Heinz Gisslinger

Chronic systemic inflammation is a key driver of polycythemia vera (PV) progression, but the immunomodulatory effects of current treatments remain poorly defined. The neutrophil-to-lymphocyte ratio (NLR) is an accessible biomarker of systemic inflammation proven in other contexts, but its role in monitoring PV disease activity has not been established. Using data from three of the largest PV clinical trials, we evaluated the effects of PV therapies on NLR and its relationship with molecular response and clinical outcomes. In 404 hematocrit-controlled patients from the ECLAP study, hydroxyurea (HU) failed to significantly lower NLR (p = 0.11) due to the parallel declines in ANC and ALC. Neither leukocyte counts nor NLR were significantly reduced by phlebotomy in ECLAP patients treated without cytoreductive therapy. In contrast, the Low-PV study showed that while phlebotomy tended to increase NLR, low-dose ropeginterferon alfa-2b (Ropeg) significantly reduced NLR (−18.2% and −36.3% in patients with low and high baseline NLR, respectively) by suppressing ANC rather than lymphocytes. NLR reduction correlated with the primary Low-PV endpoint (p = 0.021) and reduction of JAK2 variant allele frequency (VAF) [1]. The PROUD-PV/CONTINUATION-PV study confirmed the superior effect of Ropeg over HU, with a significantly greater NLR reduction at 60 months (−56.5% versus −33.6%, respectively, p = 0.019) in patients with high baseline NLR. Moreover, NLR reduction was associated with decreased JAK2^V617F VAF (p < 0.0001) and improved event-free survival (p = 0.010). These findings identify NLR as a dynamic biomarker of treatment response and prognosis in PV and support its incorporation into routine monitoring.

This study aimed to distinguish between essential thrombocythemia (ET) and prefibrotic primary myelofibrosis (pre‐PMF) using routine blood tests, with a focus on white blood cell (WBC) and platelet (PLT) levels. We evaluated the predicted probability of a pre‐PMF diagnosis based on the interaction between WBC and PLT levels using data from a logistic regression model involving 891 patients with ET and 180 patients with pre‐PMF. Patients were divided into four groups based on whether their WBC and PLT values were below or above the respective thresholds of 8.85 × 10 ⁹ /L and 793 × 10 ⁹ /L. The results showed that patients with low levels of both WBCs and PLTs had the lowest predicted probability of pre‐PMF (6%), indicating a profile more typical of ET. When either WBC or PLT levels were elevated, the probability increased to approximately 18%–19%, indicating a potential shift toward pre‐PMF features. Notably, patients with elevated levels of both WBCs and PLTs had the highest probability of a pre‐PMF diagnosis (26%), which was more than four times higher than that of the low–low group. The association between combined WBC/PLT levels and a pre‐PMF diagnosis remained significant ( p < 0.001), even when adjusting for serum lactate dehydrogenase (LDH) and splenomegaly. These findings suggest that elevated WBC and PLT levels together can serve as a practical and accessible diagnostic tool for supporting the differential diagnosis of ET or pre‐PMF in cases of uncertainty, and for deferring bone marrow biopsy in cases of early disease presenting with isolated thrombocytosis.

Background: Belantamab mafodotin (belamaf) is a BCMA-targeting antibody–drug conjugate used in triple-class refractory multiple myeloma. Despite its efficacy, keratopathy remains a significant dose-limiting toxicity. Following its withdrawal from the U.S. market in 2022, its use in Austria is limited to clinical trials or compassionate use. Methods: In this real-world, retrospective study, we analyzed 36 relapsed/refractory, BCMA-naïve multiple myeloma patients treated at the University Hospital of Vienna (January 2020–June 2024); 42% received a reduced dose (1.9 mg/kg) throughout all treatment cycles. The primary objective was to assess adverse events, particularly keratopathy, and the impact of dose modifications on toxicity and efficacy. Results: The overall response rate was 64%, with responders having significantly fewer prior therapy lines (median 3 vs. 4.5, p = 0.015). Median PFS was 7.3 months, significantly longer in responders (11.1 vs. 1.6 months, p < 0.0001); median OS was 20.1 months, also longer in responders (not reached vs. 18 months, p = 0.031). Keratopathy occurred in 75% of patients; 33% experienced grade 3–4 events. Dose reduction significantly decreased grade 3–4 keratopathy (7% vs. 52%, p = 0.004) and thrombocytopenia (33% vs. 67%, p = 0.048) without compromising efficacy. Conclusions: Belamaf dose reductions improved tolerability without loss of efficacy, supporting reduced dosing in practice.

