March 16, 2013 | by Hiu Chung So
Targeted drugs are often touted as the holy grail of cancer therapy because they're able to hone in and kill cancer cells while leaving normal cells unscathed. Or that’s how they're supposed to work.
Unfortunately for head and neck cancer patients, two such therapies fail to deliver on their promises, suggest the results of clinical trials published in separate studies in the Journal of Clinical Oncology on March 4.
The two tested drugs, erlotinib (Tarceva) and gefitinib (Iressa), both target epidermal growth factor receptors (EGFR); the malfunction of these receptors leads to cancer development. Although both drugs have shown efficacy against various other cancers — particularly nonsmall cell lung cancer — head and neck cancer patients taking these drugs in conjunction with standard chemotherapy did not exhibit any significant benefit compared to the group that underwent standard chemotherapy alone.
The results were a disappointment and a surprise to researchers and oncologists, because certuximab (Erbitux) – another EGFR inhibitor – has been shown to provide some benefit and is approved by the Food and Drug Administration for head and neck cancer patients.
Ellie Maghami, M.D., chief of City of Hope’s Division of Otolaryngology/Head and Neck Surgery, told MedPageToday that these contrasting data beg the question: "What’s the difference in the mechanism of action [between these drugs]?"
The findings also raise the possibility that other mechanisms might be in play, rending erlotinib and gefitinib ineffective, she said.
However, Maghami, who was not involved in either study, added: “What is clear is that head and neck cancers are very complex in a molecular setting,” and therapies might need to target multiple receptors and pathways to be effective.
An editorial in the same journal concurred: "Our current knowledge of EGFR as a therapeutic target in [head and neck cancers] is merely skimming the surface of a problem that is exceedingly complex."
According to the National Cancer Institute, there will be more than 50,000 cases of head and neck cancers diagnosed this year. Current standard treatment includes a combination of surgery, radiation therapy and chemotherapy. Follow-up with plastic surgery or rehabilitative therapy may also be needed to restore normal functions such as breathing, chewing, swallowing and speech.