Researchers relied on mice with group 3 medulloblastoma grown from patient tumors. The mice were developed in Roussel’s laboratory and are a powerful tool for testing the effectiveness of drugs against human tumors. Researchers used the mice to show that pemetrexed and gemcitabine worked against human group 3 tumors and that the drugs could be used in combination with existing chemotherapy agents to boost treatment effectiveness without undue risk. Cisplatin and cyclophosphamide were the other drugs used in this study.
“The finding provides a strong rationale for combination therapy with pemetrexed and gemcitabine for treatment of group 3 medulloblastoma,” Roussel said. Researchers found no evidence that mouse tumor cells develop resistance to the drugs.
Pemetrexed works by disrupting the ability of cancer cells to proliferate. Gemcitabine kills cells by triggering their suicide pathway. Researchers also found evidence the drugs work specifically against group 3 medulloblastoma. The drugs did not extend survival of mice with a different medulloblastoma subtype.
The study builds on previous St. Jude research that has helped to revolutionize understanding of the origins of medulloblastoma and laid the foundation for a new era of risk-based therapy. The goal is to maximize the likelihood of a cure and minimize long-term side effects. The approach combines clinical factors and the molecular markers associated with the different medulloblastoma subtypes to guide how radiation and chemotherapy are combined with surgery.