Emerging Treatments for Mesothelioma

Emerging treatments for mesothelioma represent a rapidly evolving landscape of investigational therapies that aim to improve outcomes beyond what current standard-of-care treatments — chemotherapy, surgery, radiation, and immunotherapy — can achieve. While mesothelioma remains a challenging cancer with limited treatment options, significant research investment over the past decade has produced several promising new approaches that are progressing through clinical trials and, in some cases, reaching clinical practice.¹

One of the most significant recent advances is Tumor Treating Fields (TTFields), a wearable device (NovoTTF-100L) that delivers alternating electric fields to disrupt cancer cell division. The STELLAR trial demonstrated that TTFields combined with pemetrexed and platinum-based chemotherapy improved median overall survival to 18.2 months compared to historical controls of 12–16 months with chemotherapy alone. The FDA approved TTFields for unresectable, locally advanced or metastatic pleural mesothelioma in 2019, making it the first new treatment modality approved for mesothelioma in 15 years.²

Other emerging approaches include CAR-T cell therapy (chimeric antigen receptor T-cell therapy), which engineers a patient's own immune cells to recognize and attack mesothelioma cells expressing specific surface proteins like mesothelin; gene therapy using suicide genes or oncolytic viruses that selectively infect and destroy cancer cells; photodynamic therapy (PDT) that uses light-activated drugs to kill tumor cells in the pleural space during surgery; and targeted therapies that exploit specific molecular vulnerabilities in mesothelioma cells, such as mutations in the BAP1 tumor suppressor gene.³

Clinical trials are the primary pathway through which these emerging treatments become available to patients. More than 100 active mesothelioma clinical trials are listed on ClinicalTrials.gov at any given time, testing new drugs, drug combinations, and treatment approaches. Participation in clinical trials gives patients access to cutting-edge therapies that may not otherwise be available, and every major advance in mesothelioma treatment has come through clinical trial research. Patients interested in emerging treatments should discuss trial eligibility with their oncologist or seek evaluation at a mesothelioma specialty center.⁴

Emerging mesothelioma treatments span several categories of investigational therapy:¹

• Tumor Treating Fields (TTFields) — The NovoTTF-100L device delivers low-intensity, intermediate-frequency (200 kHz) alternating electric fields to the thorax via adhesive transducer arrays worn on the chest. These fields interfere with cancer cell mitosis (division) by disrupting spindle fiber formation and cytokinesis. Unlike chemotherapy, TTFields do not cause systemic toxicity. The STELLAR trial led to FDA approval in combination with first-line chemotherapy. Side effects are primarily limited to skin irritation at the transducer sites²
• CAR-T cell therapy — A form of adoptive cell therapy in which a patient's T cells are extracted, genetically modified to express a chimeric antigen receptor targeting a mesothelioma-associated protein (most commonly mesothelin), expanded in the laboratory, and infused back into the patient. Early-phase trials have shown promising responses, including tumor regression, in some patients. Challenges include cytokine release syndrome, limited T-cell persistence in the tumor microenvironment, and the immunosuppressive nature of the mesothelioma tumor microenvironment³
• Gene therapy — Multiple gene therapy approaches are under investigation. Suicide gene therapy delivers genes encoding enzymes (such as herpes simplex virus thymidine kinase) that convert a non-toxic prodrug into a toxic compound selectively within tumor cells. Oncolytic viruses are engineered or naturally occurring viruses that selectively infect and kill cancer cells while sparing normal tissue. Both approaches aim to provoke anti-tumor immune responses in addition to their direct cell-killing effects
• Photodynamic therapy (PDT) — A light-based treatment in which a photosensitizing agent is administered intravenously and accumulates preferentially in tumor cells. During surgery, the pleural cavity is illuminated with a specific wavelength of light, activating the photosensitizer and generating reactive oxygen species that destroy the tumor cells. PDT is typically used as an adjunct to cytoreductive surgery to treat residual microscopic disease
• Targeted molecular therapies — Research is exploring drugs that target specific genetic alterations common in mesothelioma. BAP1 (BRCA1-associated protein 1) loss is found in approximately 60% of mesotheliomas and creates vulnerabilities that may be exploited by EZH2 inhibitors (tazemetostat) or PARP inhibitors. Other molecular targets under investigation include the mTOR pathway, VEGF/angiogenesis, and CDK4/6
• Cryotherapy/cryoablation — The use of extreme cold to destroy tumor tissue, either during surgery or through percutaneous (needle-based) techniques guided by imaging. Cryotherapy is being evaluated as a component of multimodal treatment and as a palliative intervention for localized tumor deposits

