Hypogammaglobulinemia, late-onset neutropenia, and infections following rituximab

Sepsis in patients who are immunocompromised: diagnostic challenges and future therapies

Sepsis is a life-threatening, dysregulated host response to infection. Immunosuppression is a risk factor for infections and sepsis. However, the specific immune derangements elevating the risk for infections and sepsis remain unclear in the individual patient, raising the question of whether a general state of immunosuppression exists. In this Review, we explore the relationship between immunosuppression and sepsis, detailing the definitions, causes, and clinical implications. We address the effect of primary immunodeficiencies, acquired conditions, and drugs on the risk of infection and the development of sepsis. Patients with sepsis who are immunocompromised often present with atypical symptoms and diagnostic test results can differ, making early recognition difficult. Future perspectives entail novel biomarkers to improve early sepsis detection and tailored treatments to modulate immune function. Including patients who are immunocompromised in clinical trials is crucial to enhance the relevance of research findings and improve treatment strategies for this vulnerable population.

Hypogammaglobulinemia in Children Receiving Targeted Immunotherapies for B Lineage Malignancies: Practical Guidance for Assessment and Management

Hypogammaglobulinemia is a well-defined risk factor for infection. B-cell-directed immunotherapies given in addition to conventional chemotherapy are now core elements of effective therapy for children with B lymphoid malignancies. These therapies are associated with depletion of normal B cells and consequent hypogammaglobulinemia. This review summarizes the current state of knowledge regarding the mechanism, incidence, and clinical outcomes related to hypogammaglobulinemia in children with mature B-cell non-Hodgkin lymphoma and B-cell acute lymphoblastic leukemia, as well as provides practical guidance for laboratory monitoring and considerations for immunoglobulin replacement therapy.

Impact of Rituximab on COVID-19 in Immunocompromised Patients: A Nationwide Cohort Study in Korea

Background

Anti-CD20 therapy has been associated with severe pneumonia in coronavirus disease 2019 (COVID-19) patients. This study aimed to evaluate the impact of anti-CD20 therapy on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and COVID-19-related outcomes using a nationwide cohort.

Methods

We used the K-CoV-N database, integrating the Korea Disease Control and Prevention Agency and the National Health Insurance Service. Adults (≥19 years) diagnosed with conditions warranting anti-CD20 therapy from January 2020 to December 2021 were included. Patients initiating rituximab (RTX) during the study period were defined as RTX users, whereas RTX nonusers were selected through propensity score matching. Logistic regression analyses were used to estimate the association between RTX use and SARS-CoV-2 infection, as well as COVID-19-related outcomes.

Results

Among 1 548 038 patients requiring anti-CD20 therapy, 1 457 171 were vaccinated and 90 867 were unvaccinated. In the vaccinated group, RTX use was not significantly associated with an increased risk of SARS-CoV-2 infection (adjusted odds ratio [aOR] 1.75; 95% confidence interval [CI], .82-3.72; P = .149) but was linked to higher hospitalization for COVID-19 (aOR 2.64; 95% CI, 1.14-6.10; P = .024) and intensive care unit admission (aOR 10.89; 95% CI, 1.44-82.46; P = .021). In the unvaccinated group, RTX use showed no statistically significant associations with severe COVID-19 outcomes.

Conclusions

Using a nationwide dataset, this study found that RTX use is associated with an increased risk of severe COVID-19 outcomes in vaccinated individuals. Despite rising vaccination rates, clinicians should carefully weigh the risks and benefits of anti-CD20 therapy during the COVID-19 pandemic.

How we manage immune-mediated thrombotic thrombocytopenic purpura after rituximab failure or intolerance

The use of rituximab, a B-cell-depleting agent as a pre-emptive treatment in immune-mediated thrombotic thrombocytopenic purpura (iTTP), is the current standard of care. However, for patients refractory to rituximab or for those with contraindications, further treatment guidelines are scarce. Standard immunosuppressive or chemotherapeutic agents were used routinely in the past, but most of the data proving their efficacy are stemming from experience before the routine use of rituximab. Ciclosporin A and azathioprine seem to be effective in the pre-emptive setting, but their safety profile might limit their use. Extended or intensive rituximab administration may overcome refractoriness in some patients. New therapeutic options, such as new generation anti-CD20 antibodies like obinutuzumab or the plasma cell-directed therapy daratumumab, showed important efficacy in iTTP after rituximab failure, with a favourable safety profile. There are no available comparative studies for pre-emptive treatment options in iTTP; therefore, data from large databases and multicentre studies are essential. In this review, we summarize the possible treatment options in case of rituximab failure in iTTP and try to provide a recommendation based on available literature and our own experience.

