Introduction: “The Frontline asciminib in combination” - FASCINATION study (NCT03906292) is a multicenter, prospective, open-label, interventional phase II trial to evaluate efficacy and tolerability of asciminib as first-line treatment in combination with conventional ATP-competing BCR::ABL1 inhibitors for patients (pts) with chronic myeloid leukemia (CML) in chronic phase. The aim of the study is to improve the rate of deep molecular response and thereby increase the proportion of patients in treatment-free remission (TFR) over time. Here, we report the 3-year follow-up of the trial. Methods: Adult pts with newly diagnosed BCR::ABL1-positive CML were allocated to one of four combination cohorts: nilotinib 300 mg BID plus asciminib 20 mg BID (cohort 1) or asciminib 40 mg QD (cohort 2), dasatinib 100 mg QD plus asciminib 80 mg QD (cohort 3), or imatinib 400 mg QD plus asciminib 60 mg QD (cohort 4). The primary endpoint was the rate of MR4 (BCR::ABL1 transcripts ≤0.01% on the International Scale, IS) at month 12. Patients who did not achieve MR4 at month 24 stopped asciminib combination and were treated with an ATP competing TKI monotherapy at the discretion of the investigator. Subjects with MR4 continued the previous asciminib combination treatment for one year. Patients with MR4.5 were de-escalated to asciminib monotherapy 80 mg QD for one year. At month 36, asciminib treatment was stopped for all pts. Pts with MR4 or better for at least one year entered a TFR phase. Results: Between September 2019 and January 2022, 144 pts were recruited from 21 sites in Germany. Combination therapy was commenced in 125 pts (67% male). Median age at diagnosis was 46 years (range, 19-89). 57.6, 30.3, and 12.1% were low, intermediate, and high risk according to the ELTS score, respectively. BCR::ABL1 independent mutations were identified in 22 pts (18%), most commonly ASXL1 mutations (8 pts, 7%). A total of 114 pts were eligible for evaluation of molecular response at month 12. According to the intention to treat, rate of MR4at month 12 (primary endpoint) was 37.7%. At month 24, a total of 92 pts (73.6%) were allocated to further treatment arms based on their molecular response: 45 pts did not achieve MR4 at month 24 and continued with an ATP competing TKI monotherapy, 17 pts achieved MR4 and continued the previous combination treatment, 30 pts achieved MR4.5and were de-escalated to asciminib monotherapy. A total of 101 pts were eligible for evaluation of molecular response at month 36 (secondary endpoint). Rate of MMR, MR4, MR4.5, MR5 and MR5.5was 91%, 65%, 45%, 27% and 20%, respectively. Six of 8 pts with ASXL1 mutations achieved MR4 at month 12 and 7 pts at month 36, respectively. Within the 3-year follow-up, loss of MMR was observed in 5 pts with a BCR::ABL1-E275G mutation detected in one patient. Two pts progressed to blast phase and received allogeneic stem cell transplantations (month 7 and 13, respectively). Adverse events (AEs) grade 3-4 decreased from 37.6% of pts within the first year to 24.0% and 9.6% within the second and third year, respectively. Most commonly observed AEs were lipase increase (10 pts) and hypophosphataemia (6 pts). One patient died due to a myocardial infarction (month 24). A total of 37 pts (29.6%) entered the TFR phase at month 36. Conclusions: The combination of asciminib as frontline therapy with ATP competing BCR::ABL1 inhibitors was associated with a high rate of deep molecular response but moderate tolerability in the first year. The 3-year follow-up of the FASCINATION trial shows high efficacy (even in pts with ASXL1 mutations), no evidence for development of clinically relevant BCR::ABL1 mutations and improved tolerability without any unsuspected AEs. Further follow-up is needed to investigate TFR.

The development of Philadelphia chromosome-negative classical myeloproliferative neoplasms (MPN) involves an inflammatory process that facilitates outgrowth of the malignant clone and correlates with clinical outcome measures. This raises the question to which extent inflammatory circuits in MPN depend on activation of innate immune sensors. Here, we investigate whether NLRP3, which precipitates inflammasome assembly upon detection of cellular stress, drives murine JAK2V617F mutant MPN. Deletion of Nlrp3 within the hematopoietic compartment completely prevents increased IL-1β and IL-18 release in MPN. NLRP3 in JAK2V617F hematopoietic cells, but not in JAK2 wild type radioresistant cells, promotes excessive platelet production via stimulation of the direct thrombopoiesis differentiation pathway, as well as granulocytosis. It also promotes expansion of the hematopoietic stem and progenitor cell compartment despite inducing pyroptosis at the same time. Importantly, NLRP3 inflammasome activation enhances bone marrow fibrosis and splenomegaly. Pharmacological blockade of NLRP3 in fully established disease leads to regression of thrombocytosis, splenomegaly and bone marrow fibrosis. These findings suggest that NLRP3 is critical for MPN development and its inhibition represents a new therapeutic intervention for MPN patients.

Constitutive activation of STING by gain-of-function mutations triggers manifestation of the systemic autoinflammatory disease STING-associated vasculopathy with onset in infancy (SAVI). In order to investigate the role of signaling by tumor necrosis factor (TNF) in SAVI, we used genetic inactivation of TNF receptors 1 and 2 in murine SAVI, which is characterized by T cell lymphopenia, inflammatory lung disease, and neurodegeneration. Genetic inactivation of TNFR1 and TNFR2, however, rescued the loss of thymocytes, reduced interstitial lung disease, and neurodegeneration. Furthermore, genetic inactivation of TNFR1 and TNFR2 blunted transcription of cytokines, chemokines, and adhesions proteins, which result from chronic STING activation in SAVI mice. In addition, increased transendothelial migration of neutrophils was ameliorated. Taken together, our results demonstrate a pivotal role of TNFR signaling in the pathogenesis of SAVI in mice and suggest that available TNFR antagonists could ameliorate SAVI in patients.

