Researchers at UC San Diego School of Medicine have found that palbociclib, a drug already FDA-approved for breast cancer, shows promise as a treatment for a specific type of appendix cancer. The findings, published in the Journal of Clinical Oncology, indicate that the drug is effective against peritoneal mucinous carcinomatosis (PMC) when the tumors have mutations in the GNAS gene.
The study involved 16 patients diagnosed with PMC, a rare cancer originating in the appendix that often resists standard chemotherapy. The research team, led by Andrew Lowy, MD, and Shumei Kato, MD, analyzed the genetic mutations within these cancers and observed that tumors with GNAS mutations responded favorably to palbociclib. In these patients, blood markers associated with cancer activity decreased in over 80% of cases.
Targeted Therapy for a Rare Cancer
"Finding that a breast cancer drug is successful in treating a subset of appendix cancer – where treatment options are currently limited – marks a significant advancement in our fight against this disease," said Dr. Lowy, professor in the Department of Surgery and chief of the Division of Surgical Oncology at UC San Diego School of Medicine. He emphasized that this represents the first targeted therapy for this rare cancer.
Appendix cancer is uncommon, accounting for less than 1% of all gastrointestinal cancers, with fewer than 2,000 cases diagnosed annually in the U.S., according to the American Cancer Society.
Mechanism of Action and Clinical Implications
Laboratory results indicated that palbociclib slowed or stopped the multiplication of cancer cells. This offers a potentially better-tolerated alternative to chemotherapy, which often causes severe side effects. Palbociclib inhibits cyclin-dependent kinases 4 and 6 (CDK4/6), which are involved in cell cycle progression. By targeting these kinases, the drug can halt the growth of cancer cells.
Immediate Implementation
"This medication can be implemented immediately without the need to wait for a new drug to be developed or for FDA approval," noted Dr. Kato, associate professor of medicine at UC San Diego School of Medicine. She also highlighted that the study underscores the value of repurposing existing cancer treatments.
Future Directions
The researchers plan to investigate whether combining palbociclib with traditional chemotherapies and newer targeted therapies could further improve its effectiveness. This approach could potentially offer more comprehensive treatment strategies for patients with GNAS-mutated appendix cancer.
Institutional Impact
"This groundbreaking study validates our unique position as the only National Cancer Institute (NCI)-designated Comprehensive Center in the region and our commitment to discovering and offering the most leading-edge treatment options," said Diane Simeone, MD, director of Moores Cancer Center at UC San Diego Health.