Impact of High-Efficacy Therapies for Multiple Sclerosis on B Cells

Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative autoimmune disorder of the central nervous system characterized by demyelination and neurodegeneration. Traditionally considered a T-cell-mediated disease, the crucial role of B lymphocytes in its pathogenesis, through different mechanisms contributing to inflammation and autoreactivity, is increasingly recognized. The risk of long-term disability in MS patients can be reduced by an early treatment initiation, in particular with high-efficacy therapies. The aim of this review is to provide an overview of the mechanisms of action of high-efficacy therapies for MS, with a focus on their impact on B cells and how this contributes to the drugs' efficacy and safety profiles. Anti-CD20 monoclonal antibodies, Alemtuzumab, Cladribine and sequestering therapies encompassing Natalizumab and S1P receptors modulators will be discussed and emerging therapies, including Bruton's Tyrosine Kinase inhibitors, will be presented.

Exploring Monogenic, Polygenic, and Epigenetic Models of Common Variable Immunodeficiency

Common variable immunodeficiency (CVID) is the most frequent symptomatic inborn error of immunity (IEI). CVID is genetically heterogeneous and occurs in sporadic or familial forms with different inheritance patterns. Monogenic mutations have been found in a low percentage of patients, and multifactorial or polygenic inheritance may be involved in unsolved patients. In the complex disease model, the epistatic effect of multiple variants in several genes and environmental factors such as infections may contribute. Epigenetic modifications, such as DNA methylation changes, are also proposed to be involved in CVID pathogenesis. In general, the pathogenic mechanism and molecular basis of CVID disease are still unknown, and identifying patterns of association across the genome in polygenic models and epigenetic modification profiles in CVID requires more studies. Here, we describe the current knowledge of the molecular genetic basis of CVID from monogenic, polygenic, and epigenetic aspects.

The Histologic Spectrum of Rituximab-Associated Common Variable Immunodeficiency-Like Enteropathy

Rituximab (RTX) is a monoclonal anti-CD20 antibody widely used to treat B-cell neoplasms and autoimmune conditions. RTX has recently been linked to an enteropathy characterized by diarrhea, malabsorption, and hypogammaglobulinemia, closely resembling common variable immunodeficiency (CVID) enteropathy. We present the first dedicated histopathologic assessment of RTX-associated CVID-like enteropathy. Study inclusion criteria were the presence of diarrhea, weight loss, or other gastrointestinal symptoms in the setting of current/prior RTX use and associated hypogammaglobulinemia. Twenty-two patients (15 male:7 female; mean age at biopsy/resection, 63.4 years) across 9 tertiary medical centers met inclusion criteria and had small bowel (N = 20) and/or colon (N = 17) specimens (biopsies/resections) available for review; 71.4% of specimens dated from ≤5 years of last RTX dose. Cases were systematically evaluated by gastrointestinal pathologists at each institution. Key histologic features in the small bowel included sparse/absent lamina propria plasma cells (N = 10; 50%), intraepithelial lymphocytosis (N = 12; 60%), villous atrophy (N = 11; 55%), increased crypt apoptotic bodies (N = 6; 30%), and active inflammation (N = 5; 25%). Common features in the colon included sparse/absent plasma cells (N = 7; 41.2%), increased crypt apoptotic bodies (N = 7; 41.2%), active inflammation (N = 5; 29.4%), and intraepithelial lymphocytosis (N = 4; 23.5%). Goblet cell loss was appreciated in small bowel and/or colon specimens from 2 patients. Follow-up biopsies (interval, 2 months to 4 years) were available for 7 patients and largely recapitulated the histology of the index specimens, though 1 patient demonstrated improvement in villous blunting and intraepithelial lymphocytosis. In summary, the histologic spectrum of post-RTX CVID-like enteropathy encompasses lamina propria plasma cell depletion, increased crypt apoptotic bodies, small bowel villous atrophy, and goblet cell loss. While the underlying pathophysiology remains uncertain, the clinicopathologic picture may reflect post-RTX B-cell/plasma cell impairment. Although histologic findings may be subtle and variable, pathologists should be aware of this entity and should seek a history of RTX use in patients whose biopsies exhibit these CVID enteropathy-like features.

