Multiple myeloma (MM) is a hematologic malignancy involving an abnormal clonal proliferation of plasma cells in the bone marrow, along with their excess production of monoclonal immunoglobulin (M protein).1 Malignant plasma cells on biopsy and M protein in serum and urine are required for diagnosis, with a decrease from baseline indicating a positive response to treatment.1 Myeloma-defining features include hypercalcemia, renal insufficiency, anemia, and bone lesions.1 MM is considered incurable yet treatable, and it grows slowly in its earlier Revised International Staging System (R-ISS) stages. At diagnosis of R-ISS stage I, the median 5-year survival rate is 77% and declines to 47% in R-ISS stage III.1
The substantial improvement in survival rates since the approval of the first proteasome inhibitor and immunomodulatory agent in the 2000s is due to advancements in the treatment landscape, notably combination regimens and newer generations of treatment options. At diagnosis, assessing a patient’s candidacy for autologous hematopoietic stem cell transplantation is standard of care, as it influences the choice of initial combination regimen. In transplant-eligible patients, the first-line treatment regimen includes a combination of a proteasome inhibitor, an immunomodulatory agent, and a corticosteroid. The most used regimen is known as RVd or VRd (injectable bortezomib [Velcade; Takeda], oral lenalidomide [Revlimid; Bristol Myers Squibb], dexamethasone [Decadron; Pfizer]).1
In patients who are transplant ineligible, preferred primary therapy options include VRd-based regimens or DRd (daratumumab [Darzalex; Johnson & Johnson], lenalidomide, dexamethasone).2 Anti-CD38 monoclonal antibodies, such as daratumumab, have become a mainstay in the combination regimens due to their demonstrated ability to improve outcomes.2 Several clinical trials, including PERSEUS (NCT03710603), IMROZ (NCT03319667), and MAIA (NCT02252172), have shown benefits in terms of progression-free survival (PFS) with the addition of anti-CD38 monoclonal antibodies to lenalidomide and dexamethasone–based regimens in the frontline setting.2-4
According to National Comprehensive Cancer Network (NCCN) guidelines, there is no clear consensus on the treatment of relapsed/refractory (R/R) MM with multiple agents and/or regimens. The main goal of treatment is to prolong overall survival (OS), ideally accompanied by improvements in quality of life. Although these combination regimens have extended OS, it is commonly shorter in R/R MM compared with patients newly diagnosed with MM. Novel therapies such as chimeric antigen receptor (CAR) T-cell therapies and bispecific antibodies (bsAbs) demonstrate significant and ongoing advancements in treating R/R MM.
There have been 3 approvals of bsAbs since 2022, including teclistamab (Tecvayli; Janssen Biotech), talquetamab (Talvey; Janssen Biotech), and elranatamab (Elrexfio; Pfizer). These bsAbs can be further separated. Teclistamab and elranatamab target B-cell maturation antigen (BCMA); talquetamab targets G protein–coupled receptor, class C, group 5, member D (GPRC5D). In addition, the field has grown with the expanded indications for 2 FDA-approved BCMA-targeted CAR T-cell therapies, idecabtagene vicleucel (Abecma; Bristol Myers Squibb) and ciltacabtagene autoleucel (Carvykti; Johnson & Johnson). With updated clinical evidence, the NCCN guidelines now place CAR T-cell therapies in earlier lines of therapy, and they remain a fourth line alongside the 3 bsAbs.
In April 2024, ciltacabtagene autoleucel moved from the fifth line to include an option as a second line for patients who are refractory to lenalidomide and have been exposed to a proteasome inhibitor.5 In April 2024, the FDA also announced an expanded indication for idecabtagene vicleucel to be included as a third-line option for R/R MM.6 With this, there is a need to reassess the role of bsAbs in therapy, particularly bsAbs that also target BCMA. Whether bsAbs offer significant benefits if introduced earlier as monotherapy similar to CAR T-cell therapy or in combination regimens remains an area of ongoing investigation.
