Predictive Molecular Tumour Testing: What Are the Obstacles between Bench and Bedside?

Table 1

Types of K-ras mutation performed in the pivotal clinical trials.

Author	Publication	K-ras mutation analysis	Validation and sensitivity
Peeters et al. [24]	Randomized Phase III Study of Panitumumab with Fluorouracil, Leucovorin, and Irinotecan (FOLFIRI) Compared with FOLFIRI Alone as Second-Line Treatment in Patients with Metastatic Colorectal Cancer	Blinded central laboratory using a validated K-ras mutation allele-specific PCR kit (DxS Ltd, Manchester, UK)^1	Validated sensitivity cutoffs not published
Amado et al. [12]	Wild-type KRAS Is Required for Panitumumab Efficacy in Patients with Metastatic Colorectal Cancer	Blinded central laboratory using a validated K-ras mutation allele-specific PCR kit (DxS Ltd, Manchester, UK)^1	Validated sensitivity cutoffs not published
Karapetis et al. [6]	K-ras Mutations and Benefit from Cetuximab in Advanced Colorectal Cancer	PCR K-ras analyses for exon 2 mutations in the Department of Clinical Biomarkers-Oncology at Bristol-Myers Squibb, Hopewell, N.J.	Validated sensitivity cutoffs not published
Van Cutsem et al. [25]	Cetuximab and Chemotherapy as Initial Treatment for Metastatic Colorectal Cancer	K-ras mutations in codons 12 and 13 with the use of a polymerase-chain-reaction (PCR) clamping and melting curve method	Sensitivity and validation published^2
Douillard et al. [5]	Randomized, Phase III Trial of Panitumumab with Infusional Fluorouracil, Leucovorin, and Oxaliplatin (FOLFOX4) versus FOLFOX4 Alone as First-Line Treatment in Patients with Previously Untreated Metastatic Colorectal Cancer	K-ras testing as per allele-specific polymerase chain reaction (DxS, Manchester, United Kingdom)	Sensitivity and validation published^3

(1) Identifies seven somatic mutations located in codons 12 and 13 (Gly12Asp, Gly12Ala, Gly12Val, Gly12Ser, Gly12Arg, Gly12Cys, and Gly13Asp).
(2) All relevant codon 12/13 K-ras mutations previously described detected. Sensitivity confirmed using a dilution series (up to 500-fold excess of K-ras wild-type DNA) of DNA derived from K-ras mutant and wild-type cell lines and on clinical FFPE CRC biopsies with tumor cell content <5%. Validated against specific cell lines with defined wild-type or K-ras mutations, and comparative analysis, using an alternative technique (DxS K-ras Mutation Detection Kit, DxS Ltd, Manchester, UK,)).
(3) External laboratory validated the assay for analytic/diagnostic performance, established acceptance criteria, and performed the K-ras analysis in a blinded fashion. Sensitivity parameters not published.