Introduction Ropeginterferon alfa-2b (ropeg), a next-generation mono-pegylated interferon (IFN) demonstrated a favorable safety and tolerability profile in phase 3 trials for treatment of polycythemia vera (PV). Hepatotoxicity is an important class effect of alfa IFN. This post-authorization study evaluated the hepatotoxicity risk and overall safety of ropeg in a real-world PV cohort. Methods This phase 4, prospective, non-interventional safety study was conducted in Austria (8 sites), Germany (20 sites), and Romania (6 sites). Ropeg-naïve PV patients aged ≥18 years who gave informed consent and had no relevant contraindications were eligible to receive ropeg during routine clinical care. The primary endpoint was the incidence of hepatotoxicity defined as: (1) Significant elevations in ALT (alanine amino transferase), AST (aspartate amino transferase), and/or GGT (gamma-glutamine transferase), defined as ≥3× upper limit of normal [ULN]) and/or total bilirubin (>2× ULN) and (2) Treatment-emergent hepatobiliary adverse drug reactions (ADRs) in the first 6 months of treatment. Additional endpoints included patient characteristics, incidence of cardiovascular events over the entire 18-month observation period, and all treatment-emergent adverse events. Results A total of 229 PV patients were enrolled and treated; 42.4% were female. Age and time since diagnosis varied considerably (age: median 58.0 years, range 23-91; time since diagnosis: median 0.9 years, range 0-30). At baseline, 58.5% of patients presented with PV-related symptoms, 17.0% had pre-existing liver disease and 56.3% of patients were classified as high risk for thromboembolic events; 25.3% already had experienced such an event. Cardiovascular disease was present in 61.1% and cardiovascular risk factors in 60.3% of patients at baseline. Prior cytoreduction was documented in 38.4% of patients, with a median of 1.0 (range 1-4) previous therapies. Ropeg was administered at a median starting dose of 100 µg/2 weeks. Dose individualization resulted in a median 2-weekly dose of 200 µg (IQR: 125-250) at 18 months. Regarding the primary endpoint, in the first 6 months, significant elevations in liver parameters were reported in 32 patients (14.0%; incidence rate per 100 patient-years [IR/100 PY]: 45.21 [95% CI: 33.45–59.77]; no hepatobiliary ADRs occurred in this period. Excluding patients with a significant elevation of liver parameters at baseline, 9.1% had significant elevations (IR/100 PY: 30.20 [95% CI: 20.37, 43.11]). Over the entire 18-month period, a lower incidence of significant elevations in liver parameters was observed (IR/100 PY: 30.83 [95% CI: 24.91, 37.72], or 23.24 [17.94, 29.62] excluding patients with significant elevations at baseline). One hepatobiliary ADR (grade 2 hepatic cirrhosis) occurred. Hepatotoxicity led to dose reduction, interruption or discontinuation in 2.6%, 3.5% and 1.3% of patients, respectively. Elevated liver parameters were more common among patients with pre-existing liver disease (37.2% vs 8.4% in those without pre-existing disease; p<0.0001). Thromboembolic events occurred in 11 patients (4.8%) during the entire study, all of whom had pre-existing cardiovascular disease and/or significant cardiovascular risk factors. One was a major adverse cardiovascular event (acute myocardial infarction) in a patient with a medical history of three prior major thromboembolic events. No new safety concerns emerged. Aside from liver enzyme elevations, the most common ADRs included fatigue (19.7%), pruritus (14.8%), and headache (6.6%), which may be difficult to distinguish from PV-related symptoms. Notably, typical IFN-related toxicity such as flu-like illness, autoimmune thyroiditis and depression were rare (3.1%, 1.7% and <1%, respectively).Prophylaxis with NSAIDs was uncommon (≤3%). A total of 13 (5.7%) patients discontinued treatment due to ADRs in the first 6 months and 15 (6.6%) thereafter. Conclusion This study underscores the heterogeneity of PV patient characteristics in clinical practice. Despite pre-existing liver disease in 17% of patients, hepatoxicity on ropeg occurred at a low overall rate, consistent with registration trials and prescribing information. In contrast to trial populations, substantial co-morbidity was observed, with more cardiovascular events in patients with history of cardiovascular risk. Our prospective investigation of a large PV cohort confirms the safety of ropeginterferon alfa-2b in a real-world setting.

AbstractIn humans, blood Classical CD14+ monocytes contribute to host defense by secreting large amounts of pro-inflammatory cytokines. Their aberrant activity causes hyper-inflammation and life-threatening cytokine storms, while dysfunctional monocytes are associated with ‘immunoparalysis’, a state of immune hypo responsiveness and reduced pro-inflammatory gene expression, predisposing individuals to opportunistic infections. Understanding how monocyte functions are regulated is critical to prevent these harmful outcomes. We reveal platelets’ vital role in the pro-inflammatory cytokine responses of human monocytes. Naturally low platelet counts in patients with immune thrombocytopenia or removal of platelets from healthy monocytes result in monocyte immunoparalysis, marked by impaired cytokine response to immune challenge and weakened host defense transcriptional programs. Remarkably, supplementing monocytes with fresh platelets reverses these conditions. We discovered that platelets serve as reservoirs of key cytokine transcription regulators, such as NF-κB and MAPK p38, and pinpointed the enrichment of platelet NF-κB2 in human monocytes by proteomics. Platelets proportionally restore impaired cytokine production in human monocytes lacking MAPK p38α, NF-κB p65, and NF-κB2. We uncovered a vesicle-mediated platelet-monocyte-propagation of inflammatory transcription regulators, positioning platelets as central checkpoints in monocyte inflammation.

Introduction: Currently, six tyrosine kinase inhibitors (TKIs) are approved for chronic phase chronic myeloid leukemia (CML). Unfortunately, treatment sequence has never been tested prospectively, and, therefore, it remains unclear which TKI should be chosen, especially after first-line treatment with more potent second generation (2G)-TKIs. The original goal of the “Bosutinib Dose Optimization Study” (BODO) study was to evaluate whether a bosutinib step-in dosing regimen decreases gastrointestinal (GI) toxicity while maintaining optimal efficacy in patients (pts) with CML after failure or intolerance to 2G-TKIs. Despite its premature study end, it thereby contains one of the largest cohorts of 2nd generation TKI treatment after failure/intolerance of a 2G-TKI in first line. Methods: This is a sub-analysis of the BODO trial (NCT03205267), a multicenter, open-label single arm phase II study testing tolerability and efficacy of 2nd and 3rd line bosutinib step-in dosing in chronic phase CML pts intolerant and/or refractory to previous imatinib and/or nilotinib, and/or dasatinib therapy. Bosutinib was commenced with 300 mg QD and was (in the absence of > grade 1 toxicities) dose-increased by increments of 100 mg daily dosing every 14 days up to a maximum dose of 500 mg QD. 127 pts were planned to be recruited. However, due to slow recruitment, the trial had to be stopped prematurely after inclusion of 57 pts. For this analysis, we focused on the 45 patients treated with either nilotinib (n=23) or dasatinib (n=22) as first-line therapy. Cumulative incidence curves of response to bosutinib were calculated and compared using Gray's test. Results: 45 pts (n=28 males; median age 51 years, range: 19 - 77) were included in the analysis. The ECOG status was 0 (n=36, 80%) or 1 (n=9, 20%). Prior to study inclusion, a median daily dose of 600 mg nilotinib (range: 300 - 800) and 100 mg of dasatinib (range: 57 - 200) had been administered. The median duration of previous nilotinib and dasatinib therapy was 20.0 months (range: 23 days - 8.0 years) and 16.6 months (range: 3.7 - 34.3 months, p = 0.184), respectively. 18 (40%) pts were intolerant, 17 resistant (38%), and 10 (22%) both intolerant and resistant to previous TKI treatment. 17 (38%) pts entered the study in molecular response (at least major molecular remission (MMR) at screening). The odds of being in MMR at screening were higher in patients with longer pretreatment duration (OR = 1.9; CI: 1.1, 3.7; p = 0.038 per additional year of pretreatment). The corresponding probabilities of MMR were 40% (CI: 26, 54%), 58% (CI: 42, 71%), 68% (CI: 51, 80%) at 3, 6, and 12 months, and 79% (CI: 62, 89%) at 18 and 24 months, respectively. Median time to MMR was 4.9 months. MMR probabilities by pretreatment did not differ between nilotinib and dasatinib (p=0.788). 3 out of 4 intolerant pts without MMR at baseline reached MMR or a better molecular response level with bosutinib. 24 pts refractory to previous therapy (16 resistant; 8 both resistant and intolerant) were lacking baseline MMR, of which 16 pts achieved MMR or better (1 pt with MR4.5, 2 with MR4 and 13 with MMR). In the 24 refractory pts without MMR at baseline, the cumulative MMR and MR4 rates by 1 year were 48% (CI: 26, 68%) and 10% (CI: 2, 27%), respectively. One patient reached MR4.5 after 15.2 months of bosutinib therapy. Response to bosutinib was not significantly different in patients pretreated with either dasatinib or nilotinib. 33 pts received bosutinib for at least 6 months and also had a 6-months molecular response evaluation. At 6 months, median dose levels of bosutinib were not significantly different between responders and non-responders. No disease progressions were reported during the study and follow up. All pts had ≥1 any grade treatment emergent adverse event (TEAE), occuring a median of 15 days after starting bosutinib (range: 1 - 225 days). Cumulative probability of grade 3/4 TEAEs, and serious adverse events by 1 year was 69% (53, 81%) and 26% (CI: 13, 40%), respectively. The most common TEAE was diarrhea with a cumulative probability of 63% (CI: 47, 76%) by 1 month. Conclusion: Despite of the limitations of a single-arm study with incomplete recruitment, bosutinib was able to induce optimal responses in two thirds of pts previously resistant to 2G-TKIs while GI toxicity rarely led to treatment discontinuation. We conclude that bosutinib is a safe option after intolerance/failure of a 2G-TKI in first-line.

