Table 4.
Clinical efficacy of osimertinib treatment according to brain metastasis
| Efficacy | Total (n=19) | Both Mutyper and Cobas v2 (n=15) | Mutyper only (n=3) | Cobas v2 only (n=1) | p-value | Without BM (n=4) | With BM (n=15) | p-value |
|---|---|---|---|---|---|---|---|---|
| Type of response, n (%) | ||||||||
| Complete | 0 | 0 | 0 | 0 | 0.501 | 0 | 0 | 0.311 |
| Partial | 13 (68) | 11 (73) | 2 (67) | 0 | 4 (100) | 9 (60) | ||
| Stable disease | 5 (26) | 3 (20) | 1 (33) | 1 (100) | 0 | 5 (33) | ||
| Progression | 1 (5) | 1 (7) | 0 | 0 | 0 | 1 (7) | ||
| Best % change in target lesion from baseline, median (range) | −40.6 (−82.0 to 51.7) | −44.4 (−82.0 to 51.7) | −39.3 (−44.6 to −26.2) | - | 0.578 | −47.9 (−82.0 to −41.5) | −40.0 (−68.4 to 51.7) | 0.072 |
| Objective response rate, n (%) | 13/19 (68) | 11/15 (73) | 2/3 (67) | 0/1 (0) | 0.311 | 4/4 (100) | 7/13 (60) | 0.255 |
| ex19del | 10/11 (91)a) | 9/9 (100)b) | - | 0/1 (0) | 3/3 (100) | 7/8 (88) | ||
| L858R/L861Q | 3/7 (43)a) | 1/4 (25)b) | 2/3 (67) | - | 1/1 (100) | 2/6 (33) | ||
| G719A | 0/1 (0)a) | -b) | - | - | - | 0/1 (0) | ||
| Disease control rate, n (%) | 18/19 (95) | 14 (93) | 3 (100) | 1 (100) | 0.869 | 4/4 (100) | 14/15 (93) | > 0.99 |
| CNS responsec), n (%) | ||||||||
| Completed) | 4 (27) | 4 (33) | 0 | 0 | 0.754 | - | 4 (27) | - |
| Non-progression | 11 (73) | 8 (67) | 2 (100) | 1 (100) | - | 11 (73) | ||
| Progression | 0 | 0 | 0 | 0 | - | 0 | ||
| PFS, median (95% CI, mo) | 11.1 (0.0 to 26.7) | - | - | - | - | 19.2 (2.5 to 35.9) | 11.1 (7.4 to 14.8) | 0.459 |
| Time to response, median (95% CI, mo) | 1.7 (1.6 to 1.8) | - | - | - | - | 1.6 (1.6 to 1.8) | 1.7 (1.6 to 1.8) | 0.666 |
| Duration of response, median (95% CI, mo) | 17.6 (3.5 to 31.7) | - | - | - | - | 17.6 (0.6 to 34.6) | 9.3 (3.7 to 14.9) | 0.628 |
BM, brain metastasis; CI, confidence interval; CNS, central nervous system; ctDNA, circulating tumor DNA; PFS, progression-free survival.
a)
Results of the tissue-based test at diagnosis (p=0.032),
b)
Results of the ctDNA test at diagnosis (p=0.014). Discordant cases were excluded (n=2),
c)
All cases were evaluated as non-target lesions,
d)
No cases were treated with radiation to the brain.