Merck Serono, a division of Merck KGaA, Darmstadt, Germany, today highlighted a further analysis of the large randomized Phase II OPUS study demonstrating an association between early tumor shrinkage and long-term median overall survival (OS) of more than 2 years for patients with KRAS wild-type metastatic colorectal cancer (mCRC) treated with Erbitux® (cetuximab) plus FOLFOX standard chemotherapy. This correlation was not seen in the chemotherapy-alone arm of the study. The study will be presented at the annual Gastrointestinal (GI) Cancers Symposium of the American Society of Clinical Oncology (ASCO).
“The latest long-term survival data from the OPUS and CRYSTAL studies, using the FOLFOX and FOLFIRI standard chemotherapies respectively, show that the strong tumor shrinkage of Erbitux directly translates into extended survival for patients.”
This latest analysis shows that the majority of patients (69%) with KRAS wild-type mCRC demonstrated tumor shrinkage of 20% or more in the first 8 weeks of 1st line treatment with Erbitux and FOLFOX. These patients experienced a long-term median OS of 26.2 months. Patients treated with FOLFOX chemotherapy alone whose tumors shrank by 20% or more in the same period (46%) experienced median OS of only 21.8 months.
These results support recent findings from the Phase III CRYSTAL trial, which found that early tumor shrinkage achieved with Erbitux in combination with FOLFIRI standard chemotherapy led to a long-term median OS of 2.4 years (28.3 months).
"The OPUS and CRYSTAL studies show, for the first time in colorectal cancer, that there is a correlation between early tumor shrinkage during the first weeks of treatment and extended survival. This effect seems to be unique to treatment with chemotherapy and Erbitux since a similar association was not observed with chemotherapy alone in this analysis, nor has it been proved for any other colorectal cancer treatment," said Professor Carsten Bokemeyer, lead investigator of the OPUS trial, Head of the Department for Oncology, Hematology and Bone Marrow Transplantation in the Center for Internal Medicine at the University Medical Center in Hamburg, Germany. "The result is both scientifically of extreme interest and immediately medically relevant for improving patient care through the personalized medicine approach with Erbitux."
Further Erbitux data to emerge from ASCO GI came from the randomized Phase II CORE.1.2.002 study that included 152 patients. The results showed that administration of Erbitux every second week in combination with FOLFOX resulted in sustained efficacy and safety in the treatment of mCRC patients with KRAS wild-type tumors, which were equivalent to the results demonstrated with the weekly administration. Response rates of 51% and 63% were seen in the weekly administration arm and in the arm where Erbitux was given every second week, respectively. There was no significant difference between the two arms.
"Results from both the CORE.1.2.002 and OPUS studies confirm the high activity of Erbitux with the standard FOLFOX oxaliplatin-based chemotherapy regimen," said Dr. Wolfgang Wein, Executive Vice President, Oncology, Merck Serono. "The latest long-term survival data from the OPUS and CRYSTAL studies, using the FOLFOX and FOLFIRI standard chemotherapies respectively, show that the strong tumor shrinkage of Erbitux directly translates into extended survival for patients."
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