT-Digital PCR: A Comparison of Different Platforms for the Evaluation of Residual Disease in Chronic Myeloid Leukemia

BACKGROUND

Tyrosine kinase inhibitors (TKIs) are the cornerstone of successful clinical management of patients with chronic myeloid leukemia (CML). Quantitative monitoring of the percentage of the fusion transcript BCR-ABL1 (breakpoint cluster region–c-abl oncogene 1, non-receptor tyrosine kinase) BCR-ABL1IS (%BCR-ABL1IS) by reverse transcription–quantitative PCR (RT-qPCR) is the gold standard strategy for evaluating patient response to TKIs and classification into prognostic subgroups. However, this approach can be challenging to perform in a reproducible manner. Reverse-transcription digital PCR (RT-dPCR) is an adaptation of this method that could provide the robust and standardized workflow needed for truly standardized patient stratification.

METHODS

BCR-ABL1 and ABL1 transcript copy numbers were quantified in a total of 102 samples; 70 CML patients undergoing TKI therapy and 32 non-CML individuals. 3 commercially available digital PCR platforms (QS3D, QX200 and Raindrop) were compared with the platform routinely used in the clinic for RT-qPCR using the EAC (Europe Against Cancer) assay.

RESULTS

Measurements on all instruments correlated well when the %BCR-ABL1IS was ≥0.1%. In patients with residual disease below this level, greater variations were measured both within and between instruments limiting comparable performance to a 4 log dynamic range.

CONCLUSIONS

RT-dPCR was able to quantify low-level BCR-ABL1 transcript copies but was unable to improve sensitivity below the level of detection achieved by RT-qPCR. However, RT-dPCR was able to perform these sensitive measurements without use of a calibration curve. Adaptions to the protocol to increase the amount of RNA measured are likely to be necessary to improve the analytical sensitivity of BCR-ABL testing on a dPCR platform.

Abstract 951: Role of the MSC-derived exosomal and endogenous JAK2-SET/PP2A-β-catenin-modulator miR-300 in leukemic stem/progenitor proliferation and survival in CML

MiR-300 is a microRNA predicted to target multiple components of the BCR-ABL1/JAK2/hnRNPA1/SET/PP2A/β-catenin pathway, which is essential for survival/self-renewal of leukemic progenitors and quiescent TKI-resistant Ph+ hematopoietic stem cells (HSCs). Nanostring arrays analysis of bone marrow (BM) cells from healthy individuals (n = 5) and CML patients (n = 10) showed gradual inhibition of miR-300 expression (CML-CPmiR-300&gt;CML-BCmiR-300).

MiR-300 transduction in CMLCD34+ cells and BCR-ABL1+ cell lines decreased JAK2, β-catenin, hnRNPA1 and SET expression and increased PP2A activity. Targets were confirmed by miR-300 expression in BCR-ABL1+ cells expressing Flag-tagged miR-300-targets lacking or carrying a wild-type or mutated 3’UTR. Restored miR-300 expression in CMLCD34+ cells and/or BCR-ABL1+ cell lines impaired proliferation and clonogenic potential, markedly reduced LTC-ICs, and increased TKI sensitivity. Notably, miR-300 expression was inhibited by BCR-ABL1 in proliferating cells. Accordingly, imatinib restored miR-300 expression in CD34+ dividing progenitors and BCR-ABL1+ cell lines without altering miR-300 levels in quiescent (CFSEMAX) CMLCD34+ cells (n = 3), consistent with the BCR-ABL1 kinase-dependent activation of the Jak2/SET/PP2A/β-catenin pathway in CML progenitors but not quiescent Ph+ HSCs. Surprisingly, miR-300 levels were increased in CD34+CD38- compared to CD34+CD38+ CML cells, and &gt;20-fold higher in CFSEMAX compared to dividing CMLCD34+ cells (n = 4).

To determine whether enhanced miR-300 expression in quiescent cells depends on cell autonomous events or is induced by the BM microenvironment, we exposed BCR-ABL+ cells to conditioned medium (CM) of HS-5 or hTERT mesenchymal stem cells (MSC). CM strongly decreased proliferation, induced imatinib but not FTY720 (PP2A activator) resistance, increased miR-300 levels, decreased BCR-ABL1 activity and Jak2 expression but not its activity, and did not alter β-catenin levels or PP2A activity. Interestingly, miR-300 was found in MSC-derived exosomes, and its expression increased in BCR-ABL1+ cells exposed to exosomes. Accordingly, proliferation of CML-BCCD34+and LAMA-84 cells was strongly reduced upon exposure to MSC-derived exosomes. These effects were abolished when we used CM from MSCs transduced with a miR-300 antagomir.

Altogether our results indicate that downregulation of miR-300 appears necessary for the activation of JAK2/SET/PP2A/β-catenin survival signals in CML progenitors. Conversely, increased miR-300 levels (endogenous and MSC-derived) seem to be required for HSC quiescence.

Citation Format: Rossana Trotta, Giovannino Silvestri, Lorenzo Stramucci, Justin J. Ellis, Justine Yu, Jason J. Harb, Paolo Neviani, Guido Marcucci, Klara Srutova, Polakova K. Machova, Denis-Claude Roy, Peter Hokland, Michael Deininger, Ravi Bhatia, Carlo Gambacorti-Passerini, Dragana Milojkovic, Alistair Reid, Jane Apperley, Ferenc Livak, Jianfei Qi, Maria R. Baer, Danilo Perrotti. Role of the MSC-derived exosomal and endogenous JAK2-SET/PP2A-β-catenin-modulator miR-300 in leukemic stem/progenitor proliferation and survival in CML. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 951.

