CAR-T Cell Therapy for Mesothelioma

What Is CAR-T Cell Therapy?

CAR-T (Chimeric Antigen Receptor T-cell) therapy is a form of immunotherapy that uses a patient’s own immune cells, genetically engineered to recognize and attack cancer. Unlike checkpoint inhibitors that release the “brakes” on the immune system, CAR-T therapy creates an entirely new weapon, T-cells specifically designed to find and kill mesothelioma cells.

This approach has transformed treatment for certain blood cancers (leukemias and lymphomas), with some patients achieving complete remission. Now researchers are adapting this technology for solid tumors like mesothelioma.

How CAR-T Therapy Works

The process involves several steps:

1. Collection (Leukapheresis)

T-cells are extracted from the patient’s blood through a process similar to blood donation. These are the immune cells that will be modified.

2. Engineering

In a laboratory, the T-cells are genetically modified using viral vectors (typically lentivirus) to express a chimeric antigen receptor (CAR). This receptor is designed to recognize a specific protein on cancer cells.

3. Expansion

The modified CAR-T cells are multiplied in the laboratory until there are hundreds of millions of them, enough to mount an effective attack on the tumor.

4. Conditioning

Before receiving CAR-T cells, patients undergo lymphodepleting chemotherapy (typically fludarabine and cyclophosphamide) to make “space” for the new cells and reduce immune suppression.

5. Infusion

The engineered cells are infused back into the patient, where they seek out cancer cells expressing the target protein.

6. Attack

When CAR-T cells encounter their target, they:

• Bind to the cancer cell
• Activate and proliferate
• Release cytotoxic granules (perforin and granzymes)
• Produce interferon-gamma (IFN-γ)
• Directly kill the tumor cell

Why Mesothelin?

Most mesothelioma CAR-T therapies target mesothelin (MSLN), a protein that is:

• Highly expressed on 75-90% of pleural mesothelioma cells
• Minimally present on normal tissues (limited to mesothelial surfaces)
• An ideal target because CAR-T cells attack tumors while largely sparing healthy tissue

Mesothelin is also overexpressed in ovarian cancer, pancreatic cancer, and lung adenocarcinoma, making these therapies potentially applicable to multiple cancer types.

Current Clinical Trials

SynKIR-110 (STAR-101 Study)

SynKIR-110, developed by Verismo Therapeutics, received FDA fast-track designation in April 2023. It is an autologous T-cell therapy using a novel KIR-CAR (Killer Immunoglobulin-like Receptor CAR) design that may enhance recognition and killing of mesothelin-expressing cells. The STAR-101 trial (NCT05568680) is running at MD Anderson Cancer Center in Houston, Texas; the University of Pennsylvania in Philadelphia; the University of Wisconsin Carbone Cancer Center in Madison; and the University of Kansas Cancer Center in Westwood. Eligible cancers include mesothelioma, ovarian cancer, and cholangiocarcinoma. Fast-track designation recognizes SynKIR-110’s potential to address a serious condition with unmet medical need and allows for expedited FDA review.

A2B694 (EVEREST-2 Study)

A mesothelin-targeting CAR-T therapy being evaluated for mesothelioma, lung cancer, and ovarian cancer.

Status: Currently recruiting Results Expected: 2029

Logic-Gated CAR-T (Tmod Platform)

A seamless Phase 1/2 study evaluates mesothelin-targeting Tmod CAR-T products in patients with recurrent, unresectable, or metastatic solid tumors. The “logic-gated” design may improve specificity and safety.

