All-out assault on cancer works, new study finds
Research using multiple genetic drugs on tumours advances field of individualized medicine
Hitting cancer with an all-out salvo of genetically matched therapies works better than using them one at a time, according to a study led by UC San Diego researchers.
If the results are confirmed, it could change the standard of care for the worst of cancers. It would also represent an advance for the field of individualized medicine, which seeks to craft treatment plans for each patient.
In total, 83 patients were treated. Of those, 73 received matched therapy, usually with targeted drugs specifically developed for certain genetic abnormalities. The rest didn’t get any matched therapy, but received other treatments.
Of patients given drugs that matched more than half of tumour mutations, half responded. Of the remaining whose tumours were less well matched or totally unmatched, just 22 per cent responded.
Results from what is called the I-PREDICT study were published in the journal Nature Medicine.
All patients had lethal, metastatic cancers that had become resistant to previous treatments. They were treated at UCSD Moores Cancer Center and Avera Cancer Institute in Sioux Falls, S.D. Patients were followed until the disease progressed, they could no longer endure treatment or they died.
Researchers not involved with the IPREDICT study praised it, while cautioning that more work is needed.
“You have to do bigger and randomized trials,” said Dr. Ravi Salgia, a thoracic oncologist at City of Hope. “But this is a great first step to show that this is feasible.”
Hitting several mutations at once makes sense because cancers are often driven by more than one mutation, said John Carpten, director of the Institute of Translational Genomics at the University of Southern California.
“In this specific study, the authors were actually able to utilize multiple therapies and show that it can be a more effective approach,” he said.
Genetically matched therapy has resulted in notable advances over the years.
Beginning with such breakthrough treatments as the breast cancer drug Herceptin, a growing number of cancer drugs have been developed that target mutations that drive tumour growth. They have resulted in a number of remissions and cures of otherwise fatal cancers.
Usually, one genetically matched drug is given at a time, said Dr. Razelle Kurzrock, a study leader at UCSD Moores Cancer Center. When the cancer develops resistance, another therapy is given.
The one-at-a-time approach is intended to give patients repeated reprieves, prolonging their life. But the study indicated that patients respond even better and live longer with an all-out attack, Kurzrock said.
She likened the strategy to blocking off roads. The more blocked off, the harder it is to escape.
The current approach to genetically targeted cancer therapy sometimes produces poor results, said Dr. Jason Sicklick, also at UCSD Moores Cancer Center.
By contrast, the Nature Medicine study used multiple targeted drugs, including gene-targeted drugs and immunotherapy. The entire treatment program was personalized to each patient, Sicklick said.
“We reviewed the molecular signature of each person’s tumour individually and then crafted a treatment plan”