Anti-tumor efficacy
Three studies compared the OS of the alectinib group versus the crizotinib group (heterogeneity: I2 = 55%, P = 0.02). The OS of the alectinib group was better than that of the crizotinib group (HR: 0.66, 95% confidence interval [CI]: [0.47–0.92], p = 0.02; Fig. 2). The OSR at all time points tended to favor the alectinib group but was not statistically significant (OSR-6 m, RR: 0.97, [0.91–1.04], p = 0.36; OSR-12 m, RR: 0.89, [0.79–1.02], p = 0.09; OSR-18 m, RR: 0.83, [0.68-1.00], p = 0.05; OSR-24 m, RR: 0.74, [0.50–1.09], p = 0.13; and OSR-30 m, RR: 0.76, [0.52–1.11], p = 0.16; Figure S2). With prolonged survival, the OS advantage of alectinib increased compared with that of crizotinib (Fig. 3A and Figure S3A).
Three studies compared the PFS of the alectinib group versus the crizotinib group (heterogeneity: I2 = 56%, P = 0.10). The PFS of the alectinib group was better than that of the crizotinib group (HR: 0.35, [0.25–0.49], p < 0.00001; Fig. 2). The PFSR at all time points significantly favored the alectinib group (PFSR-6 m, RR: 0.87, [0.81–0.95], p = 0.0009; PFSR-12 m, RR: 0.63, [0.55–0.72], p < 0.00001; PFSR-18 m, RR: 0.51, [0.43–0.62], p < 0.00001; PFSR-24 m, RR: 0.38, [0.27–0.53], p < 0.00001; and PFSR-30 m, RR: 0.39, [0.27–0.56], p < 0.00001; Figure S4). With prolonged survival, the PFS advantage of alectinib increased compared with that of crizotinib (Fig. 3B and Figure S3B). In the subgroup analysis, significant changes were not observed in PFS according to age, sex, race category, or treatment line. The following might be unfavorable factors for alectinib treatment: smoking status = active smoker, Eastern Cooperative Oncology Group-performance status [ECOG-PS] = 2, disease stage = postoperative recurrence, and the ALK testing method = reverse transcription-polymerase chain reaction (RT-PCR). However, baseline CNS metastases and previous brain radiation might be favorable factors for alectinib treatment (Fig. 4).
Three studies compared the CNS-PFS of the alectinib group versus the crizotinib group (heterogeneity: I2 = 0%, P = 0.71). The CNS-PFS of the alectinib group was better than the crizotinib group (HR: 0.17, [0.11–0.24], p < 0.00001; Fig. 2). The CNS-PFSR at all time points significantly favored the alectinib group (CNS-PFSR-6 m, RR: 0.88, [0.80–0.96], p = 0.005; CNS-PFSR-12 m, RR: 0.70, [0.64–0.76], p < 0.00001; CNS-PFSR-18 m, RR: 0.66, [0.60–0.73], p < 0.00001; CNS-PFSR-24 m, RR: 0.58, [0.51–0.66], p < 0.00001; and CNS-PFSR-30 m, RR: 0.58, [0.47–0.72], p < 0.00001; Figure S5). With prolonged survival, the CNS-PFS advantage of alectinib increased compared with that of crizotinib (Fig. 3C and Figure S3C).
Three studies compared the DOR of the alectinib group versus the crizotinib group (heterogeneity: I2 = 0%, P = 0.41). The DOR of the alectinib group was better than the crizotinib group (HR: 0.31, [0.23–0.42], p < 0.00001; Fig. 2). The objective response rate [ORR] (74.45% vs. 86.58%, RR: 0.87, [0.80–0.94], p = 0.0003) and the partial response [PR] (71.92% vs. 82.11%, RR: 0.88, [0.81–0.96], p = 0.004) were better in the alectinib group. The disease control rate [DCR] (90.54% vs. 94.21%, RR: 0.95, [0.88–1.04], p = 0.27) and the complete response [CR] (2.52% vs. 4.47%, RR: 0.57, [0.26–1.32], p = 0.20) were similar between the groups. Due to the high ORR and similar DCR in the alectinib group, less stable disease [SD] (16.09% vs. 7.63%, RR: 2.01, [13.1–3.10], p = 0.001) was found in the alectinib group (Fig. 5).
