ERIC recommendations for TP53 mutation analysis in chronic lymphocytic leukemia-2024 update.

In chronic lymphocytic leukemia (CLL), analysis of TP53 aberrations (deletion and/or mutation) is a crucial part of treatment decision-making algorithms. Technological and treatment advances have resulted in the need for an update of the last recommendations for TP53 analysis in CLL, published by ERIC, the European Research Initiative on CLL, in 2018. Based on the current knowledge of the relevance of low-burden TP53-mutated clones, a specific variant allele frequency (VAF) cut-off for reporting TP53 mutations is no longer recommended, but instead, the need for thorough method validation by the reporting laboratory is emphasized. The result of TP53 analyses should always be interpreted within the context of available laboratory and clinical information, treatment indication, and therapeutic options. Methodological aspects of introducing next-generation sequencing (NGS) in routine practice are discussed with a focus on reliable detection of low-burden clones. Furthermore, potential interpretation challenges are presented, and a simplified algorithm for the classification of TP53 variants in CLL is provided, representing a consensus based on previously published guidelines. Finally, the reporting requirements are highlighted, including a template for clinical reports of TP53 aberrations. These recommendations are intended to assist diagnosticians in the correct assessment of TP53 mutation status, but also physicians in the appropriate understanding of the lab reports, thus decreasing the risk of misinterpretation and incorrect management of patients in routine practice whilst also leading to improved stratification of patients with CLL in clinical trials.

The complexities of T-cell dysfunction in chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is a B-cell malignancy characterized by profound alterations and defects in the T-cell compartment. This observation has gained renewed interest as T-cell treatment strategies, which are successfully applied in more aggressive B-cell malignancies, have yielded disappointing results in CLL. Despite ongoing efforts to understand and address the observed T-cell defects, the exact mechanisms and nature underlying this dysfunction remain largely unknown. In this review, we examine the supporting signals from T cells to CLL cells in the lymph node niche, summarize key findings on T-cell functional defects, delve into potential underlying causes, and explore novel strategies for reversing these deficiencies. Our goal is to identify strategies aimed at resolving CLL-induced T-cell dysfunction which, in the future, will enhance the efficacy of autologous T-cell-based therapies for CLL patients.

Mutational profile of previously treated chronic lymphocytic leukemia patients progressing on acalabrutinib or ibrutinib.

Chronic lymphocytic leukemia (CLL) progression during Bruton tyrosine kinase (BTK) inhibitor treatment is typically characterized by emergent B-cell receptor pathway mutations. Using peripheral blood samples from relapsed/refractory CLL patients in ELEVATE-RR (NCT02477696) (median 2 prior therapies), we report clonal evolution data for patients progressing on acalabrutinib or ibrutinib (median follow-up 41 months). Paired (baseline and progression) samples were available for 47 (excluding 1 Richter) acalabrutinib-treated and 30 (excluding 6 Richter) ibrutinib-treated patients. At progression, emergent BTK mutations were observed in 31 (66%) acalabrutinib-treated and 11 (37%) ibrutinib-treated patients (median variant allele fraction [VAF]: 16.1% vs 15.6%). BTK C481S mutations were most common in both groups; T474I (n = 9; 8 co-occurring with C481) and the novel E41V mutation within the pleckstrin homology domain of BTK (n = 1) occurred with acalabrutinib, while neither mutation occurred with ibrutinib. L528W and A428D co-mutations presented in one ibrutinib-treated patient. Pre-existing TP53 mutations were present in 25 (53.2%) acalabrutinib-treated and 16 (53.3%) ibrutinib-treated patients at screening. Emergent TP53 mutations occurred with acalabrutinib and ibrutinib (13% vs 7%; median VAF: 6.0% vs 37.3%, respectively). Six acalabrutinib-treated patients and one ibrutinib-treated patient had emergent TP53/BTK co-mutations. Emergent PLCG2 mutations occurred in 3 (6%) acalabrutinib-treated and 6 (20%) ibrutinib-treated patients. One acalabrutinib-treated patient and 4 ibrutinib-treated patients had emergent BTK/PLCG2 co-mutations. While common BTK C481 mutations were observed with both treatments, patterns of mutation and co-mutation frequency, mutation VAF, and uncommon BTK variants varied with acalabrutinib (T474I and E41V) and ibrutinib (L528W, A428D) in this patient population.

