PEEL Therapeutics Developing Cancer Drug from Plant Toxin

August 24, 2020 – SALT LAKE CITY, UTAH – Researchers have modified a derivative of a plant toxin and linked it to a nanocarrier to create a powerful new therapeutic for childhood tumors. The new drug and its ability to eliminate chemoresistant tumors in mice is described in a new study published in Cancer Research, a journal of the American Association for Cancer Research. An exclusive license to develop the drug has been obtained by Peel Therapeutics, Inc.

Scientists from Children’s Hospital of Philadelphia (CHOP) have been testing the new cancer drug for several years in the laboratory to understand its potential to treat the most aggressive of childhood tumors. The drug is a derivative of camptothecin, a toxin isolated from the bark and stem of Camptotheca acuminata (Camptotheca, Happy tree) used for thousands of years for cancer treatment in Traditional Chinese Medicine. Camptothecin poisons cancer cells and has been chemically modified to make chemotherapies like irinotecan and topotecan, drugs used today to treat childhood solid tumors, pancreatic and colorectal cancer. CHOP researchers worked with a pharmacologically enhanced camptothecin derivative called SN22. Their newly engineered drug is made from multiple SN22 molecules reversibly linked to a biocompatible carrier fully eliminated by the body after delivering its payload.

In preclinical studies, this new drug accumulates in tumors 50 to 100 times more than irinotecan without causing toxicity or eliciting chemoresistance. Peel Therapeutics, a USA-Israeli biotech company, has licensed the new drug from CHOP to prepare an Investigational New Drug submission to the FDA. As highlighted in the paper, the engineered SN22 produced remarkably long-term remission in 80 to 100% of mice with drug-resistant tumors including neuroblastoma, Ewing sarcoma, and rhabdomyosarcoma. Many tumors completely disappeared after 4 doses and remained undetectable for over 6 months without ever returning. The CHOP study published in Cancer Research demonstrated that the drug is protected from enzymes that inactivate camptothecins and unaffected by cell transporters that pump out chemotherapies from cancer cells. Importantly for children, the paper describes that the engineered drug appears to have a better safety profile with less toxicities than irinotecan.

​PEEL Therapeutics CEO and Co-Founder, Dr. Joshua Schiffman, is a pediatric oncologist and expressed excitement for PEEL’s involvement with this new drug. “At Peel, we look for therapies inspired by evolution. The SN22 nanoparticle is the perfect example of a drug at the intersection of nature and technology. The increased delivery and decreased toxicities of this drug may offer very important advantages to patients with solid tumors, including children and adults.”