A promising new case report may add to the list of benefits immunotherapy offers for mesothelioma patients. The report indicates immune checkpoint inhibitors (ICIs) may have the power to change a patient’s surgery eligibility. This could open new treatment options for patients historically considered ineligible for surgery.
ICIs have already improved many aspects of mesothelioma treatment. In one study, ICIs helped patients live longer, better lives compared to chemotherapy (chemo). These drugs work by blocking a process cancer cells use to evade the immune system. This allows the immune system to recognize and attack cancer cells. Unlike chemo, ICIs also work equally well for all three main mesothelioma cell types.
The new case report may mean ICIs can provide benefits to even more mesothelioma patients.
FDA-Approved Immunotherapy for Pleural Mesothelioma
In late 2020, the U.S. Food and Drug Administration (FDA) approved an immunotherapy drug combo for pleural mesothelioma. The drugs, Opdivo® (nivolumab) and Yervoy® (ipilimumab), are both ICIs. The mesothelioma patient in the new case report received Opdivo+Yervoy as his first treatment.
Doctors Treated Sarcomatoid Mesothelioma With Checkpoint Inhibitors
The new report describes one patient’s encouraging response to ICI treatment. The patient was 69 years old when he reported chest pain. After imaging tests and biopsies, doctors diagnosed him with stage 3 pleural mesothelioma. They also determined he had one of the rarest cell types: sarcomatoid mesothelioma. At the time of diagnosis, his case was considered inoperable.
Mesothelioma Cell Types
Mesothelioma occurs in three main cell types.
- Epithelioid mesothelioma: This is the most common mesothelioma cell type and responds best to treatment.
- Sarcomatoid mesothelioma: This is the least common mesothelioma cell type. Sarcomatoid tumors respond well to ICI treatment but not chemotherapy.
- Biphasic mesothelioma: This cell type is a mixture of epithelioid and sarcomatoid cells. Its response to treatment depends on how many of each cell type it has.
Instead of surgery, the doctors treated the patient for three months with Opdivo+Yervoy immunotherapy. In response, his tumor shrank by about half. This means the patient’s body cleared around 50% of the tumor cells. The cancer also did not spread during this time. These positive results convinced the doctors to reassess the patient’s surgery eligibility.
After checking again, the doctors found him eligible for a pleurectomy and decortication (P/D). Combining P/D with other forms of treatment often does the best job of improving pleural mesothelioma prognosis. During the operation, the surgeons were able to remove all visible tumor tissue from the patient.
After surgery, doctors sent the removed tumor tissue for testing. Less than 1% of the tested mesothelioma cells were still alive. That means the ICIs may have killed 99% of the patient’s tumor cells even before surgery.
At his last follow-up, the patient had no signs that the cancer had returned.
How Does This Compare to Other Treatments for Sarcomatoid Mesothelioma?
In the past, sarcomatoid mesothelioma patients generally had limited treatment options. Doctors had tried treating them with many approaches, including surgery. But they failed to improve survival for sarcomatoid patients. As such, many sarcomatoid cases were considered inoperable. This left patients with only one real option: chemo.
What Does Inoperable Mean?
Doctors may consider a patient’s cancer inoperable for a couple of reasons. In some cases, the tumor may be in or on important structures that make it impossible to remove safely. In other cases, past studies may indicate surgery would not be worth the risk because it cannot improve survival.
The most recent data on chemo for sarcomatoid patients comes from a clinical study. After receiving chemo, patients whose tumors had all or some sarcomatoid cells lived about nine months.
The 69-year-old patient from the new case study may have a good chance of surviving much longer than nine months. His ICI treatment lasted three months. Doctors last checked in on him five months after his surgery, and he had no signs of cancer.
That means ICIs plus surgery eliminated all outward signs of his mesothelioma. Eight months after diagnosis, the cancer had not returned. This could give him a shot at becoming a long-term mesothelioma survivor.
What Does This Mean for Current and Future Mesothelioma Patients?
The success of this case study means treatment standards may change in the near future. It provides evidence that ICI immunotherapy can change surgery eligibility. It also shows surgery can provide clear benefits for sarcomatoid patients. But the case study covers only one patient.
Additional studies may demonstrate these trends in larger groups of patients. If the trends hold, it is possible that:
- Surgery-based treatments may become more common for sarcomatoid mesothelioma.
- Pre-treatment with ICIs may become a way for patients to qualify for surgery.
- Established survival statistics for mesothelioma may substantially improve.
Some mesothelioma experts have already signaled their interest in related studies. Their research may help bring ICIs and surgery to more mesothelioma patients. Patients interested in this treatment should discuss it with their oncologists. The doctor can help them weigh the potential risks and benefits.