Secondary Neutropenias

Neutrophils are a critical component of immunity, particularly against bacteria and other pathogens, but also in inflammation and tissue repair. As a consequence, individuals with neutropenia, defined by a reduction in absolute neutrophil counts, exhibit a strong propensity to severe infections that typically present with muted symptoms. Neutropenias encompass a heterogeneous set of disorders, comprising primary neutropenias, in which specific genes are mutated, and the more common secondary neutropenias, which have diverse non-genetic causes. These include hematological and other cancers, involving both direct effects of the cancer itself and indirect impacts via the chemotherapeutic, biological agents and cell-based approaches used for treatment. Other significant causes of secondary neutropenias are non-chemotherapeutic drugs, autoimmune and other immune diseases, infections and nutrient deficiencies. These collectively act by impacting neutrophil production in the bone marrow and/or destruction throughout the body. This review describes the biological and clinical manifestations of secondary neutropenias, detailing their underlying causes and management, with a discussion of alternative and emerging therapeutic approaches.

Impact of rituximab on IgG and IgM levels in patients with autoimmune bullous diseases: a cohort study

Rituximab (RTX) causes hypogammaglobulinemia in a variety of autoimmune diseases. However, the exact incidence and clinical significance in patients with autoimmune bullous diseases (AIBD) remain undetermined. In this cohort study, we enrolled patients with AIBD treated with RTX at a tertiary dermatology center between 2019 and 2021. Serum IgG and IgM levels, cumulative RTX dosage, and other factors were measured at baseline and during a follow-up visit. We used multivariate linear regression to assess the effect of RTX on immunoglobulin levels over time, adjusting for factors such as cumulative RTX dose, time since last infusion, and steroid use. Hypogammaglobulinemia was defined as IgG < 600 mg/dL and IgM < 40 mg/dL. Logistic regression was employed to evaluate adjusted risk factors for developing hypogammaglobulinemia. Age at first infusion was negatively correlated with both IgG (p < 0.0001) and IgM levels (p = 0.002). Total cumulative RTX dosage was negatively associated with IgM levels (p < 0.001). Daily steroid dosage was positively correlated with IgM levels (p = 0.023). Mycophenolate mofetil was associated with lower IgG levels (p = 0.029). Daily steroid dosage was found to be associated with a lower risk of hypo-IgM development (p = 0.0497). No serious infusion-related adverse effects or mortality were observed. There were four cases of infection with no association with cumulative RTX dosage (p = 0.299). Our study shows an association between RTX and lower serum IgM levels in patients with AIBD, highlighting the need to assess serum immunoglobulin levels before RTX therapy to optimize its use and minimize adverse effects.

Resolution of hypogammaglobulinemia-associated recurrent Campylobacter bacteraemia after hematopoietic cell transplantation (HCT)

Primary or secondary hypogammaglobulinemia is associated with persistent norovirus and Campylobacter infections despite immunoglobulin replacement therapy. Allogeneic hematopoietic cell transplantation for hematologic indications can lead to immune reconstitution by correcting a previously undiagnosed concurrent primary immunodeficiency.

Antibody-Based Immunotherapies for the Treatment of Hematologic Malignancies

Despite the great advancements in treatment strategies for hematological malignancies (HMs) over the years, their effective treatment remains challenging. Conventional treatment strategies are burdened with several serious drawbacks limiting their effectiveness and safety. Improved understanding of tumor immunobiology has provided novel anti-cancer strategies targeting selected immune response components. Currently, immunotherapy is counted as the fourth pillar of oncological treatment (together with surgery, chemo- and radiotherapy) and is becoming standard in the treatment regimen, alone or in combination therapy. Several categories of immunotherapies have been developed and are currently being assessed in clinical trials for the treatment of blood cancers, including immune checkpoint inhibitors, antigen-targeted antibodies, antibody-drug conjugates, tumor vaccines, and adoptive cell therapies. However, monoclonal antibodies (mAbs) and their derivatives have achieved the most notable clinical outcome so far. Since the approval of rituximab for treating B-cell malignancies, the availability of mAbs against tumor-specific surface molecules for clinical use has flourished. Antibody-based therapy has become one of the most successful strategies for immunotherapeutic cancer treatment in the last few decades, and many mAbs have already been introduced into standard treatment protocols for some hematologic malignancies. To further increase the efficacy of mAbs, they can be conjugated to radioisotopes or cytostatic drugs, so-called antibody-drug conjugates. Moreover, with the growing recognition of T-cell immunity's role in cancer development, strategies aimed at enhancing T cell activation and inhibiting mechanisms that suppress T cell function are actively being developed. This review provides a comprehensive overview of the current status of immunotherapeutic strategies based on monoclonal antibodies and their derivatives, including antibody-drug conjugates, bispecific T-cell engagers, and checkpoint inhibitors, approved for the treatment of various HMs.

