CRYSTAL analysis shows clinical benefit of Erbitux in RAS wild-type mCRC patients

Merck Serono, the biopharmaceutical division of Merck, has announced new biomarker findings from a retrospective analysis of the completed Phase III study CRYSTAL that compared Erbitux® (cetuximab) plus FOLFIRI with FOLFIRI alone. The analysis involved a subgroup of patients with KRAS wild-type (exon 2) metastatic colorectal cancer (mCRC). A significant clinical improvement was observed in patients with RAS wild-type tumors when Erbitux was added to FOLFIRI in 1st line mCRC.¹ The new data will be presented at the 2014 American Society of Clinical Oncology (ASCO) Annual Meeting (May 30-June 3) during the Gastrointestinal (Colorectal) session on June 2, 2014 from 10:00 to 10:12 am. The results of this analysis reinforce Merck's commitment to improve patient care, and underpins Merck's leading role in the highly innovative area of personalized cancer care.

In this new analysis, 430 (65% of 666 patients) patient tumor samples with wild-type KRAS (exon 2) status were assessed for additional RAS mutations (defined as mutations in exons 3 or 4 of KRAS and/or exons 2, 3 or 4 of NRAS). Of these, 367 were RAS wild-type, while 63 presented a mutation. The analysis shows a 27.7% increase in response rate (RR), a 3.0-month increase in median progression-free survival (PFS), and an 8.2-month increase in median overall survival (OS) in mCRC patients with RAS wild-type tumors (n=367) receiving 1st line Erbitux plus FOLFIRI, compared with patients receiving FOLFIRI alone (RR: 66.3% vs. 38.6%, respectively; odds ratio: 3.11; 95% confidence interval [CI]: 2.03-4.78; p<0.0001; PFS: median 11.4 months vs. 8.4 months, respectively; hazard ratio [HR]: 0.56; 95% CI: 0.41-0.76; p=0.0002; OS: median 28.4 months vs. 20.2 months, respectively; HR: 0.69; 95% CI: 0.54-0.88; p=0.0024).¹

"The data from this analysis clearly demonstrate a clinical benefit from treating RAS wild-type metastatic colorectal cancer patients with Erbitux plus FOLFIRI, compared with FOLFIRI alone," said Dr Steven Hildemann, Global Chief Medical Officer and Head of Global Medical and Safety for Merck Serono. "This CRYSTAL analysis contributes to our evolving understanding of this disease, and confirms that RAS biomarker testing is essential for patient- centric care and a truly personalized approach to metastatic colorectal cancer."

"The new analysis from the CRYSTAL study is in line with the results seen from other studies with anti-epidermal growth factor receptor treatments in metastatic colorectal cancer patients with RAS wild-type tumors," said Professor Fortunato Ciardiello, Professor of Medical Oncology at the Seconda Università degli Studi di Napoli in Naples, Italy, and lead author of the CRYSTAL RAS analysis. "Importantly, these results reinforce that RAS testing should be conducted at the point of diagnosis in order to support physicians in selecting the most appropriate 1st line treatment for their mCRC patients."

In the patient group with either KRAS exon 2 mutations identified in the initial KRAS analysis (n=397) or other RAS mutations (n=63) receiving Erbitux plus FOLFIRI (n=246) no benefit was observed, compared with FOLFIRI alone (n=214) (RR: 31.7% vs. 36.0%, respectively; odds ratio: 0.85; 95% CI: 0.58-1.25; p=0.40; PFS: median 7.4 months vs. 7.5 months, respectively; HR: 1.10; 95% CI: 0.85-1.42; p=0.47; OS: median 16.4 months vs. 17.7 months, respectively; HR: 1.05; 95% CI: 0.86-1.28; p=0.64).1 This subgroup analysis confirms the findings of OPUS and other studies which have shown that patients with RAS mutations do not benefit from anti-EGFR therapy.

Following an update to the Erbitux label that was approved by the European Commission in December 2013, Erbitux is now indicated for the treatment of patients with epidermal growth factor receptor-expressing RAS wild-type mCRC in combination with irinotecan-based chemotherapy, in 1st line in combination with FOLFOX, or as a single agent in patients who have failed oxaliplatin- and irinotecan-based therapy and who are intolerant to irinotecan. Erbitux is contraindicated in combination with oxaliplatin-containing chemotherapy in patients with mutant RAS mCRC or for whom RAS mCRC status is unknown.²

About CRYSTAL

CRYSTAL (Cetuximab combined with iRinotecan in 1st-line therapY for metaSTatic colorectAL cancer) was a randomized, Phase III study involving 1,198 chemo-naïve patients with EGFR-expressing mCRC in Stage IV, of whom 666 had confirmed KRAS wild-type (exon 2) tumors. The study showed that progression-free survival, overall survival time and response rate were significantly better in patients with KRAS wild-type mCRC who received Erbitux plus FOLFIRI, compared with FOLFIRI alone.³