anti-CD20 Monoclonal Antibody Research Articles

Potential role of IGF-1R in the interaction between orbital fibroblasts and B lymphocytes: an implication for B lymphocyte depletion in the active inflammatory phase of thyroid-associated ophthalmopathy

BackgroundThyroid eye disease (TED) is an inflammatory process involving lymphocyte-mediated immune response and orbital tissue damage. The anti-insulin-like growth factor-1 receptor (IGF-1R) antibodies produced by B lymphocytes are involved in the activation of orbital fibroblasts and the inflammatory process of orbital tissue damage in TED. The purpose of this study was to explore the role of IGF-1R in the mechanistic connection between orbital fibroblasts and B lymphocytes in TED.MethodsOrbital fibroblasts sampled from orbital connective tissues and peripheral B lymphocytes isolated from peripheral blood, which were obtained from 15 patients with TED and 15 control patients, were co-cultured at a ratio of 1:20. The level of IGF-1R expression in orbital fibroblasts was evaluated by flow cytometry and confocal microscopy. Transient B lymphocyte depletion was induced with anti-CD20 monoclonal antibody rituximab, while the IGF-1R pathway was blocked by the IGF-1R binding protein. The expression levels of interleukin-6 (IL-6) and regulated upon activation, normal T cell expressed and secreted (RANTES) in the co-culture model were quantified via ELISA.ResultsIGF-1R expression was significantly elevated in TED orbital fibroblasts compared to that of controls. A 24-h co-culture of orbital fibroblasts with peripheral B lymphocytes induced elevated expression levels of IL-6 and RANTES in each group (TED patients and controls), with the highest levels occurring in TED patients (T + T group). Rituximab and IGF-1R binding protein significantly inhibited increased levels of IL-6 and RANTES in the co-culture model of TED patients.ConclusionsIGF-1R may mediate interaction between orbital fibroblasts and peripheral B lymphocytes; thus, blocking IGF-1R may reduce the local inflammatory response in TED. Rituximab-mediated B lymphocyte depletion played a role in inhibiting inflammatory responses in this in vitro co-culture model, providing a theoretical basis for the clinical application of anti-CD20 monoclonal antibodies in TED.

Rituximab Induced Rare Cystic Lesion in Lungs in a Nephrotic Child: A Case Report

Rituximab has been extensively used for managing B-cell lymphomas due to its anti-CD20 monoclonal antibody activity. Over the last decade, its application has been extended to manage frequent relapsing or steroid-dependent nephrotic syndrome. Its use has been comparatively safe, but few cases of adverse effects on the lung have been reported in the adult population. These lung injury presentations are rarely reported in a pediatric group with only four cases in the literature. Below is a rare case of rituximab-induced lung injury in a 9-year-old boy with frequent relapse of nephrotic syndrome, which developed after four days of rituximab infusion. Suspecting infection and sepsis, several antibiotics were started, but with no improvement in respiratory complaints, even antifungal and antituberculosis treatments were initiated. Finally, setting up a casual relation with the time of infusion to the development of complaints, association with rituximab was suspected. The patient responded to steroid therapy with complete resolution of respiratory complaints. To our knowledge, this is the first reported case of rituximab-induced cystic lesion in lungs from India.

Alemtuzumab treatment for multiple sclerosis in Austria: An observational long-term outcome study.

Observational real-world study to analyze the clinical effects of alemtuzumab (ALEM) and subsequent disease-modifying therapy (DMT) usage in multiple sclerosis (MS). Data retrieved from the Austrian MS treatment registry (AMSTR) included baseline (BL) characteristics (at ALEM start), annualized relapse rate (ARR), 6-month confirmed progression independent of relapse activity (PIRA; ≥ 0.5-point Expanded Disability Status Scale (EDSS) score increase), 6-month confirmed disability improvement (CDI; ≥ 0.5-point EDSS decrease), and safety outcomes until initiation of a subsequent DMT. The EDSS was re-baselined at 30 days from ALEM start (BL EDSS). Eighty-seven ALEM-treated patients (median age: 32 years, 72% female, 14% treatment-naïve) were followed for a median of 55 (interquartile range 31-68) months. We found significant reductions in the ARR from 1.16 before ALEM to 0.15 throughout Years 1-9 (p < 0.001). Subsequent DMTs were initiated in 19 patients (22%, 74% anti-CD20 monoclonal antibodies). At Year 5 (n = 53), more patients achieved CDI (58%, 95% confidence interval (CI) 45%-71%) than had experienced PIRA (14%, CI 7.5%-24%), and 58% remained relapse-free. Shorter MS duration (p < 0.001, hazard ratio (HR) 0.86 (CI 0.80-0.93)) and no previous high-efficacy treatment (p < 0.001, HR 5.16 (CI 2.66-10.0)) were the best predictors of CDI, while PIRA was associated with a higher number of previous DMTs (p = 0.04, HR 3.06, CI 1.05-8.89). We found no new safety signals. ALEM had long-lasting beneficial effects on the ARR and disability improvement, especially when initiated early in the course of the disease. Only a subset of patients received subsequent DMTs.

