Table 2. Summary of osimertinib resistance mechanism detected in 32 patients.
| Resistance mechanism | EGFR T790M status | Mutation status | Patient count |
|---|---|---|---|
| EGFR L718Q | T790M loss | Acquired | 1 |
| EGFR C797S | T790M maintain (in cis) | Acquired | 2 |
| EGFR C797S + EML4-ALK fusion + ERBB2 amp | T790M maintain (in cis) | Acquired | 1 |
| EGFR C797S + MET amp | T790M maintain (in cis) | Primary + acquired | 1 |
| BRAF V600E | T790M loss | Primary | 1 |
| BRAF V600E | T790M loss | Acquired | 1 |
| ERBB2 amp | T790M loss | Acquired | 1 |
| ERBB2 amp + PIK3CA E545K | T790M loss | Primary + acquired | 1 |
| KRAS G12V | T790M loss | Acquired | 1 |
| MET exon 14 skipping c.2887+96G>A | T790M maintain | Acquired | 1 |
| MET amp | T790M loss | Acquired | 2 |
| MET amp + TP53 M237I + RB1 c.1961-1G>C | T790M loss | acquired (TP53 LOH) | 1 |
| PIK3CA E545K, Q546P + TP53 H193R | T790M loss | Acquired | 1 |
| TP53 L257V | T790M loss | Acquired | 1 |
| TP53 E286K | T790M loss | Acquired | 1 |
| TP53 E198X + RB1 D604G | T790M loss | Acquired | 1 |
| TP53 Y220C + RB1 V190M, p.V193fs + PTEN T319fs | T790M loss | Acquired (TP53 LOH) | 1 |
| Unknown | T790M loss | 11 | |
| Unknown | T790M loss | 2 |
Amp, amplifications; LOH, loss of heterozygosity.