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A promising new trial is providing hope for patients with Bacillus Calmette-Guerin (BCG) unresponsive non-muscle invasive bladder cancer (NMIBC). Updated results from the CORE1 trial were presented at the 2022 Society for Immunotherapy of Cancer Annual Meeting.

While bladder removal surgery is the gold standard treatment for BCG unresponsive NMIBC, the trial’s aim is to find an alternative option to help patients keep their bladders while preventing cancers from coming back. It combines immune checkpoint inhibitors with an oncolytic virus, CG0070, that is genetically engineered to attack cancer cells. The solution containing the virus is infused into the bladder to ignite an immune response, and that response is in turn amplified by the immunotherapy treatment that releases the natural brakes on the immune system.

Patients were given six weekly infusions of the virus inside their bladders, followed by three weekly maintenance therapies given every three months in the first year and every six months in the second year. Patients also received an immune checkpoint inhibitor, pembrolizumab, every six weeks until year two.

“The oncolytic virus is thought to work through a two-pronged attack,” said Dr. Roger Li, a genitourinary surgeon at Moffitt Cancer Center and the CORE1 trial’s lead investigator. “First by targeting and destroying the cancer cells, and secondly, to stimulate an anti-tumor immune response.”

Dr. Roger Li, Genitourinary Oncology Program

Dr. Roger Li, Genitourinary Oncology Program

There were two previous clinical trials that were performed using CG0070: a phase 1 V006 trial and a phase 2 BOND2 trial. These trials proved the treatment to be safe and efficacious, laying the groundwork for the CORE1 trial.

Li says clinical trials in the BCG unresponsive setting have traditionally been difficult due to patient heterogeneity and disagreements over trial endpoints.

“Typically, patients with this disease have their bladders surgically removed,” said Li. “Thus, interpretation of the efficacy data on drugs that can be used inside the bladder to keep the cancers from coming back can be difficult.”

Now with completed enrollment of 35 patients in the CORE1 trial, researchers are starting to get a better idea of how efficacious and tolerable the treatment is.

“We’re seeing extremely promising preliminary results from this study,” said Li. “In the first 32 patients enrolled, 28 had derived a complete response, with over 70% of them maintaining that response until the one-year milestone. In comparison, pembrolizumab monotherapy has demonstrated response rates of 41% and 20%, strongly suggestive of the synergistic mechanism of action between it and the oncolytic virus.”