Tumor Treating Fields for Mesothelioma Faces Criticism

Tumor Treating Fields for mesothelioma is coming under fire from some other researchers.

The treatment uses electricity to interfere with division of cancer cells. The FDA approved it for mesothelioma last year under the Humanitarian Device Exemption. It is only the second treatment ever approved for asbestos cancer. 

But scientists in Italy and the Netherlands are disputing some of the findings from the STELLAR trial of TTFields. They published separate articles in a recent issue of The Lancet Oncology.

STELLAR tested Tumor Treating Fields along with chemotherapy as a novel mesothelioma treatment. The FDA based its approval on the STELLAR results. 

But the newly published articles suggest that there were problems with the trial. Both say Tumor Treating Fields is not ready for routine use in mesothelioma patients.

Patients Not Sick Enough

One criticism of TTFields for mesothelioma comes from researchers at the University of Siena in Italy. Dr. Marcella Barbarino and colleagues say patients in the STELLAR trial were not sick enough. 

More than half of the mesothelioma patients in the trial had a performance status of 0. Performance status tells how well a patient is able to perform their daily activities. The lower the status, the more functional a patient is.

“A better performance status is a pivotal prognostic factor in malignant pleural mesothelioma and certainly contributes to the long overall survival shown in this study,” writes Dr. Barbarino. 

The researchers also say some critical information is missing from the study. There is nothing about the asbestos exposure of study subjects. 

Giovani Ceresoli is the author of the Tumor Treating Fields study. He wrote a response to the criticism. Ceresoli says the performance status of STELLAR patients was in line with other current mesothelioma trials. 

He also points out that all the patients came from areas with high occupational or environmental asbestos exposure.

Questions About Survival Data with Tumor Treating Fields

The second published criticism of Tumor Treating Fields came from Cornedine Jannette de Gooijer of The Netherlands Cancer Institute. 

de Gooijer says Ceresoli and colleagues used out-of-date data. They based their  comparison of survival results on a landmark 2003 trial of mesothelioma chemotherapy. 

But mesothelioma survival has improved over time. de Gooijer and colleagues say, compared to more current trials, the survival advantage with Tumor Treating Fields is not very big. 

“The lack of difference with contemporary studies…makes it hard to appraise the data of the STELLAR,” de Gooijer writes. 

de Gooijer concludes that it is too early to start using Tumor Treating Fields for mesothelioma in daily practice. They recommend larger randomized studies to prove that the treatment works. 

Sources:

Ceresoli GL, et al, “Tumour Treating Fields in combination with pemetrexed and cisplatin or carboplatin as first-line treatment for unresectable malignant pleural mesothelioma (STELLAR): a multicentre, single-arm, prospective, phase 2 trial”, The Lancet Oncology, 2019; 20: 1702-1709

de Gooijer, CJ, et al, “Tumor Treating Fields for Mesothelioma”, Lancet Oncology, January 2020, https://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(19)30828-9/fulltext

Barbarino, M, et al, “Tumor Treating Fields for Mesothelioma”, Lancet Oncology, January 2020, https://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(19)30829-0/fulltext