Subgroup analysis was conducted according to patients have baseline CNS metastases or not. In patients with CNS lesions at baseline, alectinib group was better than the crizotinib group in PFS (HR: 0.23, [0.11–0.49], p = 0.0001), systemic progression without previous CNS disease progression (HR: 0.35, [0.15–0.83], p = 0.02) and CNS progression without previous systemic disease progression(HR: 0.18, [0.09–0.36], p < 0.00001). In patients without CNS lesions at baseline, alectinib group was also better than the crizotinib group in PFS (HR: 0.43, [0.30–0.60], p < 0.00001) and CNS progression without previous systemic disease progression (HR: 0.14, [0.06–0.33], p < 0.00001). Similar death without previous CNS or systemic disease progression was found bwtween the two groups in patients with or without CNS lesions at baseline (Table S5).
According to the assessment of independent review committee (IRC), alectinib group was better than the crizotinib group in OS (HR: 0.66, [0.47–0.92], p = 0.02), PFS (HR: 0.42, [0.34–0.52], p < 0.00001), CNS-PFS (HR: 0.18, [0.11–0.27], p < 0.00001) and DOR (HR: 0.32, [0.17–0.60], p = 0.0004). According to the assessment of investigators, alectinib group was also better than the crizotinib group in OS (HR: 0.66, [0.47–0.92], p = 0.02), PFS (HR: 0.35, [0.25–0.49], p < 0.00001), CNS-PFS (HR: 0.14, [0.06–0.31], p < 0.00001) and DOR (HR: 0.31, [0.22–0.43], p < 0.00001) (Table S6). Table S6 also showed the results of responses and CNS responses assessed by IRC and investigators.
Toxicity
In summary, crizotinib treatment was associated with more grade 3–5 AEs (53.63% vs. 37.37%, RR: 1.43, [1.09–1.87], p = 0.009). The total AEs (98.74% vs. 98.16%, RR: 1.01, [0.99–1.03], p = 0.40), serious AEs (29.02% vs. 24.47%, RR: 1.12, [0.88–1.44], p = 0.34), fatal AEs (3.15% vs. 2.11%, RR:1.51, [0.62–3.69], p = 0.37), AEs leading to treatment discontinuation (15.77% vs. 10.79%, RR: 1.37, [0.93–2.02], p = 0.11), AEs leading to dose reduction (21.13% vs. 19.86%, RR: 1.11, [0.77–1.60], p = 0.57), AEs leading to dose interruption (39.43% vs. 26.58%, RR: 1.38, [0.90–2.12], p = 0.15), and death (0% vs. 0.53%, RR: 0.20, [0.01–4.16], p = 0.30) were comparable between the two groups (Table 2).
Table 2
Summary of adverse events.
