Gene-expression profiling of tumors may soon become a routine part of how an oncologist decides on the best way to treat an expanding number of malignancies. While many technologies are in early stages of clinical validation, few have made it to the market. As in the early days of 2-D electrophoresis, though, finding meaningful predictive differences in a sea of data remains elusive.
Increasing progress in validating multiple-gene signatures has reduced the firehose effect. In February 2007, the FDA okayed Agendia’s (www.agendia.com) MammaPrint for the prediction of breast cancer returning within 5 to 10 years from initial diagnosis. It became the first multivariate in vitro diagnostic assay to be approved by the agency.
Fifteen percent of stage 1 breast cancers recur, and among those patients with recurrences, chemotherapy will benefit a minority. Since oncologists can’t predict who will respond the most to chemo, standard practice is to prescribe it to all patients. Treatment regimens cost between $15,000 and $30,000 per patient and have serious side effects.
Companies are thus developing gene-signature tests that aid in identifying patients most likely to benefit from treatment for various types of cancers. Thus far insurance providers have been willing to pay for tests because they potentially save on chemotherapy costs.