Atezolizumab Immunotherapy May Improve Preoperative Treatment for Pleural Mesothelioma

A doctor wearing blue gloves uses a small syringe to extract immunotherapy from a vial

Doctors may recommend chemotherapy before surgery for pleural mesothelioma. However, some patients may experience tumor progression during chemotherapy treatment. As a result, they could become ineligible for surgery. Patients who experience this may find it disheartening. Research shows treatment plans that include surgery can improve survival.

Researchers recently presented data that may help mesothelioma patients feel more confidence in pre-surgery treatment. In the study, pleural mesothelioma patients received chemotherapy and immunotherapy prior to surgery. This treatment regimen kept tumors from progressing for about one and a half years.

Immunotherapy and Chemotherapy Prior to Surgery Deemed Safe

The immunotherapy drug in this study is called atezolizumab. It is also known by its brand name, Tecentriq®. Atezolizumab has not been extensively studied in pleural mesothelioma. As such, researchers needed to evaluate atezolizumab’s safety before looking at its efficacy.

To do so, researchers only tested the new treatment approach. The new approach has not yet been compared to traditional pre-surgical chemotherapy.

Understanding Atezolizumab (Tecentriq®)

Atezolizumab is an immunotherapy drug. It belongs to a class of drugs called checkpoint inhibitors. Checkpoint inhibitors help prevent cancer cells from evading the immune system.

Atezolizumab interferes with the PD-L1 checkpoint. This allows the patient’s immune cells to target and kill cancer cells. Other immunotherapy drugs such as Opdivo® (nivolumab) also target this checkpoint.

The study plan called for all enrolled patients to undergo the same general treatment regimen:

  • Four cycles of chemotherapy treatment with immunotherapy: Chemotherapy consisted of pemetrexed and cisplatin. Immunotherapy consisted of atezolizumab (Tecentriq®).
  • Pleural mesothelioma surgery: Patients could undergo pleurectomy/decortication or extrapleural pneumonectomy.
  • Radiation therapy (optional): Patients who received extrapleural pneumonectomy could undergo radiation therapy after surgery.
  • Maintenance immunotherapy with atezolizumab: Patients could continue atezolizumab treatment for up to one year.

Doctors monitored patients closely for reactions related to atezolizumab. If no patients experienced certain severe side effects, the treatment approach would be considered safe.

At last follow-up, study patients had not experienced any severe side effects from atezolizumab. As a result, researchers determined this new treatment approach meets safety criteria.

Since the new regimen meets safety criteria, additional studies may compare the following:

  • Pleural mesothelioma patients treated with chemotherapy before surgery
  • Pleural mesothelioma patients treated with chemotherapy and atezolizumab before surgery

An additional study could determine if adding atezolizumab improves survival versus chemotherapy alone. The current study is not designed to make that determination. However, researchers are monitoring survival.

Note: All enrolled patients were deemed eligible for surgery at the time of enrollment. The study did not test this new treatment regimen in patients with inoperable pleural mesothelioma.

Researcher Calls Pre-surgical Atezolizumab With Chemotherapy “Rather Encouraging”

Researchers had been following study patients for about 20 months as of September 2021. At that time, the study had not yet reached a median survival. Thus, the median survival will be better than 20 months.

An earlier study found a median survival of 18 months for traditional cancer-directed pleural mesothelioma treatment. As such, this new approach may represent a substantial improvement once results are final.

Researchers also reported median progression-free survival (PFS). Median PFS is the point at which half of patients have experienced mesothelioma growth and half have not. Patients achieved a median PFS of 18.6 months with the new treatment regimen.

Boris Sepesi, MD, of The University of Texas MD Anderson Cancer Center is one of the lead researchers on the study. He recently spoke with The ASCO Post about these results. Dr. Sepesi called the performance of pre-surgical atezolizumab and chemotherapy “rather encouraging.”

However, Dr. Sepesi refused to even speculate about the regimen’s efficacy because the study is not yet complete. His position may remain unchanged even when the study wraps because it was not designed to evaluate efficacy.

Atezolizumab May Expand Treatment Options for Pleural Mesothelioma

Despite Dr. Sepesi’s tempered enthusiasm, mesothelioma patients may find this study “rather encouraging.” Doctors found atezolizumab safe as an addition to presurgical chemotherapy. In addition, the new treatment approach kept mesothelioma from progressing for about one and a half years.

Investigators will have to perform additional research to understand the efficacy of this new combination. In the meantime, patients may be able to access atezolizumab by participating in a clinical trial.

Any mesothelioma patient interested in a clinical trial should discuss treatment options with a doctor. A mesothelioma specialist can help the patient understand the best treatment approach for their situation.