Combining Immunotoxin and Chemotherapy for Pleural Mesothelioma
Name of the Trial
Phase I Study of SS1(dsFv)-PE38 Immunotoxin in Combination with Pemetrexed Disodium and Cisplatin in Patients with Unresectable Malignant Epithelial Pleural Mesothelioma (NCI-08-C-0026). See the protocol summary.
Dr. Raffit Hassan, NCI Center for Cancer Research
Why This Trial Is Important
Malignant mesothelioma is a rare cancer that affects the tissue lining the chest (pleura) or the abdomen (peritoneum). Based on the appearance of the cancer cells under a microscope, mesothelioma is classified as epithelial, sarcomatoid, or mixed; epithelial mesothelioma is associated with slightly better outcomes than the other types.
Patients with pleural mesothelioma (mesothelioma of the pleura) that cannot be removed by surgery (unresectable or inoperable) are usually treated with combination chemotherapy using the drugs pemetrexed and cisplatin. Although this therapy can delay progression of the disease, the benefits are often short lived and most patients die within 2 years.
Researchers hope an experimental immunotoxin called SS1(dsFv)-PE38 (or SS1P) can improve the outcomes of patients with unresectable mesothelioma. SS1P is a genetically engineered biological agent in which part of a bacterial toxin is linked to an antibody that recognizes the protein mesothelin. Mesothelin is found in abundance on the surface of epithelial mesothelioma cells and cells of several other types of cancer. In laboratory studies, combining SS1P with chemotherapy leads to increased antitumor activity compared to either therapy alone.
In this trial, patients with inoperable epithelial pleural mesothelioma will be given SS1P in combination with pemetrexed and cisplatin. The dose of SS1P will be increased in consecutive groups of 3-6 patients until the maximum tolerated dose is reached. Researchers will also study any side effects of this combination treatment and examine how SS1P is broken down by the body.
"Mesothelin is highly expressed in epithelial malignant mesothelioma, making it a good target for tumor-specific therapy with SS1P," said Dr. Hassan. "Given the marked synergy between SS1P and chemotherapy in preclinical studies, combining them could potentially result in increased antitumor activity in patients."