Summary: Polycythemia vera (PV) is a myeloproliferative neoplasm primarily driven by mutations in the JAK2 gene, most notably the V617F mutation, which occurs in nearly 97% of cases. This gain-of-function mutation overactivates the JAK-STAT pathway, a critical factor in developing the PV phenotype by stimulating excessive proliferation of the erythroblastic lineage. Diagnostic methods for PV focus on detecting the JAK2 mutation—primarily through polymerase chain reaction (PCR) and next-generation sequencing, which are essential for distinguishing PV from other disorders. The variant allele frequency (VAF) of JAK2^V617F also serves as an important prognostic marker, with higher VAF linked to both increased thrombotic risk and disease progression to myelofibrosis or acute leukemia. Thus, managing allele burden is central to treatment strategies. Given the genetic complexity of PV, personalized treatment approaches are essential. Current therapies focus on JAK2 signaling, with ropeginterferon alfa-2b and JAK inhibitors as primary or secondary treatments to reduce clonal expansion and control inflammation, and aspirin to prevent thrombotic events. Emerging treatments are exploring anti-inflammatory strategies, such as anti-IL-1β antibodies, and agents targeting iron metabolism to maintain hematocrit levels without phlebotomy, potentially improving quality of life. Overall, reducing JAK2^V617F burden and controlling inflammation are crucial for managing PV progression and improving patient outcomes, with ongoing research refining these therapeutic avenues to enhance long-term strategies.

Ropeginterferon alfa-2b (RopegIFN) enables effective cytoreduction in polycythemia vera (PV). Recent analyses suggest that long-term RopegIFN therapy fulfills treatment goals important to patients with PV including good quality of life, the slowing of disease progression, and long event-free survival. Data support the use of RopegIFN in both early PV therapy and second-line and beyond.

Background: Hydroxyurea (HU) is a commonly used first‐line treatment in patients with polycythemia vera (PV). However, approximately 15%–24% of PV patients report intolerance and resistance to HU.Methods: This phase IV, European, real‐world, observational study assessed the efficacy and safety of ruxolitinib in PV patients who were resistant and/or intolerant to HU, with a 24‐month follow‐up. The primary objective was to describe the profile and disease burden of PV patients.Results: In the 350 enrolled patients, 70% were >60 years old. Most patients (59.4%) had received ≥1 phlebotomy in the 12 months prior to the first dose of ruxolitinib. Overall, 68.2% of patients achieved hematocrit control with 92.3% patients having hematocrit <45% and 35.4% achieved hematologic remission at month 24. 85.1% of patients had no phlebotomies during the study. Treatment‐related adverse events were reported in 54.3% of patients and the most common event was anemia (22.6%). Of the 10 reported deaths, two were suspected to be study drug‐related.Conclusion: This study demonstrates that ruxolitinib treatment in PV maintains durable hematocrit control with a decrease in the number of phlebotomies in the majority of patients and was generally well tolerated.