Reassessing the Chronic Lymphocytic Leukemia International Prognostic Index in the era of targeted therapies.

We evaluated the prognostic value of the Chronic Lymphocytic Leukemia International Prognostic Index (CLL-IPI) using a pooled dataset of CLL-patients treated first-line with targeted drugs (N=991) or chemoimmunotherapy (N=1,256). With a median observation time of 40.5 months, the 3-year progression-free survival (PFS)-rates for targeted drug-treated patients varied by CLL-IPI risk group: 96.5% (low), 87.6% (intermediate), 82.4% (high), and 78.7% (very high). Differences between consecutive CLL-IPI risk groups were observed for intermediate vs. low (HR=3.296, 95%-CI 1.576-6.894, p=0.002), for high vs. intermediate (HR=1.365, 95%-CI 1.003-1.858, p=0.048), but not for very high vs. high. CLL-IPI factors ß2-microglobulin, IGHV mutational status, and TP53 status each retained prognostic value for PFS. The 3-year overall survival (OS)-rates by CLL-IPI risk group were 100%, 96%, 93.9%, and 89.4% with no differences between consecutive risk groups. Age, Binet stage, ß2-microglobulin, and TP53 status each retained prognostic value for OS. In chemoimmunotherapy patients (median observation time 66.9 months), 3-year PFS-rates for CLL-IPI risk groups were 78.1%, 51.4%, 40.1%, and 16.5%. Corresponding 3-year OS-rates were 97.4%, 93.1%, 81.8%, and 57.3%. In a matched-pair analysis, PFS-differences in targeted therapies (N=812) versus chemoimmunotherapy (N=812) across all risk groups, and OS-differences in all but low-risk patients were demonstrated. The CLL-IPI maintains its prognostic value in predicting PFS outcomes with targeted drugs. With the caveat of a short observation time its impact in predicting survival appears diminished. Targeted therapies showed enhanced outcomes over chemoimmunotherapy, highlighting their effectiveness across various risk groups. Our findings support ongoing assessment of prognostic tools in CLL treatment evolution. CLL2-BIG (NCT02345863), CLL2-BAG (NCT02401503), CLL2-BIO (NCT02689141), CLL2-BCG (NCT02445131), CLL2-GIVe (NCT02758665), CLL13 (NCT02950051), CLL14-trial (NCT02242942), CLL1 (NCT00262782), CLL8 (NCT00281918), and CLL11 (NCT01010061).

Activity of venetoclax in patients with relapsed or refractory chronic lymphocytic leukaemia: analysis of the VENICE-1 multicentre, open-label, single-arm, phase 3b trial.

