Sherwood JL, Brown H, Rettino A, *et al*. Key differences between 13 KRAS mutation detection technologies and their relevance for clinical practice. *ESMO Open* 2017;2:e000235. 10.1136/esmoopen-2017-000235

Tables 3A and 3B have been amended to reflect the error in the use of reagents by the third-party laboratory (IMGM, Munich) for the ddPCR Q61H assay (see appendix). The therascreen® KRAS RGQ PCR Kit Q61 assay does not test for Q61H; the PrimePCR™ ddPCR™ Mutation Assay was not performed for Q61H due to an error at the participating laboratory. This was identified after publication, as referred to in the Letter to the Editor (<http://dx.doi.org/10.1136/esmoopen-2017-000294>). A new abbreviation "NP" = "not performed" has been added to explain that no ddPCR assay for codon Q61 was performed.

In the abstract, the corrected sentence now reflects a lower number of total data points (718 instead of 728) because of the removal of 5 data points for ddPCR p.Q61H mutation results for 100 mutant copies input and 5 data points for 50 mutant copies input, respectively. Overall 406/718 data points across all 13 technologies were identified correctly. The digital PCR assay (KRAS PrimePCR™ ddPCR™, Bio-Rad Laboratories) identified 70% (100 copies) and 65% (50 copies) of samples correctly.

The ddPCR results section is corrected to reflect that for codon Q61H, the incorrect PrimePCR™ KRAS mutation assay had been used (p.Q61H c.183A\>C instead of p.Q61H c.183A\>T assay): The PrimePCR ddPCR KRAS Mutation Assays were able to identify codon 12 and 13 mutations down to 1% with the 100 copy input. However, across both admixture and wild-type control samples the assay identified the incorrect mutation in nine different mutation/allele frequency combinations (see [table 3](#T1){ref-type="table"}). When performing the p.Q61H assay, a mistake was made and the incorrect reagent detection of c.183A\>C instead of c.183A\>T, was used. Therefore, table 3 and figure 1 reflect data only for codons 12 and 13.

###### 

*KRAS* mutation detection success by codon, concentration and technology for (A.) 100 mutant copies input, (B.) 50 mutant copies input and (C.) wild-type only.

  --------------------------------- -------------------------------- ---------------------------------------------- ------------ ---------------------------- --------------------- ----------------------------- ------------------------- --------------------------------------- -------------------- ------------------------------ -------------------- --------- -------
  \(A\)                                                                                                                                                                                                                                                                                                                                                                

                                    Nominal total copies of WT DNA   Real-time Quantitative PCR                     MALDI-TOF    Next Generation Sequencing   Droplet Digital PCR   Sanger Capillary Sequencing                                                                                                                                                        

  therascreen®\                     cobas® *KRAS* Mutation test      Idylla™ *KRAS* Mutation Test (Point of care)   iPlex® Pro   UltraSEEK™                   Thunderbolts™         Oncomine™\                    Sentosa® SQ NSCLC Panel   Ion AmpliSeq™ Cancer Hotspot panel v2   Trusight® Tumor 15   PrimePCR\                      ABI3730 Sequencing             
  *KRAS* RGQ PCR Kit                                                                                                                                                                Focus Assay                                                                                                          ddPCR Mutation Assays *KRAS*                                  

  p.G12C                            20                               ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD                          x NMD                     ✓ MD 14.3%                              ✓ MD 20.5%           ✓ MD 11.1%                     x NMD                *X* IMD   ✓ NMD

  10                                ✓ MD                             ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD 4.7%                     ✓ MD 6.6%                 ✓ MD 5.7%                               ✓ MD 5.7%            ✓ MD 4.8%                      ✓ MD                 ✓ NMD     

  5                                 ✓ MD                             ✓ NMD                                          ✓ MD         ✓ MD                         ✓ MD                  ✓ MD 3.7%                     ✓ MD 2.4%                 ✓ NMD 3.1%                              ✓ MD 2.6%            ✓ MD 2.7%                      ✓ MD                 ✓ NMD     

  1                                 ✓ NMD                            ✓ NMD                                          ✓ MD         ✓ MD                         ✓ MD                  ✓ NMD                         ✓ MD 0.5%                 ✓ NMD -                                 ✓ NMD 0.0%           ✓ NMD 0.0%                     ✓ MD                 ✓ NMD     

  0.5                               ✓ NMD                            ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  ✓ NMD                         ✓ MD 0.3%                 ✓ NMD -                                 ✓ NMD 0.0%           ✓ NMD 0.0%                     x NMD                ✓ NMD     

  p.G12D                            20                               ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD                          ✓ MD 17.2%                ✓ MD 19.6%                              ✓ MD 25.6%           ✓ MD 27.5%                     ✓ MD 31.1%           ✓ MD      ✓ NMD