FDA Approval Summary: Ciltacabtagene Autoleucel for Relapsed or Refractory Multiple Myeloma.

In February 2022, the U.S. Food and Drug Administration approved ciltacabtagene autoleucel, a chimeric antigen receptor (CAR) T cell therapy targeting the B-cell maturation antigen (BCMA), for adult patients with relapsed/refractory multiple myeloma (RRMM) after ≥4 lines of therapy including an immunomodulatory agent, a proteasome inhibitor, and an anti-CD38 monoclonal antibody. Approval was based on overall response rate (ORR), complete response (CR) rate and duration of response (DOR) in 97 adult patients in a single-arm, open-label, multicenter phase 2 trial (CARTITUDE-1 [NCT03548207]). Patients received a single infusion of ciltacabtagene autoleucel, preceded by lymphodepleting chemotherapy. Of the 97 patients evaluable, ORR was 97.9% (95% CI: 92.7, 99.7) with stringent CR rate of 78.4% (95% CI: 68.8, 86.1). After median follow-up of 18 months, median DOR was 21.8 months (95% CI: 21.8, not estimable [NE]) in responders (PR or better) and NE (95% CI: 21.8 months, NE) in patients who achieved stringent CR. Serious adverse reactions occurred in 55% of 97 patients evaluated for safety. Grade 3 or higher cytokine release syndrome and neurologic toxicities occurred in 5% and 11%, respectively, leading to a Risk Evaluation and Mitigation Strategy. Neurologic toxicities included immune effector cell associated neurologic syndrome (ICANS) typically seen with CAR-T products, Parkinsonism, peripheral neuropathy, cranial nerve palsies and Guillain-Barre Syndrome (GBS). One fatal case of hemophagocytic lymphohistiocytosis/macrophage activation syndrome occurred. Prolonged and recurrent grade 3 or 4 cytopenias occurred; a single patient required hematopoietic stem cell rescue.

Is drug interference still an issue for pretransfusion testing of patients on anti CD38 and other monoclonal antibody therapies?

Certain therapies that target CD markers on some blood cells can affect pretransfusion testing. Key examples are anti-CD38, CD47 monoclonal antibody (mAb) therapies such as daratumumab (DARA) and magrolimab, which have presented a challenge for transfusion medicine laboratories around the globe. Scientists have been faced with not only introducing a protocol to provide safe blood to patients but also investigating the most effective method to remove the pretransfusion pan-agglutinating interference caused. A number of papers in the last 5 years have reported on various methods to remove pretransfusion interference; however, most of these studies have been conducted only in a few countries. Most recent reviews on this topic have focused on techniques and reagents to remove pretransfusion interference, and dithiothreitol is currently the gold standard for removing DARA interference. However, it was clear from this review that while many laboratories have developed processes for addressing interference in pretransfusion testing, and DARA interference may not be a major issue, there are still laboratories around the world, that may not have adequately addressed this issue. In addition, the impact of mAb interference on widely used techniques such as flow cytometry is unclear.

Ocrelizumab and ofatumumab comparison: an Italian real-world propensity score matched study.

