Patients Characteristics
There were 108 Osimertinib-treated advanced NSCLC patients recruited in this study, 14 of whom underwent LCT and the other 94 did not. There were 18.1% (17/94) of patients in non-LCT group and 8 patients in LCT group received Osimertinib as first-line treatment. Local consolidative therapy was performed at a median time of 2.2 months (range, 1.5-10.0 months) after Osimertinib initiation. Three patients received surgical resection (brain=1, lung=2), 3 received cranial radiotherapy (stereotactic radiosurgery=1, whole brain radiotherapy=2) and the other 8 received ablative extracranial radiotherapy (lung=4, lymph node=3, bone=1). Among the 4 patients receiving irradiation to the lung, stereotactic body radiotherapy was performed in 3 patients. The clinical characteristics of the enrolled patients at the time of developing oligo-residual disease were presented in Table 1. Patients with less metastatic lesions (p=0.018), receiving first-line Osimertinib treatment (p=0.003) and without lung metastasis (p=0.006), were more likely to receive LCT.
Table 1. Disease characteristics of patients in non-LCT group and LCT group
|
no-LCT (94)
|
LCT (14)
|
p value
|
Sex
|
|
|
0.63
|
female
|
54(57.4%)
|
9(64.3%)
|
|
male
|
40(42.6%)
|
5(35.7%)
|
|
Age (years)
|
|
|
0.36
|
Median (range)
|
62(38-83)
|
61(35-70)
|
|
Smoking
|
|
|
0.29
|
no
|
53(56.4%)
|
10(71.4%)
|
|
yes
|
41(43.6%)
|
4(28.6%)
|
|
T stage
|
|
|
0.30
|
T0-2
|
78(83.0%)
|
13(92.9%)
|
|
T3-4
|
16(17.0%)
|
2(7.1%)
|
|
N stage
|
|
|
0.36
|
N0
|
48(51.1%)
|
9(64.3%)
|
|
N1-3
|
46(48.9%)
|
5(35.7%)
|
|
EGFR mutation
|
|
|
0.49
|
19del
|
45(47.9%)
|
7(50.0%)
|
|
L858R
|
44(46.8%)
|
7(50.0%)
|
|
others
|
5(5.3%)
|
0(0.0%)
|
|
No. mets
|
|
|
0.018
|
≤2
|
42(44.7%)
|
11(78.6%)
|
|
>2
|
52(55.3%)
|
3(21.4%)
|
|
No. mets. organs
|
|
|
0.13
|
≤2
|
86(91.5%)
|
14(100%)
|
|
>2
|
8(8.5%)
|
0(0.0%)
|
|
Lung mets
|
|
|
0.006
|
no
|
31(33.0%)
|
10(38.0%)
|
|
yes
|
63(67.0%)
|
4(28.6%)
|
|
Bone mets
|
|
|
0.51
|
no
|
66(70.2%)
|
11(78.6%)
|
|
yes
|
28(29.8%)
|
3(21.4%)
|
|
Adrenal gland mets
|
|
|
1.00
|
no
|
89(94.7%)
|
14(100%)
|
|
yes
|
5(5.3%)
|
0(0.0%)
|
|
Brain mets
|
|
|
0.07
|
no
|
64(68.1%)
|
6(42.9%)
|
|
yes
|
30(31.9%)
|
8(57.1%)
|
|
LN mets
|
|
|
0.29
|
no
|
53(56.4%)
|
10(71.4%)
|
|
yes
|
41(43.6%)
|
4(28.6%)
|
|
Osimertinib
|
|
|
0.003
|
First-line
|
17(18.1%)
|
8(57.1%)
|
|
Second-line
|
77(81.9%)
|
6(42.9%)
|
|
Abbreviation: LCT, local consolidative therapy; No, number; mets, metastasis; LN, lymph node.
Survival Outcomes
With a median follow-up of 43.6 months (range, 9.3-114.1 months), 69 patients developed progressive disease. The median progression-free survival (PFS) of the whole cohort was 14.0 months. The median PFS of patients in the non-LCT group was 12.8 months and the median PFS of patients in the LCT group was not yet reached. 1-year and 3-year PFS rate were 85.7%, 54.5% for patients in the LCT group and 53.7%, 16.6% for patients in the non-LCT group, respectively. The difference of PFS between two groups was statistically significant (p=0.01, HR=0.48, 95%CI 0.27 to 0.88, figure 2). Sex (p=0.02, HR=2.71, 95%CI 1.14-6.42), T stage (p=0.01, HR=1.30, 95%CI 1.06-1.59) and LCT (p=0.004, HR=0.29, 95%CI 0.12-0.68) were found to be independent predictors of PFS (shown in table 2).