BACKGROUND: Most patients with chronic lymphocytic leukaemia progress after treatment or retreatment with targeted therapy or chemoimmunotherapy and have limited subsequent treatment options. Response levels to the single-agent venetoclax in the relapsed setting is unknown. We aimed to assess venetoclax activity in patients with or without previous B-cell receptor-associated kinase inhibitor (BCRi) treatment. METHODS: This multicentre, open-label, single-arm, phase 3b trial (VENICE-1) assessed activity and safety of venetoclax monotherapy in adults with relapsed or refractory chronic lymphocytic leukaemia, stratified by previous exposure to a BCRi. Eligible participants were aged 18 years or older with previously treated relapsed or refractory chronic lymphocytic leukaemia. Presence of del(17p) or TP53 aberrations and previous BCRi treatment were permitted. Patients received 5-week ramp-up to 400 mg of oral venetoclax once daily and were treated for up to 108 weeks, with 2 years follow-up after discontinuation, or optional extended access. The primary activity endpoint was complete remission rate (complete remission or complete remission with incomplete marrow recovery) in BCRi-naive patients. Analyses used the intent-to-treat (ie, all enrolled patients, which coincided with those who received at least one dose of venetoclax). This study was registered with ClinicalTrials.gov, NCT02756611, and is complete. FINDINGS: Between June 22, 2016, and March 11, 2022, we enrolled 258 patients with relapsed or refractory chronic lymphocytic leukaemia (180 [70%] were male; 252 [98%] were White; 191 were BCRi-naive and 67 were BCRi-pretreated). Median follow-up in the overall cohort was 49·5 months (IQR 47·2-54·1), 49·2 months (47·2-53·2) in the BCRi-naive group, and 49·7 months (47·4-54·3) in the BCRi-pretreated group. Of 191 BCRi-naive patients, 66 (35%; 95% CI 27·8-41·8) had complete remission or complete remission with incomplete marrow recovery. 18 (27%; 95% CI 16·8-39·1) of 67 patients in the BCRi-pretreated group had complete remission or complete remission with incomplete marrow recovery. Grade 3 or worse treatment-emergent adverse events were reported in 203 (79%) and serious adverse events were reported in 136 (53%) of 258 patients in the overall cohort. The most common treatment-emergent adverse event was neutropenia (96 [37%]) and the most common and serious adverse event was pneumonia (21 [8%]). There were 13 (5%) deaths reported due to adverse events; one of these deaths (autoimmune haemolytic anaemia) was possibly related to venetoclax. No new safety signals were identified. INTERPRETATION: These data demonstrate deep and durable responses with venetoclax monotherapy in patients with relapsed or refractory chronic lymphocytic leukaemia, including BCRi-pretreated patients, suggesting that venetoclax monotherapy is an effective strategy for treating BCRi-naive and BCRi-pretreated patients. FUNDING: AbbVie.

Daratumumab monotherapy in refractory warm autoimmune hemolytic anemia and cold agglutinin disease.

Autoimmune hemolytic anemia (AIHA) is a rare autoantibody-mediated disease. For steroid and/or rituximab-refractory AIHA, there is no consensus on optimal treatment. Daratumumab, a monoclonal antibody targeting CD38, could be beneficial by suppression of CD38+ plasmacells and thus autoantibody secretion. In addition, since CD38 is also expressed by activated T-cells, daratumumab may also act via immunomodulatory effects. We evaluated efficacy and safety of daratumumab monotherapy in an international retrospective study including 19 adult patients with heavily pretreated refractory AIHA. In warm AIHA (wAIHA, n=12), overall response was 50% with a median response duration of 5.5 months (range, 2-12 months) including ongoing response in 2 patients after 6 and 12 months. Of 6 non-responders, 4 had Evans syndrome. In cold AIHA (cAIHA, n=7) overall hemoglobin (Hb) response was 57%, with ongoing response in 3/7 patients. One additional non-anemic cAIHA patient was treated for severe acrocyanosis and reached a clinical acrocyanosis response as well as a Hb increase. Of 6 cAIHA patients with acrocyanosis, 4 had improved symptoms after daratumumab treatment. In two patients with wAIHA treated with daratumumab in whom we prospectively collected blood samples, we found complete CD38+ T cells depletion after daratumumab, as well as altered T-cell subset differentiation and a severely diminished capacity for cell activation and proliferation. Reappearance of CD38+ T-cells coincided with disease relapse in one patient. In conclusion, our data show that daratumumab therapy may be a treatment option for refractory AIHA. The observed immunomodulatory effects that may contribute to the clinical response deserve further exploration.

Venetoclax Initiation in Chronic Lymphocytic Leukemia: International Insights and Innovative Approaches for Optimal Patient Care.

