PHOSPHORYLATION-DEPENDENT ASSOCIATION OF WRN WITH RPA IS REQUIRED FOR RECOVERY OF REPLICATION FORKS STALLED AT SECONDARY DNA STRUCTURES.

The WRN protein mutated in the hereditary premature aging disorder Werner syndrome plays a vital role in handling, processing, and restoring perturbed replication forks. One of its most abundant partners, Replication Protein A (RPA), has been shown to robustly enhance WRN helicase activity in specific cases when tested in vitro. However, the significance of RPA-binding to WRN at replication forks in vivo has remained largely unexplored. In this study, we have identified several conserved phosphorylation sites in the acidic domain of WRN that are targeted by Casein Kinase 2 (CK2). Surprisingly, these phosphorylation sites are essential for the interaction between WRN and RPA, both in vitro and in human cells. By characterizing a CK2-unphosphorylatable WRN mutant that lacks the ability to bind RPA, we have determined that the WRN-RPA complex plays a critical role in fork recovery after replication stress whereas the WRN-RPA interaction is not necessary for the processing of replication forks or preventing DNA damage when forks stall or collapse. When WRN fails to bind RPA, fork recovery is impaired, leading to the accumulation of single-stranded DNA gaps in the parental strands, which are further enlarged by the structure-specific nuclease MRE11. Notably, RPA-binding by WRN and its helicase activity are crucial for countering the persistence of G4 structures after fork stalling. Therefore, our findings reveal for the first time a novel role for the WRN-RPA interaction to facilitate fork restart, thereby minimizing G4 accumulation at single-stranded DNA gaps and suppressing accumulation of unreplicated regions that may lead to MUS81-dependent double-strand breaks requiring efficient repair by RAD51 to prevent excessive DNA damage.

Phosphorylation status of MUS81 is a modifier of Olaparib sensitivity in BRCA2-deficient cells.

The MUS81 complex is crucial for preserving genome stability through resolution of branched DNA intermediates in mitosis and also for the processing of deprotected replication forks in BRCA2-deficient cells. Because of the existence of two different MUS81 complexes in mammalian cells that act in M- or S-phase, whether and how the PARPi sensitivity of BRCA2-deficient cells is affected by loss of MUS81 function is unclear. Here, using a mutant of MUS81 that impairs its function in M-phase, we show that viability of BRCA2-deficient cells but not their PARPi sensitivity requires a fully-functional MUS81 complex in mitosis. In contrast, expression of a constitutively-active MUS81 is sufficient to confer PARPi resistance. From a mechanistic point of view, our data indicate that deregulated action of the mitotic active form of MUS81 in S-phase leads to the cleavage of stalled replication forks before their reversal, bypassing fork deprotection, and engaging a Polθ-dependent DSBs repair. Collectively, our findings describe a novel mechanism leading to PARPi resistance that involves unscheduled MUS81-dependent cleavage of intact, unreversed replication forks. Since this cleavage occurs mimicking the phosphorylated status of S87 of MUS81, our data suggest that hyperphosphorylation of this residue in S-phase might represent a novel biomarker to identify resistance to PARPi.

Should treatment of hypogammaglobulinemia with immunoglobulin replacement therapy (IgRT) become standard of care in patients with chronic lymphocytic leukemia?

Hypogammaglobulinemia (HGG) is a frequent finding in patients with hematological malignancies, and is commonly described in chronic lymphocytic leukemia (CLL) before or after treatment. We reviewed published literature available online in the last thirty years through Medline search of indexed articles focusing on the main differences and advantages of the products now available on the market, namely intravenous Ig (IVIg) and subcutaneous Ig (SCIg) preparations. IgRT is effective and safe in the prophylaxis of infections in a selected group of patients with CLL and hypogammaglobulinemia and is therefore a valuable tool for clinicians in the everyday management of infectious risk. We encourage the use of SCIg formulations as they appear to have similar efficacy but better cost-effectiveness and tolerability.

Predictors of ibrutinib-associated atrial fibrillation: 5-year follow-up of a prospective study.

