Effective Neutralizing Antibody Response Against SARS-CoV-2 Virus and Its Omicron BA.1 Variant in Fully Vaccinated Hematological Patients

SARS-CoV-2 and its variants cause CoronaVIrus Disease 19 (COVID-19), a pandemic disease. Hematological malignancies increase susceptibility to severe COVID-19 due to immunosuppression. Anti-SARS-CoV-2 neutralizing antibodies protect against severe COVID-19. This retrospective real-life study aimed to evaluate seropositivity and neutralizing antibody rates against SARS-CoV-2 and its Omicron BA.1 variant in hematological patients. A total of 106 patients with different hematologic malignancies, who have mostly received three or more vaccine doses (73%), were included in this study. Serum was collected between May and June 2022. The primary endpoint was anti-SARS-CoV-2 antibody response against ancestral (wild type; wt) and Omicron BA.1 virus, defined as a neutralizing antibody titer ≥ 1:10. Adequate neutralizing antibody response was observed in 75 (71%) and 87 (82%) of patients for wt and Omicron BA.1 variants, respectively.However, patients with B-cell lymphoproliferative disorders and/or those treated with anti-CD20 monoclonal antibodies in the prior 12 months showed a lower seropositivity rate compared to other patients against both Omicron BA.1 variant (73% vs 91%; P = 0.02) and wt virus (64% vs 78%; P = 0.16). Our real-life experience confirmed that full vaccination against SARS-CoV-2 induces adequate neutralizing antibody protection for both the wt virus and Omicron BA.1 variants, even in hematological frail patients. However, protective measures should be maintained in hematological patients, especially those with B-cell lymphoproliferative diseases treated with anti-CD20 monoclonal antibodies, because these subjects could have a reduced neutralizing antibody production.

Safety of Subcutaneous Daratumumab in Anti-CD38 Monoclonal Antibody-Naïve Patients with Plasma Cell Disorders: A Multicenter Real-Life Experience

BACKGROUND

Daratumumab, an anti-CD38 monoclonal antibody, is used for treatment of multiple myeloma (MM) and light chain amyloidosis at an intravenous dosage of 16 mg/kg or at a subcutaneous fixed dose of 1800 mg. However, the subcutaneous formulation has only recently been approved in Europe, and real-life data on its safety are still few.

OBJECTIVE

In this multicenter retrospective real-life experience, we provided evidence for the safety of subcutaneous daratumumab in plasma cell disorders.

PATIENTS AND METHODS

A total of 189 patients diagnosed with MM or light chain amyloidosis were included in this retrospective study, and all subjects were daratumumab-naïve. Primary endpoint was safety of subcutaneous daratumumab, especially for infusion-related reaction (IRR) incidence and severity. All patients received premedication with dexamethasone, paracetamol, and antihistamine, with montelukast usage in 85% of cases.

RESULTS

Eight patients (4%) experienced IRRs, mainly of grade I-II, and other frequent toxicities were: hematological (thrombocytopenia, 4%; neutropenia, 5%; lymphopenia, 6%) and non-hematological (pneumonia, 4%; diarrhea, 2%; and cytomegalovirus reactivation, 0.5%). In our multicenter retrospective real-life experience, subcutaneous daratumumab was well-tolerated with an excellent safety profile with a very low (4%) IRR incidence, even in frailer MM patients with severe renal impairment or increased body weight.

CONCLUSIONS

Subcutaneous daratumumab was safe in a real-life setting including patients with severe renal failure and advanced disease. However, further studies on larger and prospective cohorts are required to confirm our real-life observations.

Inter-intra instrument comparison and standardization of a 10-color immunophenotyping for B and T cell non-Hodgkin lymphoma diagnosis and monitoring

Harmonization of flow cytometry protocols from instrument settings to antibody panel and reagents is highly encouraged for inter-laboratory data comparison in both research and clinical settings, especially for minimal residual disease monitoring evaluation in hematological diseases across centers. Here, we described inter-intra instrument comparison of two standardized 10-color staining dried tubes for B- and T-cell lymphoproliferative disorder diagnosis and monitoring on two different flow cytometers, a Beckman Coulter NaviosEx and a Beckman Coulter DxFlex. A total of 47 consecutive patients were enrolled, and 39 of them were evaluable for further studies. We show highly comparable results between the two cytometers for cell frequency and fluorescence intensity signals for both standardized 10-color staining dried tubes. For this latter, fluorescence of each antibody and subject was normalized on the mean value obtained from the entire study cohort thus reducing the effects of biological variability and allowing comparison between instruments with different detector sensitivity. In summary, dried tubes were confirmed as an optimal standardized diagnostic tool, especially when associated with EuroFlow standardized procedures by minimizing technical and biological variability. However, data analysis is still operator-dependent, and more efforts are needed to develop automated or semi-automated software for flow cytometry data analysis for diagnostic purposes.

