Between July 1, 2014, and December 1, 2021, 304 patients with BRAF-altered NSCLC were identified at the First Affiliated Hospital of Zhengzhou University. Of these, 86, 4, 40, and 171 patients were diagnosed with stages I, II, III, and IV, respectively (Table 1). A total of 29 patients (9.5%) had brain metastases at the time of diagnosis of metastatic disease, and 23 patients (23.3%) presented with liver metastases at initial diagnosis. Most patients (286, 94.1%) were diagnosed with adenocarcinoma, and 224 patients (73.7%) were never smokers or light former smokers (< 10 pack-years). The median age was 64 years (27–98). These characteristics were consistent with the known clinical phenotype of BRAF-altered NSCLCs (16, 24, 27, 28). A total of 21 patients had KRAS mutations and BRAF mutations, congruent with previous studies, which reported that KRAS mutations were the most common with BRAF mutations. In addition, our data revealed that 11 patients had simultaneous EGFR sensitive mutations, including EGFR 19 exon deletion and 21 exon L858R and BRAF mutations, one patient with BRAF mutation and ALK fusion mutation, and one patient with BRAF mutation and CCDC6-RET fusion (Supplemental table 1). A higher proportion of patients in the treatment cohort had a light smoking history (< 10 pack-years) compared with patients in the full BRAF mutation cohort and immunophenotypic cohort (36% versus 17% and 12%, respectively). BRAF mutations were detected by NGS or PCR in 234 patients (77%) and 66 patients (21.7%), respectively, and four patients (1.3%) were tested by NGS and PCR simultaneously. BRAF V600E was the most commonly identified mutation in 196 patients (64.5%). Other common BRAF mutations, BRAF non-V600E mutations including BRAF G469A and BRAF K601E, were also tested (Fig. 1). The treatment regimens and drugs used in this study are summarized in Supplemental table 2.
Table 1
characteristics
|
total BRAF mutated (n = 304)
|
Immunophenotypic cohort (n = 263)
|
Treatment cohort (n = 41)
|
p Value
|
Age median(range), years
|
64 (27–98)
|
64 (27–98)
|
64 (37–81)
|
0.95
|
Sex
Male
Female
|
161(53.0)
143(47.0)
|
137(52.1)
126(47.9)
|
24(57.1)
17(42.9)
|
0.74
|
Smoking status
Never smoker
Light (< 10py)
Heavy (≥ 10py)
Not specified
|
221(72.5)
3(0.9)
67(22.3)
13 (4.3)
|
191(72.3)
2(0.8)
57(22.0)
13(4.9)
|
30(73.2)
1(2.4)
10(24.4)
0(0)
|
0.008
|
Histology
Adenocarcinoma
Squamous
Small cell
Adenosquamous
Sarcomatoid
Neurocrine
Large cell
Mucoepidermoid
Not specified
|
286 (94.1)
7 (2.3)
1(0.3)
4(1.3)
2(0.7)
1(0.3)
1(0.3)
1(0.3)
1(0.3)
|
249 (94.7)
4 (1.5)
1 (0.4)
3 (1.1)
2 (0.8)
1 (0.4)
1 (0.4)
1 (0.4)
1 (0.4)
|
37(90.2)
4(9.8)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
|
0.78
|
Stage
I
II
III
IV
NA
|
86(28.3)
4(1.3)
40 (13.2)
171(56.3)
3(1.0)
|
86(32.7)
3(1.1)
35(13.3)
136(51.7)
3(1.1)
|
0(0)
1(2.4)
5(12.2)
35(85.4)
0(0)
|
0.006
|
Brain metastases
Yes
No
NA
|
28(9.2)
182(59.9)
94(30.9)
|
22(8.4)
149(56.7)
92(35.0)
|
6(14.6)
33(80.5)
2(4.9)
|
0.004
|
ICI combined therapy
First line
Second or later line
|
|
|
25
16
|
|
Immunophenotype
PD-L1 expression was tested in 150 patients with BRAF-mutated NSCLCs (29 patients in the treatment cohort and 121 in the immunophenotypic cohort). Tumor PDL1 expression was low (< 1%), intermediate (1–49%), and high (≥ 50%) in 70 (46.7%), 58 (38.7%), and 22 (14.6%) patients, respectively (Table 2). TMB data were available for 38 patients with BRAF-mutated NSCLCs (11 in the treatment cohort and 27 in the immunophenotypic cohort). Of these, 28 patients had tumors with less than 10 mut/Mb (73.7%), and 10 patients (26.3%) had tumors ≥ 10 mut/Mb. To avoid comparing TMBs quantified from different NGS panels, we restricted the comparative analysis to the cohort of patients who had undergone NGS and TMB determination using MSK-IMPACT, which is the most frequently used panel. The median TMB of the BRAF-mutated lung cancers was 6.3 mut/Mb (0-27.92).