Table 2. Univariate and multivariate analysis of progression-free survival
|
|
Univariate analysis
|
Multivariate analysis
|
|
HR (95%CI)
|
p value
|
HR (95%CI)
|
p value
|
sex
|
1.79(1.12-2.89)
|
0.02
|
2.71(1.14-6.42)
|
0.02
|
Age(years)
|
0.84(0.52-1.35)
|
0.47
|
|
|
smoking
|
1.61(0.99-2.59)
|
0.05
|
0.59(0.24-1.44)
|
0.25
|
T stage
|
0.35(0.20-0.63)
|
<0.001
|
1.30(1.06-1.59)
|
0.01
|
N stage
|
0.95(0.59-1.52)
|
0.82
|
|
|
EGFR mutation
|
0.94(0.62-1.44)
|
0.78
|
|
|
No. mets
|
0.92(0.57-1.47)
|
0.72
|
|
|
No. mets. organs
|
0.51(0.22-1.18)
|
0.12
|
|
|
lung mets
|
1.26(0.77-2.06)
|
0.37
|
|
|
bone mets
|
1.55(0.94-2.55)
|
0.08
|
|
|
adrenal gland mets
|
2.49(0.90-6.91)
|
0.08
|
|
|
brain mets
|
1.38(0.85-2.27)
|
0.19
|
|
|
LN mets
|
1.14(0.70-1.84)
|
0.60
|
|
|
Osimertinib
|
0.73(0.42-1.27)
|
0.27
|
|
|
LCT
|
0.48(0.27-0.88)
|
0.02
|
0.29(0.12-0.68)
|
0.004
|
Abbreviation: LCT, local consolidative therapy; No, number; mets, metastasis; LN, lymph node.
By the time of data-cut off, 34 patients had died and the median OS was 77.1 months. The 1-, 3-, 5-year OS rate were 96.1%, 84.7% and 65.8%, in the entire cohort, retrospectively. Patients receiving LCT had a numerically longer overall survival (OS) (85.8 vs 77.1 months, p=0.58, figure 3) and after adjusting potential confounding factors using Cox analyses, LCT was associated with a non-significantly prolonged OS (HR=0.37, 95%CI 0.12-1.16, p=0.089) (shown in table 3).
Table 3. Univariate and multivariate analysis of overall survival
|
Univariate analysis
|
Multivariate analysis
|
|
HR (95%CI)
|
p value
|
HR (95%CI)
|
p value
|
sex
|
1.78(0.90-3.52)
|
0.09
|
1.30(0.62-2.73)
|
0.49
|
age(years)
|
0.66(0.33-1.32)
|
0.24
|
|
|
smoking
|
1.45(0.71-2.89)
|
0.29
|
|
|
T stage
|
0.27(0.12-0.57)
|
0.001
|
0.29(0.12-0.70)
|
0.006
|
N stage
|
0.53(0.26-1.06)
|
0.07
|
0.55(0.26-1.16)
|
0.12
|
EGFR mutation
|
1.25(0.67-2.34)
|
0.48
|
|
|
No. mets
|
0.99(0.51-1.99)
|
0.99
|
|
|
No. mets. organs
|
0.27(0.09-0.77)
|
0.02
|
1.01(0.27-4.30)
|
0.92
|
lung mets
|
1.91(0.89-4.10)
|
0.09
|
2.0(0.72-6.99)
|
0.11
|
bone mets
|
0.95(0.46-1.95)
|
0.89
|
|
|
adrenal gland mets
|
1.94(0.46-8.17)
|
0.35
|
|
|
brain mets
|
1.68(0.84-3.36)
|
0.14
|
|
|
LN mets
|
2.05(1.02-4.10)
|
0.04
|
1.80(0.82-3.96)
|
0.15
|
Osimertinib
|
1.07(0.31-3.71)
|
0.91
|
|
|
LCT
|
1.39(0.43-4.52)
|
0.58
|
0.37(0.12-1.16)
|
0.09
|
Abbreviation: LCT, local consolidative therapy; No, number; mets, metastasis; LN, lymph node.
Patterns of treatment failure
There were 67% (63/94) of patients in non-LCT group suffered Osimertinib treatment failure. Among them, 55.6% (35/63) of patients developed progressive disease only at the originally existed residual lesions (termed as original failure), 23.8% (15/63) of patients developed progressive disease only at distant new sites (termed as distant failure) and the rest (20.6%) patients developed progressive disease at both sites (termed as mixed failure). The most common sites of progressive disease were brain (21.6%), lung (16.2%), bone (16.2%) and lymph node (14.9%). Additionally, 27.0% (17/63) of patients with progressive disease received certain kind of salvage local therapy. Of note, 21 of the 30 patients with oligo-residual cranial lesions who didn’t receive LCT had progressive disease, 10 of whom developed progressive disease in the brain. Moreover, 7 of the 10 patients developed more than 5 progressive cranial lesions after Osimertinib treatment failure. Salvage brain radiotherapy were performed in 4 of the 7 patients, all of which were whole brain radiotherapy (WBRT).
There were totally 6 patients in the LCT group suffered failure. The failure patterns included brain (3/6 patients), bone (17%) and primary lesion (33%). 4 of 6 patients were original failure and the others were mixed failure. The details of the patterns of treatment failure for two groups were shown in figure 4.