Background: Phase II trials with 2nd- or 3nd-generation Tyrosine Kinase Inhibitors (TKI) with or without immunotherapy yield promising results in Ph+ ALL. However, Imatinib (IM) in combination with chemotherapy regimens of different intensity, followed by allogeneic SCT is still the standard treatment in younger patients with newly diagnosed Ph+ALL in many countries. Aims: GMALL Trial 08/2013 (NCT02881086), evaluated a concept with dose reduced induction and intensive consolidation in combination with imatinib followed by allogeneic SCT independent of MRD response in patients (pts) aged 18-55 years (yrs). Age-adapted TBI-based conditioning regimen was proposed in all patients (8 Gy TBI vs 12 Gy TBI). Methods: Patients received a 6 week induction phase with IM 600 mg/d together with low intensity chemotherapy (VCR, Dexa, PEG-ASP) and intrathecal chemo-prophylaxis. Four doses of Rituximab were added if CD20 expression of blasts was >20%. BM evaluation after 3 weeks separated induction I and II. Consolidation treatment (C1) with Dexa, VCR, HDMTX, HDAC, VP16 followed. Donor search was initiated in all pts at diagnosis. Allogeneic SCT was scheduled after the first consolidation. After an amendment a TKI change was recommended if the MRD value was above >10-3 BCR::ABL1/ABL1 after C1. MRD was based on quantitative RT-PCR for BCR::ABL1, additional MRD assessment with IG/TCR PCR was recommended. Results: Between 09/2016 and 07/2022, 174 patients with a median age of 42 (18-55) years were recruited and evaluable. 70 (40%) patients had a WBC ≥30000/µl. Hematologic CR rates after induction I, II and consolidation I were 85%, 96% and 95%. Early death and failure rates after consolidation 1 were 4% and 1% respectively. Molecular Remission (MolCR) was defined as PCR negativity for BCR::ABL1 transcripts with at least 10 000 ABL1 copies. The MolCR rate increased from 9% after induction 1 to 24% after induction 2 and was 42% after consolidation 1. Intermediate MRD positivity defined as BCR::ABL1/ABL1 below <10-4 was observed in 9%, 18% and 21% resp. 38% of the patients were still MRD positive with quantitative MRD >10-4 BCR::ABL1/ABL1 after the consolidation 1; 9 patients were switched to Dasatinib according to the recommendations after the amendment. Overall survival (OS) at 3 years was 76%; remission duration at 3 years was 89% with a median follow up of 52 months. 3y-OS was 89%, 73% and 75% for patients aged 18-25, 26-45 and 46-55 years respectively (p>.05). WBC at diagnosis <> 30.000/µl showed no significant difference with 3y-OS of 76% vs 76% (p>.05). 159/174 pts were transplanted in CR1 (98% of CR pts). The median time to SCT was 4 months and the overall survival rate after 3 years was 81%. OS at 3 yrs was similar (79% vs 82%) for matched sibling or matched unrelated SCT. The treatment-related mortality after 3 years was 16% (15% for pts <45yrs and 16% for ≥45 yrs). OS after SCT was not impacted by status of BCR::ABL1 MRD after consolidation 1/before SCT as defined above. Results of IG/TCR MRD and IKZFplus profile will be available. Summary: Dose reduced induction including PEG-ASP in combination with IM was feasible and yielded high response rates leading to a molecular CR rate of 42% already after consolidation 1. The SCT realization rate (98%) was extremly high. In conclusion, this multicenter trial for younger patients with Ph+ ALL showed an excellent long term survival rate with imatinib combined with low-intensity chemotherapy followed by allogeneic SCT. It remains open to further trials to determine the prognostic role of BCR::ABL1 MRD in SCT-focused regimens. The role of alternative TKIs and immunotherapies with the goal to reduce SCT indications will be evaluated in the ongoing GMALL EVOLVE trial (NCT06061094). The trial was funded by Deutsche Krebshilfe.

Outcome of adult ALL was improved significantly using pediatric (ped) -based therapy over the past decade. However, many groups still see an indication for stem cell transplantation (SCT) in patients (pts) with high-risk (HR) features. The GMALL Trial 08/2013 (NCT02881086) for pts aged 18-55 years (yrs) with newly diagnosed ALL/LBL is a ped-based regimen with MRD-based stratification and risk adapted SCT (Gökbuget et al, ASH 2021). Induction has 2 phases (IP1/IP2) and is followed by intensive consolidation I (C1). Indication for SCT is based on features detected at diagnosis (B-precursor: WBC >30,000/μl, proB subtype, KMT2a-rearrangement; T-lineage: early/mature subtype), no achievement of hematologic CR after IP1 or molecular failure after C1. SCT was scheduled after C1. Standard risk (SR) therapy consists of cycles with HDMTX/PEG-ASP, HDAC/CYCLO, reinduction and maintenance with MP/MTX up to a total treatment duration of 2.5 yrs. The trial included a randomization for Ph negative HR ALL pts with available donor and molecular CR (molCR i.e. negative MRD with a sensitivity of 0.01% by quantitative PCR of IG/TR in GMALL reference lab) after IP2. Pts were either scheduled for SCT (matched related/unrelated) or SR chemotherapy with MRD follow-up. The statistical assumption (primary endpoint) was to detect in 88 pts with a power >90% and a 2-sided α-level of 5% an improvement of disease-free survival (DFS) from 70% to 86% at 3.5 yrs. Events were hematologic relapse (hemR), molecular relapse (molR), secondary malignancy or death in CR (TRM). HemR was defined by conventional criteria. MolR was defined as MRD >=0.01% after prior molCR. Probabilities of TRM and hemR were calculated with competing risks. Between 8/16-8/22 1023 pts from 78 centers were included in the trial. 285 pts had HR ALL. 102 pts (37%) achieved molCR after IP2; 96 pts were randomized (91%). Pt characteristics were evenly distributed between both arms; median age was 31 (18-55) yrs and 63% had B- (36% c/preB; 26% pro B) and vs 38% T-subtype (19% early; 14% mature; 5% thymic) respectively (resp). Scheduled therapy was performed in 79% (38/48) for SCT arm and 88% (42/48) for SR arm resp. Deviations resulted from pt wish (N=7; of this N=6 in SCT arm), randomization despite exclusion criteria (N=3 e.g. pt with SR ALL) and unavailable donor/other (N=2/1).Three pts were not eligible for evaluation of treatment realization since they dropped out (2 pt wish, 1 wrong diagnosis); they were included in the outcome analysis. All analyses were performed in the intent-to-treat population. 3y DFS was identical in both arms (SCT arm 76% [61, 86]; SR arm 71% [55, 82]) (p>.05). Six (13%) vs 4 (8%) pts died in CR in SCT vs SR arm resp. (3yTRM: 13% [5; 24] vs 9% [3; 19]). 5 (10%)/ 7(15%) had hemR in SCT vs SR arm resp (3y RR: 11% [4; 22] vs 15% [7; 27]). 9/12 hemR were preceded by molR whereas 3 pts had hemR w/o prior molR. 9/11 pts with molR progressed to hemR and 9/11 died whereas 3/3 pts with direct hemR died. 3y OS was 76% vs 75%C in SCT vs SR arm resp (p>.05). Post-hoc analyses of subtypes revealed differences. In B-lineage the 3y DFS for SCT (N=31) vs SR (N=29) arm was 81% vs 56% resp (p=0.04). 