The management of Multiple Sclerosis (MS) has undergone transformative evolution with the introduction of high-efficacy disease-modifying therapies (DMTs), specifically anti-CD20 monoclonal antibodies, such as ocrelizumab (OCR) and ofatumumab (OFA). This is an independent retrospective cohort study in Relapsing MS (RMS) patients followed at eight Italian MS centers who initiated treatment with OCR or OFA in the participating centers and with at least 12months on therapy. A generalized linear regression model inverse probability of treatment weight (IPTW) PS-adjusted was performed to evaluate the relationship between annualized relapse rate (ARR) and treatment groups. No evidence of disease activity-NEDA-3 at 12-month score was also collected. Safety profile of the investigated DMTs was recorded. A total cohort of 396 RMS patients fulfilled the required criteria and were enrolled in the study. Out of them, 216 had a prescription of OCR and 180 of OFA. The mean follow-up was 13.2 ± 1.9months. The estimated means for ARR did not show differences between the two groups, 0.059 for patients on OCR and 0.038 for patients on OFA (p = 0.185). The generalized regression model IPTW PS-adjusted did not reveal differences between patients on OCR and OFA (ExpBOFA 0.974, 95%CI 934-1.015, p = 0.207). NEDA-3 at 12months was experienced by 199(92.1%) patients on OCR and 170(94.4%) patients on OFA (p = 0.368). Generally, both therapies exhibit good tolerability. The treatment with OCR and OFA resulted in comparable control of disease activity with good safety profile. Our results need further validation in larger multicentre studies with long-term follow-up.

Preclinical characterization of a novel investigational monoclonal antibody CM313 with potent CD38-positive cell killing activity

IntroductionCM313 is currently under clinical investigation for treatments of multiple myeloma, systemic lupus erythematosus, and immune thrombocytopenia. We aimed to report the preclinical profile of the novel therapeutic anti-CD38 monoclonal antibody (mAb) CM313, with an emphasis on the difference with other CD38-targeting mAb.MethodsThe binding of CM313 to CD38 recombinant protein across species was assessed using ELISA. The binding of CM313 to CD38-positive (CD38+) cells was detected using flow cytometry assays. CM313-induced complement-dependent cytotoxicity (CDC), antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP) and apoptosis on different CD38+ cells were assessed by LDH release assays or flow cytometry assays. The effect of CM313 on CD38 enzymatic activity was measured using fluorescence spectroscopy. CM313 immunotoxicity in human blood was assessed using flow cytometry assays, ELISA, and LDH release assays. Anti-tumor activity of CM313 was assessed in multiple mouse xenograft models. Safety profile of CM313 were evaluated in cynomolgus monkeys and human CD38 transgenic (B-hCD38) mice.ResultsThere exist unique sequences at complementarity-determining regions (CDR) of CM313, which facilitates its affinity to CD38 is consistently higher across a spectrum of CD38+ cell lines than daratumumab. In vitro studies showed that CM313 induces comparable killing activity than daratumumab, including ADCC, CDC, ADCP, apoptosis induced by Fc-mediated cross-linking, and effectively inhibited the enzymatic activity of CD38. However, CM313 showed more potent CDC than isatuximab. In vivo, CM313 dose-dependently inhibited xenograft tumor growth, both as a monotherapy and in combination with dexamethasone or lenalidomide. Furthermore, CM313 was well tolerated with no drug-related clinical signs or off-target risks, as evidenced by 4-week repeat-dose toxicology studies in cynomolgus monkeys and B-hCD38 mice, with the later study showing no observed adverse effect level (NOAEL) of 300mg/kg once weekly.DiscussionCM313 is a novel investigational humanized mAb with a distinct CDR sequence, showing comparable killing effects with daratumumab and stronger CDC activity than isatuximab, which supports its clinical development.

PD-1 Receptor (+) T cells are associated with the efficacy of the combined treatment with regulatory t cells and rituximab in type 1 diabetes children via regulatory t cells suppressive activity amelioration

An imbalance between exaggerated autoaggressive T cell responses, primarily CD8 + T cells, and impaired tolerogenic mechanisms underlie the development of type 1 diabetes mellitus. Disease-modifying strategies, particularly immunotherapy focusing on FoxP3 + T regulatory cells (Treg), and B cells facilitating antigen presentation for T cells, show promise. Selective depletion of B cells may be achieved with an anti-CD20 monoclonal antibody (mAb).In a 2-year-long flow cytometry follow-up, involving 32 peripheral blood T and B cell markers across three trial arms (Treg + rituximab N = 12, Treg + placebo N = 13, control N = 11), we observed significant changes. PD-1 receptor (+) CD4 + Treg, CD4 + effector T cells (Teffs), and CD8 + T cell percentages increased in the combined regimen group by the end of follow-up. Conversely, the control group exhibited a notable reduction in PD-1 receptor (+) CD4 + Teff percentages.Considering clinical endpoints, higher PD-1 receptor (+) expression on T cells correlated with positive responses, including a higher mixed meal tolerance test AUC, and reduced daily insulin dosage. PD-1 receptor (+) T cells emerged as a potential therapy outcome biomarker. In vitro validation confirmed that successful Teff suppression was associated with elevated PD-1 receptor (+) Treg levels. These findings support PD-1 receptor (+) T cells as a reliable indicator of treatment with combined immunotherapy consisting of Tregs and anti-CD20 mAb efficacy in type 1 diabetes mellitus.