Hematopoietic stem cell transplantation activity worldwide in 2012 and a SWOT analysis of the Worldwide Network for Blood and Marrow Transplantation Group including the global survey

Data on 68 146 hematopoietic stem cell transplants (HSCTs) (53% autologous and 47% allogeneic) gathered by 1566 teams from 77 countries and reported through their regional transplant organizations were analyzed by main indication, donor type and stem cell source for the year 2012. With transplant rates ranging from 0.1 to 1001 per 10 million inhabitants, more HSCTs were registered from unrelated 16 433 donors than related 15 493 donors. Grafts were collected from peripheral blood (66%), bone marrow (24%; mainly non-malignant disorders) and cord blood (10%). Compared with 2006, an increase of 46% total (57% allogeneic and 38% autologous) was observed. Growth was due to an increase in reporting teams (18%) and median transplant activity/team (from 38 to 48 HSCTs/team). An increase of 167% was noted in mismatched/haploidentical family HSCT. A Strengths, Weaknesses, Opportunities, Threats (SWOT) analysis revealed the global perspective of WBMT to be its major strength and identified potential to be the key professional body for patients and authorities. The limited data collection remains its major weakness and threat. In conclusion, global HSCT grows over the years without plateauing (allogeneic>autologous) and at different rates in the four World Health Organization regions. Major increases were observed in allogeneic, haploidentical HSCT and, to a lesser extent, in cord blood transplantation.

Next-Generation Sequencing-Assisted DNA-Based Digital PCR for a Personalized Approach to the Detection and Quantification of Residual Disease in Chronic Myeloid Leukemia Patients

Recent studies indicate that 40% of chronic myeloid leukemia patients who achieve sustained undetectable BCR-ABL1 transcripts on tyrosine kinase inhibitor therapy remain disease-free after drug discontinuation. In contrast, 60% experience return of detectable disease and have to restart treatment, thus highlighting the need for an improved method of identifying patients with the lowest likelihood of relapse. Here we describe the validation of a personalized DNA-based digital PCR (dPCR) approach for quantifying very low levels of residual disease, which involves the rapid identification of t(9;22) fusion junctions using targeted next-generation sequencing coupled with the use of a dPCR platform. t(9;22) genomic breakpoints were successfully mapped in samples from 32 of 32 patients with early stage disease. Disease quantification by DNA-based dPCR was performed using the Fluidigm BioMark platform on 46 follow-up samples from 6 of the 32 patients, including 36 samples that were in deep molecular remission. dPCR detected persistent disease in 81% of molecular-remission samples, outperforming both RT-dPCR (25%) and DNA-based quantitative PCR (19%). We conclude that dPCR for BCR-ABL1 DNA is the most sensitive available method of residual-disease detection in chronic myeloid leukemia and may prove useful in the management of tyrosine kinase inhibitor withdrawal.

Economics and Outcome After Hematopoietic Stem Cell Transplantation: A Retrospective Cohort Study

Hematopoietic stem cell transplantation (HSCT) is a lifesaving expensive medical procedure. Hence, more transplants are performed in more affluent countries. The impact of economic factors on patient outcome is less defined. We analyzed retrospectively a defined cohort of 102,549 patients treated with an allogeneic (N = 37,542; 37%) or autologous (N = 65,007; 63%) HSCT. They were transplanted by one of 404 HSCT centers in 25 European countries between 1999 and 2006. We searched for associations between center-specific microeconomic or country-specific macroeconomic factors and outcome. Center patient-volume and center program-duration were significantly and systematically associated with improved survival after allogeneic HSCT (HR 0·87; 0·84-0·91 per 10 patients; p < 0·0001; HR 0·90;0·85-0·90 per 10 years; p < 0·001) and autologous HSCT (HR 0·91;0·87-0·96 per 10 patients; p < 0·001; HR 0·93;0·87-0·99 per 10 years; p = 0·02). The product of Health Care Expenditures by Gross National Income/capita was significantly associated in multivariate analysis with all endpoints (R(2) = 18%; for relapse free survival) after allogeneic HSCT. Data indicate that country- and center-specific economic factors are associated with distinct, significant, systematic, and clinically relevant effects on survival after HSCT. They impact on center expertise in long-term disease and complication management. It is likely that these findings apply to other forms of complex treatments.

Haploidentical Hematopoietic Stem Cell Transplantation: A Global Overview Comparing Asia, the European Union, and the United States

One of the major projects of the Worldwide Network for Blood and Marrow Transplantation (WBMT) is to promote hematopoietic stem cell transplantation (HSCT) in emerging countries in the world. For these countries, HLA haploidentical HSCT (haplo-HSCT) from family members is an attractive approach because of its cost effectiveness. To learn the current status, including recent trends, of haplo-HSCT, the WBMT invited speakers from major transplant centers in 3 regions (Asia, Europe, and North America) to present at its annual WBMT Joint Session. This article represents the direct reports from these 3 speakers in addition to introductions by 2 WBMT speakers who address data from the Global Transplant Activity survey. It must be emphasized, however, that certain promising results of haplo-HSCT presented in this article were obtained at well-experienced institutes.