3y OS was 80% vs 60% resp (p>.05). One pt relapsed in the SCT arm (not transplanted per pt wish) vs 8 pt with hem/molR (1 molR) in SR arm. 2/8 relapse cases had BCR::ABL-like (JAK/STAT) an 2/8 KMT2Ar ALL. In T-ALL DFS for SCT (N=17) vs SR arm (N=19) was 67% vs 94% (p=0.04). 3y OS was 69% vs 100% resp. 4 pts relapsed in SCT arm vs 1 (including 1 molR) in SR arm. Further analyses of long-term effects and quality of life is ongoing. The GMALL trial 08 demonstrated a successful randomization of SCT in a complex multicentre setting. The primary endpoint was not reached. Overall results were similar comparing SCT vs SR therapy in HR pts with early molCR. While SCT pts had a higher TRM, SR therapy was associated with more relapses. In B-precursor ALL the trend was in favor of SCT in contrast to T-ALL with better outcomes in the SR arm. Whereas upcoming relapse was often identified by MRD testing, salvage after molR or hemR was rarely successful and outcome was extremely poor. This indicates the role of careful upfront definition of SCT indications. In further GMALL trials the upfront use of Blinatumomab for further improvement of B-precursor ALL with MolCR will be evaluated whereas SCT indication may be maintained in selected HR pts despite molCR. GMALL 08/2013 is an independent academic trial funded by the Deutsche Krebshilfe (111440).

Recurrent problems of patients with myelofibrosis (MF) are cytopenias, debiliating disease-related symptoms and splenomegaly. Whereas the latter are usually addressed by the JAK1/2 inhibitors ruxolitinib and fedratinib, cytopenias often remain critical. Momelotinib, a JAK1/2 inhibitor recently approved for the treatment of anemic MF patients, was shown to improve anemia via a direct inhibition of activin A receptor type I. In this German-wide, multicenter, retrospective analysis the safety and efficacy profile of momelotinib was evaluated in a real world setting within a cohort of 60 MF patients independent of pre-treatment. The median duration of treatment was 12 weeks. As a new, but manageable safety finding, creatinine increase (CTC°1–2) was detected in 10/60 patients (17

The transcription factor CCAAT/enhancer binding protein alpha (CEBPA) is a key regulator of myelopoiesis and granulocyte differentiation.1, 2 The intronless CEBPA gene on chromosome 19q13.1 encodes two DNA-binding protein isoforms: a full-length 42-kDa protein (p42) and a shorter 30-kDa isoform (p30), initiated from two distinct start sites.2 The p42 isoform contains two N-terminal transactivation domains (TAD1, TAD2), whereas the p30 isoform lacks TAD1. Both isoforms contain the highly conserved C-terminal basic DNA-binding domain and the leucine zipper (bZIP) involved in DNA binding and protein dimerization. In younger adult patients, mutations of CEBPA (CEBPAmut) are present in 5%–10% of newly diagnosed acute myeloid leukemia (AML); the frequency in older patients is considerably lower.2-5 There are two mutational patterns: the first one clusters at the N-terminus involving the two TADs, typically frame-shift mutations; the second one at the C-terminus affecting bZIP, typically in-frame mutations. Out-of-frame TAD mutations result in the truncated p30 isoform that has been shown to act as a dominant negative of the p42 isoform and to be associated with increased proliferation and minimal differentiation of myeloid progenitors.2, 6 Depending on the position, in-frame bZIP mutations cause a p42 isoform defective either in DNA binding or homo- and heterodimerization.3, 7 Approximately half of the CEBPAmut AML exhibit biallelic mutations (CEBPAbi), typically consisting of one TAD and one bZIP mutation on separate alleles.3, 4 Based on specific genetic features and its prognostic impact, CEBPAbi was defined as a distinct entity within the 2016 WHO classification and was categorized as favorable in the risk stratification of the 2017 European LeukemiaNet (ELN) recommendations. Recent studies in pediatric and adult AML have demonstrated CEBPAbZIP mutations, and in particular, in-frame mutations (CEBPAbZIP_inf), to be associated with a unique gene-expression profile and favorable outcome, regardless of the mono- or biallelic status.8-10 Based on these data, the former entity of AML with CEBPAbi was expanded by single mutations in bZIP (smbZIP-CEBPA) in the current 2022 WHO classification and replaced by AML with CEBPAbZIP_inf (irrespective of the allelic status) within the 2022 International Consensus Classification (ICC) of myeloid neoplasm and acute leukemias.11, 12 Furthermore, CEBPAbZIP_inf (irrespective of the allelic status) is now categorized as favorable in the 2022 ELN risk stratification.13 To evaluate the prognostic impact of CEBPAbZIP, in particular to further characterize CEBPAbZIP_inf mutations, we retrospectively analyzed 528 intensively treated adult CEBPAmut AML patients (median age: 54 years, range: 18–82; ≤60 years: n = 340, >60 years: n = 188) enrolled in treatment trials of the German-Austrian AML Study Group (AMLSG) and/or entered into the AMLSG BiO Registry study (NCT01252485). CEBPA mutation status was evaluated centrally in two reference laboratories of the AMLSG; assays were harmonized and cross-validated between the two laboratories. Sequences were analyzed for type of CEBPA mutations (insertions/deletions either in-frame or frameshift, missense, and nonsense mutations), the precise localization of mutations (TAD1/2 and bZIP), and allelic status. Two hundred forty-three (46%) patients were enrolled in one of 12 AMLSG treatment trials (Supporting Information S1: Appendix) and 285 (54%) received intensive treatment according to the standard of care. The study was conducted in accordance with the Declaration of Helsinki. Written informed consent for treatment and genetic testing was obtained from all patients. Complete remission (CR), including CR with incomplete hematologic recovery during induction cycles 1 and 2, was achieved in 425/501 (85%) evaluable patients. Allogeneic hematopoietic-cell transplantation (HCT) in the first CR (CR1) was performed in 109 (21%) patients. The median follow-up time was 55.5 months (95% confidence interval [95% CI], 51.2–59.5). Median event-free survival (EFS) and median overall survival (OS) were 20.0 (95% CI: 14.4–30.6) and 172.4 months (95% CI: 72.5–NA), respectively. The 5-year EFS and OS rates were 42% and 55%, respectively. One hundred forty-one (26.7%) patients relapsed, and 195 (36.9%) died. Of the 528 patients, 263 (49.8%) exhibited ≥2 CEBPA mutations (dmCEBPA), and 265 had monoallelic CEBPA mutations (smCEBPA). To further refine CEBPA mutation types and to address their prognostic impact, patients were categorized into eight groups based on allelic status (dmCEBPA vs. smCEBPA) and mutation type: (1) dmCEBPA with in-frame insertion/deletion in bZIP (dmCEBPAbZIP_InDel_inf, n = 220), (2) frame-shift insertion/deletion or nonsense mutation in bZIP (dmCEBPAbZIP_InDel_fs, n = 13), (3) missense mutation in bZIP (dmCEBPAbZIP_ms, n = 22), (4) other (dmCEBPAother, n = 8), (5) smCEBPAbZIP_InDel_inf (n = 46), (6) smCEBPAbZIP_InDel_fs (n = 32), (7) smCEBPAbZIP_ms (n = 11), or (8) smCEBPAother (n = 176). These eight groups differed significantly with regard to several clinical and concurrent genetic features as well as achievement of CR1 and outcome (Supporting Information S1: Table 1). To evaluate the prognostic impact of the eight CEBPA mutation types, we performed conditional inference tree models for EFS and OS. Of the eight equally relevant groups, dmCEBPAbZIP_InDel_inf and smCEBPAbZIP_InDel_inf patients separated from the other groups in the first tree based on significantly lower cumulative incidences of events (refractory disease, relapse, and/or death). No further partitioning was observed (Supporting Information S1: Figure 1). Assuming a prognostic impact primarily for mutation type rather than allelic status, subsequent conditional inference tree models were performed by splitting up CEBPA mutation types and allelic status for EFS and OS. In both the models, the CEBPAbZIP_InDel_inf group again separated significantly from the other three groups in the first tree without further separation, confirming the significantly favorable prognosis, regardless of the allelic status (Figure 1A and Supporting Information S1: Figure 2). Based on these findings, patients were subsequently categorized as CEBPAbZIP_InDel_inf (n = 266), CEBPAbZIP_InDel_fs (n = 45), CEBPAbZIP_ms (n = 33), or CEBPAother (n = 184), irrespective of the allelic status. These four groups differed significantly with regard to several clinical and concurrent genetic features as well as achievement of CR1. Most obviously, CEBPAbZIP_InDel_inf patients were younger (median age in years: 49 vs. 66 vs. 60 vs 61; p < .001) and achieved a higher CR1 rate (91.4% vs. 81.8% vs. 83.3% vs. 76.2%; p < .001) (Supporting Information S1: Table 2). Irrespective of the allelic status, CEBPAbZIP_InDel_inf patients had a significantly improved EFS (median [95% CI] 49.8 months [16.9–82.7] vs. 11.5 [8.3–14.6] for CEBPAbZIP_InDel_fs vs. 12.6 [6.2–19.1] for CEBPAbZIP_ms vs 14.6 [7.7–21.5] for CEBPAother; p < .001) and OS (median [95% CI] NA for patients with CEBPAbZIP_InDel_inf [NA–NA] vs. 25.7 months [10.2–41.3] for CEBPAbZIP_InDel_fs vs. 54.3 [14.6–NA] for CEBPAbZIP_ms vs. 45.5 [13.1–77.9] for CEBPAother; p < .001) (Figure 1B,C). Of note, a sensitivity analysis in which survival times were censored at the date of HCT in CR1 revealed almost identical results (Supporting Information S1: Figure 3). Multivariate Cox models for EFS and OS adjusted for sex, type of AML, FLT3-ITD, NPM1 mutation status, white blood cell (WBC) count (log10 transformed), bone marrow blasts, and age including HCT in CR1 as a time-dependent variable (Supporting Information S1: Appendix) revealed increasing age and higher WBC as unfavorable factors, whereas CEBPAbZIP_InDel_inf, NPM1mut, and HCT in CR1 were favorable (Table 1). A recent meta-analysis of 1010 adult CEBPAmut AML from six different study groups characterized CEBPA mutational subgroups in more detail by evaluating their clinical and genetic features as well as their prognostic impact.14 In line with our data, the authors showed that CEBPAbZIP_InDel_inf mutations represent a subset of AML with distinct disease biology and clinical outcomes. Despite certain limitations, in particular, the retrospective nature spanning almost three decades with evolving different treatment approaches, both studies independently confirm the less favorable impact of in-frame bZIP missense mutations (currently subsumed in the category AML with CEBPAbZIP_inf in the ICC and ELN risk classification). The less favorable impact of bZIP missense mutations might be explained by the finding that bZIP missense mutations localize differently and therefore have diverse functional consequences. CEBPAbZIP_InDel_inf predominantly affects the fork region of bZIP, while CEBPAbZIP_ms cluster in the basic region (Supporting Information S1: Figure 4). These different mutation patterns imply that CEBPAbZIP_ms impair DNA binding, while CEBPAbZIP_InDel_inf affects dimerization. Murine data have shown that missense mutations in the basic region of bZIP lead to a myeloproliferative disease transforming into overt AML,7 while AML arises upon transplantation of transgenic cells carrying the most common in-frame insertion in bZIP (K313dup, K-allele) alone or in combination with an N-terminal mutation (L-allele), with the K/L combination driving the most aggressive AML.15 In this retrospective, exploratory analysis of 528 adult patients with newly diagnosed intensively treated patients with CEBPAmut AML, we further refined the prognostic impact of different CEBPA mutation types, in particular, CEBPA mutations that are located in the bZIP domain. Our study shows that the beneficial effect is restricted to CEBPA bZIP InDel in-frame mutations, irrespective of the allelic status, whereas CEBPA bZIP missense mutations are associated with inferior outcomes. Our data as well as the data from Georgi et al. provide novel and clinically relevant results contributing to a further refinement of CEBPAmut AML in the current ICC and WHO classifications as well as for risk stratification as recommended by the ELN. The authors greatly acknowledge the members of the German-Austrian AML Study Group (AMLSG) for providing patient samples and clinical information. Open Access funding enabled and organized by Projekt DEAL. Frank G. Rücker, Andrea Corbacioglu, Hartmut Döhner, and Konstanze Döhner designed the study. Frank G. Rücker, Andrea Corbacioglu, Sibylle Cocciardi, Verena I. Gaidzik, Annika Meid, and Sophia Aicher performed experiments and validated data. Frank G. Rücker, Julia Krzykalla, Daniela Weber, and Axel Benner performed statistical analyses. Frank G. Rücker, Andrea Corbacioglu, Julia Krzykalla, Daniela Weber, Axel Benner, Hartmut Döhner, and Konstanze Döhner analyzed the results. Claudia Lengerke, Ulrich Germing, Gerald Wulf, Maisun A. Samra, Lino L. Teichmann, Michael Lübbert, Michael W. M. Kühn, Martin Bentz, Jörg Westermann, Lars Bullinger, Frank Stegelmann, Anika Schrade, Felicitas Thol, Michael Heuser, and Arnold Ganser collected and provided patient samples and clinical information. Frank G. Rücker, Andrea Corbacioglu, Hartmut Döhner, and Konstanze Döhner wrote the first draft of the manuscript; and all authors undertook manuscript writing, editing, and approval, revised the manuscript, and reviewed and approved the final version. Frank G. Rücker reports honoraria from and consultancy for Jazz Pharmaceuticals, Novartis, and BMS/Celgene; travel support from Jazz Pharmaceuticals. Michael Lübbert reports an advisory role for Abbvie, Astex Pharmaceuticals, Imago BioSciences, Janssen, Otsuka, and Syros; research support from Janssen and Cheplapharm. Michael W. M. Kühn reports honoraria from and consultancy for Pfizer, Kura Oncology, Jazz Pharmaceuticals, BMS/Celgene, and Abbvie; speakers bureau of Gilead. Lars Bullinger reports honoraria from Abbvie, Amgen, Astellas, BMS/Celgene, Daiichi Sankyo, Gilead, Janssen, Jazz Pharmaceuticals, Menarini, Novartis, Pfizer, Roche, and Sanofi; research support from