With the rapid emergence of new agents with similar mechanisms and overlapping indications, there is a need to discuss their potential unique roles in our growing landscape, given the absence of head-to-head trials. By integrating emerging evidence and practical considerations and outlining key differences, we aim to provide an updated overview of the role of BCMA-directed therapies that can be used to facilitate clinical decision-making. We will also closely compare the BCMA-directed bsAbs and their optimal timing relative to CAR T-cell therapy to provide nuanced insights into the implications of any observed differences with a focus on efficacy and safety. The practical considerations will consider factors such as cost-effectiveness and pharmacy operational efficiency, as these are often incorporated decision-making when there may be optimal usage of 1 of 3 available bsAbs across institutions.
Examining Efficacy and Safety Between the BCMA-Directed bsAbs
Teclistamab and elranatamab are structurally similar bsAbs that target BCMA and CD3, recruiting T cells to attack the abnormal plasma cells. With both having symmetrical BCMA-binding Fab domains, their main structural distinction lies in their Fc backbone. Based on our literature search, no biochemical structural analyses demonstrate differences in BCMA epitope binding or binding affinities. Therefore, it is difficult to predict differences in efficacy grounded on any potential variations in their mechanism or drug properties. In the absence of head-to-head trials, it is crucial to closely compare and critically appraise nuanced differences to inform clinical decision-making on the optimal use of each.
Teclistamab was the first bsAb to receive approval in 2022, followed by elranatamab in 2023.7,8 In the phase 1 MajesTEC-1 trial (NCT03145181), the overall response rate for teclistamab was 63% with a complete response (CR) rate or better of 39.4%.9 The median time to response was approximately 1 month.9 After a median follow-up of 14.1 months, the median PFS was 11.3 months.9 The median OS of 18.3 months and median duration of response (DOR) of 18.4 months were both immature.9 Long-term follow-up data from MajesTEC-1 were presented at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting. At an extended follow-up period of 30.4 months, the overall response rate remained at 63%; however, the CR rate was 46.1%.10 The median PFS remained the same at 11.4 months.10 Consequently, an increased median OS of 22.2 months and an increased median DOR of 24 months were seen for all responders.10 The extended follow-up confirms that the responses are durable and deepened over time.
In a multi-institutional real-world study with a patient population comprising a higher proportion of high-risk MM and a significantly higher proportion with penta-drug refractoriness, teclistamab maintained a very good partial response (PR) rate or better of 51% compared with 58.8% in MajesTEC-1.11 Teclistamab showed similar efficacy with an overall response rate of 66% in a second study composed of a heavily pretreated patient population with a significantly high portion of penta-drug refractory disease.12 Whereas the extended follow-up strengthens the reliability of the observed data, the real-world evidence provides complementary data showing how teclistamab may perform in practice, suggesting comparable efficacy in a heavily pretreated, high-risk patient population.
The study design of the phase 2 MagnetisMM-3 trial (NCT04649359) for elranatamab was similar to MajesTEC-1, which included comparable methodologies with minor differences in the participant selection criteria.13 Among the notable key differences was the inclusion of triple-class exposed participants in MajesTEC-1 compared with triple-class refractory participants in MagnetisMM-3. In MagnetisMM-3, after a median follow-up of 14.7 months, the objective response rate was 61%, with a CR rate of 35%.13 The median time to response was approximately 1 month.13
Long-term follow-up data from MagnetisMM-3 were presented at the 2024 ASCO Annual Meeting. With an extended follow-up of 28.4 months, the objective response rate remained at 61%, with a CR at 37.4%.14 The median OS was 24.6 months, with a median PFS at 17.2 months.14 A comparison between the 2 studies demonstrated that teclistamab had a higher stringent CR rate at more than 2-fold that of elranatamab.9,13 It is also important to recognize the differences in the characteristics of participants at baseline, which may limit this takeaway. In addition to slight differences across the proportions of ISS risk stage, cytogenetics risk profile, median number of lines of previous therapy, and penta-drug refractoriness, the percentage of extramedullary disease (EMD) was 17% for teclistamab vs 31.7% for elranatamab. However, EMD was strictly defined as true soft tissue plasmacytomas for teclistamab, whereas this was broadened to include extramedullary and/or paramedullary disease with a soft tissue component for elranatamab. Based on this information, it is difficult to conclude whether elranatamab may be more efficacious in patients with poor prognostic features.