  10                                ✓ MD                             ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD 11.4%                    ✓ MD 11.8%                ✓ MD 14.3%                              ✓ MD 13.2%           x NMD                          ✓ MD                 ✓ NMD     

  5                                 ✓ MD                             ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD 7.6%                     ✓ MD 5.8%                 ✓ MD 6.7%                               ✓ MD 5.1%            ✓ MD 7.3%                      ✓ MD                 ✓ NMD     

  1                                 ✓ NMD                            ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  ✓ MD 1.5%                     ✓ MD 1.2%                 ✓ NMD -                                 ✓ MD 1.0%            ✓ MD 1.6%                      ✓ MD                 ✓ NMD     

                                    0.5                              ✓ NMD                                          ✓ NMD        ✓ MD                         ✓ NMD                 ✓ MD                          ✓ NMD                     ✓ MD 0.6%                               ✓ NMD -              ✓ NMD 0.0%                     ✓ NMD 0.0%           x NMD     ✓ NMD

  p.G13D                            20                               ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD                          x NMD                     ✓ MD 13.9%                              ✓ MD 14.6%           ✓ MD 10.4%                     x NMD                ✓ MD      ✓ NMD

  10                                ✓ MD                             ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD 2.7%                     ✓ MD 7.4%                 ✓ MD 7.7%                               ✓ MD 8.6%            ✓ MD 6.4%                      ✓ MD                 ✓ NMD     

  5                                 ✓ NMD                            ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD 3.9%                     ✓ MD 3.1%                 ✓ MD 4.6%                               ✓ MD 1.6%            ✓ MD 3.8%                      ✓ MD                 ✓ NMD     

  1                                 ✓ NMD                            ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  ✓ NMD                         ✓ MD 0.9%                 ✓ NMD -                                 ✓ NMD 0.0%           ✓ NMD 0.0%                     ✓ MD                 ✓ NMD     

  0.5                               ✓ NMD                            ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  x NMD                         ✓ MD 0.4%                 ✓ NMD -                                 ✓ NMD 0.0%           ✓ NMD 0.0%                     x NMD                ✓ NMD     

  p.G12V                            20                               ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD                          x NMD                     ✓ MD 30.6%                              ✓ MD 39.4%           ✓ MD 27.8%                     x NMD                ✓ MD      ✓ NMD

  10                                ✓ MD                             ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD 5.9%                     ✓ MD 16.2%                ✓ MD 24.5%                              ✓ MD 15.6%           ✓ MD 13.6%                     x IMD                ✓ NMD     

  5                                 ✓ MD                             ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD 6.1%                     ✓ MD 8.1%                 ✓ MD 9.6%                               ✓ MD 8.3%            ✓ MD 8.5%                      ✓ MD                 ✓ NMD     

  1                                 ✓ MD                             ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ NMD                         ✓ MD 1.3%                 ✓ NMD 1.6%                              ✓ MD 1.4%            ✓ MD 1.5%                      ✓ MD                 ✓ NMD     

  0.5                               ✓ MD                             ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  ✓ NMD                         ✓ MD 1.0%                 ✓ NMD -                                 ✓ NMD 0.0%           ✓ NMD 0.0%                     x NMD                ✓ NMD     

  p.Q61H                            20                               NA                                             ✓ MD         ✓ MD                         ✓ MD                  ✓ MD                          x NMD                     ✓ MD 6.3%                               ✓ MD 7.8%            ✓ MD 1.1%                      x NMD                NP        ✓ NMD

  10                                NA                               ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  ✓ MD 2.3%                     ✓ MD 2.7%                 ✓ NMD 2.4%                              ✓ MD 3.0%            ✓ MD 4.3%                      NP                   ✓ NMD     

  5                                 NA                               ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  ✓ NMD                         ✓ MD 1.2%                 ✓ NMD 2.5%                              ✓ MD 1.8%            ✓ MD 1.5%                      NP                   ✓ NMD     

  1                                 NA                               ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ NMD                 ✓ NMD                         ✓ MD 0.2%                 ✓ NMD -                                 ✓ NMD 0.0%           ✓ NMD 0.0%                     NP                   ✓ NMD     

  0.5                               NA                               ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ NMD                 ✓ NMD                         ✓ MD 0.1%                 ✓ NMD -                                 ✓ NMD 0.0%           ✓ NMD 0.0%                     NP                   ✓ NMD     

  \(B\)                                                                                                                                                                                                                                                                                                                                                                