Adverse events
|
Studies involved
|
Crizotinib
|
Alectinib
|
Risk ratio
|
95% CI
|
I2(%)
|
P
|
Event/total
|
%
|
Event/total
|
%
|
Total adverse events
|
3
|
313/317
|
98.74%
|
373/380
|
98.16%
|
1.01
|
0.99–1.03
|
0
|
0.4
|
Grade 3–5 adverse events
|
3
|
170/317
|
53.63%
|
142/380
|
37.37%
|
1.43
|
1.09–1.87
|
59
|
0.009
|
Serious adverse events
|
3
|
92/317
|
29.02%
|
93/380
|
24.47%
|
1.12
|
0.88–1.44
|
14
|
0.34
|
Fatal adverse events
|
2
|
10/213
|
4.69%
|
8/277
|
2.89%
|
1.51
|
0.62–3.69
|
0
|
0.37
|
Adverse event leading to treatment discontinuation
|
3
|
50/317
|
15.77%
|
41/380
|
10.79%
|
1.37
|
0.93–2.02
|
16
|
0.11
|
Adverse event leading to dose reduction
|
2
|
45/213
|
21.13%
|
55/277
|
19.86%
|
1.11
|
0.77–1.60
|
0
|
0.57
|
Adverse event leading to dose interruption
|
3
|
125/317
|
39.43%
|
101/380
|
26.58%
|
1.38
|
0.90–2.12
|
72
|
0.15
|
Death
|
2
|
0/317
|
0.00%
|
2/380
|
0.53%
|
0.2
|
0.01–4.16
|
-
|
0.3
|
Abbreviations: CI: confidence interval. |
Subgroup analysis of the total AEs found that there was a greater increase in constipation, nausea, diarrhea, alanine aminotransferase (ALT), vomiting, aspartate aminotransferase (AST), peripheral edema, dysgeusia, and visual impairment as well as a greater decrease in appetite and neutrophil count associated with the crizotinib group. However, increased blood bilirubin, bronchitis and anemia were found in the alectinib group. Total AEs with an incidence greater than 10% according to the combination of the crizotinib group and the alectinib group are summarized in Table 3, Table S7 and Table S8.
Table 3
Total adverse events with an incidence of greater than 10% according to combination of the two groups.
Adverse events
|
Studies involved
|
Crizotinib
|
Alectinib
|
Total incidence
|
Risk ratio
|
95% CI
|
I2(%)
|
P
|
Event/total
|
%
|
Event/total
|
%
|
Constipation
|
2
|
79/166
|
47.59%
|
84/228
|
36.84%
|
41.37%
|
1.29
|
1.02–1.63
|
0
|
0.03
|
Nausea
|
3
|
177/317
|
55.84%
|
47/380
|
12.37%
|
32.14%
|
4.15
|
3.13–5.51
|
40
|
< 0.00001
|
Diarrhea
|
3
|
177/317
|
55.84%
|
45/380
|
11.84%
|
31.85%
|
4.67
|
2.84–7.68
|
62
|
< 0.00001
|
ALT increased
|
3
|
115/317
|
36.28%
|
89/380
|
23.42%
|
29.27%
|
1.83
|
1.17–2.86
|
68
|
0.008
|
Vomiting
|
3
|
146/317
|
46.06%
|
33/380
|
8.68%
|
25.68%
|
5
|
3.54–7.07
|
0
|
< 0.00001
|
Upper respiratory tract infection
|
1
|
20/104
|
19.23%
|
28/103
|
27.18%
|
23.19%
|
0.71
|
0.43–1.17
|
-
|
0.18
|
Nasopharyngitis
|
2
|
35/166
|
21.08%
|
54/228
|
23.68%
|
22.59%
|
0.73
|
0.51–1.05
|
20
|
0.09
|
Increased blood alkaline phosphatase
|
1
|
8/62
|
12.90%
|
33/125
|
