Panitumumab has proven efficacy in patients with metastatic or locally advanced colorectal cancer patients, provided that they have no activating KRAS mutation in their tumour. Simvastatin blocks the mevalonate pathway and thereby interferes with the post-translational modification of KRAS. We hypothesize that the activity of the RAS-induced pathway in patients with a KRAS mutation might be inhibited by simvastatin. This would theoretically result in increased sensitivity to panitumumab, potentially comparable with tumours with wild-type KRAS. A Simon two-stage design single-arm, phase II study was designed to test the safety and efficacy of the addition of simvastatin to panitumumab in colorectal cancer patients with a KRAS mutation after failing fluoropyrimidine-based, oxaliplatin-based and irinotecan-based therapy. The primary endpoint of this study was the proportion of patients alive and free from progression 11 weeks after the first administration of panitumumab, aiming for at least 40%, which is comparable with, although slightly lower than, that in KRAS wild-type patients in this setting. If this 40% was reached, then the study would continue into the second step up to 46 patients. Explorative correlative analysis for mutations in the KRAS and related pathways was carried out. One of 14 patients was free from progression at the primary endpoint time. The median progression-free survival was 8.4 weeks and the median overall survival status was 19.6 weeks. We conclude that the concept of mutant KRAS phenotype expression modulation with simvastatin was not applicable in the clinic.
Departments of aClinical Oncology
bClinical Pharmacy and Toxicology
cPathology, Leiden University Medical Center
dDepartment of Internal Medicine, Diaconessenhuis Leiden, Leiden
eDepartment of Internal Medicine, Reinier de Graaf Hospital, Delft
fDepartment of Internal Medicine and Clinical Oncology, Haga Hospital, The Hague, The Netherlands
* Jara M. Baas and Lisanne L. Krens contributed equally to the writing of this article.
Correspondence to Jara M. Baas, MD, Department of Clinical Oncology, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands Tel: +31 71 526 3486; fax: +31 71 526 6760; e-mail: firstname.lastname@example.org
Received April 9, 2015
Accepted May 5, 2015