Ibrutinib-associated atrial fibrillation (IRAF) emerged among the adverse events of major interests in ibrutinib-treated patients as real-world studies showed a higher incidence compared to clinical trials. We prospectively analyzed predictors of IRAF in 43 single-center consecutive patients affected by chronic lymphocytic leukemia that started therapy with ibrutinib between 2015 and 2017. Key secondary endpoints were to describe the management of IRAF and survival outcomes. During a median follow-up period of 52 months, we registered 45 CV events, with a total of 23 AF events in 13 patients (CI 30.0% (95% CI: 16.5-43.9)). Pre-existent cardiovascular risk factors, in particular hypertension, a previous history of AF and a high Shanafelt risk score emerged as predictors of IRAF. Baseline echocardiographic evaluation of left atrial (LA) dimensions confirmed to predict IRAF occurrence and cut-off values were identified in our cohort: 32 mm for LA diameter and 18 cm2 for LA area. No difference in progression free survival and overall survival emerged in patients experiencing IRAF. Following AF, anticoagulation was started in all eligible patients, and cardioactive therapy was accordingly modified. Echocardiography represents a highly reproducible and widespread tool to be included in the work-up of ibrutinib candidates; the identification of IRAF predictors represents a useful guide to clinical practice.

Reply to "successful early use of anti-SARS-CoV-2 monoclonal neutralizing antibodies in SARS-CoV-2 infected hematological patients-A Czech multicenter experience": A case series of SARS-CoV-2 Omicron infection and aggressive lymphoma in the Sotrovimab era.

A prospective multicentre experience of early administration of anti-SARS-CoV-2 spike protein neutralizing monoclonal antibodies (MA) with efficacy among patients with hematological malignancies and early-stage COVID- 19 was reported by Weinbergerová et al. The study validated the safety and efficacy of MA early use among hematological patients with newly diagnosed early-stage COVID-19 in terms of alleviating infection course and decreasing mortality. However no reference to new variant (Delta and Omicron) or other MA (e.g., Sotrovimab) has been reported. We reported our monocentric experience of 8 aggressive lymphoma patients with Omicron infection, 7 of whom treated with this MA in our Institution between December 2021 and February 2022. Among the patients treated with Sotrovimab nobody experienced neither SARS-CoV2 reactivation, nor other infectious events. One patients on active lymphoma treatment was hospitalized for pneumonia and treated with remdesivir. In 4/8 patients negativization of molecular swab occurred concomitantly to symptoms resolution with a median of 5.25 days, while the other 4 patients remained persistently positive with a median of 26.3 days. In this group, in order to maintain the chemo/chemoimmunotherapy (CT/CIT) dose-density, lymphoma treatment was reassumed independently on molecular swab analysis. SARS-CoV-2 negativization occurred with a median of 7.7 days after the resumption of CT/CIT. The one patient treated with remdesivir, although still positive to molecular swab, restarted R-COMP regimen at symptoms resolution too, but experienced an Omicron pneumonia exacerbation. This is the first case series reported in literature of patients affected by Omicron variant in which Sotrovimab seems to provide a resolution of COVID-19 disease, even in patient with molecular swab positive persistence too. Patients with aggressive lymphoma histologies should not be deprived of the best available treatment of their disease after sotrovimab administration, even in the presence of a still positive Omicron swab.

Seroconversion to mRNA SARS-CoV-2 Vaccines in Hematologic Patients.

Hematologic patients show lower responses to SARS-CoV-2 vaccines, but predictors of seroconversion are lacking. In this prospective cohort study, hematologic patients undergoing SARS-CoV-2 mRNA vaccination at a single center in Milan, Italy, were sampled for anti-Spike and anti-Nucleocapsid IgG titer at 5 ± 1 weeks and at 3 months from the second vaccine dose. Patients (N = 393) received either BNT162b2 (Pfizer-BioNTech, 48%) or MRNA-1273 (Moderna, 52%), and 284 (72%) seroconverted and 100% persisted at 3 months. Non-response was higher in chronic lymphocytic leukemia (CLL) and lymphoma patients, and in those treated with small molecules and monoclonal antibodies. In myeloid neoplasms, lower responses were detected in patients with acute myeloid leukemia treated with venetoclax plus hypomethylating agents and in patients with myelofibrosis receiving ruxolitinib. Multivariable analysis showed that seroconversion was favorably associated with a diagnosis other than indolent lymphoma/CLL [OR 8.5 (95% CI 4.1-17.6)], lack of B-cell-depleting therapy [OR 3.15 (1.7-5.9)], and IgG levels within the normal range [OR 2.2 (1.2-4.2)]. We developed a simple algorithm according to these 3 risk factors [(A) diagnosis of indolent lymphoma/CLL, (B) B-cell-depleting treatment, and (C) low IgG] to predict non-response. IgG levels and treatment may be modifiable risk factors and should be considered for timing of vaccine administration.

