Comparison 1. Anti‐leukaemic therapy plus alemtuzumab versus anti‐leukaemic therapy alone (anti‐leukaemic therapy identical in both groups; unconfounded).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 PFS ‐ overall analysis	2	356	Hazard Ratio (Fixed, 95% CI)	0.58 [0.44, 0.76]
2 PFS ‐ subgrouped by treatment regimens	2		Hazard Ratio (Fixed, 95% CI)	Subtotals only
2.1 combinations with chemotherapy	1	335	Hazard Ratio (Fixed, 95% CI)	0.61 [0.47, 0.81]
2.2 not combined with another chemotherapy	1	21	Hazard Ratio (Fixed, 95% CI)	0.17 [0.05, 0.60]
3 PFS ‐ subgrouped by starting point of alemtuzumab	2	356	Hazard Ratio (Fixed, 95% CI)	0.58 [0.44, 0.76]
3.1 relapse therapy	1	335	Hazard Ratio (Fixed, 95% CI)	0.61 [0.47, 0.81]
3.2 consolidation therapy	1	21	Hazard Ratio (Fixed, 95% CI)	0.17 [0.05, 0.60]
4 Treatment related mortality	2	356	Risk Ratio (M‐H, Fixed, 95% CI)	0.57 [0.17, 1.90]
5 ORR ‐ overall analysis	2	356	Risk Ratio (M‐H, Fixed, 95% CI)	1.10 [0.99, 1.23]
6 ORR ‐ subgrouped by treatment regimens	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
6.1 combinations with chemotherapy	1	335	Risk Ratio (M‐H, Fixed, 95% CI)	1.08 [0.97, 1.21]
6.2 not combined with another chemotherapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	1.41 [0.92, 2.14]
7 ORR ‐ subgrouped by starting point of alemtuzumab	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
7.1 relapse therapy	1	335	Risk Ratio (M‐H, Fixed, 95% CI)	1.08 [0.97, 1.21]
7.2 consolidation therapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	1.41 [0.92, 2.14]
8 CRR ‐ overall analysis	2	356	Risk Ratio (M‐H, Fixed, 95% CI)	2.61 [1.26, 5.42]
9 CRR ‐ subgrouped by treatment regimens	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
9.1 combinations with chemotherapy	1	335	Risk Ratio (M‐H, Fixed, 95% CI)	2.98 [1.30, 6.83]
9.2 not combined with another chemotherapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	1.36 [0.28, 6.56]
10 CRR ‐ subgrouped by starting point of alemtuzumab	2	356	Risk Ratio (M‐H, Fixed, 95% CI)	2.61 [1.26, 5.42]
10.1 relapse therapy	1	335	Risk Ratio (M‐H, Fixed, 95% CI)	2.98 [1.30, 6.83]
10.2 consolidation therapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	1.36 [0.28, 6.56]
11 CMV reactivation ‐ overall analysis	2	350	Risk Ratio (M‐H, Fixed, 95% CI)	10.52 [1.42, 77.68]
12 CMV reactivation ‐ subgrouped by treatment regimens	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
12.1 combinations with chemotherapy	1	329	Risk Ratio (M‐H, Fixed, 95% CI)	9.05 [0.49, 166.84]
12.2 not combined with another chemotherapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	11.92 [0.76, 187.84]
13 CMV reactivation ‐ subgrouped by starting point of alemtuzumab	2	350	Risk Ratio (M‐H, Fixed, 95% CI)	10.52 [1.42, 77.68]
13.1 relapse therapy	1	329	Risk Ratio (M‐H, Fixed, 95% CI)	9.05 [0.49, 166.84]
13.2 consolidation therapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	11.92 [0.76, 187.84]
14 Infections (all grades) ‐ overall analysis	2	350	Risk Ratio (M‐H, Fixed, 95% CI)	1.32 [1.01, 1.74]
15 Infections (all grades) ‐ subgrouped by treatment regimens	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
15.1 combinations with chemotherapy	1	329	Risk Ratio (M‐H, Fixed, 95% CI)	1.16 [0.88, 1.53]
15.2 not combined with another chemotherapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	19.25 [1.27, 291.20]
16 Infections (all grades) ‐ subgrouped by starting point of alemtuzumab	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
16.1 relapse therapy	1	329	Risk Ratio (M‐H, Fixed, 95% CI)	1.16 [0.88, 1.53]
16.2 consolidation therapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	19.25 [1.27, 291.20]
17 Anaemia grade 3/4 ‐ overall analysis	2	350	Risk Ratio (M‐H, Fixed, 95% CI)	0.63 [0.33, 1.20]
18 Anaemia grade 3/4 ‐ subgrouped by treatment regimens	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
18.1 combinations with chemotherapy	1	329	Risk Ratio (M‐H, Fixed, 95% CI)	0.53 [0.26, 1.06]
18.2 not combined with another chemotherapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	4.58 [0.25, 85.33]
19 Anaemia grade 3/4 ‐ subgrouped by starting point of alemtuzumab	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
19.1 relapse therapy	1	329	Risk Ratio (M‐H, Fixed, 95% CI)	0.53 [0.26, 1.06]
19.2 consolidation therapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	4.58 [0.25, 85.33]
20 Neutropenia grade 3/4 ‐ overall analysis	2	350	Risk Ratio (M‐H, Fixed, 95% CI)	1.25 [0.97, 1.61]
21 Neutropenia grade 3/4 ‐ subgrouped by treatment regimens	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
21.1 combinations with chemotherapy	1	329	Risk Ratio (M‐H, Fixed, 95% CI)	1.15 [0.89, 1.48]
21.2 not combined with another chemotherapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	13.75 [0.88, 213.65]
22 Neutropenia grade 3/4 ‐ subgrouped by starting point of alemtuzumab	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
22.1 relapse therapy	1	329	Risk Ratio (M‐H, Fixed, 95% CI)	1.15 [0.89, 1.48]
22.2 consolidation therapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	13.75 [0.88, 213.65]
23 Thrombocytopenia grade 3/4 ‐ overall analysis	2	350	Risk Ratio (M‐H, Fixed, 95% CI)	1.05 [0.58, 1.89]
24 Thrombocytopenia grade 3/4 ‐ subgrouped by treatment regimens	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
24.1 combinations with chemotherapy	1	329	Risk Ratio (M‐H, Fixed, 95% CI)	0.85 [0.45, 1.59]
24.2 not combined with another chemotherapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	8.25 [0.50, 136.33]
25 Thrombocytopenia grade 3/4 ‐ subgrouped by starting point of alemtuzumab	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
25.1 relapse therapy	1	329	Risk Ratio (M‐H, Fixed, 95% CI)	0.85 [0.45, 1.59]
25.2 consolidation therapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	8.25 [0.50, 136.33]
26 SAEs ‐ overall analysis	2	350	Risk Ratio (M‐H, Fixed, 95% CI)	1.34 [0.95, 1.89]
27 SAEs ‐ subgrouped by treatment regimens	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
27.1 combinations with chemotherapy	1	329	Risk Ratio (M‐H, Fixed, 95% CI)	1.33 [0.94, 1.87]
27.2 not combined with another chemotherapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	2.75 [0.12, 60.70]
28 SAEs ‐ subgrouped by starting point of alemtuzumab	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
28.1 relapse therapy	1	329	Risk Ratio (M‐H, Fixed, 95% CI)	1.33 [0.94, 1.87]
28.2 consolidation therapy	1	21	Risk Ratio (M‐H, Fixed, 95% CI)	2.75 [0.12, 60.70]