Venetoclax, a highly selective, oral B-cell lymphoma 2 inhibitor, provides a robust targeted-therapy option for the treatment of chronic lymphocytic leukemia (CLL), including patients with high-risk del(17p)/mutated-TP53 and immunoglobulin heavy variable region unmutated CLL and those refractory to chemoimmunotherapy across all age groups. Due to the potent pro-apoptotic effect of venetoclax, treatment initiation carries a risk of tumor lysis syndrome (TLS). Prompt and appropriate management is needed to limit clinical TLS, which may entail serious adverse events and death. Venetoclax ramp-up involves gradual, stepwise increases in daily venetoclax dosing from 20 mg to 400 mg (target dose) over 5 weeks; adherence to on-label scheduling provides a tumor debulking phase, reducing the risk of TLS. The key components of safe venetoclax therapy involve assessment (radiographic evaluation and baseline blood chemistry), preparation (adequate hydration), and initiation (blood chemistry monitoring). In addition to summarizing the evidence for venetoclax's efficacy and safety, this review uses hypothetical patient scenarios based on risk level for TLS (high, medium, low) to share the authors' clinical experience with venetoclax initiation and present global approaches utilized in various treatment settings. These hypothetical scenarios highlight the importance of a multidisciplinary approach and shared decision-making, outlining best practices for venetoclax initiation and overall optimal treatment strategies in patients with CLL.

Improved Innate Immune Function in Patients with Chronic Lymphocytic Leukemia Treated with Targeted Therapy in Clinical Trials.

PURPOSE: Patients with chronic lymphocytic leukemia (CLL) have increased risk of severe infections. Although adaptive immune dysfunction is well described, clinical tools for identifying patients at risk are lacking, warranting investigation of additional immune components. In contrast to chemotherapy, targeted agents could spare or even improve innate immune function. Therefore, we investigated innate immune phenotypes and function in patients with CLL before and during targeted treatment. EXPERIMENTAL DESIGN: Baseline and consecutive blood samples were collected from patients with CLL treated with acalabrutinib (n = 17) or ibrutinib+venetoclax (n = 18) in clinical trials. Innate immune function was assessed by TruCulture, a whole-blood ligand-stimulation assay quantifying cytokine release in response to standardized stimuli. Innate immune phenotypes were characterized by flow cytometry. As a proxy for infections, we mapped antimicrobial use before and during treatment. RESULTS: At baseline, patients with CLL displayed impaired stimulated cytokine responses to the endotoxin lipopolysaccharide (LPS) along with deactivated monocytes, enrichment of myeloid-derived suppressor cells and metamyelocytes, and elevated (unstimulated) proinflammatory cytokines. Two/three cycles of acalabrutinib or ibrutinib normalized LPS-stimulated responses, in parallel with decreased duration of infections. Innate immune profiles and elevated proinflammatory cytokines further normalized during longer-term acalabrutinib or ibrutinib+venetoclax, paralleled by decreased infection frequency. CONCLUSIONS: Innate immune impairment and infection susceptibility in patients with CLL were restored in parallel during targeted therapy. Thus, targeted treatment may reduce the risk of infections in CLL, as currently under investigation in the PreVent-ACaLL phase 2 trial of acalabrutinib+venetoclax for high-risk CLL (NCT03868722).

Six-year follow-up and subgroup analyses of a phase 2 trial of venetoclax for del(17p) chronic lymphocytic leukemia.

