TABLE 1.

Interim results from ongoing Phase I/II studies of Immune checkpoint blockade in AML and MDS

Reference	Agent	Immune check point pathway	Study design	Trial regimen	Study population (N)	ORRs (%)	8-week mortality	Overall survival	Comments
[25]	Pidilizumab	PD-1/PD-L1	Phase I	Single arm Monotherapy	AML, N = 8; MDS, N = 1	13%, CR in 1 AML patient	NR	NR	Clinically modest benefit as single agent. Safe and well tolerated at 0.2–6mg/kg dose.
[36]	Nivolumab	PD-1	Phase 1/2	Combined with azacitidine in R/R AML	AML, N=53	34% (CR/CRi=11, HI=7)	8%	At 6 months follow up, OS was not reached in patients with CR, and 9.7 months in patients who had HI	Safe and tolerable. Durable CR rates, encouraging median OS in first salvage of 9.3 months. Grade 2–4 immune adverse events in 28% of patients and steroid responsive in all but 1 case.
[67]	Nivolumab	PD-1	Phase 2	Combined with azacitidine in frontline MDS	MDS, N=17	80% (CR=6, HI+mCR=6, HI=1)	NR	NR	Impressive response rates in the frontline setting. Immune mediated toxicities manageable with steroids
[67]	Nivolumab	PD-1		Monotherapy in R/R MDS	MDS, N=15	0%			No benefit of single agent nivolumab in MDS with prior HMA failure
[67]	Ipilimumab	CTLA4		Monotherapy in R/R MDS	MDS, N=16	30% (CR=1, mCR=2, HI=2)			Single-agent Ipilimumab is capable of inducing responses in previously treated MDS patients.
[48]	Pembrolizumab	PD-1/PD-L1	Phase 1b	Single-arm in R/R intermediate ½ or high risk MDS after HMA failure (4 cycles)	N =28	15% (4 of 27 evaluable patients; 1 PR and 3 with mCR)	0%	49% at 6 months	Manageable safety profile and potential activity in patients with MDS after HMA failure.
[57]	Ipilimumab	CTLA4	Phase 1	Single arm in R/R MDS after HMA failure	N=11	0%	0%	Median OS 12 months	5 patients had stable disease, 4 of 5 had durable response>6 months. 3 patients underwent transplant post-ipilimumab and did not experience additional toxicities suggesting feasibility. Treatment with 3mg/kg is well tolerated and effective in disease stabilization. Immune mediated reactions responsive to steroids
[74]	Ipilimumab	CTLA4	Phase I	Single arm in R/R AML after ASCT	N=12	42%	NR	With median follow up of 15 months, 12 month OS was 49%	Ipilimumab effective in post-transplant relapse setting. Response rates are higher in extramedullary AML. Effective dose is 10 mg/kg

Abbreviations used: AML-acute myelogenous leukemia, MDS-myelodysplasia, CR-complete remission, NR-not reported, HMA-hypomethylating agent, ASCT-allogeneic stem cell transplant, OS-overall survival, HI-hematological improvement, N-number of patients. PR-partial remission, mCR-marrow complete response. Pts-patients