BCMA-Targeted Therapies in Multiple Myeloma: Teclistamab vs CAR-T vs Antibody-Drug Conjugates

Author: Alisha GC

B-cell maturation antigen (BCMA) has emerged as one of the most promising therapeutic targets in multiple myeloma due to its selective expression on plasma cells and critical role in tumor survival signaling. Several innovative immunotherapies targeting BCMA have recently transformed the treatment landscape for relapsed or refractory multiple myeloma (RRMM). These include bispecific antibodies such as Teclistamab, chimeric antigen receptor T-cell (CAR-T) therapies including Idecabtagene vicleucel and Ciltacabtagene autoleucel, and antibody-drug conjugates such as Belantamab mafodotin. Each therapeutic modality uses a distinct mechanism to eliminate malignant plasma cells while overcoming resistance to conventional therapies such as proteasome inhibitors, immunomodulatory drugs, and anti-CD38 antibodies. This review provides a comprehensive comparison of BCMA-targeted therapies, focusing on their molecular design, mechanisms of action, clinical efficacy, safety profiles, and emerging mechanisms of resistance.

Multiple myeloma is a malignant plasma cell disorder characterized by clonal expansion of antibody-producing plasma cells in the bone marrow. Despite advances in treatment with proteasome inhibitors, immunomodulatory drugs, and monoclonal antibodies, most patients eventually develop relapsed or refractory disease.

Recent advances in cancer immunotherapy have identified BCMA (B cell maturation antigen) as a highly effective therapeutic target.

BCMA is expressed almost exclusively in:

• Plasma cells

• Malignant myeloma cells

Importantly, it plays a crucial role in plasma cell survival by interacting with ligands BAFF and APRILwhich activate intracellular pathways such as:

• NF-κB signaling

• PI3K–AKT pathway

• MAP kinase signaling

Because of its limited expression and biological significance, BCMA has become the focus of several next-generation immunotherapies.

Three major BCMA-targeted therapeutic classes have emerged:

1. Bispecific antibodies

2. CAR-T cell therapies

3. Antibody-drug conjugates

Each approach uses a unique strategy to destroy malignant plasma cells.

In BCMA-targeted therapy, these antibodies bind:

• BCMA on myeloma cells

• CD3 on T cells

This double bond brings cytotoxic T-lymphocytes into direct contact with tumor cells and triggers immune-mediated killing.

Teclistamab

Teclistamab is one BCMA × CD3 bispecific IgG4 antibody designed to redirect T cells against malignant plasma cells.

When both targets are engaged:

1. T cell receptor clustering occurs

2. T cells are activated

3. Cytotoxic granules containing perforin and granzyme B are released

4. Tumor cells undergo apoptosis

Unlike CAR-T therapy, Teclistamab uses the patient’s existing T cells without genetic modification.

Advantages of bispecific antibodies

Restrictions

Chimeric antigen receptor T-cell (CAR-T) therapy represents one of the most advanced forms of personalized cancer immunotherapy.

In this approach:

1. T cells are collected from the patient.

2. These cells are genetically engineered to express a CAR receptor targeting BCMA.

3. The modified cells are expanded in the laboratory.

4. CAR-T cells are infused back into the patient.

Once infused, CAR-T cells recognize BCMA-expressing tumor cells and trigger strong cytotoxic immune responses.

Two BCMA CAR-T therapies have shown remarkable clinical success.

Idecabtagene Vicleucel (Abecma)

This CAR-T therapy showed high response rates in heavily pretreated patients.

Key clinical findings include:

Ciltacabtagene Autoleucel (Carvykti)

Ciltacabtagene autoleucel has shown even higher response rates.

Clinical studies reported:

Benefits of CAR-T therapy

Restrictions

Antibody-drug conjugates (ADCs) combine the specificity of monoclonal antibodies with the cytotoxic potency of cytotoxic agents.

These molecules consist of three components:

1. Monoclonal antibody directed against BCMA

2. Cytotoxic payload

3. Chemical linker

After binding of BCMA:

1. ADC is internalized in the tumor cell.

2. The linker is split.

3. The cytotoxic payload is released.

4. Tumor cell death occurs.

Belantamab Mafodotin

Belantamab mafodotin was the first BCMA-targeted ADC approved for multiple myeloma.

Its cytotoxic payload monomethyl auristatin F (MMAF) disrupts the formation of microtubules and induces apoptosis.

Advantages of antibody-drug conjugates

Restrictions

• Ocular toxicity (keratopathy)

• Lower response rate compared to CAR-T therapies

• Potential drug resistance

Despite impressive responses, resistance remains a major challenge.

Loss of BCMA antigen

Tumor cells can reduce or eliminate BCMA expression, preventing immune recognition.

The mechanisms include:

• Genetic mutations

• Alternative splicing

• Excretion of soluble BCMA

T-cell dysfunction

Chronic immune activation can lead to T-cell exhaustioncharacterized by:

Immunosuppressive bone marrow microenvironment

The myeloma bone marrow niche contains suppressive immune cells including:

These cells produce inhibitory cytokines that dampen anti-tumor immune responses.

Next-generation therapies are being developed to improve treatment durability.

Bispecific antibodies with two targets

New agents target several plasma cell antigens simultaneously, for example:

• BCMA + GPRC5D

• BCMA + FcRH5

This strategy reduces antigen escape.

Combination immunotherapy

Combining BCMA therapies with:

• Checkpoint inhibitors

• Immunomodulatory drugs

• Cytokine treatments

may improve T-cell function and persistence.

The future of multiple myeloma treatment is likely to involve combination immunotherapy approaches integrate:

Advances in immunotechnology and molecular profiling will enable personalized treatment strategies for patients with relapsed or refractory disease.

BCMA-targeted therapies have revolutionized the treatment of multiple myeloma by providing highly effective immunotherapeutic options for patients with refractory disease. Bispecific antibodies such as Teclistamab enable rapid redirection of the immune system, while CAR-T cell therapies provide deep and lasting responses through engineered cellular immunity. Antibody-drug conjugates provide a complementary approach by delivering potent cytotoxic agents directly to tumor cells. Continued research aimed at overcoming resistance mechanisms and optimizing combination strategies will be essential to improve long-term outcomes and achieve durable remissions in multiple myeloma.

Q1. What is BCMA and why is it important in multiple myeloma?
BCMA is a plasma cell surface receptor that regulates survival signaling and is highly expressed on malignant myeloma cells, making it an ideal therapeutic target.

Q2. What are the three main BCMA-targeted therapies?
The main classes include bispecific antibodies, CAR-T cell therapy and antibody-drug conjugates.

Q3. Which BCMA therapy is most effective?
CAR-T therapies currently show the highest response rates, but bispecific antibodies provide faster and more accessible treatment.

Q4. What are the main side effects of BCMA immunotherapy?
Common toxicities include cytokine release syndrome, infections, neurotoxicity, and ocular toxicity depending on the type of therapy.

Q5. Can patients receive multiple BCMA treatments?
Yes, sequential or combination therapies are being explored to overcome resistance and improve outcomes.