Imugene Ltd (ASX: IMU) shares are having a strong start to the session on Tuesday.

At the time of writing, the ASX 300 stock is up 11% to 4.9 cents.

Why is this ASX 300 stock jumping?

The catalyst for today's strong gain has been the release of a clinical trial update on its Phase 1 MAST (Metastatic Advanced Solid Tumours) trial. It is evaluating the safety and efficacy of novel cancer-killing virus CF33-hNIS (VAXINIA).

According to the release, a bile tract cancer patient in Imugene's Phase 1 MAST trial remains a complete response, now surpassing more than two years in remission.

In addition, the ASX 300 stock confirms that its Bile Tract Cancer Expansion part of the trial has now cleared its first cohort. This follows the first three patients being evaluated for safety and experiencing no dose limiting toxicities (DLTs). Management notes that it is now open for full enrolment of up to 10 patients.

It has been a big 12 months for VAXINIA. The company highlights that it received FDA Fast Track Designation in November 2023 for the clinical program and its treatment of Bile Tract Cancer. This allows for closer cooperation with the US FDA to expedite the program and the subsequent approval process, including potential for accelerated approval and priority review.

This was then complemented by the receipt of Orphan Drug Designation from the US FDA for VAXINIA's treatment of Bile Tract Cancer in September, which provides a range of incentives in addition to seven years market exclusivity upon FDA approval.

Patent extension granted

Also potentially giving the ASX 300 stock a lift is news that it has been granted a patent extension in the United States.

Imugene has received a patent extension to 2040 from the US Patent and Trademark Office (USPTO) for patent application number 16/324,541. This patent protects its oncolytic virotherapy CF33, including VAXINIA (CF33-hNIS) and CHECKVacc (CF33-hNIS-antiPDL1)

Commenting on both developments, the ASX 300 stock's CEO, Leslie Chong, said:

Imugene receiving this patent extension to 2040 from the US patent office is a significant milestone for the CF33 family of oncolytic viruses. The US is the core healthcare market, and we are delighted to strengthen the patent life.

We're also very pleased to see the two-year milestone reached for the Bile Tract Cancer patient who has maintained a complete response in our MAST study. Most importantly this is an outstanding result for the patient given the limited treatment options available, but also demonstrates the excellent potential of the CF33 oncolytic virus for this and other cancer types. We continue to enroll into the bile tract cancer expansion of the MAST trial.