Disease-Modifying Treatments for Multiple Sclerosis Affect Measures of Cellular Immune Responses to EBNA-1 Peptides.

Epstein-Barr virus (EBV) has been strongly implicated in the pathogenesis of multiple sclerosis (MS). Despite this, there are no routinely used tests to measure cellular response to EBV. In this study, we analyzed the cellular response to EBV nuclear antigen-1 (EBNA-1) in people with MS (pwMS) using a whole blood assay. This cross-sectional study took place in a dedicated MS clinic in a university hospital. We recruited healthy controls, people with epilepsy (PWE), and pwMS taking a range of disease-modifying treatments (DMTs) including natalizumab, anti-CD20 monoclonal antibodies (mAbs), dimethyl fumarate (DMF), and also treatment naïve. Whole blood samples were stimulated with commercially available PepTivator EBNA1 peptides and a control virus-cytomegalovirus (CMV) peptide. We recorded the cellular response to stimulation with both interferon gamma (IFN-γ) and interleukin-2 (IL-2). We also compared the cellular responses to EBNA1 with IgG responses to EBNA1, viral capsid antigen (VCA), and EBV viral load. We recruited 86 pwMS, with relapsing remitting MS, in this group, and we observed a higher level of cellular response recorded with IFN-γ (0.79 IU/mL ± 1.36) vs healthy controls (0.29 IU/mL ± 0.90, p = 0.0048) and PWE (0.17 IU/mL ± 0.33, p = 0.0088). Treatment with either anti-CD20 mAbs (0.28 IU/mL ± 0.57) or DMF (0.07 IU/mL ± 0.15) resulted in a cellular response equivalent to control levels or in PWE (p = 0.26). The results of recording IL-2 response were concordant with IFN-γ: with suppression also seen with anti-CD20 mAbs and DMF. By contrast, we did not record any differential effect of DMTs on the levels of IgG to either EBNA-1 or VCA. Nor did we observe differences in cellular response to cytomegalovirus between groups. This study demonstrates how testing and recording the cellular response to EBNA-1 in pwMS may be beneficial. EBNA-1 stimulation of whole blood samples produced higher levels of IFN-γ and IL-2 in pwMS compared with controls and PWE. In addition, we show a differential effect of currently available DMTs on this response. The functional assay deployed uses whole blood samples with minimal preprocessing suggesting that employment as a treatment response measure in clinical trials targeting EBV may be possible.

The landscape of real-world evidence of rituximab utilization and clinical outcomes in patients with cancer, rheumatoid arthritis, and multiple sclerosis: A scoping review.

Rituximab (RTX) is an anti-CD20 monoclonal antibody that is used to treat various conditions in cancer, rheumatoid arthritis (RA), and multiple sclerosis (MS). Although RTX has been used in the United States for almost 3 decades, questions remain regarding its real-world utilization and effectiveness. To describe the state of observational research and real-world evidence evaluating RTX in oncology, RA, and off-label use in MS. A broad search was conducted in MEDLINE, Embase, and CINAHL covering the period of January 2010 to June 2022. Two reviewers independently screened all identified records for each disease category (cancer, RA, MS) beginning with title review, followed by abstract, and full-text review to identify relevant publications to include in the final analysis. Data were extracted and summarized for each disease based on overall trends, similarities, and differences across included studies and stratified by disease state. A total of 260 studies met eligibility criteria, with 79 studies for the RA cohort, 144 for cancer, and 37 for MS. Across all disease cohorts, most studies (n = 189; 72.7%) were retrospective. 171 (65.8%) studies used hospital or electronic health record data as their data source and 65 (23.2%) used registry databases. Most studies (n = 153; 58.8%) assessed the effectiveness of RTX measured by disease-specific endpoints, followed by safety (n = 60; 23.1%), treatment patterns (n = 32; 12.3%), and descriptive analyses assessing treatment adherence and economic burden of disease (n = 16; 6.2%). Although safety was not the primary outcome for most studies, the majority of studies across all disease states still reported some form of safety measure. Conclusive statements on RTX's benefit varied across disease states, with MS having the most (n = 30; 81.1%) studies suggesting the drug's positive benefit. There were limited studies assessing RTX use, associated economic burden, and biosimilar switching. The findings underscore the need for health care providers to better understand the treatment landscape and utilization of RTX, particularly in terms of patient selection, timing of initiation, and long-term outcomes. Real-world evidence can help support health care decisions and treatment using rituximab.

