Table 1.
Baseline Demographic, Clinical and Treatment Characteristics of Patients with Acquired T790M Mutation
| Characteristics | All Patients (n = 87) | Patients with T790M (n = 55) | p value* |
|---|---|---|---|
| Age, year | |||
| Mean (± SD) | 61.7 ± 9.7 | 61.5 ± 10.1 | 0.693 |
| Gender, No. (%) | |||
| Female | 50 | 33 (66.0) | 0.532 |
| Male | 37 | 22 (59.5) | |
| Ethnicity, No. (%) | |||
| Chinese | 68 | 41 (60.3) | 0.294 |
| Malay | 12 | 10 (83.3) | |
| India | 7 | 4 (57.1) | |
| Smoking history, No. (%) | |||
| Never smoker | 70 | 44 (62.9) | 0.887 |
| Former or current smoker | 17 | 11 (64.7) | |
| Baseline ECOG, No. (%) | |||
| 0–1 | 80 | 52 (65.0) | 0.244 |
| 2–4 | 7 | 3 (42.9) | |
| Tumour stage, No. (%) | |||
| IIIB | 8 | 5 (62.5) | 0.822 |
| IVA | 28 | 19 (67.9) | |
| IVB | 51 | 31 (60.9) | |
| Histology, No. (%) | |||
| Adenocarcinoma | 86 | 55 (64.0) | 0.187 |
| Large cell carcinoma | 1 | 0 (0) | |
| EGFR mutation subtype, No. (%) | |||
| Exon 19 deletion | 54 | 38 (70.4) | 0.077 |
| Exon 21 L858R point mutation | 33 | 17 (51.5) | |
| First-line EGFR-TKI treatment, No. (%) | |||
| Gefitinib | 57 | 40 (70.2) | 0.134 |
| Erlotinib | 14 | 6 (42.9) | |
| Afatinib | 16 | 9 (56.3) | |
| EGFR-TKI treatment before biopsy, No. (%) | |||
| 1st generation EGFR-TKI only | 60 | 38 (63.3) | 0.683 |
| 2nd generation EGFR-TKI only | 16 | 9 (56.3) | |
| 1st followed by 2nd generation EGFR-TKI | 11 | 8 (72.7) | |
| Best tumour response to EGFR-TKI, No. (%) | 0.008 | ||
| Partial response | 72 (82.8) | 49 (68.1) | |
| Stable disease | 15 (17.2) | 6 (40.0) | |
| Progression-free survival on EGFR-TKI, months | |||
| Median (95% CI) | 12.4 (10.9–13.9) | 12.6 (9.4–15.8) | 0.977 |
| Duration from EGFR-TKI initiation to re-biopsy, months | |||
| Median (95% CI) | 17.3 (12.2–22.4) | 18.5 (13.1–23.9) | 0.321 |
Notes: *Chi-Square test for categorical variables; independent t-test for continuous variables. Bold p value was statistically significant.
Abbreviations: ECOG, Eastern Cooperative Oncology Group; EGFR, epidermal growth factor receptor; TKI, tyrosine kinase inhibitor.