Table 2
PD-L1 expression and TMB status in BRAF mutated patients
|
Total BRAF mutated
|
Immunophenotypic cohort
|
ICI treatment cohort
|
p Value
|
PD-L1 expression TPS (%)
Negative (< 1)
Intermediate (1–49)
High (≥ 50)
|
n = 150
70(46.7)
58(38.7)
22(14.7)
|
n = 121
65(53.7)
42(34.7)
14(11.6)
|
n = 29
5(17.2)
16(55.2)
8(27.6)
|
0.01
|
PD-L1 expression TPS (%) median
|
17.31
|
15.04
|
26.58
|
0.18
|
TMB (muts/Mb)
Low (< 5)
Intermediate (5–10)
High (≥ 10)
|
n = 38
17 (44.7)
11 (28.9)
10 (26.3)
|
n = 27
13 (48.1)
13 (48.1)
1 (3.7)
|
n = 11
4(36.4)
6(54.5)
1(9.1)
|
0.09
|
TMB (muts/Mb)
Median (range)
|
7.3 (0-27.9)
|
0.7 (0-27.9)
|
9.2(2.1–20.1)
|
0.1
|
Efficacy
A total of 41 patients were administered ICI combinations. Of these, 24 patients were administered ICI combinations in the first-line setting, and 17 patients were administered ICI combinations in the later-line settings. Fifteen (36.6%, 95%CI, 21.2%-52.0%) of 41 patients whose responses were evaluable achieved an objective response at the data cutoff. The ORR in the 1st line was 41.7% (95%CI, 20.4%-62.9%), and the 2nd or later line was 29.4% (95%CI, 5.3%-53.6%); however, no statistical difference was observed in both groups (p = 0.52). The DCR of the 1st line was 75% (95%CI, 56.3%-93.7%) and the 2nd or later line was 58.8% (95%CI, 32.7%-84.9%) (p = 0.32) (Supplemental table 3 and Supplemental Fig. 1A and 1B). The PFS of all patients treated with ICIs is shown in Fig. 2A. The median PFS was 6 months (95%CI, 3.3–8.7) (Fig. 2B). The median OS for all ICI-treated patients was 21.9 months (95%CI, 17.8–26.1) (Fig. 2C). In the subgroup analysis, we found that the median PFS in the first-line treatment was numerically longer than that beyond 1st line (6 m versus 7 m, p = 0.40) (Fig. 3A). In addition, the median OS of patients who received ICI combined therapies in the first-line was significantly longer than that in the 2nd or later line (29 m versus 12m, p = 0.01) (Fig. 3B).
BRAF mutations are classified as BRAF V600E mutations and non-V600E mutations. Patients harboring BRAF V600E mutations could benefit from anti-BRAF targeted therapy. In the present study, the ORR for patients with V600E mutations was 36.0% (95%CI, 15.8%-56.2%), and the ORR for patients with non-V600E mutations was 37.5% (95%CI, 10.9%-64.1%) (Supplemental Fig. 1C and 1D). In addition, the best changes in the longest diameter of target lesions stratified by mutation status were illustrated in Fig. 3C. The median PFS for BRAF V600E mutations was 5 months (95%CI, 2.26–7.75), and the median PFS for BRAF non-V600E mutations was 10 months (95%CI, 1.56–18.45), however, no significant difference was observed (p = 0.74) (Supplemental Fig. 2A). Additionally, no difference was found in the OS between patients with BRAF V600E mutations and BRAF non-V600E mutations (Supplemental Fig. 2B).
The correlation of ICI efficacy with PD-L1 and TMB
Previous studies have demonstrated that PD-L1 expression and TMB are associated with ICI (29, 30). Hence, in the present report, we also evaluated prognostic biomarkers for the efficacy of ICI combined therapies in BRAF-altered NSCLC. The best changes in the longest diameter of the target lesions stratified by PD-L1 expression levels are depicted in Fig. 3D. No significant correlation was found in activities between PD-L1 expression levels (median 36% versus 18%, p = 0.06, Fig. 4A) or TMB (median 8.5 versus 7.3 mut/mb, p = 0.79, Fig. 4B) between responders (best response PR) and non-responders (SD/PD). In addition, no statistical correlation was observed between the maximum change in the sum of target lesions and TMB (r = 0.17, 95%CI, 0.29–0.83, p = 0.23, Fig. 4C) or PD-L1 levels (r = 0.004,95% CI, -0.46-0.35, p = 0.76, Fig. 4D). However, patients with higher PD-L1 expression appeared to have longer PFS (7 mons (PD-L1 ≥ 1%) versus 1.5 mons (PD-L1 < 1%), p = 0.004). No statistical difference was observed between TMB and PFS (Supplemental Fig. 3A and 3B). Additionally, no significant difference was found between OS and PD-L1 expression levels or TMB (Supplemental Fig. 3C and 3D).
Adverse events
A total of 28 patients treated with ICIs had documented adverse effects when administered ICI combined therapies (Supplemental table 4). Generally, there is a manageable toxicity profile in BRAF-mutated patients who received ICI combined therapies. The most common adverse events were hematologic toxicities, including neutropenia (39.3%), anemia (21.4%), and thrombocytopenia (14.3%); however, the incidence of severe adverse events (≥ grade 3) was 7.1%, 0, and 3.6%, respectively. In addition, nine patients (32.1%) developed mild liver injury. Only 3 patients developed interstitial lung disease, and 1 patient discontinued treatment due to interstitial lung disease. Other adverse effects, including gastrointestinal effects, skin effects, and hypothyroidism, are summarized in Supplemental table 4.