Autoimmune Nodopathy

Autoimmune nodopathy (AN), a newly established category of autoimmune disease, refers to an immune-mediated neuropathy associated with development of autoantibodies against membrane proteins, including neurofascin 186, neurofascin 155, contactin-1, and contactin-associated protein 1 located in the nodes of Ranvier or paranodes. Subclass analysis of these autoantibodies reveals predominant elevation of immunoglobulin (G4. Patients with AN show clinical and laboratory characteristics such as distal-predominant sensorimotor disturbance, sensory ataxia, poor response to intravenous immunoglobulin, and highly elevated cerebrospinal fluid protein levels. B cell-depletion therapy using an anti-CD20 monoclonal antibody is effective for patients with AN. Autoantibody measurement is beneficial not only for diagnosis but also for deciding treatment strategies for AN.

Obinutuzumab as Initial or Second-line Therapy in Patients with Primary Membranous Nephropathy

IntroductionB-cell lymphocytes have been demonstrated to play a key role in the pathogenesis underlying membranous nephropathy (MN). The aim of this study was to evaluate the therapeutic efficacy and safety of obinutuzumab, a glycoengineered type II anti-CD20 monoclonal antibody in individuals with MN. MethodsWe retrospectively analysed data from 59 consecutive patients with primary MN who provided consent to receive obinutuzumab and were followed for at least 6 months. The primary outcomes were complete (proteinuria <0.3 g/d) or partial (proteinuria <3.5 g/d with ≥ 50% reduction) remission of proteinuria. ResultsTwenty patients received obinutuzumab as initial therapy and 39 patients were previously treated with at least one immunosuppressant (second-line therapy). Fifty patients (84.7%) achieved complete or partial remission of proteinuria during the median follow-up of 9.4 months. The likelihood of remission was significantly higher when obinutuzumab was used as initial therapy than as second line therapy after adjusting for the baseline estimated glomerular filtration rate, 24-hour urinary protein levels, and anti-phospholipase A2 receptor (PLA2R) status (adjusted HR, 4.5; 95%CI 2.1 to 9.5, P <0.001). Circulating CD19+ B-cell count decreased to <5 cells/μL in all patients within 2 weeks after infusion. Serum anti-PLA2R concentrations decreased to <14 relative units/mL in 43 out of 48 patients with PLA2R–related MN. Following Obinutuzumab administration, a significant reduction in 24-hour urine protein and increase in serum albumin were observed. No serious adverse events were observed. ConclusionObinutuzumab may represent a promising and well-tolerated therapeutic option for individuals with primary MN. The potential of obinutuzumab was highlighted as an initial therapy for primary MN.

CAR-T CELLS IN CHRONIC LYMPHOCYTIC LEUKEMIA

The treatment outcomes of patients with chronic lymphocytic leukemia (CLL) have considerably improved with the introduction of targeted therapies based on Bruton kinase inhibitors (BTKIs), venetoclax, and anti-CD20 monoclonal antibodies. However, despite these consistent improvements, patients who become resistant to these agents have poor outcomes and need new and more productive therapeutic strategies. Among these new treatments, a potentially curative approach consists of the use of chimeric antigen receptor T (CAR-T) cell therapy, which achieved remarkable success in various B-cell malignancies, including B-cell Non-Hodgkin Lymphomas (NHLs) and B-acute lymphoblastic Leukemia (ALL). However, although CAR-T cells were initially used for the treatment of CLL, their efficacy in CLL patients was lower than in other B-cell malignancies. This review analyses the possible mechanisms of these failures. It highlights some recent developments that could offer the perspective of the incorporation of CAR-T cells in treatment protocols for relapsed/refractory CLL patients. Keywords: Chronic Lymphoid Leukemia; CLL; CAR-T Cells; Relapsed/resistant CLL:

Moving from insulin substitution to the treatment of the underlying autoimmune disease in type 1 diabetes.

