Immusol confident in herpes-based viral therapy for cancer

SAN DIEGO—Immusol has entered into a license agreement with Baylor College of Medicine for the exclusive, worldwide rights to a novel oncolytic viral therapy using herpes simplex viruses (HSVs), which the company believes will be superior to adenovirus-based oncolytic viral therapies being worked on by other companies. The financial terms of the license agreement were not disclosed.

Baylor researchers have already been working in the area of oncolytic viral therapies against a wide variety of solid tumors, but this in-licensed therapy reportedly represents Baylor's most advanced viral therapy to date, having shown safety and strong efficacy in a number of preclinical animal tumor models. Immusol plans to file anINDfor treating solid tumors with the therapy later this year.

"The recent approval of the first oncolytic viral therapy for head and neck cancer by the Chinese state food and drug administration, together with the increasing number of clinical trials for oncolytic viral therapies worldwide signal the coming of age of oncolytic viral therapy as a new and important modality for cancer treatment," says Dr. Flossie Wong-Staal, Immusol's CSO and executive vice president of research and development. "We believe that the Baylor oncolytic viral therapy has significant advantages over many other oncolytic viruses, including higher potency and efficacy in metastatic tumors."

One of the reasons Immusol has high expectations for the viral therapy is because of the many advantages that an HSV-based therapy could offer.

"For one thing, HSV is much more aggressive in nature than adenovirus," says Dr. Zhu Shen, Immusol's senior director for business development. "It kills tumor cells at a faster rate and relatively low multiplicity of infection."

"Another benefit is that there is an antiviral therapy specifically for herpes that is on the market and approved," she adds. "So, we have this therapy available to terminate a viral treatment using HSV if there is any concern for safety. With adenovirus, you don't have that, and it's nice to have this added safety comfort with HSV-based therapy."

Also, several sensitive animal models exist that can mimic susceptibility patterns in humans with regard to HSV, which is not the case with adenovirus, Shen says. Furthermore, HSV has a larger genome, which leaves open the possibility to insert genes that could be synergistic with the viral therapy. Adenovirus' smaller genome makes such efforts more difficult.

"Another consideration is that the herpes virus is not highly immunogenic, as is the case with adenovirus," notes Wong-Staal.

There are challenges before Immusol can even get to human trials, though, much less a commercial product. Wong-Staal says that producing a virus is much more difficult than making a chemical compound, and the six-month minimum that is anticipated for initial production is the key limiting factor that could keep the company out of clinics until the end of this year.