Bayer and Jazz Pharmaceuticals. Verena I. Gaidzik reports an advisory role for Jazz Pharmaceuticals, Abbvie, and Boehringer-Ingelheim; speakers bureau of Pfizer, Janssen, and Abbvie; and travel support from Abbvie. Frank Stegelmann reports honoraria from and consultancy for AOP Pharma, MorphoSys, BMS/Celgene, Incyte, Novartis, and Pfizer. Felicitas Thol reports an advisory role for Novartis, BMS, Abbvie, Menarini, and Rigel. Michael Heuser reports honoraria from Certara, Jazz Pharmaceuticals, Janssen, Novartis, and Sobi; paid consultancy for Abbvie, Amgen, BMS/Celgene, Glycostem, LabDelbert, Pfizer, PinotBio, and Servier; and research funding to his institution from Abbvie, Agios, Astellas, BMS/Celgene, Glycostem, Jazz Pharmaceuticals, Karyopharm, Loxo Oncology, and PinotBio. Hartmut Döhner declares being in an advisory role for Abbvie, Agios, Amgen, Astellas, AstraZeneca, Berlin Chemie, BMS/Celgene, Daiichi Sankyo, GEMoaB, Gilead, Janssen, Jazz Pharmaceuticals, Novartis, Servier, Stemline, and Syndax; research funding from Abbvie, Agios, Amgen, Astellas, BMS/Celgene, Jazz Pharmaceuticals, Kronos Bio, Novartis, and Pfizer. Konstanze Döhner reports an advisory role for Amgen, BMS/Celgene, Daiichi Sankyo, Janssen, Jazz Pharmaceuticals, Novartis, and Roche; research funding from Agios, Astex, Astellas, BMS/Celgene, and Novartis. All other authors declare no competing interest. The remaining authors declared no conflicts of interest. This work was supported in part by Collaborative Research Center SFB 1074, projects B3 and B12 (K.D.) and project Z1 (H.D.). The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions. For original data, please contact Konstanze Döhner ([email protected]). Individual participant data will not be shared. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Background: “The Frontline asciminib in combination” - FASCINATION study (NCT03906292) is a multicenter, prospective, open-label, interventional phase II trial to evaluate efficacy and tolerability of asciminib – a first-in-class BCR::ABL1 inhibitor specifically targeting the ABL myristoyl pocket (STAMP) - as first-line treatment in combination with conventional ATP-competing BCR::ABL1 inhibitors (nilotinib, dasatinib, or imatinib) for patients (pts) with chronic myeloid leukemia (CML) in chronic phase. Aims: The aim of the study was to pilot asciminib in combination with ATP competing tyrosine kinase inhibitors (TKI) as first-line therapies in CML pts to improve the rate of deep molecular response (MR4) after 1 year of therapy. A higher rate of patients in deep molecular response compared to standard therapies could increase the proportion of patients in treatment-free remission (TFR) over time. Here, we report results of the pre-planned interim analysis of the primary endpoint according to the protocol. Methods: Adult pts with newly diagnosed BCR::ABL1-positive CML were included in the study until 3 months after diagnosis. A <4 week pretreatment with hydroxyurea was permitted. Pts treated for <6 weeks with nilotinib 300 mg BID, dasatinib 100 mg QD, or imatinib 400 mg QD were eligible for recruitment and allocated to one of four respective cohorts (Table). Cohorts were filled consecutively and were designed to allow assessment of QD and BID asciminib-based combinations to optimize quality of life (QoL) and compliance. Asciminib therapy was commenced 12 weeks after start of nilotinib, dasatinib, or imatinib, and after complete recovery of normal hematopoiesis. Dose of asciminib was based on pharmacokinetic data (area under the curve) of the combination cohorts within the phase I trial (NCT02081378). Nilotinib 300 mg BID was combined with asciminib 20 mg BID (cohort 1), or asciminib 40 mg QD (cohort 2), dasatinib 100 mg QD was combined with asciminib 80 mg QD (cohort 3), and imatinib 400 mg QD was combined with asciminib 60 mg QD (cohort 4). The primary endpoint was the rate of MR4 (BCR::ABL1 transcripts ≤0.01% on the International Scale, IS) at month 12. Results: Between 2019 and 2022, 144 pts were recruited from 21 sites in Germany. Two pts were screening failures and 17 pts did not tolerate the initial TKI and were excluded from the study before start of asciminib. Combination therapy was commenced in 125 pts (66% male). Median age at diagnosis was 45.5 years (range, 19.0-89.0), 57.3, 28.1, and 14.6% were low, intermediate, and high risk according to the ELTS score, respectively. Adverse events grade 3-4 were observed in 37.6% of the pts. A total of 21 pts (17%) discontinued the combination therapy within the first 12 months due to dermal toxicity (n=4), gastroenterological toxicity (n=4), treatment failure/progression (n=3), cytopenia (n=2), papillitis/ocular papilla edema (n=1), polyneuropathy (n=1), pain (n=1), incompliance (n=1), and withdrawal of consent (n=4). One patient who progressed to blast phase received an allogeneic stem cell transplantation. A total of 114 pts were eligible for evaluation of molecular response at month 12. According to intention to treat, rate of MR4 at month 12 was 37.7% (95%-CI: 30.1-45.8%). Summary/Conclusion: The combination of asciminib as frontline therapy with ATP competing BCR::ABL1 inhibitors is associated with a high rate of deep molecular response but also impaired tolerability. Longer follow up is planned to investigate asciminib maintenance treatment after deep molecular response and TFR.Keywords: Chronic myeloid leukemia, Tyrosine kinase inhibitor, Clinical trial, BCR::ABL

The approved dose of bosutinib in chronic phase CML is 400 mg QD in first-line and 500 mg QD in later-line treatment. However, given that gastrointestinal (GI) toxicity typically occurs early after treatment initiation, physicians often tend to start therapy with lower doses although this has never been tested systematically in prospective trials in the Western world. The Bosutinib Dose Optimization (BODO) Study, a multicenter phase II study, investigated the tolerability and efficacy of a step-in dosing concept of bosutinib (starting at 300 mg QD) in chronic phase CML patients in 2(nd) or 3(rd) line who were intolerant and/or refractory to previous TKI treatment. Of 57 patients included until premature closure of the study due to slow recruitment, 34 (60%) reached the targeted dose level of 500 mg QD following the 2-weekly step-in dosing regimen. While the dosing-in concept failed to reduce GI toxicity (grade II-IV, primary study endpoint) to < 40% (overall rate of 60%; 95% CI: 45-74%), bosutinib treatment (mean dosage: 403 mg/day) showed remarkable efficacy with a cumulative major molecular remission (MMR) rate of 79% (95% CI: 66 to 88%) at month 24. Of thirty patients refractory to previous therapy and not in MMR at baseline, 19 (64%) achieved an MMR during treatment. GI toxicity did not significantly impact on patient-reported outcomes (PRO) and led to treatment discontinuation in only one patient. Overall, the results of our trial support the efficacy and safety of bosutinib after failure of second-generation TKI pre-treatment. Trial registration: NCT02577926.