ABSTRACT: Chromosome 17p deletion (del[17p]) is associated with poor prognosis in patients with chronic lymphocytic leukemia (CLL). Venetoclax is approved for treatment of previously untreated and relapsed/refractory (R/R) CLL, including patients with del(17p), based on the open-label, multicenter, phase 2 M13-982 trial (NCT01889186). Here, we detail the 6-year follow-up analysis for M13-982. A total of 158 patients with previously untreated (n = 5) or R/R (n = 153) del(17p) CLL received 400 mg venetoclax daily after initial ramp-up until progressive disease. After a median follow-up of 70 months, the best objective response rate (ORR) was 77% (21% complete remission [CR] and 49% partial remission [PR]), with a median duration of response (DOR) of 39.3 months (95% confidence interval [CI], 31.1-50.5). The median progression-free survival (PFS) was 28.2 months (95% CI, 23.4-37.6), and median overall survival (OS) was 62.5 months (95% CI, 51.7-not reached), with 16% of patients remaining on treatment after 6 years. Multivariable analysis did not identify statistically significant correlation between patient subgroups defined by clinical or laboratory variables and ORR or PFS. The most common grade ≥3 adverse events were neutropenia (42%), infections (33%), anemia (16%), and thrombocytopenia (16%). Post hoc comparative analyses of PFS and OS from treatment initiation, from a 24-month landmark, and by minimal residual disease status were performed between patients with del(17p) in the M13-982 and MURANO studies in the interest of understanding these data in another context. These long-term data show the continued benefits of venetoclax in patients with del(17p) CLL. The trial was registered at www.clinicaltrials.gov as #NCT01889186.

Electron transport chain and mTOR inhibition synergistically decrease CD40 signaling and counteract venetoclax resistance in chronic lymphocytic leukemia.

CD40 signaling upregulates BCL-XL and MCL-1 expression in the chronic lymphocytic leukemia (CLL) lymph node microenvironment, affording resistance to the BCL-2 inhibitor, venetoclax. Venetoclax resistance in the therapeutic setting and after long-term laboratory selection has been linked to metabolic alterations, but the underlying mechanism(s) are unknown. We aimed here to discover how CD40 stimulation as a model for tumor microenvironment-mediated metabolic changes, affects venetoclax sensitivity/resistance. CD40 stimulation increased oxidative phosphorylation and glycolysis, but only inhibition of oxidative phosphorylation countered venetoclax resistance. Furthermore, blocking mitochondrial import of pyruvate, glutamine or fatty acids affected CLL metabolism, but did not prevent CD40-mediated resistance to venetoclax. In contrast, inhibition of the electron transport chain (ETC) at complex I, III or V attenuated CLL activation and ATP production, and downregulated MCL-1 and BCL-XL, correlating with reduced CD40 surface expression. Moreover, ETC inhibition equaled mTOR1/2 but not mTOR1 inhibition alone for venetoclax resistance, and all three pathways were linked to control of general protein translation. In line with this, ETC plus mTOR inhibition synergistically counteracted venetoclax resistance. These findings link oxidative CLL metabolism to CD40 expression and cellular signaling, and may hold clinical potential.

Fixed-duration ibrutinib-venetoclax versus chlorambucil-obinutuzumab in previously untreated chronic lymphocytic leukaemia (GLOW): 4-year follow-up from a multicentre, open-label, randomised, phase 3 trial.