CAR-T + Checkpoint Inhibitor Combinations

Researchers are combining CAR-T therapy with checkpoint inhibitors (pembrolizumab, nivolumab) to:

• Prevent T-cell exhaustion
• Enhance tumor killing
• Extend duration of response

Engineering Advances

Researchers are developing next-generation CAR-T approaches to overcome solid tumor challenges:

Metabolic Engineering

The tumor microenvironment creates hostile conditions for CAR-T cells through elevated adenosine and nutrient restriction. New approaches include:

• ADA1-expressing CAR-T cells that convert adenosine to inosine, improving cell survival
• Enhanced metabolic flexibility for better persistence
• Reduced exhaustion markers (lower PD-1, TIM-3, LAG-3 expression)

Alternative Cell Sources

NK Cell-Based Approaches:

• Natural killer (NK) cells precomplexed with bispecific engagers
• Cytokine-induced memory-like programming (IL-12/15/18)
• Tumor-penetrating peptides for enhanced infiltration

Armed CAR-T Strategies

• Oncolytic viruses (IL-12-armed HSV-2) to improve tumor microenvironment
• Direct intratumoral injection for better penetration
• Combination with radiation therapy

Early Results

Mesothelioma-specific CAR-T results are still emerging from Phase 1 trials. Early signals from investigator presentations include objective responses (partial and, in some cases, complete) in a subset of patients with heavily pretreated disease, along with lower severe cytokine release syndrome rates than in blood cancer CAR-T.

Mature efficacy data from completed mesothelioma trials is not yet published in peer-reviewed literature. Results from ongoing trials, including EVEREST-2 and TNhYP218 at the NCI, will provide clearer guidance on survival benefits.

Potential Side Effects

CAR-T therapy can cause significant side effects that require specialized management:

Cytokine Release Syndrome (CRS)

When CAR-T cells activate, they release inflammatory signals (cytokines) that can cause:

• Fever
• Low blood pressure
• Difficulty breathing
• Organ dysfunction

Management: Tocilizumab (IL-6 blocker), steroids, supportive care

CRS occurs in 70-90% of blood cancer CAR-T patients but may be lower in solid tumor trials.

Neurotoxicity (ICANS)

Immune Effector Cell-Associated Neurotoxicity Syndrome can cause:

• Confusion
• Difficulty speaking
• Tremors
• Seizures (rare)

Usually temporary and reversible with treatment.

Risks Beyond CRS and ICANS

Patients also face infection risk during lymphodepletion and recovery, prolonged cytopenias (low blood counts), and tumor lysis syndrome (rare in solid tumors but still a possibility).

Challenges in Solid Tumors

CAR-T therapy has been more successful in blood cancers than solid tumors. Mesothelioma presents three specific challenges. Physical barriers matter: the tumors create dense stroma that limits CAR-T infiltration, so engineered cells may not reach the cancer cells they are designed to kill. The tumor microenvironment is immunosuppressive, with tumors producing factors that exhaust T-cells and with regulatory cells actively suppressing immune responses. Antigen heterogeneity is another obstacle, since not all cancer cells express the target protein equally, and tumor cells can downregulate target antigens under pressure. Current research specifically addresses these challenges through engineering improvements like metabolic engineering and armed CAR-T strategies.

Who May Be Eligible

CAR-T trials for mesothelioma typically require:

• Confirmed diagnosis of malignant mesothelioma
• Mesothelin expression (determined by biopsy)
• Previous treatment (most trials are for relapsed/refractory disease)
• Adequate organ function
• Acceptable performance status
• Specific HLA type (some trials require HLA-A*02)
• Ability to travel to participating centers

Finding CAR-T Trials

Search for mesothelioma CAR-T trials at ClinicalTrials.gov, using the terms “mesothelioma CAR-T” or “mesothelin CAR.” The NCI Cancer Information Service (1-800-4-CANCER) can also connect callers with investigators. Major cancer centers like MD Anderson, the University of Pennsylvania, and the University of Wisconsin should be contacted directly, as many run trial sites for ongoing mesothelin CAR studies.

The Future of CAR-T in Mesothelioma

Research is advancing rapidly:

• Off-the-shelf CAR-T (allogeneic) could eliminate manufacturing delays
• Multi-target CARs may prevent tumor escape
• Local delivery (intrapleural injection) could improve penetration
• Combination strategies with checkpoint inhibitors may enhance durability

While CAR-T therapy for mesothelioma remains experimental, fast-track designations and active trials suggest it may become an important treatment option in the coming years.