Table 3.
Characteristics of the patients with stage IV lung cancer harboring uncommon mutation receiving a first-line tyrosine kinase inhibitor (TKI), classified by the drug susceptibility of EGFR mutation †.
| Single Sensitizing Uncommon Mutation | Multiple Sensitizing Uncommon Mutations | A Sensitizing Mutation and a Resistant Uncommon Mutation | Other Resistant Uncommon Mutations | p Value * | |
|---|---|---|---|---|---|
| n | 27 (47%) | 7 (12%) | 5 (9%) | 18 (32%) | |
| Age (year), mean ± SD | 67 ± 12 | 64 ± 11 | 77 ± 13 | 61 ± 10 | 0.0971 |
| Age (year), median (IQR) | 64 (56–78) | 63 (60–73) | 84 (75–85) | 64 (49–70) | 0.0971 |
| Age (year), n (%) | 0.3426 | ||||
| <65 | 14 (52%) | 5 (71%) | 1 (20%) | 11 (61%) | |
| ≥65 | 13 (48%) | 2 (29%) | 4 (80%) | 7 (39%) | |
| Sex, n (%) | 0.4195 | ||||
| Female | 17 (63%) | 4 (57%) | 1 (20%) | 10 (56%) | |
| Male | 10 (37%) | 3 (43%) | 4 (80%) | 8 (44%) | |
| Smoking history, n (%) | 0.0286 | ||||
| Never | 20 (74%) | 7 (100%) | 1 (20%) | 12 (67%) | |
| Current | 7 (26%) | 0 (0%) | 4 (80%) | 6 (33%) | |
| Performance status, n (%) | 0.1784 | ||||
| ECOG 0-1 | 21 (78%) | 6 (86%) | 3 (60%) | 9 (50%) | |
| ECOG 2-4 | 6 (22%) | 1 (14%) | 2 (40%) | 9 (50%) | |
| Number of metastatic sites, n (%) | 0.1168 | ||||
| =1 | 9 (33%) | 5 (71%) | 4 (80%) | 9 (50%) | |
| ≥2 | 18 (67%) | 2 (29%) | 1 (20%) | 9 (50%) | |
| Metastatic site, n (%) | |||||
| Brain | 7 (26%) | 1 (14%) | 1 (20%) | 5 (28%) | 0.9629 |
| Leptomeningeal | 0 (0%) | 0 (0%) | 0 (0%) | 2 (11%) | 0.3571 |
| Lung | 13 (48%) | 2 (29%) | 0 (0%) | 5 (28%) | 0.1805 |
| Bone | 18 (67%) | 2 (29%) | 1 (20%) | 9 (50%) | 0.1168 |
| Pleural | 15 (56%) | 3 (43%) | 3 (60%) | 8 (44%) | 0.8305 |
| Pericardial | 3 (11%) | 1 (14%) | 0 (0%) | 1 (6%) | 0.8033 |
| Liver | 7 (26%) | 0 (0%) | 0 (0%) | 2 (11%) | 0.3156 |
| Adrenal | 2 (7%) | 0 (0%) | 1 (20%) | 2 (11%) | 0.5715 |
| TKI medication, n (%) | 0.1599 | ||||
| Afatinib | 5 (19%) | 3 (43%) | 0 (0%) | 9 (50%) | |
| Gefitinib | 16 (59%) | 3 (43%) | 4 (80%) | 8 (44%) | |
| Erlotinib | 6 (22%) | 1 (14%) | 1 (20%) | 1 (6%) | |
| Initial response to TKI, n (%) | 0.0062 | ||||
| Partial response | 11 (41%) | 5 (71%) | 2 (40%) | 1 (6%) | |
| Stable disease | 12 (44%) | 1 (14%) | 2 (40%) | 7 (39%) | |
| Progressive disease | 4 (15%) | 1 (14%) | 1 (20%) | 10 (56%) | |
| Response rate to TKI | 11 (41%) | 5 (71%) | 2 (40%) | 1 (6%) | 0.0037 |
| Disease control rate with TKI | 23 (85%) | 6 (86%) | 4 (80%) | 8 (44%) | 0.0188 |
| Median PFS on TKI (month) | 7.7 | 13.5 | 72.5 | 3.1 | 0.0583 |
| Median OS (month) | 18.4 | 20.5 | 11.0 | 14.7 | 0.7754 |
* Kruskal-Wallis test or Fisher’s exact test or Log-rank test. † Mutation site classified by susceptibility: “Single sensitizing uncommon mutation” included exon18 G719X and exon21 L861Q; “multiple sensitizing mutations” included exon18 G719X + exon20 S768I, exon18 G719X + exon21 L861Q, and exon21 L858R + exon20 S768I; “a sensitizing mutation and a resistant uncommon mutation” included exon18 G719X + exon18 other and exon21 L858R + exon20 Q812*; “other resistant uncommon mutations” included exon 18 other mutation, exon 20 insertion, and exon 20 point mutation.