CD38 is a transmembrane glycoprotein with ectoenzymatic activity involved in regulation of migration, signal transduction, and receptor-mediated adhesion. CD38 is highly expressed on various malignant cells, including multiple myeloma (MM), and at relatively low levels in other tissues, making it a suitable target for therapeutic antibodies. Several anti-CD38 therapies have been, or are being, developed for the treatment of MM, including daratumumab and isatuximab (SAR650984), respectively. Studies have shown that anti-CD38 therapies are effective in the treatment of relapsed/refractory MM and are well tolerated, with infusion reactions being the most common side effects. They can be used as monotherapy or in combination with immunomodulatory agents, such as pomalidomide, or proteasome inhibitors to potentiate their activity. Here we examine isatuximab and several anti-CD38 agents in development that were generated using new antibody engineering techniques and that may lead to more effective CD38 targeting. We also summarize trials assessing these antibodies in MM, other malignancies, and solid organ transplantation. Finally, we propose that further research on the mechanisms of resistance to anti-CD38 therapy and the development of biomarkers and new backbone regimens with CD38 antibodies will be important steps in building more personalized treatment for patients with MM.

Longer-term outcomes with the anti-CD38 antibody isatuximab in combination with carfilzomib-dexamethasone (Isa-Kd) were evaluated in the randomized Phase 3 trial IKEMA (NCT03275285), in a prespecified, follow-up analysis of progression-free survival (PFS, primary study endpoint), final complete response (CR) using Hydrashift Isa immunofixation assay, minimal residual disease (MRD) negativity, and safety. Enrolled patients had relapsed/refractory multiple myeloma (1–3 prior treatment lines). Isa 10 mg/kg was administered intravenously weekly in cycle 1 then biweekly. Efficacy analyses were performed in the intent-to-treat population (Isa-Kd: n = 179, Kd: n = 123) and safety evaluated in treated patients (Isa-Kd: n = 177, Kd: n = 122). Consistent with the primary interim analysis, the addition of Isa to Kd prolonged PFS (HR 0.58, 95.4% CI: 0.42–0.79; median PFS 35.7 [95% CI: 25.8–44.0] vs 19.2 [95% CI: 15.8–25.0] months). PFS benefit was observed with Isa-Kd across subgroups, including patients with poor prognosis. The stringent CR/CR rate was 44.1% vs 28.5% (odds-ratio: 2.09, 95% CI: 1.26–3.48), the MRD negativity rate 33.5% vs 15.4% (odds-ratio: 2.78, 95% CI: 1.55–4.99) and the MRD negativity CR rate 26.3% vs 12.2%, with Isa-Kd vs Kd. The safety profile of Isa-Kd was similar to that reported in the prior interim analysis. These findings further support Isa-Kd as a standard-of-care treatment for relapsed multiple myeloma patients.Clinical trial information: ClinicalTrials.gov, NCT03275285.

Background: Patients with relapsed/refractory multiple myeloma are at increased risk of infection. Infections during treatment with teclistamab, the first B‐cell maturation antigen‐directed bispecific antibody approved for triple‐class–exposed relapsed/refractory multiple myeloma, was examined in the phase 1/2 MajesTEC‐1 study.Methods: Patients (N = 165) received subcutaneous teclistamab 1.5 mg/kg weekly after a step‐up dosing schedule (0.06 mg/kg and 0.3 mg/kg, each separated by 2–4 days). Patients were monitored frequently for infections; prophylaxis and management were per institutional guidelines.Results: At a median follow‐up of 22.8 months (range, 0.3–33.6), infections were reported in 132 patients (80.0%). Grade 3/4 infections occurred in 91 patients (55.2%), including COVID‐19 (21.2%), respiratory infections (19.4%), Pneumocystis jirovecii pneumonia (4.2%), viral infections (4.2%), and gastrointestinal infections (1.2%). Twenty‐one patients died from infections (18 from COVID‐19). Median time to first onset of any‐grade and grade 3 to 5 infections was 1.7 and 4.2 months, respectively. Overall, 70.9% of patients had ≥1 postbaseline immunoglobulin G (IgG) level <400 mg/dL; median time to IgG <400 mg/dL was 1.2 months (range, 0.2–19.8) and 46.1% received ≥1 dose of IgG replacement. Grade 3/4 neutropenia occurred in 65.5% of patients (median time to grade ≥3 neutropenia/febrile neutropenia was 2.3 months [range, 0–18.1]).Conclusion: Based on the infection profile of B‐cell maturation antigen–targeted bispecific antibodies such as teclistamab, it is recommended that clinicians and patients remain vigilant for a range of infection types throughout treatment to facilitate prompt intervention. Appropriate screening, prophylaxis, and management of infections, hypogammaglobulinemia, and neutropenia are important.Clinical trial registration: NCT03145181/NCT04557098 (ClinicalTrials.gov)Plain Language Summary: Before starting teclistamab, patients should be up to date with vaccinations (including COVID‐19) and screened for hepatitis B and C and HIV. Teclistamab should not be given to patients with any active infections. Prophylactic antimicrobials should be administered per institutional guidelines. Prophylaxis for Pneumocystis jirovecii pneumonia and herpes simplex/varicella zoster virus is recommended during teclistamab treatment. Close monitoring of infections and immunoglobulin G (IgG) levels should continue throughout teclistamab treatment. IgG replacement (administered every 3–6 weeks) should be used to maintain IgG ≥400 mg/dL. Growth factors should be considered for grade ≥3 neutropenia with infection/fever and grade 4 neutropenia.

