The National Cancer Center has launched a project to find patients with a rare type of lung cancer for clinical tests on a new drug that may be effective in combating the disease.
The rare cancer is caused by a genetic anomaly that occurs when a particular gene, called “ret proto-oncogene” or RET, fuses with another gene. The RET fusion gene is found in 1 percent to 2 percent of adenocarcinoma, the most common kind of lung cancer.
In 2012, research teams in Japan and other countries reported that the RET fusion gene greatly contributes to the growth of a type of cancer. They also reported that a drug called Vandetanib, used for treatment of certain tumors of the thyroid gland, hinders the role of the RET fusion gene and so may be effective in treating the lung cancer it causes.
“It is an important discovery originating in Japan and we wanted to bring the new drug to Japanese patients first of all,” Koichi Goto, head of the Thoracic Oncology Department at the NCC Hospital East and leader of the project, said in reference to the background of the program aimed at developing “individualized” treatment.
Vandetanib, which is already authorized overseas, and other drugs that block the growth of cancer by targeting specific genetic anomalies, are called molecular target drugs. For lung cancer, relatively common mutations, such as in the epidermal growth factor receptor, or EGFR, have been discovered and drugs targeting them have proved effective.
While interest is growing over the possible discovery of a molecular target drug for the RET fusion gene, studies have made little headway as the number of patients is small.
Although a number of genetic anomalies for lung cancer have been found in recent years, each occurs in under 5 percent of cases, Goto said. Even if basic studies discover substances considered effective in treatments, the shortage of patients prevents clinical tests that are indispensable to getting government approval for new drugs.
According to government data, some 73,000 people died of lung cancer in Japan in 2013. Assuming a frequency rate of the RET fusion gene of 1 percent, about 730 people were affected by the gene.
Because of this, Goto has sought the aid of medical institutions engaging in lung cancer treatments nationwide to screen patients so as to launch doctor-led clinical tests on Vandetanib.
The project will cover adult patients with advanced lung cancer free of EGFR mutations in cancer cells. Patients having the RET fusion gene may be able to participate in clinical trials.
While clinical tests will be conducted at the NCC and six other specialized institutions, the number of establishments involved in the screening work rose to 183 as of the end of October, from just 58 in February 2013, when the project started.
The project had 14 patients registered for clinical tests at the end of October. It plans to involve three more patients.
Clinical trials are due to be completed in March and will then be subject to yearlong follow-up studies, Goto said.
For clinical trials involving a small number of patients, there are no clear standards for results that warrant the authorization of a new drug as an effective therapy.
No country, including Japan, has a “clear answer” to the issue, Goto said. “But molecular target drugs for rare genetic anomalies will continue to increase and our clinical tests will undoubtedly serve as an important litmus test.”