Myeloproliferative neoplasms (MPN) are characterized by uncontrolled expansion of myeloid cells, disease‐related mutations in certain driver‐genes including JAK2, CALR, and MPL, and a substantial risk to progress to secondary acute myeloid leukemia (sAML). Although behaving as stem cell neoplasms, little is known about disease‐initiating stem cells in MPN. We established the phenotype of putative CD34⁺/CD38⁻ stem cells and CD34⁺/CD38⁺ progenitor cells in MPN. A total of 111 patients with MPN suffering from polycythemia vera, essential thrombocythemia, or primary myelofibrosis (PMF) were examined. In almost all patients tested, CD34⁺/CD38⁻ stem cells expressed CD33, CD44, CD47, CD52, CD97, CD99, CD105, CD117, CD123, CD133, CD184, CD243, and CD274 (PD‐L1). In patients with PMF, MPN stem cells often expressed CD25 and sometimes also CD26 in an aberrant manner. MPN stem cells did not exhibit substantial amounts of CD90, CD273 (PD‐L2), CD279 (PD‐1), CD366 (TIM‐3), CD371 (CLL‐1), or IL‐1RAP. The phenotype of CD34⁺/CD38⁻ stem cells did not change profoundly during progression to sAML. The disease‐initiating capacity of putative MPN stem cells was confirmed in NSGS mice. Whereas CD34⁺/CD38⁻ MPN cells engrafted in NSGS mice, no substantial engraftment was produced by CD34⁺/CD38⁺ or CD34⁻ cells. The JAK2‐targeting drug fedratinib and the BRD4 degrader dBET6 induced apoptosis and suppressed proliferation in MPN stem cells. Together, MPN stem cells display a unique phenotype, including cytokine receptors, immune checkpoint molecules, and other clinically relevant target antigens. Phenotypic characterization of neoplastic stem cells in MPN and sAML should facilitate their enrichment and the development of stem cell‐eradicating (curative) therapies.

We have recently reported the association of diffuse large B-cell lymphomas following JAK1/2 inhibitor treatment in patients with myeloproliferative disorders (MPD). While this is a rare event, the outcome of these patients is rather poor. In the past years, CAR-T cell treatment has emerged as the standard of care in transplant eligible patients with relapsed or refractory DLBCL after at least one line of treatment [1,2]. Here we report successful treatment of a 47-year-old patient with axicabtagene ciloleucel [3], who developed a refractory DLBCL after being treated with ruxolitinib for 13 months due to his prior existing JAK2 positive myeloproliferative disorder. Keywords: CAR-T cells; Aggressive B-cell lymphoma; Immunosuppression; JAK1/2 Inhibition; Myeloproliferative Disorders

Myeloproliferative neoplasms (MPN) are chronic stem cell disorders characterized by enhanced proliferation of myeloid cells, immune deregulation, and drug resistance. JAK2 somatic mutations drive the disease in 50–60% and CALR mutations in 25–30% of cases. Published data suggest that JAK2‐V617F‐mutated MPN cells express the resistance‐related checkpoint PD‐L1. By applying RNA‐sequencing on granulocytes of 113 MPN patients, we demonstrate that PD‐L1 expression is highest among polycythemia vera patients and that PD‐L1 expression correlates with JAK2‐V617F mutational burden (R = 0.52; p < .0001). Single nucleotide polymorphism (SNP) arrays showed that chromosome 9p uniparental disomy (UPD) covers both PD‐L1 and JAK2 in all MPN patients examined. MPN cells in JAK2‐V617F‐positive patients expressed higher levels of PD‐L1 if 9p UPD was present compared to when it was absent (p < .0001). Moreover, haplotype‐based association analyses provided evidence for germline genetic factors at PD‐L1 locus contributing to MPN susceptibility independently of the previously described GGCC risk haplotype. We also found that PD‐L1 is highly expressed on putative CD34⁺CD38⁻ disease‐initiating neoplastic stem cells (NSC) in both JAK2 and CALR‐mutated MPN. PD‐L1 overexpression decreased upon exposure to JAK2 blockers and BRD4‐targeting agents, suggesting a role for JAK2‐STAT5‐signaling and BRD4 in PD‐L1 expression. Whether targeting of PD‐L1 can overcome NSC resistance in MPN remains to be elucidated in forthcoming studies.