26.40%
|
21.93%
|
0.49
|
0.24–0.99
|
-
|
0.05
|
AST increased
|
2
|
73/255
|
28.63%
|
36/255
|
14.12%
|
21.37%
|
2.03
|
1.41–2.91
|
37
|
0.0001
|
Pyrexia
|
1
|
24/104
|
23.08%
|
14/103
|
13.59%
|
18.36%
|
1.7
|
0.93–3.09
|
-
|
0.08
|
Peripheral edema
|
3
|
80/317
|
25.24%
|
46/380
|
12.11%
|
18.08%
|
1.93
|
1.39–2.67
|
0
|
< 0.0001
|
Dysgeusia
|
3
|
94/317
|
29.65%
|
25/380
|
6.58%
|
17.07%
|
4.96
|
1.98–12.41
|
63
|
0.0006
|
Creatine phosphokinase increased
|
1
|
14/104
|
13.46%
|
21/103
|
20.39%
|
16.91%
|
0.66
|
0.36–1.23
|
-
|
0.19
|
Malaise
|
1
|
20/104
|
19.23%
|
13/103
|
12.62%
|
15.94%
|
1.52
|
0.80–2.90
|
-
|
0.2
|
Blood bilirubin increased
|
3
|
5/317
|
1.58%
|
103/380
|
27.11%
|
15.49%
|
0.07
|
0.03–0.17
|
0
|
< 0.00001
|
Visual impairment
|
2
|
75/255
|
29.41%
|
4/255
|
1.57%
|
15.49%
|
16.55
|
1.42-193.51
|
78
|
0.03
|
Fatigue
|
2
|
35/213
|
16.43%
|
40/277
|
14.44%
|
15.31%
|
1.18
|
0.57–2.41
|
59
|
0.66
|
Sinus bradycardia
|
2
|
17/166
|
10.24%
|
38/228
|
16.67%
|
13.96%
|
1.51
|
0.16–14.43
|
77
|
0.72
|
Decreased appetite
|
2
|
44/166
|
26.51%
|
9/228
|
3.95%
|
13.45%
|
7.34
|
3.64–14.77
|
0
|
< 0.00001
|
Rash
|
3
|
36/317
|
11.36%
|
55/380
|
14.47%
|
13.06%
|
0.75
|
0.40–1.43
|
52
|
0.39
|
Bronchitis
|
2
|
12/166
|
7.23%
|
36/228
|
15.79%
|
12.18%
|
0.5
|
0.27–0.94
|
0
|
0.03
|
Dry skin
|
1
|
13/104
|
12.50%
|
12/103
|
11.65%
|
12.08%
|
1.07
|
0.51–2.24
|
-
|
0.85
|
Stomatitis
|
1
|
12/104
|
11.54%
|
13/103
|
12.62%
|
12.08%
|
0.91
|
0.44–1.91
|
-
|
0.81
|
Neutrophil count decreased
|
2
|
39/166
|
23.49%
|
7/228
|
3.07%
|
11.68%
|
7.57
|
3.37–17.03
|
0
|
< 0.00001
|
Blood creatinine increased
|
1
|
11/104
|
10.58%
|
13/103
|
12.62%
|
11.59%
|
0.84
|
0.39–1.78
|
-
|
0.65
|
White blood cell count decreased
|
1
|
15/62
|
24.19%
|
6/125
|
4.80%
|
11.23%
|
5.04
|
2.06–12.35
|
-
|
0.0004
|
Anemia
|
3
|
15/317
|
4.73%
|
58/380
|
15.26%
|
10.47%
|
0.31
|
0.18–0.53
|
0
|
< 0.0001
|
Abbreviations: AST: aspartate aminotransferase; ALT: alanine aminotransferase; CI: confidence interval. |
In subgroup analysis of grade 3–5 AEs there was greater ALT increase, AST increase, neutrophil count decrease, electrocardiogram QT prolongation, nausea increase, and vomiting increase associated with the crizotinib group. However, anemia was associated with the alectinib group. Grade 3–5 AEs with an incidence greater than 1% according to the combination of the crizotinib group and the alectinib group are summarized in Table 4, Table S9 and Table S10.
Table 4
Grade 3–5 adverse events with an incidence of greater than 10% according to combination of the two groups.