Background: Teclistamab, a B‐cell maturation antigen × CD3 bispecific antibody, demonstrated an overall response rate of 63.0% in 165 heavily pretreated patients with relapsed or refractory multiple myeloma in the phase 1/2 MajesTEC‐1 study. Cytokine release syndrome (CRS), a known manifestation of T‐cell redirection, was observed in 119 of 165 patients (72.1%).Methods: Patients received once‐weekly teclistamab 1.5 mg/kg subcutaneously after two step‐up doses (0.06 and 0.3 mg/kg). CRS was graded according to American Society for Transplantation and Cellular Therapy criteria and managed according to the study protocol, including use of tocilizumab and/or steroids.Results: Most cases of CRS occurred during the step‐up dosing schedule of teclistamab and were grade 1 (50.3% of patients) or grade 2 (21.2% of patients); a single case of grade 3 CRS was reported in a patient with concurrent grade 3 pneumonia. All CRS cases resolved and none led to treatment discontinuation. Overall, 33.3% of patients had >1 CRS event; CRS recurrence was reduced when tocilizumab was administered for the first CRS event compared with when it was not (20.0% vs. 62.2%, respectively). Baseline characteristics such as tumor burden and cytokine levels did not appear to predict CRS incidence or severity.Conclusions: Findings of this study support the need for preemptive planning and prompt management of CRS in patients treated with T‐cell–engaging bispecific antibodies. Intervention with tocilizumab for CRS appears to decrease the likelihood of patients experiencing subsequent CRS events without compromising response to teclistamab.Plain language summary: Cytokine release syndrome (CRS), observed in 72.1% of patients treated with teclistamab in the MajesTEC‐1 study, was mostly grade 1 or 2 and manageable, without requiring treatment discontinuation. Most CRS occurred during the step‐up schedule, requiring vigilance during treatment initiation. Ensure fever is resolved and patients have no signs of infection before initiating the teclistamab step‐up schedule or administering the next teclistamab dose, to avoid exacerbating CRS. Tocilizumab reduced the risk of subsequent CRS in patients receiving it for their first CRS event (20.0% vs. 62.2% in those not receiving it), without affecting response to teclistamab. No baseline characteristics, including tumor burden or cytokine levels, appeared to clearly predict for CRS occurrence or severity.

Although the treatment of relapsed/refractory multiple myeloma has improved dramatically over the past decade, the disease remains incurable; therefore, additional therapies are needed. Novel combi...

Teclistamab, a BCMAxCD3-directed bispecific antibody, has shown high response rates and durable remissions in triple-class-exposed patients with relapsed/refractory multiple myeloma. We performed a retrospective study evaluating the efficacy and safety of teclistamab in 210 patients treated at 9 academic centers from five countries within the IMWG Immunotherapy Working Group Committee. Patients were heavily pretreated, with 83% having triple-class refractory disease and 44% with prior BCMA-targeted therapy. With a median follow-up of 5.3 months, the overall response rate (ORR) was 67% in 188 response-evaluable patients, including 55% with a very good partial response or better. The 6-month progression-free survival (PFS) and overall survival rates were 53% (95% CI, 46–61%) and 73% (67–80%), respectively. Patients who received prior BCMA-directed therapy compared to BCMA-treatment-naïve patients had a lower ORR (58.3 vs 74.0%; P = 0.03) and PFS (6-month PFS 43% [95% CI, 33–55%] vs 63% [54–73%]; logrank P = 0.004). Step-up dosing occurred in an outpatient setting for 23% of patients. CRS occurred in 54% of patients, and infections were reported in 56.2% of patients, with 22% having grade ≥3 infections. In this multicenter real-world study, we found that teclistamab can lead to rapid responses in heavily pretreated myeloma patients with comparable efficacy and safety profiles, as demonstrated in MajesTEC-1.