Medical College of Wisconsin researchers within the Froedtert & MCW Cancer Network are one of only three U.S. groups participating in an international clinical trial to test a new immunotherapy drug. The drug, called BI 1387446, will be used alone or with another immunotherapy agent to treat patients with metastatic cancer that has not responded to existing therapies. Metastatic cancer is cancer that has spread beyond where it started. Immunotherapy boosts the body’s immune system to combat cancer.
“The effectiveness of immunotherapy is about 30% in some cancers, which is likely not close to realizing its full potential,” said Jonathan Thompson, MD, MS, a hematologist/oncologist and MCW faculty member and researcher. “There needs to be another significant advance to improve that. The concept of drugs like BI 1387446, which is a STING agonist, has the potential to be among the most important strategies in cancer therapies for the next five years or so.”
Dr. Thompson became the primary investigator of the trial at Froedtert Hospital after the passing of Matthew Riese, MD, PhD.
Cancer tumors can be characterized as “cold” or “hot,” with the latter being more likely to respond to immune therapies. STING agonists turn cold tumors hot and draw immune cells to the tumor.
“A STING agonist causes lots of inflammation within the tumor and attracts an immune response,” Dr. Thompson said. “In preclinical models, even if it is injected into one tumor, it can generate an immune response in multiple sites of metastatic disease.”
The first part of the trial will focus on melanoma, where researchers will inject BI 1387446 into superficial lesions. The second part will expand to include any kind of metastatic cancer, with physicians using imaging to inject tumors deeper inside the body.
The study will test the STING agonist in combination with anti-PD-1 immunotherapy, which Dr. Thompson called the “existing backbone of immunotherapy.” Anti-PD-1 therapy blocks the ability of cancer cells to form a chemical shield that protects them from the body’s own immune system.
“We use the STING agonist to get immune cells into the tumor, then use the anti-PD-1 to increase their activity,” Dr. Thompson said. “It steps on the gas of T cells, which are part of the immune system and makes them work better than they normally would.”
The Phase I trial will evaluate the safety and dosage of the drug. It builds on basic research conducted at MCW in collaboration with Versiti Blood Center of Wisconsin. The drug’s manufacturer enlisted MCW researchers in the trial because of their experience in studying STING agonists.
“We emphasize that participation in a Phase I trial is largely altruistic,” Dr. Thompson said. “We’re not sure it will benefit patients, but it offers the potential of a new drug, and participants will be helping people who have the same kind of cancer down the road.”