Background: High-risk essential thrombocythemia (HR ET) is characterized by thrombocytosis, thrombohemorrhagic events and systemic symptoms. Patients (pts) can experience intolerance, inadequate response or loss of response to first-line cytoreductive therapies (hydroxyurea [HU] or interferon alfa-2a). Bromodomain and extraterminal (BET) domain protein inhibition is a novel therapeutic strategy that downregulates inflammatory cytokines and may inhibit differentiation and proliferation of abnormal megakaryocytes involved in ET pathogenesis. Results from the Phase 2 MANIFEST study (NCT02158858) suggested potentially encouraging clinical efficacy in pts with myelofibrosis treated with pelabresib (PELA), an oral, small-molecule, investigational BET inhibitor. Aims: To present preliminary results from Arm 4 of the MANIFEST study investigating PELA monotherapy in pts with HR ET refractory or intolerant to HU. Methods: Eligible pts had platelets >600 x 109/L and ≥2 symptoms (average score ≥3/total symptom score [TSS] ≥15 in Myeloproliferative Neoplasm Symptom Assessment Form [MPN-SAF]). Pts received oral PELA monotherapy 225 mg QD. The primary endpoint was complete hematologic response (CHR; normalization of platelet count (≤400 x 109/L), white blood cell (WBC) count (≤10 x 109/L) confirmed after one cycle [after 3 weeks]) and normal spleen size. Secondary endpoints included partial HR (PHR; platelets 400–600 x 109/L and WBC ≤10 x 109/L), symptom improvement (≥50% reduction in MPN-SAF TSS) and safety. Pharmacodynamic biomarker assessments included genotyping, circulating cytokines and gene expression changes during treatment via peripheral blood sampling and bone marrow biopsies. Results: As of July 2022, 20 pts with HR ET received PELA; 70% (14/20) of pts were ongoing treatment, and 35% (7/20) reached 24 wks. Median age was 64 yrs (42–83), median Hgb 13 (10–16) g/dL, median platelet count 772 (418–1255) x 109/L and median TSS 32.7 (6.9–123). The majority of pts had a hematologic response (90% [18/20] unconfirmed CHR or PHR); confirmed CHR was observed in 40% (8/20) (Table 1). Median platelet and WBC count at Wk 12 was 446 x 109/L and 8.2 x 109/L, respectively. TSS reduction was reported in 86% (12/14 pts); median TSS reduction at Wk 12 was –31%. Hgb levels remained stable through Wk 24. The most common nonhematologic AEs were nausea (60%; 10% Gr 3), diarrhea (35%; 5% Gr 3) and dysgeusia (35%; no Gr 3). Hemorrhagic or thromboembolic events were reported in 30% of pts (15% Gr 3). No events of thrombocytopenia and no Gr 4 events or higher were reported. Baseline mutation data were available for 17 pts: JAK2V617F (8/17 pts; variant allele frequency [VAF] range 8–67%), CALR (8/17 pts; VAF range 14–27%) and MPL (1/17 pts; VAF 25%). Among the six patients with JAK2 mutation, two patients with highest JAK2 VAF showed a VAF decrease with PELA treatment (67% to 20% at end of treatment, and 52% to 40% at 24 wks). A cluster of seven cytokines (hepcidin, MMP-9, BDNF, TIMP-3, MMP-1, DKK-1 and RANTES) were downregulated post PELA at 2 wks (13/13 pts). A 65% ± SD 0.246 decrease in IL8 gene expression was also observed 4 hrs after first PELA dose (n=18), 41% ± SD 0.778 at 2 wks (n=13), and 22% ± SD 0.982 at 6 wks (n=11). Conclusion: Preliminary results from Arm 4 of the MANIFEST study suggest potential clinical benefit with PELA monotherapy in pts with HR ET refractory or intolerant to HU as supported by hematologic responses and symptom improvement. Safety data suggest a tolerable and manageable safety profile. Mutation data and other pharmacodynamic analyses indicate potential biomarker changes after PELA monotherapy.© 2023 American Society of Clinical Oncology, Inc. Reused with permission. This abstract was accepted and previously presented at the 2023 ASCO Annual Meeting. All rights reserved. Keywords: Myeloproliferative disorder, Essential Thrombocytemia, Inhibitor

7019 Background: High-risk essential thrombocythemia (HR ET) is characterized by thrombocytosis, thrombohemorrhagic events and systemic symptoms. Pts can experience intolerance, inadequate response or loss of response to first-line cytoreductive therapies (hydroxyurea [HU] or interferon alfa-2a). BET protein inhibition is a novel therapeutic strategy that downregulates inflammatory cytokines and may inhibit differentiation and proliferation of abnormal megakaryocytes involved in ET pathogenesis. Results from the Phase 2 MANIFEST study (NCT02158858) suggested potentially encouraging clinical efficacy in pts with myelofibrosis treated with Pelabresib (PELA), an oral, small-molecule, investigational BET inhibitor. Here we present preliminary results from MANIFEST Arm 4 investigating PELA monotherapy in HR ET refractory or intolerant to HU. Methods: Eligible pts had platelets > 600 x 10 9 /L and ≥ 2 symptoms (average score ≥3/ TSS≥15). Pts received PELA monotherapy 225 mg QD. The primary endpoint was complete hematologic response (CHR; normalization of platelet count (≤400 x 10 9 /L), WBC count (≤10 x 10 9 /L) confirmed after one cycle [after 3 weeks]) and normal spleen size. Secondary endpoints included partial HR (PHR; platelets 400–600 x 10 9 /L and WBC ≤10 x 10 9 /L), symptom improvement (≥50% TSS reduction) and safety. Results: As of July 2022, 20 pts with HR ET were treated: median age 64 yrs (42–83), median Hgb 13 (10–16) g/dL, median platelet count 772 (418–1255) x 10 9 /L and median TSS 32.7 (6.9–123). The majority of pts had a hematologic response (90% [18/20] unconfirmed CHR or PHR); confirmed CHR was observed in 40% (8/20) (Table). Median platelet and WBC count at Wk 12 was 446 x10 9 /L and 8.2 x 10 9 /L, respectively. TSS reduction was reported in 86% (12/14 pts); median TSS reduction at Wk 12 was –31%. Hgb levels remained stable through Wk 24. The most common nonhematologic AEs were nausea (60%; 10% Gr 3), diarrhea (35%; 5% Gr 3) and dysgeusia (35%; no Gr 3). Hemorrhagic or thromboembolic events were reported in 30% pts (15% Gr 3). No events of thrombocytopenia and no Gr 4 events or higher were reported. Conclusions: Preliminary results from Arm 4 of the MANIFEST study suggest potential clinical benefit with PELA monotherapy in pts with HR ET refractory or intolerant to HU as supported by hematologic responses and symptom improvement. Safety results are consistent with the known safety profile of PELA and as expected in the underlying study population. Clinical trial information: NCT02158858 . [Table: see text]