BACKGROUND: In the GLOW study, fixed-duration ibrutinib-venetoclax showed superior progression-free survival versus chlorambucil-obinutuzumab in patients with previously untreated chronic lymphocytic leukaemia who were older or had comorbidities, or both, at a median follow up of 27·7 months. In this Article, we report updated outcomes from GLOW after a 46-month median follow-up. METHODS: GLOW was a randomised, multicentre, phase 3 study done at 67 hospital centres across 14 countries. Patients aged 65 years and older or 18-64 years with previously untreated chronic lymphocytic leukaemia and a cumulative illness rating scale score of more than 6 or creatinine clearance less than 70 mL/min, or both, and an Eastern Cooperative Oncology Group performance status of 2 or less were randomly assigned (1:1) via an interactive web system with permuted blocks (block size of four) and stratified by IGHV mutational status and the presence of del11q aberration to the ibrutinib-venetoclax group (three cycles of ibrutinib lead-in [420 mg/day, orally], followed by 12 cycles of ibrutinib plus venetoclax [400 mg/day, orally, including a 5-week dose ramp-up]) or the chlorambucil-obinutuzumab group (six cycles of chlorambucil [0·5 mg/kg, orally, on days 1 and 15 of each cycle], and obinutuzumab [1000 mg, intravenously, on days 1 (or 100 mg on day 1 and 900 mg on day 2), 8, and 15 of cycle 1 and day 1 of cycles 2-6]). The primary endpoint was progression-free survival in the intention-to-treat population, assessed by an independent review committee. The safety population included all randomised patients who received at least one dose of the study treatment. This study is registered with ClinicalTrials.gov (NCT03462719) and the EU Clinical Trials Register (EudraCT 2017-004699-77). FINDINGS: Between May 4, 2018, and April 5, 2019, 211 patients (122 [58%] were male and 89 [42%] were female) were randomly assigned to receive ibrutinib-venetoclax (n=106) or chlorambucil-obinutuzumab (n=105). At a median of 46 months (IQR 43-47) of follow-up, progression-free survival remained superior for the ibrutinib-venetoclax group (hazard ratio 0·214 [95% CI 0·138-0·334]; p<0·0001); 42-month progression-free survival rates were 74·6% (95% CI 65·0-82·0) for ibrutinib-venetoclax and 24·8% (16·5-34·1) for chlorambucil-obinutuzumab. Following the primary analysis, one patient in the chlorambucil-obinutuzumab group had a serious adverse event of myelodysplastic syndrome. Treatment-related deaths were reported in one patient receiving ibrutinib-venetoclax (cardiac failure, pneumonia, and sinus node dysfunction) and in one patient receiving chlorambucil-obinutuzumab (pneumonia). There were 15 deaths in the ibrutinib-venetoclax group (of which three were due to post-treatment infections) and 30 deaths in the chlorambucil-obinutuzumab group (of which 10 were due to post-treatment infections). INTERPRETATION: After 4 years of follow-up, ibrutinib-venetoclax continues to significantly prolong progression-free survival (vs chemoimmunotherapy) in patients with previously untreated chronic lymphocytic leukaemia, supporting its use as a first-line option. FUNDING: Janssen Research & Development and Pharmacyclics.

High-throughput Proteomics Identifies THEMIS2 as Independent Biomarker of Treatment-free Survival in Untreated CLL.

It remains challenging in chronic lymphocytic leukemia (CLL) to distinguish between patients with favorable and unfavorable time-to-first treatment (TTFT). Additionally, the downstream protein correlates of well-known molecular features of CLL are not always clear. To address this, we selected 40 CLL patients with TTFT ≤24 months and compared their B cell intracellular protein expression with 40 age- and sex-matched CLL patients with TTFT >24 months using mass spectrometry. In total, 3268 proteins were quantified in the cohort. Immunoglobulin heavy-chain variable (IGHV) mutational status and trisomy 12 were most impactful on the CLL proteome. Comparing cases to controls, 5 proteins were significantly upregulated, whereas 3 proteins were significantly downregulated. Of these, only THEMIS2, a signaling protein acting downstream of the B cell receptor, was significantly associated with TTFT, independently of IGHV and TP53 mutational status (hazard ratio, 2.49 [95% confidence interval, 1.62-3.84]; P < 0.001). This association was validated on the mRNA and protein level by quantitative polymerase chain reaction and ELISA, respectively. Analysis of 2 independently generated RNA sequencing and mass spectrometry datasets confirmed the association between THEMIS2 expression and clinical outcome. In conclusion, we present a comprehensive characterization of the proteome of untreated CLL and identify THEMIS2 expression as a putative biomarker of TTFT.

T-cell dysfunction by pseudohypoxia and autocrine purinergic signaling in chronic lymphocytic leukemia.