Implementation of International Prognostic Index with flow cytometry immunophenotyping for better risk stratification of chronic lymphocytic leukemia

BACKGROUND

Current chronic lymphocytic leukemia (CLL) International Prognostic Index (IPI) stratifies patients based on clinical, molecular, and biochemical features; however, B-cell markers also influence CLL outcomes. Here, prognostic roles of CD11c, CD38, and CD49d were first evaluated, and then an immunophenotypic score was combined with CLL-IPI for risk stratification of CLL patients.

METHODS

A total of 171 CLL subjects were included, and surface marker expression was assessed by flow cytometry. Levels ≥30% were chosen as cut-off of positivity to a marker; then values of 1 (for CD11c and CD38) or 3 (for CD49d) were assigned and scores determined for each patient's clone immunophenotype.

RESULTS

CD49d positivity was significantly associated with simultaneous expression of CD11c and/or CD38, unmutated IGHV status, and higher β2-microglobulin levels compared to those with CD49d negativity. Moreover, CD49d⁺ patients experienced a shorter progression-free survival and time to treatment. When the immunophenotypic score was combined with CLL-IPI, patients with high-risk immunophenotype had a significantly lower time-to-treatment regardless CLL-IPI.

CONCLUSIONS

Our results suggested clinical utility of an integrated prognostic score for better risk stratification of CLL patients. These results require further validation in prospective larger studies.

Real-world evidence of cytomegalovirus reactivation in non-Hodgkin lymphomas treated with bendamustine-containing regimens

Cytomegalovirus (CMV) reactivation during chemotherapy or after organ or hematopoietic stem cell transplantation is a major cause of morbidity and mortality, and the risk of reactivation increases with patients’ age. Bendamustine, an alkylating agent currently used for treatment of indolent and aggressive non-Hodgkin lymphomas, can augment the risk of secondary infections including CMV reactivation. In this real-world study, we described an increased incidence of CMV reactivation in older adults (age >60 years old) with newly diagnosed and relapsed/refractory indolent and aggressive diseases treated with bendamustine-containing regimens. In particular, patients who received bendamustine plus rituximab and dexamethasone were at higher risk of CMV reactivation, especially when administered as first-line therapy and after the third course of bendamustine. In addition, patients with CMV reactivation showed a significant depression of circulating CD4⁺ T cell count and anti-CMV IgG levels during active infection, suggesting an impairment of immune system functions which are not able to properly face viral reactivation. Therefore, a close and early monitoring of clinical and laboratory findings might improve clinical management and outcome of non-Hodgkin lymphoma patients by preventing the development of CMV disease in a subgroup of subjects treated with bendamustine more susceptible to viral reactivation.

Prophylactic letermovir decreases cytomegalovirus reactivation after stem cell transplantation: a single-center real-world evidence study

Cytomegalovirus (CMV) reactivation is a major cause of morbidity and mortality after organ or hematopoietic stem cell transplantation (HSCT). Letermovir (LTV) is a novel antiviral agent approved for CMV prophylaxis after allogeneic transplantation. In this single-center real-world study, we evidenced the efficacy and safety of LTV for CMV prophylaxis in allogeneic HSCT recipients. A total of 133 consecutive patients who underwent autologous or allogeneic HSCT were included in the study, and a subgroup of 13 allogeneic HSCT recipients received CMV prophylaxis with LTV 240 mg/daily from day +7 to +100 (allo-LTV cohort). All patients in the allo-LTV cohort were at moderate or high risk of reactivation based on donor/recipient serology status, and 62% also received haploidentical HSCT and cyclophosphamide which further increased the CMV reactivation risk. CMV infection rate was also compared to that observed in allogeneic HSCT patients without CMV prophylaxis and autologous recipients who have the lowest reported CMV infection incidence and were used as a control cohort. In our experience, patients receiving LTV showed a significant decline in CMV reactivation incidence to similar rates described in autologous HSCT recipients (7.7% of allogeneic LTV-treated vs 68% of allogeneic recipients without prophylaxis vs 15% of autologous patients; p> 0.0001). The only patient in the allo-LTV cohort with CMV reactivation was a 25-year-old female with a diagnosis of very high-risk acute lymphoblastic leukemia who received a haploidentical HSCT after ex vivo T cell depletion. CMV reactivation occurred beyond LTV course, at +187 days from transplantation. In addition, we confirmed efficacy and safety of valganciclovir 450 mg/daily as pre-emptive therapy or for treatment of CMV disease in allogeneic and autologous HSCT recipients who experienced CMV reactivation even after LTV prophylaxis. However, further clinical trials in larger populations and longer follow-up are required to confirm our preliminary results.