Secondary hypogammaglobulinemia: diagnosis and management of a pediatric condition of clinical importance

PURPOSE OF REVIEW

Secondary hypogammaglobulinemia, or low serum immunoglobulins, is associated with a variety of medications or medical conditions and may be symptomatic and lead to increased infectious risk. There is limited data regarding the study of acquired, or secondary, hypogammaglobulinemia (SHG) in pediatrics. The data to date has suffered from methodologic issues including retrospective study design, lack of baseline immunoglobulin measurements, and limited longitudinal follow-up.

RECENT FINDINGS

There is emerging research on the impact of B-cell depleting therapies, specifically rituximab and chimeric antigen T-cells, along with other autoimmune and malignant disease states, in the development of SHG in pediatric patients. This review will also summarize other relevant pediatric conditions related to SHG.

SUMMARY

The clinical relevance of SHG in pediatrics is increasingly appreciated. Improved understanding of the specific etiologies, risk factors, and natural history of SHG have informed screening and management recommendations.

Overview of secondary immunodeficiency

In contrast to inborn errors of immunity (IEI), which are inherited disorders of the immune system that predispose to infections, malignancy, atopy, and immune dysregulation, secondary immunodeficiencies and immune dysregulation states (SID) are acquired impairments in immune cell function and/or regulation, and may be transient, reversible, or permanent. SIDs can derive from a variety of medical comorbidities, including protein-losing conditions, malnutrition, malignancy, certain genetic syndromes, prematurity, and chronic infections. Medications, including immunosuppressive and chemotherapeutic drugs, can have profound effects on immunity and biologic agents used in rheumatology, neurology, and hematology/oncology practice are increasingly common causes of SID. Iatrogenic factors, including surgical procedures (thymectomy, splenectomy) can also contribute to SID. A thorough case history, medication review, and laboratory evaluation are necessary to identify the primary driver and determine proper management of SID. Careful consideration should be given to whether a primary IEI could be contributing to autoimmunity, malignancy, and posttreatment complications (e.g., antibody deficiency). SID management consists of addressing the driving condition and/or removing the offending agent if feasible. If SID is suspected to be permanent, then antibiotic prophylaxis, additional immunization, and immunoglobulin replacement should be considered.

Hypogammaglobulinemia and Infection Events in Patients with Autoimmune Diseases Treated with Rituximab: 10 Years Real-Life Experience

OBJECTIVES

To investigate predictors of hypogammaglobulinemia (HGG) and severe infection event (SIE) in patients with autoimmune disease (AID) receiving rituximab (RTX) therapy.

METHODS

This was a retrospective study conducted in a tertiary medical center in China. Predictors of HGG or SIE were assessed using Cox analysis. Restricted cubic spline (RCS) analysis was applied to examine the correlation between glucocorticoid (GC) maintenance dose and SIE.

RESULTS

A total of 219 patients were included in this study, with a cumulative follow-up time of 698.28 person-years. Within the study population, 117 patients were diagnosed with connective tissue disease, 75 patients presented with ANCA-associated vasculitis, and 27 patients exhibited IgG4-related disease. HGG was reported in 63.3% of the patients, where an obvious decline in IgG and IgM was shown three months after RTX initiation. The rate of SIE was 7.2 per 100 person-years. An increase in the GC maintenance dose was an independent risk factor for both hypo-IgG (HR 1.07, 95% CI 1.02-1.12, p = 0.003) and SIE (HR 1.06, 95% CI 1.02-1.1, p = 0.004). Further RCS analysis identified 7.48 mg/d prednisone as a safe threshold dose for patients who underwent RTX treatment to avoid a significantly increased risk for SIE.

