Oncologists can use colorectal cancer patients' own immune system to boost the effects of chemotherapy and increase progression-free survival, according to Phase III study results presented at the AACR 102nd Annual Meeting 2011, held here April 2-6.
Patients with advanced colorectal cancer are typically treated with combination chemotherapy with fluorouracil or the derivative product, capecitabine with or without levofolinic acid with irinotecan (FOLFIRI) or oxaliplatin (FOLFOX) given alone, or with the monoclonal antibodies bevacizumab, cetuximab or panitumumab.
"These combinations have been successful in inducing tumor regression, retarding disease progression and increasing overall survival. However, the average progression-free survival and overall survival are still no more than eight to 10 months and 20 to 22 months, respectively," said Pierpaolo Correale, M.D., Ph.D., an oncologist at the Siena University School of Medicine in Italy.
This study was started in 2005, before monoclonal antibodies were routinely used. Correale and colleagues added gemcitabine to FOLFOX followed by granulocyte-macrophage colony stimulating factor and low-dose aldesleukine (GOLFIG) to boost the immune system in an effort to fight cancer.
The researchers randomized 130 patients to receive GOLFIG or FOLFOX for a maximum of 12 cycles and then receive maintenance treatment until disease progression. The study was designed to follow the patients in both arms until death, but was ended early due to significantly better results seen with the GOLFIG regimen.
So far, the patients who received GOLFIG had a progression-free survival of 16.5 months compared with the 7.5 months recorded in those patients who received FOLFOX.
"Based on our experience and results to date, we believe that the GOLFIG regimen is superior to FOLFOX chemotherapy in terms of efficacy and comparable in terms of toxicity and cost," said Correale. "We were very surprised to find such a significant difference in terms of overall survival with this low number of patients."
The challenge for the future will be to compare GOLFIG regimen with regimens containing monoclonal antibodies, he said.
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