What Is Tumor Treating Fields (TTFields) Therapy?

How TTFields Work

Tumor Treating Fields (TTFields) represent a novel, non-invasive treatment modality that uses alternating electric fields at specific frequencies (150–200 kHz) to interfere with cancer cell division. The electric fields disrupt the formation of the mitotic spindle during cell division and cause abnormal cell membrane blebbing, leading to cell death. Because TTFields primarily affect dividing cells, they selectively target rapidly dividing cancer cells while having minimal impact on most healthy tissues.

The treatment is delivered through adhesive transducer arrays (electrode pads) placed on the skin of the torso. The arrays are connected to a portable battery-powered device that the patient carries in a shoulder bag or backpack, allowing treatment to continue during daily activities.

FDA Approval and Clinical Evidence

The FDA granted humanitarian device exemption (HDE) approval for the NovoTTF-100L system (marketed as Optune Lua) in May 2019 for treatment of unresectable malignant pleural mesothelioma in combination with standard pemetrexed-based chemotherapy. The approval was based on the STELLAR trial, a single-arm study of 80 patients.

The STELLAR trial demonstrated a median overall survival of 18.2 months with TTFields plus chemotherapy, compared to approximately 12 months with chemotherapy alone in historical controls. The one-year survival rate was 62%, and the treatment showed a manageable safety profile with the most common side effect being mild-to-moderate skin irritation beneath the electrode arrays.

What Treatment Involves

Patients prescribed TTFields therapy receive training from Novocure device specialists on array placement and device operation. The transducer arrays are applied to the shaved skin of the chest and back in a configuration optimized by treatment planning software. Arrays are replaced every few days to maintain skin health and signal quality.

For maximum effectiveness, the device should be worn at least 18 hours per day. Patients can remove the device for bathing and other brief periods. The portable design allows patients to maintain normal activities during treatment, including work and travel, though the device and arrays are visible under clothing.

Candidacy and Considerations

TTFields may be appropriate for patients with unresectable pleural mesothelioma who are receiving first-line pemetrexed-platinum chemotherapy. Patients with implanted electronic devices (such as pacemakers) near the chest may not be eligible. The treatment is not a substitute for surgery in patients who are surgical candidates.

Ongoing clinical trials are evaluating TTFields in combination with immunotherapy and in other treatment settings. Patients should discuss TTFields eligibility with their oncologist or a specialized mesothelioma center.

Access and Financial Assistance

TTFields therapy has associated costs for the device and ongoing supplies. Many insurance plans and Medicare cover the treatment, and Novocure offers financial assistance programs. Patients with asbestos-related mesothelioma may also pursue legal compensation to help cover treatment expenses. Contact Danziger & De Llano at 1-800-400-1805 to discuss your legal options.