AML a. Pathologically or morphologically confirmed de novo or secondary AML at the time of initial diagnosis. b. Achievement of no better than morphologic PR, as defined initially by the AML Working Group criteria (Cheson et al, 2003), and also quoted in the more recent ELN criteria (Döhner et al, 2010), while on active treatment with HMAs and at the time of completion of the 4 th HMA treatment cycle. c. AML patients are eligible only if th ey received first line therapy with HMAs (decitabine or azacitidine) for 4 cycles and achieved only PR at the end of cycle 4. d. AML patients shall remain on HMA therapy while receiving investigational therapies. 4.1.2. Exclusion Criteria Any prospective patient will be excluded from the study if any of the following criteria apply: Medical Conditions Pregnancy Exclusion: SELLAS Life Sciences Group Galinpepimut -S Protocol : SLS17 -201/MK3475 -770 Protocol v1.1 (Amendment 1.0) 12 April 2019 Page 125 1. A WOCBP who has a positive urine pregnancy test (e.g. within 72 hours) prior to treatment. If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required. Prior/Concomitant Therapy 2.