Currently a paradigm change occurs in type 1 diabetes from insulin substitution to the treatment of the underlying autoimmune disease. Teplizumab, a humanized monoclonal anti CD3 antibody, is the first FDA approved disease modifying treatment of preclinical stage 2 diabetes. Research of drugs like Golimumab, a monoclonal antibody specific for TNF alpha, baricitinib, a tyrosine kinase inhibitor, or frexalimab, a monoclonal antibody against the CD40-Ligand, is still ongoing. Repurposing drugs that have been used in other indications like the calcium channel blocker Verapamil, antithymocyte globulin (ATG), an antibody preparation used in solid organ transplantation, glucagon-like peptide-1 agonists, utilized in type 2 diabetes and obesity, or the antiviral drugs pleconaril and ribavirin have shown positive effects in preserving beta-cell function. While new therapies to halt autoimmunity and restore beta-cells in stages one to three are being developed, replacing beta-cell function via inducible pluripotent stem cells have shown glucose control and insulin independence in long-standing type 1 diabetes albeit with concomitant immunosuppression. Multicenter multinational initiatives developing a clinical trial network like INNODIA or a research platform with the goal of stopping type 1 diabetes in its early stages like EDENT1FI will be instrumental to study these new strategies.

Tinostamustine (EDO-S101), an Alkylating Deacetylase Inhibitor, Enhances the Efficacy of Daratumumab in Multiple Myeloma by Upregulation of CD38 and NKG2D Ligands.

Multiple myeloma is a malignancy characterized by the accumulation of malignant plasma cells in bone marrow and the production of monoclonal immunoglobulin. A hallmark of cancer is the evasion of immune surveillance. Histone deacetylase inhibitors have been shown to promote the expression of silenced molecules and hold potential to increase the anti-MM efficacy of immunotherapy. The aim of the present work was to assess the potential effect of tinostamustine (EDO-S101), a first-in-class alkylating deacetylase inhibitor, in combination with daratumumab, an anti-CD38 monoclonal antibody (mAb), through different preclinical studies. Tinostamustine increases CD38 expression in myeloma cell lines, an effect that occurs in parallel with an increment in CD38 histone H3 acetylation levels. Also, the expression of MICA and MICB, ligands for the NK cell activating receptor NKG2D, augments after tinostamustine treatment in myeloma cell lines and primary myeloma cells. Pretreatment of myeloma cell lines with tinostamustine increased the sensitivity of these cells to daratumumab through its different cytotoxic mechanisms, and the combination of these two drugs showed a higher anti-myeloma effect than individual treatments in ex vivo cultures of myeloma patients' samples. In vivo data confirmed that tinostamustine pretreatment followed by daratumumab administration significantly delayed tumor growth and improved the survival of mice compared to individual treatments. In summary, our results suggest that tinostamustine could be a potential candidate to improve the efficacy of anti-CD38 mAbs.

Safety and biologic activity of a canine anti-CD20 monoclonal antibody in dogs with diffuse large B-cell lymphoma.

To explore the safety and utility of combining low dose single-agent doxorubicin with a canine specific anti-CD20 monoclonal antibody (1E4-cIgGB) in client owned dogs with untreated B-cell lymphoma. Forty-two client-owned dogs with untreated B-cell lymphoma. A prospective, single arm, open label clinical trial of dogs with B-cell lymphoma were enrolled to receive 1E4-cIgGB and doxorubicin in addition to 1 of 3 immunomodulatory regimens. B-cell depletion was monitored by flow cytometry performed on peripheral blood samples at each visit. Dogs demonstrated a statistically significant depletion in CD21+ B-cells 7 days following the first antibody infusion (median fraction of baseline at 7 days = 0.04, P < .01) that persisted throughout treatment (median fraction of baseline at 21 days = 0.01, P < .01) whereas CD5+ T-cells remained unchanged (median fraction of baseline at 7 days = 1.05, P = .88; median fraction of baselie at 7 days = 0.79, P = .42; Figure 1; Supplemental Table 3). Recovery of B-cells was delayed, with at Day 196, only 6/17 dogs (35%) remaining on the study had CD21+ counts >0.5 of baseline, indicating sustained B cell depletion at 4+ months after the final treatment. 1E4-cIgGB was well tolerated with only 1 dog exhibiting a hypersensitivity event within minutes of the last antibody infusion. The canine 1E4-cIgGB anti-CD20 monoclonal antibody is apparently safe when administered with doxorubicin and effectively depletes B-cells in dogs with DLBCL.

Sequencing of anti-CD19 therapies in the management of diffuse large B-cell lymphoma.

