Zanubrutinib, rituximab and lenalidomide induces deep and durable remission in TP53 mutated B-cell prolymphocytic leukemia: a case report and review of literature

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Advanced Pathogenetic Concepts in T-Cell Prolymphocytic Leukemia and Their Translational Impact

T-cell prolymphocytic leukemia (T-PLL) is the most common mature T-cell leukemia. It is a typically aggressively growing and chemotherapy-resistant malignancy with a poor prognosis. T-PLL cells resemble activated, post-thymic T-lymphocytes with memory-type effector functions. Constitutive transcriptional activation of genes of the T-cell leukemia 1 (TCL1) family based on genomic inversions/translocations is recognized as a key event in T-PLL’s pathogenesis. TCL1’s multiple effector pathways include the enhancement of T-cell receptor (TCR) signals. New molecular dependencies around responses to DNA damage, including repair and apoptosis regulation, as well as alterations of cytokine and non-TCR activation signaling were identified as perturbed hallmark pathways within the past years. We currently witness these vulnerabilities to be interrogated in first pre-clinical concepts and initial clinical testing in relapsed/refractory T-PLL patients. We summarize here the current knowledge on the molecular understanding of T-PLL’s pathobiology and critically assess the true translational progress around this to help appraisal by caregivers and patients. Overall, the contemporary concepts on T-PLL’s pathobiology are condensed in a comprehensive mechanistic disease model and promising interventional strategies derived from it are highlighted.

Preliminary Study of Ruxolitinib and Venetoclax for Treatment of Patients with T-Cell Prolymphocytic Leukemia Refractory to, or Ineligible for Alemtuzumab