Introduction: Polycythemia vera (PV) is characterized by trilineage blood cell expansion, PV-associated symptoms, and the risk of thromboembolic complications, progression to post-PV myelofibrosis, and acute leukemia. Cytoreductive treatment with hydroxyurea (HU) or ropeginterferon-alpha is approved in EU for the treatment of high-risk patients (pts) with PV. In addition, ruxolitinib (RUX) is approved for HU-intolerant/-resistant PV. However, RUX vs. best available therapy (BAT) has not been investigated as first-line treatment of pts with untreated PV. We hypothesized that RUX may have higher efficacy in such early-line PV pts. Methods: The clinical trial entitled “Ruxolitinib versus Best Available Therapy in pts with high-risk PV or high-risk ET” (RuxoBEAT; NCT02577926) is a multicenter, open-label, two-arm phase-IIb trial with a target population of 190 pts in each stratum. Crossover from BAT to RUX is possible in eligible pts after 6 months. Pts with PV in the RUX arm received a starting dose of 10 mg BID and may increase their dose up to 20 mg BID. The primary endpoint is the clinicohematologic complete response (CR) rate at month 6, as defined by Barosi et al (Blood 2009), using a strict score of zero for the four symptoms by patient-reported outcome measures (PROM, Table 2) and an adjusted level alpha = 0.005 at a power of 80%. Secondary endpoints include overall response rate (CR+PR), freedom from phlebotomy, changes in blood counts, spleen size, and PROM, using p values descriptively. The interim trial data were recently reviewed by the DMC, and, due to the low likelihood of reaching the primary endpoint (CR rate improvement), the DMC has recommended that the trial should continue without recruitment of new pts. Therefore, this pre-specified interim analysis was performed after 78 (instead of 95) PV pts were randomized 1:1 to RUX vs. BAT. A maximum of 6 weeks of previous PV-directed therapy was allowed. Differences between RUX and BAT at month 6 and between baseline and end of month 6 data for each treatment were calculated using Fisher´s exact test/ McNemar Test (for unpaired/ paired binary variables) or the Mann-Whitney-U test/ Wilcoxon signed-rank test (for unpaired/ paired ordered or continuous variables). Results: 78 first-line pts (33% were pre-treated for a median of 22 days [range 1-42]) were included in the intention-to-treat set (n=44 vs 34 randomized to RUX vs. BAT, resp.) and analyzed at the 6-month time point. Baseline characteristics are listed in Table 1. In pts on RUX or BAT, CR rates at 6 months were comparable (2.3% and 2.9%, p=1.0), while overall response (CR+PR) rates were 77.3% with RUX and 55.9% with BAT (p=0.054). Also, at month 6 (Table 2), pts on RUX showed significantly lower hematocrit (40.8% vs 42.1%, p=0.046), and PROM symptom points for pruritus (1 vs 4, p=0.001) and fatigue (2.5 vs 5, p=0.031), and a trend towards less headache, abdominal discomfort, and weight loss, while the number of platelets was lower with BAT vs. RUX (254/nl vs 386/nl, p=0.013). There was no difference between RUX and BAT in the number of white blood cells (WBC), spleen size, or other symptoms at this time point. When each treatment arm was analyzed separately for changes between baseline and month 6, RUX treatment significantly reduced platelet counts, WBC, hemoglobin and hematocrit, phlebotomy rates, spleen size and fraction of pts with splenomegaly (Table 2), and significantly improved PROMs for pruritus, early satiety, and quality of life. During the same time period, BAT significantly reduced platelet counts, WBC, hematocrit, and phlebotomy rates, but failed to impact on hemoglobin, spleen size, fraction of pts with splenomegaly, or any of the symptoms (Table 2). Safety analysis revealed 301 adverse events (AE) in both assigned treatment groups, including 153 AE in the RUX and 148 AE in the BAT group (11.8% and 8.1% grade ≥3, resp.). There was no significant difference in the percentage of grade ≥3 AE between both groups (p=0.358), and there were no consistent patterns of grade ≥3 AE in either of the two arms. Conclusion: In this interim analysis, first-line treatment with ruxolitinib for 6 months in high-risk pts with PV led to clinically meaningful improvements in overall response, hemoglobin and hematocrit, phlebotomy rates, splenomegaly, and patient-reported pruritus and fatigue severity, while BAT only improved platelet counts, WBC, hematocrit, and phlebotomy rates, without having an impact on symptoms.

Background: Phase II trials with 2nd or 3rd generation Tyrosine Kinase Inhibitors (TKI) with/without immunotherapy yield promising results in Ph+ ALL. However, Imatinib (IM) in combination with chemotherapy regimens of different intensities followed by allogeneic SCT is still the standard treatment for younger patients (pts) in many countries. Aims: GMALL Trial 08/2013 (NCT02881086) evaluates a concept with dose-reduced induction (ind) and intensive consolidation (CI) in combination with IM followed by SCT independent of MRD response in patients (pts) aged 18-55 years (yrs). Dose reduced conditioning (8 Gy TBI vs 12 Gy TBI) was recommended in pts older than 45 yrs. Methods: The 6 week ind included IM 600 mg/d together with low intensity chemotherapy (VCR, Dexa, PEG-ASP) and intrathecal prophylaxis. Bone marrow evaluation after 3 weeks separated ind I and II. Four doses of Rituximab were added if CD20 was >20%. C I (Dexa, VCR, HDMTX, HDAC, VP16) followed. Donor search was initiated in all pts at diagnosis. SCT was scheduled after C I; after an amendment, a TKI change was recommended if MRD >10-3 after CI. MRD was assessed by quantitative (RQ)-PCR of BCR::ABL in a central reference laboratory. Additional MRD assessment with IG/TR RQ-PCR was recommended. Results: 163 pts with a median age of 42 (18-55) yrs were evaluable. 64 (39%) pts had a WBC >=30,000/µL. CR rates after ind I, II and CI were 85%, 95% and 93%. Early death and failure rates were 5% and 1% after CI, respectively. Molecular complete remission (MolCR) rates, defined as PCR negativity for BCR::ABL1 transcripts with at least 10000 ABL1 copies, were 10% after ind I, 24% after ind II and 43% after CI. Low positive MRD (≤10-4) was observed in 8%, 19% and 20%, respectively, whereas the remaining pts experienced molecular failure (MolF) with MRD >10-4. 27/48 pts with MolF (59%) had MRD ≥10-3; 10/27 pts were switched to another TKI. Data are yet available from 8/10 pts. These pts. were switched to Dasatinib (n=7) or Ponatinib (n=1). Only 1/8 pts with available data had a molecular remission after 4 weeks of ponatinib. Overall survival (OS) at 1 yr was 82% and 74% at 3 yrs; remission duration (RD) was 92% and 89%, resp. OS at 3 yrs was 88%, 70% and 75% for pts aged 18-25, 26-45 and 46-55 yrs resp (p>0.05). WBC at diagnosis <> 30000/µL had no impact on 3y-OS of 73% vs 76% (p>0.05). 138 pts (85%) were transplanted in CR1 as scheduled after CI (Median time to SCT: 4 mo) with OS 86% and 81% at 1 and 3 yrs. OS was similar (86% vs 79% at 3 yrs, p>0.05) for matched sibling or matched unrelated SCT. The treatment-related mortality was 14%. OS after SCT was not impacted by status of BCR::ABL1 MRD after CI as defined above. Summary/Conclusion: Dose reduced induction including PEG-ASP in combination with IM was feasible and yielded high response rates leading to a molecular CR rate as high as 43% already after CI. A very high SCT realization rate (85%) was obtained at approximately 3 months from diagnosis likely contributing to the favorable overall outcome. It remains open to further trials whether BCR::ABL MRD at all has a prognostic impact in transplant-focused regimens. The role of alternative TKI and immunotherapies with the aim to reduce SCT indications will be evaluated in the upcoming GMALL EVOLVE trial. The trial was funded by Deutsche Krebshilfe.Keywords: Acute lymphoblastic leukemia, Treatment, Philadelphia chromosome