CONCLUSION

HGG was relatively common in RTX-treated AID patients. Patients with chronic lung disease or who were taking ≥ 7.5 mg/d prednisone during RTX treatment were at increased risk for SIE and warrant attention from physicians.

Hypogammaglobulinaemia during rituximab treatment in multiple sclerosis: A Swedish cohort study

BACKGROUND AND PURPOSE

Mechanisms behind hypogammaglobulinaemia during rituximab treatment are poorly understood.

METHODS

In this register-based multi-centre retrospective cohort study of multiple sclerosis (MS) patients in Sweden, 2745 patients from six participating Swedish MS centres were identified via the Swedish MS registry and included between 14 March 2008 and 25 January 2021. The exposure was treatment with at least one dose of rituximab for MS or clinically isolated syndrome, including data on treatment duration and doses. The degree of yearly decrease in immunoglobulin G (IgG) and immunoglobulin M (IgM) levels was evaluated.

RESULTS

The mean decrease in IgG was 0.27 (95% confidence interval 0.17-0.36) g/L per year on rituximab treatment, slightly less in older patients, and without significant difference between sexes. IgG or IgM below the lower limit of normal (<6.7 or <0.27 g/L) was observed in 8.8% and 8.3% of patients, respectively, as nadir measurements. Six out of 2745 patients (0.2%) developed severe hypogammaglobulinaemia (IgG below 4.0 g/L) during the study period. Time on rituximab and accumulated dose were the main predictors for IgG decrease. Previous treatment with fingolimod and natalizumab, but not teriflunomide, dimethyl fumarate, interferons or glatiramer acetate, were significantly associated with lower baseline IgG levels by 0.80-1.03 g/L, compared with treatment-naïve patients. Switching from dimethyl fumarate or interferons was associated with an additional IgG decline of 0.14-0.19 g/L per year, compared to untreated.

CONCLUSIONS

Accumulated dose and time on rituximab treatment are associated with a modest but significant decline in immunoglobulin levels. Previous MS therapies may influence additional IgG decline.

Optimizing Outcomes for Acute Mesenteric Ischemia in the Context of Hypogammaglobulinemia: A Detailed Analysis of Surgical and Medical Strategies

Acute mesenteric ischemia is a critical condition marked by a sudden loss of blood supply to the intestines, often leading to rapid tissue necrosis and severe clinical outcomes if untreated. In the context of hypogammaglobulinemia, an immunodeficiency characterized by decreased levels of immunoglobulins, this vascular emergency becomes even more daunting. Hypogammaglobulinemia can impair the immune system's response to both infection and ischemic injury, intensifying the severity of intestinal damage. This report describes the case of a 52-year-old female with hypogammaglobulinemia who presented with severe abdominal pain. Surgical exploration revealed 100 cm of necrotic small bowel extending from 150 cm distal to the ligament of Treitz to within 10 cm of the ileocecal valve. The necrotic section was surgically removed, and primary anastomosis was performed. This instance highlights the significant impact of immunodeficiency on the progression and management of acute mesenteric ischemia, demonstrating the critical need for early intervention and tailored management strategies, especially in immunocompromised patients, to prevent severe outcomes. The case illuminates the importance of recognizing immunodeficiency as a complicating factor in acute gastrointestinal emergencies, stressing the necessity for prompt and effective medical and surgical interventions to improve prognosis and patient outcomes in complex clinical scenarios.

Myelotoxicity and kidney dysfunction related to the use of trimethoprim-sulfamethoxazole for the treatment of Pneumocystis jirovecii pneumonia: a case report of severe adverse events with a common drug

