Table 1.
Results from NGS‐based mutation analysis prior to trastuzumab treatment and after resistance to treatment with trastuzumab
| Gene/biomarker | At baseline prior to trastuzumab treatment | After trastuzumab resistance: plasma sample | ||||
|---|---|---|---|---|---|---|
| Primary tumor tissue | Plasma sample | |||||
| Variation | Abundance | Variation | Abundance | Variation | Abundance | |
| ARID1A | p.Glu1958fs | 5.63% | p.Glu1958fs | 17% | p.Glu1958fs | 28.09% |
| FGFR1 | ND | amplification | 3.86 CN | amplification | 4.4 CN | |
| TP53 | p.Arg267Trp | 9.58% | p.Arg267Trp | 22.26% | p.Arg267Trp | 31.95% |
| HER2 | amplification | 31.58 CN | amplification | 27.31 CN | amplification | 21.4 CN |
| HER2 | ND | ND | c.1899‐1G>A | 6.67% | ||
| TMB | 2.4 mutations/Mb | 2.4 mutations/Mb | 6.3 mutations/Mb | |||
| MSI status | MSS | NA | NA | NA | NA | |
Abbreviations: CN, copy number; fs, frameshift; Glu, glutamic acid; Mb, megabase; MSI, microsatellite instability; MSS, microsatellite stability; NA, not applicable/not tested; ND, not detected; NGS, next‐generation sequencing; Pro, proline; Ser, serine; TMB, tumor mutation burden; Trp, tryptophan.