Background: Ruxolitinib (RUX), a JAK1/JAK2 inhibitor, and venetoclax (VEN), a BCL-2 inhibitor are 2 drug candidates recently identified as promising candidate for the treatment of T-Cell prolymphocytic leukemia (T-PLL). We recently reported that JAK/STAT pathway inhibition with RUX enhances BCL-2 dependence, thereby sensitizing T-PLL cells to VEN (Herbaux et al., Blood, 2021). We also showed that JAK/STAT pathway mutational status could impact RUX activity. Here, we report results on the 15 first patients who were treated with RUX and VEN oral combination for T-PLL. All patients were refractory to, or ineligible for alemtuzumab, the principal therapeutic option to date. Methods: In this multicenter retrospective study from the French Innovative Leukemia Organization, 15 patients with T-PLL (according to consensus criteria) were included. All patients were informed about the off-label use of this combination and provided informed consent. Patients received a maximum dose of RUX 15 mg twice daily, and VEN 800 mg daily. VEN was started with daily ramp-up from 20 mg to 800 mg over 6 days, with TLS prophylaxis (rasburicase and IV hydration). Responses were assessed by consensus criteria. Next generation sequencing (NGS) was performed using a custom-designed panel of 33 genes, including among others: ATM, TP53, IL2R, JAK1, JAK3, and STAT5B. CytoScan HD microarray (Affymetrix) were used to study copy number variation and or uniparental disomy. In vivo dynamic BH3 profiling (DBP) was performed on samples obtained from two patients on treatment. Results: All 15 patients were refractory or relapsing after chemotherapy (mostly bendamustine and pentostatin), except one. They were either refractory to (n=10) or ineligible (n=5) for alemtuzumab (ineligibility was decided by the treating physician based on age and comorbidities). The median age was 70 years (48-88). Within a week of starting RUX, a transient increase of the absolute lymphocyte count was observed in 66.6% of the patients. Based on the molecular status of the JAK/STAT pathway, we established 2 groups of patients. One with samples where no mutations were found (WT, n=3), and one with at least one mutation in the JAK/STAT pathway (MUT, n=12). The overall response rate (ORR) was 73.3%, with only partial responses. Five patients nearly fulfilled CR criteria except that they had persistent lymphocytosis (over 4 x 10 9/L), all of them were in the MUT group. ORR was 83.3% in the MUT group, and only one patient of the WT group obtained a PR. With a median follow-up of 73 days (22 to 368), the median progression free survival was significantly shorter in the WT group in comparison to the MUT group (1.8 months versus 5.6 months, p=0.04, Figure). Of note, four patients were treated with VEN monotherapy before the start of the combination with RUX. With that treatment, 3 of these patients achieved stable disease followed by progression within 2 to 3 months, while 1 was primary refractory to VEN monotherapy. The most frequent reported adverse events (AEs) of the RUX plus VEN combination were cytopenias, with 46.6% grade 3 or 4 thrombocytopenia and 40% grade 3 or 4 neutropenia. DBP showed that overall priming and BCL2 dependence increased in vivo (n=2) during the treatment with RUX and VEN. Finally, SNP arrays identified clonal evolution in the 3 patients evaluated sequentially (before treatment versus at progression). In one case, emergence of EZH2 and JAK1 mutation was also observed at progression using NGS. Conclusions: These preliminary results suggest promising activity of RUX plus VEN in T-PLL, and justify the development of a prospective clinical trial of this combination. Our data seem to show that this combination may be especially active for patients with JAK/STAT pathway activating mutations and that disease progression is associated with clonal evolution. Updated results will be presented at the meeting. Figure 1 Figure 1. Disclosures Herbaux: Janssen: Honoraria; Roche: Honoraria; Abbvie: Honoraria, Research Funding; Takeda: Honoraria, Research Funding. Lemonnier: Gilead: Other: travel grant; Institut Roche: Research Funding. Laribi: Jansen: Research Funding; AstraZeneca: Other: Personal Fees; Takeda: Other: Personal Fees, Research Funding; Novartis: Other: Personal Fees, Research Funding; Astellas Phama, Inc.: Other: Personal Fees; IQONE: Other: Personal Fees; AbbVie: Other: Personal Fees, Research Funding; Le Mans Hospital: Research Funding; BeiGene: Other: Personal Fees. Moreaux: Diag2Tec: Consultancy. Morschhauser: Janssen: Honoraria; Servier: Consultancy; Incyte: Membership on an entity's Board of Directors or advisory committees; Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; AstraZenenca: Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Chugai: Honoraria; Genentech, Inc.: Consultancy; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Speakers Bureau; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Genmab: Membership on an entity's Board of Directors or advisory committees. Davids: Ascentage Pharma: Consultancy, Research Funding; MEI Pharma: Consultancy, Research Funding; Merck: Consultancy; Eli Lilly and Company: Consultancy; Adaptive Biotechnologies: Consultancy; Pharmacyclics: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Research to Practice: Consultancy; BeiGene: Consultancy; Surface Oncology: Research Funding; Verastem: Consultancy, Research Funding; TG Therapeutics: Consultancy, Research Funding; Takeda: Consultancy; Astra-Zeneca: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Celgene: Consultancy; AbbVie: Consultancy; Genentech: Consultancy, Research Funding; Janssen: Consultancy; MEI Pharma: Consultancy. Ysebaert: Abbvie, AstraZeneca, Janssen, Roche: Other: Advisory Board, Research Funding. OffLabel Disclosure: Ruxolitinib and venetoclax are used offlabel for patients refractory to current therapeutic options, based on preclinical data.