Eligibility for emerging mesothelioma treatments typically requires thorough diagnostic evaluation:¹

• Confirmed histological diagnosis — Tissue biopsy with immunohistochemical confirmation of mesothelioma type and subtype is required for clinical trial enrollment
• Molecular profiling — Increasingly, emerging therapies require or benefit from molecular testing. BAP1 status, PD-L1 expression, and other biomarkers may determine eligibility for specific trials or targeted therapies
• Staging workup — CT, PET-CT, and potentially MRI to determine disease extent and stage, which affects trial eligibility
• Performance status — Most clinical trials require patients to have adequate performance status (ECOG 0–1 or sometimes 0–2) to ensure they can tolerate investigational treatments
• Prior treatment history — Many trials specify whether patients must be treatment-naive or may have received prior therapies, and which prior therapies are permitted

Accessing emerging mesothelioma treatments typically involves the clinical trial system:⁴

• Clinical trial phases — Phase I trials test safety and dosing in small groups; Phase II trials evaluate efficacy and side effects in larger groups; Phase III trials compare the new treatment to the current standard of care in large, randomized studies. FDA approval typically requires positive Phase III results
• Trial identification — ClinicalTrials.gov lists all registered clinical trials. Mesothelioma specialty centers can identify appropriate trials based on the patient's specific situation. Some trials are available only at specific institutions
• Compassionate use/expanded access — For promising treatments not yet fully approved, the FDA's expanded access program may allow eligible patients to receive investigational drugs outside of clinical trials
• Combination strategies — Many emerging treatments are being tested in combination with established therapies (chemotherapy, immunotherapy) or with each other. The optimal sequencing and combination of these new modalities is a major area of active research

The impact of emerging treatments on mesothelioma prognosis varies by the specific therapy and its stage of development:²

• TTFields — The STELLAR trial showed median overall survival of 18.2 months with TTFields + chemotherapy, with a 1-year survival rate of 62%. This represents a meaningful improvement over historical chemotherapy-alone results
• Immunotherapy combinations — CheckMate 743 demonstrated median overall survival of 18.1 months with nivolumab + ipilimumab vs. 14.1 months with chemotherapy, with some patients achieving durable long-term responses
• CAR-T therapy — Early-phase results show promising tumor responses in some patients, but long-term outcomes data are still maturing
• Gene therapy and PDT — Phase I/II results show safety and preliminary efficacy signals, but larger trials are needed to define their role in mesothelioma treatment
• Overall trajectory — The combination of multiple new treatment modalities is gradually improving mesothelioma outcomes, with the greatest gains expected as these therapies are optimally combined with surgery, chemotherapy, and immunotherapy

Patients considering or undergoing emerging mesothelioma treatments should be aware of several practical considerations:⁴

• Travel requirements — Clinical trials may require travel to specialized treatment centers. Some trials offer travel assistance or telemedicine follow-up to reduce burden
• Side effect profiles — Emerging treatments may have unfamiliar or unexpected side effects. Close monitoring and open communication with the treatment team is essential
• Financial considerations — Clinical trials typically cover the cost of the investigational treatment, but associated costs (travel, lodging, standard-of-care procedures) may not be fully covered. Many cancer centers have financial counselors who can help navigate these costs
• Hope and expectations — While emerging treatments represent genuine progress, it is important to maintain realistic expectations. Not all investigational treatments prove effective, and clinical trial participation contributes to medical knowledge regardless of individual outcome
• TTFields practical considerations — For patients using TTFields, the device must be worn for at least 18 hours per day. The transducer arrays require regular replacement, and the device includes a portable battery pack for mobility