Personalised medicine is coming of age with many products in the pipeline and growing interest in political and business circles. Benitec (OTCPK:BNIKF, OTCPK:BTEBY) is one company hoping to take advantage of this renewed interest in the field through its application of DNA-Directed RNA Interference (ddRNAi) technology - a technology designed to turn off errant genes.
Amongst other indications, Benitec is using the technology to develop a treatment for Non-Small Cell Lung Cancer (NSCLC). This cancer is noted for developing chemotherapy resistance and is particularly difficult to treat. Benitec's answer is Tribetarna, an agent that re-sensitizes NSCLC tumor cells to chemotherapy by silencing the betalll tubulin gene (TUBB3) in the tumor cells. After treatment, the patient continues with standard chemotherapy and this reduces or removes the tumor.
One study has shown 16 out of 34 NSCLC patients had tumor cells containing betalll tubulin (a protein naturally occurring in neural cells but not in lung tissue). Many studies have shown that a high concentration of this protein in tumor cells is closely related to a high rate of chemotherapy insensitivity and a poor prognosis. Preclinical work by Benitec has shown that silencing the TUBB3 gene leads to re-sensitivity to chemo agents and significantly extends survival times. Tribetarna, thus has great potential but not it is not necessarily going to be effective for every NSCLC sufferer.
In discussions with Benitec the FDA recommended that, in order to improve the targeting of Tribetarna, the company develop a companion diagnostic test to screen patients suitable for the treatment. Benitec turned to Pharmaxis to help it design and develop this test and assigned its Chief Medical Advisor to assist on the program.
A Life Sciences Connect article published yesterday shows that the issues surrounding companion diagnostic tests are by no means clear cut. On this blog I have already mentioned the FDA 510(k) approval process for such a test and now I want to consider how much Benitec needs to re-invent the wheel in order to satisfy FDA diagnostic requirements.
Pharmaxis is developing tests for other lung indications but, to the best of my knowledge, it has yet to produce a test for NSCLC. If this is correct, then the team is developing Benitec's companion test from the ground up. This may prove to be a good strategy as the FDA has not linked the need for a test to the clinical trial of Tribetarna. In other words, the lack of a test need not delay the start of a clinical trial for Tribetarna. However, there are other companies that are already well advanced in the development of tests for lung cancer and so I wonder if it would not be more prudent to enquire about possibly modifying these existing tests to look for betalll tubulin biomarkers?
Gensignia has developed a blood test to confirm lung cancer.
"The experimental test is noninvasive; it only requires a blood sample, rather than a potentially painful and risky biopsy. By analyzing molecules called microRNA in a patient's blood, physicians can determine if the abnormality detected on a scan is truly lung cancer. In a large validation study, combination of the microRNA test and low-dose CT resulted in a five-fold reduction of false-positive screening rates (from 19.4% to 3.7%)."
While this test is not directly applicable to the work being carried out by Benitec, it is clearly further advanced than the work currently being done by the company and may have the potential for suitable modification.
Of more interest is the work being done by Trovagene. Trovagene's Precision Cancer MonitoringSM seems ideally suited to Benitec's needs. As tumor cells die, DNA is released into the patient's blood and is filtered by the kidneys into the patient's urine. Trovagene's technology can detect this circulating tumor DNA in blood and urine samples.
The company has recently announced a clinical collaboration with the City of Hope (also a Benitec collaborator) to track EGFR oncogene mutations in NSCLC patients.
"Tracking various alterations in the EGFR oncogene, particularly emergence of the T790M mutation, has potential to improve therapeutic strategies for treating patients with non-small cell lung cancer," said Mihaela Cristea, M.D., lead investigator and associate professor, City of Hope Lung Cancer and Thoracic Oncology program. "We look forward to evaluating Trovagene's molecular diagnostics for the monitoring of circulating tumor DNA found in both urine and blood, with the goal of delivering highly personalized cancer treatment to improve patient outcomes."
As Tribetarna is a ddRNAi based treatment that targets the TUBB3 gene it would seem that the test could be modified to detect this DNA in a patient's urine. If this is correct, then it would seem to me that rather than re-inventing the diagnostic wheel, Benitec's management may be better off trying to engage with Trovagene. Such a partnership could save both time and money and could avoid some of the issues referred to in the Life Sciences Connect article.
Disclosure: The author is long BNIKF.
Additional disclosure: This article is not intended to be investment advice. Readers should do their own research.