Acquired hemophilia A and delta storage pool deficiency in a patient with indolent non-Hodgkin lymphoma.

B-cell lymphoproliferative diseases may be associated with acquired hemostasis disorders, such as acquired hemophilia A (AHA) caused by autoantibodies that neutralize factor VIII activity, and δ-storage pool deficiency, an abnormality of platelet function due to defective dense granules and impaired secretion. We describe the case of a 67-year-old man in whom these two acquired bleeding disorders were concomitantly present as the first clinical manifestation of an indolent non-Hodgkin lymphoma. Immunosuppressive therapy with prednisone was initially started to eradicate anti-FVIII antibodies, subsequently boosted with cyclophosphamide and rituximab, these medications being also chosen to treat the associated indolent lymphoma. Bleeding symptoms were first tackled with limited benefit by using rFVIIa and then rescued using recombinant porcine FVIII. After a 6 month's follow-up lymphoma and AHA were in remission and platelet function was improved. This case underlines the need of multiple and complex diagnostic and therapeutic approaches to rare acquired bleeding disorders associated with lymphoproliferative diseases.

Prognostic Impact and Risk Factors of Infections in Patients with Chronic Lymphocytic Leukemia Treated with Ibrutinib.

Ibrutinib represents extraordinary progress in the treatment of chronic lymphocytic leukemia (CLL). However, treatment-related adverse events limit the benefit of this agent. This observational, multicenter study focused on the incidence, risk factors, and prognostic impact of infections in 494 patients with CLL treated with an ibrutinib-based treatment. Ibrutinib was given to 89 (18%) previously untreated patients (combined with rituximab, 24) and 405 (82%) relapsed/refractory patients. Pneumonia (PN), grade ≥3 non-opportunistic infections (NOI), and opportunistic infections (OI) were recorded in 32% of patients with an overall incidence rate per 100 person-year of 15.3% (PN, 10%; NOI, 3.3%; OI, 2%). Infections were the reason for the permanent discontinuation of ibrutinib in 9% of patients. Patients who experienced pneumonia or a severe infection showed a significantly inferior survival than those who were infection-free (p < 0.0001). A scoring system based on the three factors associated with a significant and independent impact on infections-PN or severe infection in the year before starting ibrutinib, chronic obstructive pulmonary disease, ≥2 prior treatments-identified patients with a two- to threefold increase in the rate of infections. In conclusion, the results of this study highlight the adverse impact of infectious events on the outcomes of CLL patients treated with ibrutinib.

The Role of Novel Agents in Treating CLL-Associated Autoimmune Hemolytic Anemia.

Autoimmune cytopenias (AICs) have been reported as a common complication in chronic lymphocytic leukemia (CLL) with autoimmune hemolytic anemia (AIHA), accounting for most cases. According to iwCLL guidelines, AICs poorly responsive to corticosteroids are considered indication for CLL-directed treatment. Chemo-immunotherapy has classically been employed, with variable results, and little data are available on novel agents, the current backbone of CLL therapy. The use of idelalisib in the setting of AICs is controversial and recent recommendations suggest avoiding idelalisib in this setting. Ibrutinib, through ITK-driven Th1 polarization of cell-mediated immune response, is known to produce an immunological rebalancing in CLL, which stands as a fascinating rationale for its use to treat autoimmunity. Although treatment-emergent AIHA has rarely been reported, ibrutinib has shown rapid and durable responses when used to treat AIHA arising in CLL. There is poor evidence regarding the role of BCL-2 inhibitors in CLL-associated AICs and the use of venetoclax in such cases is debated. Furthermore, their frequent use in combination with anti-CD20 agents might represent a confounding factor in evaluating their efficacy. In conclusions, because of their ability to mitigate an immunological dysregulation that is (at least partly) responsible for autoimmunity in CLL, to date BTK-inhibitors stand out as the most suitable choice when treatment of autoimmune cytopenias is required.