Multiple myeloma has always struck me as a malignancy with poor respect for architecture. It begins in plasma cells, the antibody-producing residents of the bone marrow, then starts remodeling the place without permits. Walls come down. Wiring gets strange. The basement floods. Eventually the whole marrow neighborhood is hosting a very unwelcome construction project.
The review by Miller, Firestone, and Hultcrantz looks at how the newest immune therapies are being moved into that messy worksite: CAR T cells and bispecific antibodies for relapsed or refractory multiple myeloma. These are not gentle suggestions to the immune system. They are more like handing the security staff a floor plan, a flashlight, and permission to be impolite.
The New Tools in the Shed
The basic idea is elegant, which is always suspicious in medicine because elegance usually arrives carrying a clipboard full of side effects.
CAR T-cell therapy takes a patient's own T cells, engineers them in a lab to recognize a myeloma target, then sends them back in like custom-built inspectors with badges. In myeloma, the main target has been BCMA, a protein commonly found on malignant plasma cells. Two BCMA-directed CAR T products are now FDA-approved for relapsed or refractory disease: idecabtagene vicleucel and ciltacabtagene autoleucel.
Bispecific antibodies take a different route. They are off-the-shelf molecules with two binding arms: one grabs the cancer cell, the other grabs a T cell. In effect, they force an introduction. "T cell, this is the suspicious tenant in unit 4B. Please address." Current FDA-approved bispecifics include BCMA-directed agents such as teclistamab, elranatamab, and linvoseltamab, plus talquetamab, which targets GPRC5D instead of BCMA.
GPRC5D is a useful second door into the building. It appears on many myeloma cells and has relatively limited expression in normal tissues, though the keratinized tissues it does touch help explain some of talquetamab's odd side effects, such as taste changes and nail issues. Cancer therapy: occasionally effective, occasionally making lunch taste like cardboard. Medicine remains a dignified profession.
Why This Review Matters
For years, myeloma treatment has improved by stacking therapies: proteasome inhibitors, immunomodulatory drugs, steroids, anti-CD38 antibodies, transplant for eligible patients. The result has been better survival, but myeloma usually comes back. It is the contractor who returns after you changed the locks.
The newer immune therapies changed expectations in heavily treated patients. In the KarMMa study, ide-cel produced meaningful responses in relapsed and refractory myeloma. Cilta-cel also showed deep responses in CARTITUDE-1. Teclistamab and talquetamab brought T-cell redirection into a repeat-dosing antibody format, expanding the field beyond one-time cellular therapy.
Miller and colleagues focus on the next practical question: now that these therapies work, where do we put them? Late in treatment, after the marrow has been through every prior renovation? Earlier, when patients and immune cells may be in better shape? In combinations? In sequence? This is less glamorous than a headline response rate, but it is exactly where patient care lives.
The Catch, Because Biology Has a Legal Department
These treatments do not merely wake up immunity. They can make it shout.
Cytokine release syndrome, or CRS, is one of the best-known risks. Think fever, low blood pressure, inflammation, and an immune system that has found the microphone. ICANS, a neurotoxicity syndrome, can affect speech, thinking, and alertness. Cytopenias can leave patients with low blood counts. Infections are a major concern, especially because myeloma itself weakens antibody production, and these therapies may further thin the immune defenses.
That does not make the therapies bad. It makes them serious tools. A scalpel is not a butter knife, despite what some hospital cafeterias appear to believe.
The review stresses careful monitoring, infection prevention, and thoughtful sequencing. For example, if a tumor escapes one BCMA-targeted therapy, should the next treatment hit BCMA again, or pivot to GPRC5D? Should CAR T come before a bispecific antibody, or the reverse? The field is still learning the load-bearing beams.
What Could Change for Patients
If ongoing trials confirm these benefits earlier in treatment, myeloma care could shift from "use immune therapy after everything else fails" to "bring in the specialized crew before the building is half-collapsed." Earlier use might produce deeper remissions, longer disease control, and perhaps better quality time between treatments.
That is the promise. The challenge is making these therapies accessible, safer, and intelligently timed. CAR T requires collection, manufacturing, and a waiting period. Bispecific antibodies are more immediately available but often require repeated dosing and infection vigilance. Neither is casual medicine. Both are powerful additions to a treatment landscape that used to have fewer exits.
For patients, the message is not that myeloma has been solved. It has not. But the immune system, once treated as an unreliable night watchman in this disease, is now being trained, redirected, and sometimes rather effectively deputized. After enough years at the microscope, one learns to respect a good renovation plan.
References
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Miller KC, Firestone RS, Hultcrantz M. Incorporating the Next Generation of Immunotherapies Into the Treatment of Multiple Myeloma. J Natl Compr Canc Netw. 2026. DOI: 10.6004/jnccn.2026.7004
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Munshi NC, Anderson LD Jr, Shah N, et al. Idecabtagene Vicleucel in Relapsed and Refractory Multiple Myeloma. N Engl J Med. 2021;384:705-716. DOI: 10.1056/NEJMoa2024850
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Berdeja JG, Madduri D, Usmani SZ, et al. Ciltacabtagene Autoleucel, a B-cell Maturation Antigen-directed Chimeric Antigen Receptor T-cell Therapy in Patients With Relapsed or Refractory Multiple Myeloma. Lancet. 2021;398:314-324. DOI: 10.1016/S0140-6736(21)00933-8
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Moreau P, Garfall AL, van de Donk NWCJ, et al. Teclistamab in Relapsed or Refractory Multiple Myeloma. N Engl J Med. 2022;387:495-505. DOI: 10.1056/NEJMoa2203478
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Chari A, Minnema MC, Berdeja JG, et al. Talquetamab, a T-Cell-Redirecting GPRC5D Bispecific Antibody for Multiple Myeloma. N Engl J Med. 2022;387:2232-2244. DOI: 10.1056/NEJMoa2204591
Disclaimer: The image accompanying this article is for illustrative purposes only and does not depict actual experimental results, data, or biological mechanisms.