Introduction: Ropeginterferon alfa-2b (BESREMi®), a novel pegylated interferon with an extended half-life, was approved in Europe for treatment of patients with PV based on results from the phase 3 PROUD-PV and CONTINUATION-PV trials. Ropeginterferon alfa-2b treatment is recommended in hydroxyurea (HU) naïve patients as well as in those who have previously received HU. Therefore, treatment response was analyzed by prior HU treatment status, and the influence of baseline JAK2V617F allele burden and additional mutations - which may increase over time during non-disease modifying treatment - was explored. Methods: In PROUD-PV, patients aged ≥18 years, diagnosed with PV according to WHO 2008 criteria, and either cytoreduction-naïve or HU-pre-treated (for 50%), and in patients with available data (N=159), by the presence of non-driver mutations (TruSight™ Myeloid Panel, Illumina) or chromosomal aberrations (Affymetrix SNP6.0 array) at baseline. Results: After 5 years of treatment with ropeginterferon alfa-2b, high rates of CHR were sustained in both HU-naïve and HU pre-treated patients (53.1% and 61.3%, respectively), whereas in the control arm, the CHR rate was lower among HU pre-treated patients (36.0% compared to 48.0% for HU-naïve patients). Molecular response rates at 5 years in HU naïve and pre-treated patients were 71.4% and 64.5% respectively in the ropeginterferon alfa-2b arm and 26.0% versus 12.5% respectively in the control arm. Rates of adverse events (AEs), treatment-related AEs, serious AEs, and AEs leading to discontinuation were similar between the subgroups regardless of HU pre-treatment. Similar CHR rates were observed at 5 years irrespective of baseline JAK2V617F allele burden category (ropeginterferon alfa-2b arm: 57.1% versus 53.1% for allele burden ≤50% or >50%, respectively; control: 46.9% versus 38.5%, respectively). The molecular response rate in the ropeginterferon alfa-2b arm was higher among patients with baseline allele burden >50% (84.4% versus 61.3% for allele burden ≤50%); in the control arm there was no difference in molecular response rates between the allele burden subgroups (23.1% versus 20.8%, respectively). Of interest, the presence of non-driver mutations or chromosomal aberrations at baseline had no apparent influence on molecular response rates to ropeginterferon alfa-2b (64.5% compared with 70.7% in patients without these genetic abnormalities). Conclusion: High hematologic and molecular response rates in both HU-pretreated and HU-naïve patients and in those with more advanced JAK2V617F burden suggest that ropeginterferon alfa-2b is also a suitable treatment option in patients switching from HU. Disclosures: Gisslinger: AOP Orphan Pharmaceuticals GmbH: Other: Personal fees, Research Funding; Novartis: Other: Personal fees, Research Funding; PharmaEssentia: Other: Personal fees; MyeloPro Diagnostics and Research: Other: Personal fees; Janssen-Cilag: Other: Personal fees; Roche: Other: Personal fees; Celgene: Other: Personal fees. Klade: AOP Orphan Pharmaceuticals GmbH: Current Employment. Pylypenko: Communal nonprofit enterprise "Cherkasy regional oncology dispensary of Cherkasy oblast council: Current Employment. Mayer: AOP Orphan Pharmaceuticals GmbH: Research Funding. Krejcy: AOP Orphan Pharmaceuticals GmbH: Current Employment. Empson: AOP Orphan Pharmaceuticals GmbH: Current Employment. Hasselbalch: Novartis, AOP Orphan: Consultancy, Other: Advisory Board. Kralovics: AOP Orphan Pharmaceuticals GmbH: Other: Personal fees; PharmaEssentia: Other: Personal fees; Qiagen: Other: Personal fees; Novartis: Other: Personal fees; MyeloPro Diagnostics and Research: Current holder of individual stocks in a privately-held company. Kiladjian: Novartis: Membership on an entity's Board of Directors or advisory committees; AOP Orphan: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Incyte Corporation: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; PharmaEssentia: Other: Personal fees; Taiho Oncology, Inc.: Research Funding.