An experimental immunotherapy method has shown preliminary signs of activity against tumors that do not respond to other treatments. These results were presented at an international clinical trial conducted by scientists from the Princess Margaret Cancer Centre in Toronto and published today in the scientific journal Nature Medicine.
Lilian Siu, an oncologist and senior researcher from the Canadian center, stated that this study provides the first clinical evidence of the possibility of selectively activating T-cells relevant to tumors and generating anti-tumor activity. She made this statement in a release published by the University Health Network (UHN).
The researcher, who is also a professor of medicine at the University of Toronto, emphasized that the data obtained are preliminary and require confirmation in larger studies, but she considers the responses observed in some patients with limited therapeutic options encouraging.
The first phase of the START001 trial evaluated the experimental drug 'invikafusp alfa'. This drug is designed for the selective stimulation of two subgroups of T-lymphocytes, designated as Vβ6 and Vβ10, which constitute about 10% of immune system cells. According to researchers, this approach aims to concentrate the immune response specifically on cells potentially involved in fighting cancer, while avoiding excessive activation of the entire immune system. However, it has not yet been proven that this method reduces side effects.
Fifty-eight volunteers participated in the study across 10 oncology centers located in Canada, France, Spain, and the United States. The main analysis covered 52 patients with 21 different types of late-stage solid tumors. Among the 27 participants who were assigned doses for further study, four (14.8%) demonstrated an objective response, meaning a sufficient reduction in tumors to meet established clinical criteria.
In the same group, 12 patients (44.4%) recorded some degree of tumor reduction, including cases that did not meet the criteria for classification as an objective response. Regarding 18 patients whose cancers had stopped responding to previous immunotherapies, 12 of them (66.7%) achieved disease control, defined as tumor shrinkage or stabilization.
Positive reactions were noted across various types of cancer, including some forms of colorectal and lung cancer, in situations where existing immunotherapies may have limitations. Researchers also observed selective expansion of target T-lymphocytes in blood and tumors, but they stressed that the small size and diversity of the sample do not allow for definitive conclusions about efficacy, duration of response, or comparative safety.
Phase two of the trial is currently underway and is expected to provide new data on the anti-tumor activity of this treatment. The development of this drug is funded by Marengo Therapeutics, where Lilian Siu serves as a consultant and holds a capital stake.