Two Distinct Clinical Courses and Outcomes in T-Cell Prolymphocytic Leukemia

Introduction: T-cell prolymphocytic leukemia (T-PLL) is a rare type of mature T-cell neoplasm with a poor prognosis. Up to 30% of patients initially present with indolent disease course that may be observed until progression to T-PLL with aggressive behavior. We aimed to compare the clinicopathologic characteristics and outcomes of patients with initially indolent versus aggressive disease. We hypothesized that patients with indolent disease have less cytogenetic abnormalities and a favorable overall survival (OS). Methods: We identified 65 patients diagnosed with T-PLL between 2004 and 2020 who were treated at Moffitt Cancer Center. Clinical presentation, laboratory parameters, and bone marrow biopsy at the time of diagnosis were retrospectively reviewed. Patients were categorized into two groups: indolent or aggressive disease type. Patients were considered indolent if they did not have symptoms requiring immediate treatment such as B symptoms or fatigue, symptomatic lymphadenopathy, symptomatic organomegaly, hyperlymphocytosis, organ dysfunction, or cytopenias requiring transfusions. Patients with 3 or more chromosomal abnormalities were considered to have complex cytogenetics. Clinicopathologic characteristics were compared using Chi-square test. OS and factors that are potential influencers of survival were compared using the Kaplan Meier curve as well as Cox Proportional Hazards regression. Results: Of the 65 patients with T-PLL, 32 (49%) presented with indolent disease and 33 (51%) presented with aggressive disease. The median age at diagnosis was 68 years (range 43-88 years). Patients with aggressive disease presented with a higher WBC compared to those with indolent disease, with median WBC 79.7 x 10 9/L and 22.9 x 10 9/L, respectively (p=<0.001). Patients with aggressive disease also presented with a higher absolute lymphocyte count (ALC), with median ALC 47.8 x 10 9/L and 15.4 x 10 9/L (p=<0.001) (Table 1). Extra-nodal, skin, and CNS involvement was not significantly different between disease types. Flow cytometry was similar between indolent and aggressive disease with the exception with the exception of CD56 and CD57 which were rare and only observed in aggressive disease. Patients with aggressive disease were more likely to have complex karyotype compared to patients with indolent disease (p=0.023). FISH results for inversion 14 and trisomy 8 were similar between disease types. Median time from diagnosis to initial treatment was 379 days for indolent and 44 days for those with aggressive disease. 36 (55%) patients were treated with Alemtuzumab as first line treatment. A total of 15 (23%) patients ultimately underwent allogeneic hematopoietic stem cell transplant (HSCT). The median OS for the entire cohort was 30 months. The median OS for indolent and aggressive disease was 44 and 24 months, respectively (p=0.015, Figure 1). The median OS for patients who underwent HSCT compared to those who did not was 99 and 24 months, respectively (p=0.002). Among patients with indolent disease, those who underwent HSCT had a significantly longer median OS of 153 compared to 34 months for those who did not (p=0.022). There was a trend toward improved OS in patients with aggressive disease who underwent HSCT compared to those that did not (35 vs 16 months; p=0.08). In addition, there was a trend toward improved OS with earlier treatment (<12 months) in the indolent group (383 versus 86 months, p= 0.155). On multivariate analysis (Table 2), factors that negatively affected overall survival were aggressive disease type (HR 3.0, p=0.018), presence of inversion 14 (HR 2.5, p=0.032), presence of B symptoms (HR 2.4, p=0.036), and absence of HSCT (HR 0.2, p=0.001). Conclusion: Patients with T-PLL who present with aggressive disease, inversion 14, B symptoms, and those who are unable to undergo bone marrow transplant have lower overall survival. Characteristics that predict a more aggressive disease phenotype at diagnosis are high WBC, high ALC, presence of B symptoms, and complex karyotype. Figure 1 Figure 1. Disclosures Saeed: Kite Pharma: Consultancy, Other: investigator; Other-TG therapeutics: Consultancy, Other: investigator; sano-aventis U.S.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Other-Epizyme, Inc.: Consultancy; Bristol-Myers Squibb Company: Consultancy; Janssen Pharmaceutica Products, LP: Consultancy, Other: investigator; Celgene Corporation: Consultancy, Other: investigator; MEI Pharma Inc: Consultancy, Other: investigator; Nektar Therapeutics: Consultancy, Other: research investigator; MorphoSys AG: Consultancy, Membership on an entity's Board of Directors or advisory committees; Other-Secura Bio, Inc.: Consultancy; Seattle Genetics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees. Sokol: Dren Bio: Membership on an entity's Board of Directors or advisory committees; Kyowa-Kirin: Membership on an entity's Board of Directors or advisory committees.