                                    Nominal total copies of WT DNA   Real-time Quantitative PCR                     MALDI-TOF    Next Generation Sequencing   Droplet Digital PCR   Sanger Capillary Sequencing                                                                                                                                                        

  therascreen® *KRAS* RGQ PCR Kit   cobas® *KRAS* Mutation test      Idylla™ *KRAS* Mutation Test (Point of care)   iPlex® Pro   UltraSEEK™                   Thunderbolts™         Oncomine™\                    Sentosa® SQ NSCLC Panel   Ion AmpliSeq™ Cancer Hotspot panel v2   Trusight® Tumor 15   PrimePCR\                      ABI3730 Sequencing             
                                                                                                                                                                                    Focus Assay                                                                                                          ddPCR Mutation Assays *KRAS*                                  

  p.G12C                            20                               x NMD                                          ✓ MD         ✓ MD                         ✓ MD                  ✓ MD                          x NMD                     ✓ MD 10.8%                              ✓ MD 19.8%           ✓ MD 13.1%                     x NMD                ✓ MD      ✓ NMD

  10                                ✓ MD                             ✓ MD                                           ✓ MD         ✓ NMD                        ✓ MD                  x NMD                         ✓ MD 5.8%                 ✓ MD 6.3%                               ✓ MD 7.1%            x NMD                          ✓ MD                 ✓ NMD     

  5                                 ✓ NMD                            ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  ✓ MD 2.1%                     ✓ MD 2.9%                 ✓ MD 3.3%                               ✓ MD 1.9%            ✓ MD 3.6%                      ✓ MD                 ✓ NMD     

  1                                 ✓ MD                             ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  ✓ NMD                         ✓ MD 0.6%                 ✓ NMD --                                ✓ NMD 0.0%           ✓ NMD 0.0%                     ✓ MD                 ✓ NMD     

  0.5                               ✓ NMD                            ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  ✓ NMD                         ✓ MD 0.4%                 ✓ NMD --                                ✓ NMD 0.0%           ✓ NMD 0.0%                     x IMD                ✓ NMD     

  p.G12D                            20                               x NMD                                          ✓ MD         ✓ MD                         ✓ MD                  ✓ MD                          x NMD                     ✓ MD 22.0%                              ✓ MD 16.6%           ✓ MD 23.2%                     x NMD                ✓ MD      ✓ NMD

  10                                ✓ MD                             ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD 9.3%                     ✓ MD 11.5%                ✓ MD 18.4%                              ✓ MD 8.4%            ✓ MD 9.7%                      ✓ MD                 ✓ NMD     

  5                                 ✓ MD                             ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD 5.0%                     ✓ MD 5.0%                 ✓ MD 5.2%                               ✓ MD 7.6%            ✓ MD 6.7%                      ✓ MD                 ✓ NMD     

  1                                 ✓ NMD                            ✓ NMD                                          ✓ MD         ✓ MD                         ✓ MD                  ✓ NMD                         ✓ MD 1.2%                 ✓ NMD 2.2%                              ✓ MD 1.9%            ✓ NMD 0.0%                     ✓ MD                 ✓ NMD     

  0.5                               ✓ NMD                            ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  ✓ NMD                         ✓ MD 0.3%                 ✓ NMD --                                ✓ MD 1.2%            ✓ NMD 0.0%                     x IMD                ✓ NMD     

  p.G13D                            20                               x NMD                                          ✓ MD         ✓ MD                         ✓ MD                  ✓ MD                          x NMD                     ✓ MD 13.0%                              ✓ MD 6.5%            ✓ MD 15.5%                     x NMD                ✓ MD      ✓ NMD

  10                                ✓ MD                             ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  x NMD                         ✓ MD 6.6%                 ✓ MD 6.6%                               ✓ MD 6.1%            ✓ MD 2.7%                      x IMD                ✓ NMD     

  5                                 ✓ MD                             ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD 2.8%                     ✓ MD 2.9%                 ✓ NMD 2.5%                              ✓ MD 2.0%            ✓ MD 2.6%                      ✓ MD                 ✓ NMD     

  1                                 ✓ NMD                            ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  ✓ NMD                         ✓ MD 0.8%                 ✓ NMD --                                ✓ NMD 0.0%           ✓ NMD 0.0%                     ✓ MD                 ✓ NMD     

  0.5                               ✓ NMD                            ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  ✓ NMD                         ✓ MD 0.4%                 ✓ NMD --                                ✓ NMD 0.0%           ✓ NMD 0.0%                     x IMD                ✓ NMD     

  p.G12V                            20                               x NMD                                          ✓ MD         ✓ MD                         ✓ MD                  ✓ MD                          x NMD                     ✓ MD 34.3%                              ✓ MD 46.9%           ✓ MD 29.6%                     ✓ MD 26.1%           ✓ MD      ✓ NMD

  10                                ✓ MD                             ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  x NMD                         ✓ MD 17.3%                ✓ MD 13.9%                              ✓ MD 15.3%           x NMD                          x IMD                ✓ NMD     

  5                                 ✓ MD                             ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  ✓ MD 5.1%                     ✓ MD 8.5%                 ✓ MD 12.2%                              ✓ MD 7.0%            ✓ MD 10.8%                     x IMD                ✓ NMD     