Several second- and third-line immunotherapeutic options for patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) ineligible for autologous stem cell transplant are directed against the B-cell antigen CD19. The anti-CD19 monoclonal antibody tafasitamab, paired with the immunomodulator lenalidomide, mediates antibody-dependent cellular toxicity and cellular phagocytosis; the antibody-drug conjugate loncastuximab tesirine delivers the DNA-cross-linking agent tesirine via CD19 binding and internalization; and CD19-directed chimeric antigen receptor T-cell therapy (CAR-T) products are engineered from autologous T cells. While CD19 expression is assessed at diagnosis, clinically relevant thresholds of CD19 expression-which may not be detectable with current routine methodologies-have not been defined and may vary between CD19-directed treatment modalities. Determining optimal treatment sequencing strategies with CD19-directed therapy has been hampered by the exclusion of patients with prior CD19-directed therapies from major clinical trials. Antigen escape, attributed to mechanisms including epitope loss and defective cell-surface trafficking of CD19, is an important cause of CAR-T failure. Limited data suggest that CD19 expression may be maintained after non-CAR-T CD19-directed therapy and retrospective analyses indicate that some patients with disease that relapses after CAR-T may benefit from subsequent CD19-directed therapy. To date, clinical evidence on the effect of anti-CD19 therapy prior to CAR-T is restricted to small case series. Prospective studies and detailed analyses to understand how pre- and post-treatment CD19 expression correlates with clinical responses to subsequent CD19-directed therapy are needed to fully maximize treatment strategies.

Teclistamab (Tecvayli)

CADTH recommends that Tecvayli (teclistamab) be reimbursed by public drug plans for the treatment of adults with relapsed or refractory (r/r) multiple myeloma (MM) who have received at least 3 prior lines of therapy, including a proteasome inhibitor (PI), an immunomodulatory drug (IMiD), and an anti-CD38 monoclonal antibody (mAb), and who have demonstrated disease progression on the last therapy if certain conditions are met. Tecvayli should only be covered to treat adults with MM who have received at least 3 prior treatments, have disease that has not responded to their last treatment, and are in relatively good health. Tecvayli should not be reimbursed to treat those whose MM is affecting their brain or spinal cord or those showing signs that the tissue layers protecting the brain and spinal cord are affected by MM. It also should not be reimbursed in those with amyloidosis (a buildup of a protein, amyloid, in organs) that is not secondary to MM, and those with plasma cell leukemia. Tecvayli should only be reimbursed if it is prescribed and administered by health professionals at treatment centres with adequate medical resources and personnel.

E018 Prophylactic co-trimoxazole prescribing practice in patients who received rituximab therapy: comparison across indications and specialties

Abstract Background/Aims Rituximab is a chimeric anti-CD20 monoclonal antibody targeting B-cells used as part of treatment algorithms for malignancy and autoimmune diseases. As is the case of other immunosuppressive agents, rituximab increases the risk of infections. Primary prophylaxis with co-trimoxazole may be considered in high-risk cohort of patients to prevent opportunistic infection, particuarly Pneumocystis jerovecii pneumonia (PJP). To investigate the prescribing practice for prophylactic co-trimoxazole in patients who received rituximab infusion in a large tertiary referral centre. To compare practices between rheumatology and nephrology department. To compare the incidence of hospitalisation for infection (particularly PJP) between those prescribed prophylactic co-trimoxazole and those who did not. Methods This was a single centre retrospective observational study over a 3 year period assessing prophylactic co-trimoxazole prescribing practice in 185 patients attending rheumatology or renal services in Cork University Hospital (CUH) and receiving rituximab. Co-trimoxazole prophylactic treatment was defined as prophylaxis dose of co-trimoxazole (either 480mg daily or 960mg three times per week) received during rituximab treatment and at least 6 months post completion of treatment. Results 185 patients’ medical charts were reviewed. Only 28 patients received prophylaxis with co-trimoxazole. The majority of patients (n = 24, 85%) who received prophylaxis with co-trimoxazole had an underlying diagnosis of small vessel vasculitis (SVV). Co-trimoxazole was more commonly prescribed by nephrologists (n = 17, 71% primarily for SVV) as compared to rheumatologist (n = 7, 29% primarily for SVV). 156 patients were not prescribed prophylactic co-trimoxazole. The primary indication for rituximab in these patients was inflammatory arthropathy (IA) (n = 72,46%), SVV (n = 26, 16%), systemic lupus erythematosus (n = 19, 12%), with the remainder accounted for by scleroderma, undifferentiated connective tissue disease, membranous nephropathy (MN), myositis, focal segmental glomerulosclerosis and amyloid renal disease. No patient was admitted over the course of the study period with PJP. 59 patients required hospital admissions due to other infections, most commonly patients with SVV. The most common infections were respiratory tract and urinary tract infections. Overall infections requiring hospitalization were more common in the group receiving prophylaxis, perhaps highlighting the vulnerable nature and greater prednisolone prescribing in the SVV cohort. No difference was seen between groups in the prevalence of UTIs. Conclusion In this cohort co-trimoxazole prophylaxis was more commonly prescribed for patient with small vessel vasculitis and differences in prescribing patterns were seen between nephrologists and rheumatologists. With greater awareness of the heightened risk of PJP in patents receiving rituximab consideration should be given to use of antibiotic prophylaxis for other indications. Disclosure S. Tio: None. J. Morrow: None. S. Cowley: None. M. Clarkson: None. G. Murphy: None.