The direct comparison of tolerability and safety profiles in MagnetisMM-3 and MajesTEC-1 is complicated by differing criteria for discontinuation across the trials. Treatment-emergent adverse events (AEs), notably infections, constituted a smaller proportion of all discontinuations. Overall, discontinuation rates were 58% for teclistamab compared with 67% for elranatamab, and the trend was consistent with interruptions in dosing, which were 63% for teclistamab compared with 77% for elranatamab.9,13 Disease progression constituted the largest proportion of all discontinuations, representing 64% for teclistamab compared with 59% for elranatamab.9,13
Matching could clarify the inconsistencies in the trends observed. It is easier to match safety profiles given that the same criteria are used to evaluate outcomes such as infection, cytokine release syndrome (CRS), and immune effector cell–associated neurotoxicity syndrome (ICANS). For teclistamab, 76% of participants experienced all-grade infections, with 45% experiencing grade 3 or 4 infections.9 For elranatamab, 70% of participants experienced all-grade infections, with 40% experiencing grade 3 or 4 infections.13 A meta-analysis demonstrated that more than half of all patients experienced all-grade infections, with a quarter experiencing grade 3 or 4 infections.15 There was significant heterogeneity in the percentage of infections across trials.15 This variability is attributable to differences in the approaches to anti-infective prophylaxis and management. Although specific guidelines are lacking, unique recommendations include universal Pneumocystis jirovecii pneumonia prophylaxis and intravenous immunoglobulin as indicated. Given the higher risk of severe infection with BCMA-directed therapies compared with non-BCMA therapies, a comprehensive approach to anti-infective prophylaxis and management is necessary, irrespective of institutional variations.15,16 Among all participants, CRS and ICANS occurred in 72% and 3% of cases for teclistamab compared with 56% and 3% for elranatamab, respectively.9,13 This trend aligns with the use of tocilizumab (Actemra; Genentech) and corticosteroids for managing CRS. Tocilizumab and corticosteroids were administered in 36% and 9% of participants receiving teclistamab compared with 23% and 8% of participants receiving elranatamab, respectively.9,13
The onset and severity of CRS and ICANS observed followed a consistent pattern. Grade 1 or 2 CRS occurred mostly during step-up dosing with a median onset of 2 days and duration of 2 days.9,13 Given that the pattern is highly predictable, the step-up dosing is administered in an inpatient setting, whereas the maintenance dosing is administered in an outpatient setting. Based on the current evidence, no other tolerability or safety differences clearly distinguish one BCMA-directed bsAb from another.
Other Practical Considerations
Because current literature leads us to believe that the efficacy and safety profiles of the BCMA-directed bsAbs are proportionate, pharmacoeconomic considerations should be made to establish a preference for one bsAb over another (Online Table).10,14,17-19 For a typical patient with MM weighing 85 kg, lower cumulative drug acquisition costs are provided by teclistamab. Specifically, our calculations show that over 12 months, the total cost of teclistamab is $427,210 compared with $543,171 for elranatamab, which results in a 27% wholesale acquisition cost (WAC) savings. Looking closer at cost per treatment vial, the cost for teclistamab is lower, with a weighted average of $10,521 compared with $13,051 for elranatamab, yielding a 24% drug cost premium for elranatamab per vial. The average WAC price of teclistamab for a weekly dose is $9478 compared with $13,051 for elranatamab. Given the similar efficacy and safety profiles, the economic advantage of teclistamab discussed gives a potential benefit as a more long-term, cost-effective treatment option. The total cost of care over 12 months for weekly and biweekly talquetamab administration is $521,567 and $551,350, respectively.18
Patients receiving teclistamab should be hospitalized for 48 hours after all doses within the step-up dosing schedule. In contrast, elranatamab requires hospitalization for 48 hours after the first step-up dose and 24 hours after the second. This translates to a hospital stay of 7 to 9 and 5 days for teclistamab and elranatamab, respectively.9,13
The Centers for Medicare & Medicaid Services offers a new technology add-on payment (NTAP) program that provides additional payments to hospitals above the standard Medicare severity diagnosis-related group payment amount. Teclistamab received NTAP approval in October 2023; elranatamab was approved in October 2024. Hospitals can receive add-on payments until September 2025 for teclistamab and elranatamab.20 Additionally, Pfizer offers a free drug program for inpatient step-up doses of elranatamab. The program is available only to inpatient hospital pharmacies that certify they are supplying pharmacy services to an inpatient hospital. Hospitals may not seek or obtain reimbursement for the product directly or indirectly from any party.