Acquired T-cell dysfunction is common in chronic B-cell malignancies. Given the strong connection between T-cell metabolism and function, we investigated metabolic alterations as the basis of T-cell dysfunction induced by malignant cells. Using B-cell malignant cell lines and human peripheral blood mononuclear cells, we first established a model that recapitulates major aspects of cancer-induced T-cell dysfunction. Cell lines derived from chronic lymphocytic leukemia (CLL) (PGA-1, CII, and Mec-1), but not from other B-cell malignancies, altered the T-cell metabolome by generating a pseudohypoxic state. T cells were retained in aerobic glycolysis and were not able to switch to oxidative phosphorylation (OXPHOS). Moreover, T cells produced immunosuppressive adenosine that negatively affected function by dampening the activation, which could be restored by the blocking of adenosine receptors. Subsequently, we uncovered a similar hypoxic-like signature in autologous T cells from primary CLL samples. Pseudohypoxia was reversible upon depletion of CLL cells ex vivo and, importantly, after the in vivo reduction of the leukemic burden with combination therapy (venetoclax and obinutuzumab), restoring T-cell function. In conclusion, we uncovered a pseudohypoxic program connected with T-cell dysfunction in CLL. Modulation of hypoxia and the purinergic pathway might contribute to therapeutic restoration of T-cell function.

In Vitro 3D Spheroid Culture System Displays Sustained T Cell-dependent CLL Proliferation and Survival.

Chronic lymphocytic leukemia (CLL) cells are highly dependent on microenvironmental cells and signals. The lymph node (LN) is the critical site of in vivo CLL proliferation and development of resistance to both chemotherapy and targeted agents. We present a new model that incorporates key aspects of the CLL LN, which enables investigation of CLL cells in the context of a protective niche. We describe a three-dimensional (3D) in vitro culture system using ultra-low attachment plates to create spheroids of CLL cells derived from peripheral blood. Starting from CLL:T cell ratios as observed in LN samples, CLL activation was induced by either direct stimulation and/or indirectly via T cells. Compared with two-dimensional cultures, 3D cultures promoted CLL proliferation in a T cell-dependent manner, and enabled expansion for up to 7 weeks, including the formation of follicle-like structures after several weeks of culture. This model enables high-throughput drug screening, of which we describe response to Btk inhibition, venetoclax resistance, and T cell-mediated cytotoxicity as examples. In summary, we present the first LN-mimicking in vitro 3D culture for primary CLL, which enables readouts such as real-time drug screens, kinetic growth assays, and spatial localization. This is the first in vitro CLL system that allows testing of response and resistance to venetoclax and Bruton's tyrosine kinase inhibitors in the context of the tumor microenvironment, thereby opening up new possibilities for clinically useful applications.

Immunogenicity of the 13-Valent Pneumococcal Conjugated Vaccine Followed by the 23-Valent Polysaccharide Vaccine in Chronic Lymphocytic Leukemia.

Patients with Chronic Lymphocytic Leukemia (CLL) have a 29- to 36-fold increased risk of invasive pneumococcal disease (IPD) compared to healthy adults. Therefore, most guidelines recommend vaccination with the 13-valent pneumococcal conjugated vaccine (PCV13) followed 2 months later by the 23-valent polysaccharide vaccine (PPSV23). Because both CLL as well as immunosuppressive treatment have been identified as major determinants of immunogenicity, we aimed to assess the vaccination schedule in untreated and treated CLL patients. We quantified pneumococcal IgG concentrations against five serotypes shared across both vaccines, and against four serotypes unique to PPSV23, before and eight weeks after vaccination. In this retrospective cohort study, we included 143 CLL patients, either treated (n = 38) or naive to treatment (n = 105). While antibody concentrations increased significantly after vaccination, the overall serologic response was low (10.5%), defined as a ≥4-fold antibody increase against ≥70% of the measured serotypes, and significantly influenced by treatment status and prior lymphocyte number. The serologic protection rate, defined as an antibody concentration of ≥1.3 µg/mL for ≥70% of serotypes, was 13% in untreated and 3% in treated CLL patients. Future research should focus on vaccine regimens with a higher immunogenic potential, such as multi-dose schedules with higher-valent T cell dependent conjugated vaccines.