OA16 Clinical and biochemical improvement following daratumumab therapy for anti-MDA5 antibody positive dermatomyositis with rapidly progressive interstitial lung disease: a case report

Abstract Background/Aims Anti-melanoma differentiation-associated 5 gene autoantibody (anti-MDA5) positive dermatomyositis (DM) with rapidly progressive interstitial lung disease (RP-ILD) represents the most severe and difficult-to-treat form of autoimmune myositis with unfavourable 6-month survival rates despite intensive treatment strategies of combination therapy with glucocorticoids, cyclophosphamide, calcineurin inhibitors, mycophenolate mofetil and rituximab. We describe a case of anti-MDA5 positive DM with RP-ILD that was refractory to intensive combination therapy, requiring courses of rescue plasmapheresis, before eventually responding to intravenous daratumumab. Methods A 30-year-old non-smoking Chinese man who was previously well was hospitalised after 3 weeks of intermittent pyrexia, non-productive cough, lethargy, rashes and myalgia. Examination revealed typical cutaneous changes of dermatomyositis, bilateral mid-to-lower zone inspiratory crepitations in his chest with no proximal muscle weakness or synovitis. Initial investigations demonstrated elevations in creatine kinase, C-reactive protein, erythrocyte sedimentation rate, lactate dehydrogenase, ferritin and neutrophil-to-lymphocyte ratio. Although an initial chest radiograph was normal, CT thorax 4 days later showed non-specific ground-glass opacities with consolidation in both lower lobes. Anti-MDA5 antibodies were strongly positive on EUROLINE Inflammatory Myopathies 16 Ag (IgG) commercial line immunoblot. He was transferred to our centre for further care one week after hospitalisation and was intubated on arrival for type I respiratory failure. He was initiated on combination therapy of intravenous methylprednisolone, intravenous rituximab, hydroxychloroquine, tofacitinib and was also treated with plasmapheresis to remove pathogenic anti-MDA5 antibodies. Although his condition improved initially with successful extubation within one week, the disease remained active in the following months with several admissions for infection-related issues and progression of RP-ILD. Despite various combinations of immunosuppressives and further courses of plasmapheresis, at 6 months post-diagnosis he continued to require a minimum daily prednisolone dose of 45mg (0.625mg/kg/day), remaining positive for anti-MDA5 antibodies on the immunoblot assay, with persistently elevated serum ferritin and transaminases. As such, he was treated with four doses of intravenous daratumumab in an attempt to deplete the long-lasting plasma cells that may be driving the disease. Results Following daratumumab treatment, the anti-MDA5 antibody turned negative on the immunoblot assay with normalisation of ferritin and transaminases, with corresponding improvement in lung function tests and chest radiograph findings. 3 months post-daratumumab, he remains clinically well on hydroxychloroquine, tofacitinib and nintedanib, with successful continuing taper of prednisolone. Conclusion Daratumumab is an anti-CD38 monoclonal antibody licensed for the treatment of multiple myeloma which has been used off-label for other refractory autoimmune conditions such as SLE. It is postulated that besides CD19/20 positive B cells, CD38 positive long-lived autoantibody-secreting plasma cells are essential drivers of chronic inflammation in these autoimmune diseases. In our patient with anti-MDA5 DM and RP-ILD, the use of daratumumab was well-tolerated and led to definite clinical and biochemical improvement. Disclosure L. Koh: None. G. Chai: None. M. Manghani: None. X. Lim: None. B.P.L. Leung: None. C. Chua: None.