TransCode Therapeutics (RNAZ) said Thursday that the Safety Review Committee, monitoring its phase 1 clinical study, has unanimously approved to open a fourth group of patients based on "favorable" safety data from the three patients in group 3 for multiple metastatic cancers treatment.

The company is evaluating TTX-MC138 therapeutic candidate in its phase 1 clinical study to treat multiple metastatic cancers through antisense technology, it said. The dose for the fourth group will be roughly 50% higher than the dose given to the third group.

TransCode said it treated nine patients in the first three groups with TTX-MC138 and there were "no significant safety or dose limiting toxicities" seen during the first three groups, adding that six participants remain on trial for continued treatment.

The committee has also approved the enrollment of further participants in the third group to build upon the safety profile of TTX-MC138, TransCode added.

Shares of the company fell more than 6% in recent Thursday premarket activity.