Aspyrian Therapeutics Inc. said a new $40 million series B financing will help the company complete phase I/II trials of RM-1929, its experimental antibody-drug conjugate (ADC) for recurrent head and neck cancer and potentially for other cancers that have failed standard treatment. The financing was provided by Japanese billionaire Hiroshi Mikitani through his personal investment companies.

Mikitani is the CEO of the Tokyo-based online retailer Rakuten Inc. and an investor in numerous service companies and high-profile U.S. Internet businesses, including the Uber rival, Lyft. He is also a director on Aspyrian's board.

San Diego-based Aspyrian raised about $12.7 million in combined series A funds during 2015, according to SEC regulatory filings. With the additional funding it gains with the series B, it will not only accelerate the pace of RM-1929's development, but also expand its R&D activities with the goal of moving additional immunotherapies into the clinic.

"We are exploring new methods to engage and activate the immune system which, in conjunction with photoimmunotherapy, may result in a unique immunotherapy approach to safely and effectively treat both localized and metastatic cancers," said Miguel Garcia-Guzman, the company's president and CEO. Garcia-Guzman was unavailable for further comment on Thursday.

RM-1929 was developed in collaboration with photoimmunotherapy inventors Hisataka Kobayashi and Peter Choyke at the National Cancer Institute (NCI). It's an injectable formulation consisting of a chemical conjugate of the dye IR700 with the FDA-approved antibody, Erbitux (cetuximab, Eli Lilly and Co.). It targets epidermal growth factor receptor (EGFR) antigens. Aspyrian licensed the technology from the NCI.

The approach has potential applications in a number of different EGFR-expressing tumor types, including cancers of the esophagus, lung, colon and pancreas.

Treatment with photoimmunotherapy requires two steps. First, the drug is administered by infusion. Then, the patient's tumor is irradiated with near infrared light using sufficient energy to induce cell killing. Light irradiation is typically applied between 24 hours to 72 hours after drug administration to enable drug distribution within the tumor. The laser activation step can be done either on an outpatient basis by using external illumination or by needle placement of an optical fiber to illuminate a deep-seated tumor from within, the company said. Aspyrian has secured the exclusive license to use IRDye 700DX from Li-Cor, of Lincoln, Neb., for development of photoimmunotherapy products.

An actively recruiting phase I study aims to determine the safety and pharmacokinetics of RM-1929 administered by intravenous infusion using a single low energy localized light irradiation. Part two of the study will optimize the treatment by evaluating safety and clinical response using a fixed-dose level of RM-1929 – determined from part one and then moving on to a light escalation study using increasing amounts of energy directed at the tumor to optimize its anticancer effects.

Preclinical studies have shown that light-induced activation of RM-1929 elicits rapid tumor destruction of human cancer xenografts implanted in mice, improving progression-free survival and overall survival with better quality of life than when using existing standard-of-care approaches, the company said.