Grade 3–5 adverse events
|
Studies involved
|
Crizotinib
|
Alectinib
|
Total incidence
|
Risk ratio
|
95% CI
|
I2 (%)
|
P
|
Event/total
|
%
|
Event/total
|
%
|
ALT increased
|
3
|
42/317
|
12.93%
|
10/380
|
2.63%
|
7.32%
|
4.66
|
2.36–9.20
|
0
|
< 0.00001
|
AST increased
|
2
|
21/255
|
8.24%
|
9/255
|
3.53%
|
5.88%
|
2.34
|
1.10-5.00
|
0
|
0.03
|
Neutrophil count decreased
|
3
|
29/317
|
9.15%
|
2/380
|
0.53%
|
4.45%
|
11.41
|
3.64–25.72
|
0
|
< 0.0001
|
Pulmonary embolism
|
1
|
8/151
|
5.30%
|
2/152
|
1.32%
|
3.30%
|
3.41
|
0.84–13.82
|
0
|
0.09
|
Interstitial lung disease
|
2
|
6/166
|
3.61%
|
6/228
|
2.63%
|
3.05%
|
1.6
|
0.17–15.24
|
66
|
0.68
|
Creatine phosphokinase increased
|
1
|
4/151
|
2.65%
|
5/152
|
3.29%
|
2.97%
|
0.79
|
0.22–2.87
|
-
|
0.72
|
Hepatic function abnormal
|
1
|
6/104
|
5.77%
|
0/103
|
0.00%
|
2.90%
|
12.88
|
0.73-225.66
|
-
|
0.08
|
Electrocardiogram QT prolonged
|
2
|
12/255
|
4.71%
|
2/255
|
0.78%
|
2.75%
|
4.98
|
1.30-19.06
|
0
|
0.02
|
Pneumonia
|
1
|
3/151
|
1.99%
|
4/152
|
2.63%
|
2.31%
|
0.75
|
0.17–3.32
|
-
|
0.71
|
Neutropenia
|
1
|
6/151
|
3.97%
|
0/152
|
0.00%
|
1.98%
|
13.09
|
0.74-230.25
|
-
|
0.08
|
Anemia
|
2
|
1/255
|
0.39%
|
9/255
|
3.53%
|
1.96%
|
0.16
|
0.03–0.88
|
0
|
0.04
|
Maculopapular rash
|
1
|
1/104
|
0.96%
|
3/103
|
2.91%
|
1.93%
|
0.33
|
0.03–3.12
|
-
|
0.33
|
Hyponatremia
|
2
|
6/213
|
2.82%
|
3/277
|
1.08%
|
1.84%
|
2.8
|
0.21–36.84
|
60
|
0.43
|
Urinary tract infection
|
1
|
1/151
|
0.66%
|
4/152
|
2.63%
|
1.65%
|
0.25
|
0.03–2.23
|
-
|
0.21
|
Increased bilirubin conjugated
|
1
|
1/62
|
1.61%
|
2/125
|
1.60%
|
1.60%
|
1.01
|
0.09–10.90
|
-
|
0.99
|
Nausea
|
3
|
9/317
|
2.84%
|
2/380
|
0.53%
|
1.58%
|
4.71
|
1.14–19.44
|
0
|
0.03
|
Photosensitivity reaction
|
1
|
3/151
|
1.99%
|
1/152
|
0.66%
|
1.32%
|
3.02
|
0.32–28.71
|
-
|
0.34
|
Pneumonitis
|
1
|
4/151
|
2.65%
|
0/152
|
0.00%
|
1.32%
|
9.06
|
0.49-166.82
|
-
|
0.14
|
Pleural effusion
|
1
|
2/151
|
1.32%
|
2/152
|
1.32%
|
1.32%
|
1.01
|
0.14–7.05
|
-
|
0.99
|
Acute kidney injury
|
1
|
0/151
|
0.00%
|
4/152
|
2.63%
|
1.32%
|
0.11
|
0.01–2.06
|
-
|
0.14
|
Decreased appetite
|
2
|
4/166
|
2.41%
|
1/228
|
0.44%
|
1.27%
|
4.23
|
0.80-22.47
|
41
|
0.09
|
White blood cell count decreased
|
2
|
5/166
|
3.01%
|
0/228
|
0.00%
|
1.27%
|
7.75
|
0.87–68.81
|
0
|
0.07
|
Weight increased
|
2
|
1/213
|
0.47%
|
5/277
|
1.81%
|
1.22%
|
0.44
|
0.07–2.65
|
0
|
0.37
|
Vomiting
|
3
|
7/317
|
2.21%
|
0/380
|
0.00%
|
1.00%
|
10.64
|
1.28–88.57
|
0
|
0.03
|
Rash
|
3
|
3/317
|
0.95%
|
4/380
|
1.05%
|
1.00%
|
1
|
0.29–3.44
|
41
|
1
|
Abbreviations: AST: aspartate aminotransferase; ALT: alanine aminotransferase; CI: confidence interval. |