Trimethoprim-sulfamethoxazole (TMP-SMX) is the primary therapeutic option for Pneumocystis jirovecii pneumonia (PCP). Gastrointestinal symptoms and cutaneous rash are common side effects, with hyperkalemia being uncommon in patients without kidney dysfunction, and myelotoxicity being even rarer. We present the case of a male patient with hypertension and a recent diagnosis of non-Hodgkin lymphoma, undergoing rituximab treatment for two months. He was admitted to the intensive care unit due to dyspnea, tachypnea, and pleuritic pain, requiring mechanical ventilation. Chest computed tomography showed bilateral and multilobed ground-glass opacities, compromising more than 80% of the lung parenchyma. Pulmonary tuberculosis and COVID-19 were ruled out. An angiotomography and Doppler ultrasound revealed an extensive pulmonary thrombus and deep venous thrombosis. Empiric treatment with TMP-SMX for PCP was initiated, but within four days, the patient experienced metabolic acidosis and severe hyperkalemia, necessitating hemodialysis. He also presented with progressive pancytopenia and critical levels of leukopenia and thrombocytopenia. The hypothesis of TMP-SMX-induced myelotoxicity was suspected. Considering the unavailability of an alternative treatment, it was opted to continue TMP-SMX and initiate a granulocyte-colony-stimulating factor. However, the patient maintained medullary deterioration, becoming refractory to the transfusion of blood derivates. On the 17th day of treatment, a clinical decision was made to suspend TMP-SMX, leading to improvements within 48 hours in marrow and kidney functions, metabolic acidosis, and hyperkalemia. Despite all efforts, the patient died after 35 days of hospitalization due to hospital-acquired infections. This case highlights the importance of clinicians recognizing potential myelotoxicity with TMP-SMX and promptly discontinuing the drug if necessary.

Neutropenia following immune-depletion, notably CD20 targeting, therapies in multiple sclerosis

Neutropenia serves as a risk factor for severe infection and is a consequence of some immune-depleting immunotherapies. This occurs in people with multiple sclerosis following chemotherapy-conditioning in haematopoietic stem cell transplantation and potent B cell targeting agents. Whilst CD52 is expressed by neutrophils and may contribute to early-onset neutropenia following alemtuzumab treatment, deoxycytidine kinase and CD20 antigen required for activity of cladribine tablets, off-label rituximab, ocrelizumab, ofatumumab and ublituximab are not or only weakly expressed by neutrophils. Therefore, alternative explanations are needed for the rare occurrence of early and late-onset neutropenia following such treatments. This probably occurs due to alterations in the balance of granulopoiesis and neutrophil removal. Neutrophils are short-lived, and their removal may be influenced by drug-associated infections, the killing mechanisms of the therapies and amplified by immune dyscrasia due to influences on neutropoiesis following growth factor rerouting for B cell recovery and cytokine deficits following lymphocyte depletion. This highlights the small but evident neutropenia risks following sustained B cell depletion with some treatments.

Infection Risk, Mortality, and Hypogammaglobulinemia Prevalence and Associated Factors in Adults Treated with Rituximab: A Tertiary Care Center Experience

BACKGROUND

Rituximab is a human monoclonal antibody directed against the B-cell transmembrane protein CD20. Although well-tolerated, given its mechanism of action, rituximab can induce a state of severe immunosuppression, increasing the risk of opportunistic and fulminant infection and mortality.

AIM

To evaluate the risk of infection, mortality, and hypogammaglobulinemia and their associated factors among rituximab receivers.

METHOD

This was a single-center retrospective cohort study of adults treated with rituximab for various indications. Hypogammaglobulinemia was defined by a cut-off value below the normal limit (an IgG level of <7.51 g/L, an IgM level of <0.46 g/L, and/or an IgA level of <0.82 g/L). Patients who met the definition of hypogammaglobinemia solely based on IgA were excluded. Severe infection was defined as any infection that required intensive care unit admission.

RESULTS

A total of 137 adults with a mean age of 47.69 ± 18.86 years and an average BMI of 28.57 ± 6.55 kg/m2 were included. Hematological malignancies and connective tissue diseases were the most common primary diagnoses for which rituximab was used. More than half of the patients received the 375 mg/m2 dose. Rituximab's mean cumulative dose was 3216 ± 2282 mg, and the overall mortality rate was 22.6%. Hypogammaglobulinemia was diagnosed in 43.8% of the patients, and it was significantly more prevalent among males and the 375 mg/m2 and 500 mg doses. Hematological malignancy was the only predictor for infection. Patients with blood type AB or B, hematological malignancies, and corticosteroids had a significantly higher mortality rate. Receiving the 1000 mg dose and having a low CD19 were associated with a significantly lower risk of infection and mortality, respectively.

CONCLUSIONS

Hypogammaglobulinemia was diagnosed in 43.8% of the patients, and it was significantly more common among males and the 375 mg/m2 and 500 mg doses. Hematological malignancies were significantly associated with higher infection and mortality rates, while corticosteroids were significantly associated with a higher mortality. Since the culprit of mortality was infection, these findings highlight the critical need for more frequent immunological monitoring during rituximab treatment period to mitigate the burden of infection and identify candidates for immunoglobulin replacement.