(Reuters) - A targeted drug being developed by Pfizer Inc held advanced lung cancer in check longer than AstraZeneca's Iressa in newly diagnosed patients, but with a higher rate of side effects, according to data presented on Monday.
The late-stage study of 452 patients with EGFR-positive non-small cell lung cancer (NSCLC) compared Pfizer's next generation oral drug, dacomitinib, with the older standard treatment that also targets abnormal epidermal growth factor receptor genes in advanced lung cancer.
Dacomitinib delayed the cancer from worsening for 14.7 months compared with 9.2 months for Iressa, a measure known as progression-free survival, researchers reported. That translates into a 41 percent lower risk of cancer progression with the experimental medicine.
The data was presented at the American Society of Clinical Oncology meeting in Chicago.
With the increased potency, however, came stronger suppression of normal EGFR genes in healthy tissue in the skin and gastrointestinal tract, causing a higher rate of acne and diarrhea, researchers reported.
About 60 percent of patients receiving the Pfizer drug in the study had the dose lowered due to side effects. Liver enzyme abnormalities were the most common serious side effect observed in the Iressa patients.
Despite the higher rate of side effects, "the activity seen in this study should allow for consideration of this effective therapy in this patient population," Dr. Tony Mok from Chinese University of Hong Kong, who led the study, said in a statement.
Pfizer said it expects to discuss the data with regulatory authorities as it plans to seek approvals for the drug.
Boehringer Ingelheim already markets a next generation EGFR inhibitor for advanced NSCLC called Gilotrif (afatinib) that the Pfizer drug would compete with if approved.
Iressa, known chemically as gefitinib, was among the first targeted drugs that replaced chemotherapy as a treatment of choice for these patients.
About 140,000 patients worldwide and 15,000 in the United States are diagnosed each year with EGFR-positive NSCLC.
Reporting by Bill Berkrot; Editing by Phil Berlowitz