  1                                 ✓ MD                             ✓ NMD                                          ✓ MD         ✓ MD                         ✓ MD                  ✓ NMD                         ✓ MD 1.7%                 ✓ NMD --                                ✓ MD 1.8%            ✓ MD 1.8%                      x IMD                ✓ NMD     

  0.5                               ✓ MD                             ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  ✓ NMD                         ✓ MD 0.8%                 ✓ NMD --                                ✓ NMD 0.0%           ✓ NMD 0.0%                     ✓ MD                 ✓ NMD     

  p.Q61H                            20                               NA                                             ✓ MD         ✓ NMD                        ✓ MD                  ✓ MD                          x NMD                     ✓ MD 6.0%                               ✓ MD 10.3%           ✓ MD 4.5%                      x NMD                NP        ✓ NMD

  10                                NA                               ✓ MD                                           ✓ MD         ✓ MD                         ✓ MD                  x NMD                         ✓ MD 2.0%                 ✓ NMD 2.8%                              ✓ MD 3.7%            x NMD                          NP                   ✓ NMD     

  5                                 NA                               ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ MD                  ✓ NMD                         ✓ MD 1.7%                 ✓ NMD --                                ✓ MD 1.6%            ✓ NMD 0.0%                     NP                   ✓ NMD     

  1                                 NA                               ✓ NMD                                          ✓ NMD        ✓ NMD                        ✓ NMD                 ✓ NMD                         ✓ MD 0.4%                 ✓ NMD --                                ✓ NMD 0.0%           ✓ NMD 0.0%                     NP                   ✓ NMD     

  0.5                               NA                               ✓ NMD                                          ✓ MD         ✓ NMD                        ✓ NMD                 ✓ NMD                         ✓ MD 0.3%                 ✓ NMD --                                ✓ NMD 0.0%           ✓ NMD 0.0%                     NP                   ✓ NMD     

  \(C\)                                                                                                                                                                                                                                                                                                                                                                

                                    Number of copies                 Real-time Quantitative PCR                     MALDI-TOF    Next Generation Sequencing   Droplet Digital PCR   Sanger Capillary Sequencing                                                                                                                                                        

  therascreen® *KRAS* RGQ PCR Kit   cobas® *KRAS* Mutation test      Idylla™ *KRAS* Mutation Test (Point of care)   iPlex® Pro   UltraSEEK™                   Thunderbolts™         Oncomine™\                    Sentosa® SQ NSCLC Panel   Ion AmpliSeq™ Cancer Hotspot panel v2   Trusight® Tumor 15   PrimePCR\                      ABI3730 Sequencing             
                                                                                                                                                                                    Focus Assay                                                                                                          ddPCR Mutation Assays *KRAS*                                  

                                    20000                            ✓wt                                            ✓WT          ✓WT                          ✓WT                   ✓WT                           ✓WT                       ✓WT                                     ✓WT                  ✓WT                            x NMD                ✓ NMD     ✓WT

  10000                             ✓WT                              ✓wt                                            ✓WT          ✓WT                          ✓WT                   ✓WT                           ✓WT                       ✓WT                                     ✓WT                  ✓WT 0.0%                       x NMD                ✓WT       

  2000                              ✓WT                              ✓wt                                            ✓WT          ✓WT                          ✓WT                   ✓WT                           ✓WT                       ✓WT                                     ✓WT                  ✓WT 0.0%                       x NMD                ✓WT       

  1000                              ✓WT                              ✓WT                                            ✓WT          ✓WT                          ✓WT                   ✓WT                           ✓WT                       ✓WT                                     ✓WT                  x NMD                          ✓ NMD                ✓WT       

  500                               ✓WT                              ✓WT                                            ✓WT          ✓WT                          ✓WT                   x NMD                         ✓WT                       ✓WT                                     ✓WT                  x NMD                          x NMD                ✓WT       

  250                               ✓WT                              ✓WT                                            ✓WT          ✓WT                          ✓WT                   x NMD                         ✓WT                       ✓WT                                     ✓WT                  x NMD                          x NMD                ✓WT       
  --------------------------------- -------------------------------- ---------------------------------------------- ------------ ---------------------------- --------------------- ----------------------------- ------------------------- --------------------------------------- -------------------- ------------------------------ -------------------- --------- -------

✓ MD = analysis successful, mutation detected; ✓NMD = analysis successful, but no mutation detected (in the case of the Sentosa® assay, a mutation was detected but deemed to be below the defined cut-off); ✓WT = analysis successful, wild-type sample; X NMD = analysis unsuccessful, no mutation detected; X IMD = incorrect mutation detected; NA = kit does not assay codon; NP = not performed.

MALDI-TOF, Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry; PCR, polymerase chain reaction.
