Background In the absence of comparative studies of cetuximab vs. panitumumab in metastatic colorectal cancer (MCCR), we suggested performing an indirect comparison of the two drugs for this indication.

Purpose To perform an adjusted indirect comparison of the two pivotal clinical trials of cetuximab and panitumumab, designed versus the best supportive care as a common comparator in patients with chemotherapy-refractory metastatic colorectal cancer.

Material and methods On 5/04/2014 a literature search was performed in PubMed without finding indirect comparisons.

The adjusted indirect comparison was performed with the results shown in subsequent updates of the pivotal clinical trials, in which subgroups of patients with K-RAS wild-type were analysed. We tested that the homogeneity of the population studied and the results of the treatment groups, were comparable with each other directly. Progression-free survival (PFS) was taken as the most clinically relevant variable available, as it allowed a proper comparison, although it was not the primary endpoint in either study. For our study we used the Bucher´s method, which combines the studies through analysis adjusted for the result of the control group. The Comparison Indirect Treatment (ITC) application, developed by the Canadian Agency for Drugs and Technologies in Heath (CADTH) was used. The margin of equivalence (the maximum difference considered clinically irrelevant) was defined.

Results In the adjusted indirect comparison by the Bucher method, using the Wells calculator, an insignificant Hazard Ratio (HR) was obtained for cetuximab vs. panitumumab, relative to PFS. Therefore, we have no objective evidence that one drug is superior to another. The HR: 0.933 is very close to 1, and CI95% 0.624–1.396. The margin of equivalence established (0.67–1.49) is exceeded only at the lower limit, affecting a probability of 94.65% that the result is above 0.67, a result obtained by the Shakespeare calculator.

Conclusion We consider that the two treatments might be considered as equivalent alternatives when referring to PFS in the third line.

References and/or acknowledgements No conflict of interest.