On November 5, 2012, Response Genetics introduced two new testing kits. The kits are based on a groundbreaking that can help doctors predict a lung cancer patient’s response to the chemotherapy drug crizotinib.

The company already offered a similar line of products. However, when researchers introduced a new gene that was correlated with drug response, Response Genetics created a new line of products to incorporate the findings.

The newest kits search tissue samples for a gene known as ROS1.

They do not replace the existing tests, but were developed as a complement to them. Patients who have negative results on the previous tests may have a positive result with the new ROS1 kit.

Patients with a positive response on any of the tests are considered good candidates for crizotinib therapy.

“We believe it is our responsibility to help clinicians identify those patients that have the possibility of responding to XALKORI (crizotinib) by offering both established diagnostic tests … and the promising new gene translocation marker – ROS1,” the company states on its website.

ROS1 and Its Role in Lung Cancer

Everybody has the ROS1 gene, but some non-small cell cancer patients have an altered version.

The altered version contains active fusion proteins. These proteins can cause cancerous changes in other genes that control cell division, migration and metastasis.

Crizotinib can help inhibit this activity.

“This promising new marker is now readily available to pathologists and oncologists seeking fast turnaround time … on very small biopsies,” explained Response Genetics chairman and CEO Thomas Bologna.

Laboratory workers can identify the ROS1 gene in extremely small samples – including those from fine-needle aspirates.

Preclinical Research

Earlier in the year, researchers from the Massachusetts General Hospital Cancer Center discussed ROS1’s role in lung cancer treatment at the 2012 Clinical Science Symposium.

Their preliminary tests indicated the altered arrangements of the ROS1 gene was correlated with an excellent response to crizotinib. In patients with the rearranged ROS1 gene, crizotinib produced an overall response rate of up to 57.1 percent.

Researchers used one of the two tests now produced by Response Genetics to identify patients with the altered genetic pattern. They then assembled a group of 13 advanced non-small cell lung cancer patients with the altered ROS1 gene rearrangement.

Approximately 80 percent of the patients had already failed a first treatment regimen.

These patients then began a crizotinib regimen.

All patients received a standard oral dose of 250 mg. Patients participated in the treatment for four to 59 weeks, with a median duration of 20 weeks.

Overall, the patients responded well to the therapy.

Eight weeks into the study, the disease control rate was 85 percent. Six patients experienced a partial response, and one experienced a complete response. Only one patient had disease progression at the first re-staging; this patient was discontinued from the rest of the study.

The side effects of the chemotherapy were mild and well-tolerated in the study group. Only four of the patients developed grade three complications.

Moving Forward with ROS1 Research

The researchers are now enrolling patients for a phase I clinical trial to further investigate the gene’s role in predicting treatment response.

“We go to great lengths to help patients receive optimal therapy,” said Bologna.

Response Genetics’ older tests (based on a different gene) identified 3 to 5 percent and 1 to 2 percent of patients who could benefit from crizotinib. The new test could identify an additional 1 to 2 percent of patients who could be candidates for the chemotherapy drug.

This initially seems like a very small proportion of patients. However, with more than 226,000 new lung cancer cases diagnosed in 2012 alone, the new diagnostic tests could ultimately identify thousands of patients who could benefit from the potentially life-saving therapy.