Patients (or legally acceptable representative if applicable) should provide written informed consent for the trial. 12. Patients should have measurable/demonstrable active malignant disease per below: a. For patients with solid tumors: Have measurable disease based on RECIST 1.1 as determined by the as assessed by the local site SELLAS Life Sciences Group Galinpepimut -S Protocol : SLS17 -201/MK3475 -770 Protocol v1.1 (Amendment 1.0) 12 April 2019 Page 120 investigator/radiology. Measurable disease is defined as at least one lesion that can be accurately measured in at least two dimensions with spiral CT scan. Minimum measurement must be > 15 mm in the longest diameter by > 10 mm in the short axis. Tumor lesions situated in a previously irradiated area are considered measurable if progression has been demonstrated in such lesions. b. For AML patients: Have evidence of morphologic partial response (decrease of BM blast percentage to 5% to 25% and decrease of pretreatment BM blast percentage by > 50%) but absence of extramedullary disease, 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). Leukemic blast burden will be determined by a local site investigator (physician) upon clinical and BM morphologic assessment. AML patients should also have received/completed 4 cycles of HMA therapy and have PR as their best observed response at the end of these 4 cycles. 13. Patients should have provided archival tumor tissue sample or newly obtained core or excisional biopsy of a tumor lesion not previously irradiated. Formalin- fixed, paraffin embedded (FFPE) tissue blocks are preferred to slides. Newly obtained biopsies are preferred to archived tissue. Note: If submitting unstained cut slides, newly cut slides should be submitted to the testing laboratory within 14 days from the date slides are cut (details pertaining to tumor tissue submission can be found in the Procedures Manual). 14. Patients should have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 (Appendix ). 15. Have adequate organ function as defined in Table 1. Specimens must be collected within 10 days prior to the start of study treatment. SELLAS Life Sciences Group Galinpepimut -S Protocol : SLS17 -201/MK3475 -770 Protocol v1.1 (Amendment 1.0) 12 April 2019 Page 121 Table 1 Definition of Adequate Organ Function System Laboratory Value Hematological Absolute neutrophil count (ANC) ≥1500/µL Platelets ≥100 000/µL Hemoglobin ≥9.0 g/dL or ≥5.6 mmol/L1 Renal Creatinine OR Measured or calculated2 creatinine clearance (GFR can also be used in place of creatinine or CrCl) ≤1.5 × ULN OR ≥30 mL/min for participant with creatinine levels >1.5 × institutional ULN SELLAS Life Sciences Group Galinpepimut -S Protocol : SLS17 -201/MK3475 -770 Protocol v1.1 (Amendment 1.0) 12 April 2019 Page 122 Hepatic Total bilirubin ≤1.5 ×ULN OR direct bilirubin ≤ULN for participants with total bilirubin levels >1.5 × ULN AST (SGOT) and ALT (SGPT) ≤2.5 × ULN (≤5 × ULN for participants with liver metastases) Coagulation International normalized ratio (INR) OR prothrombin time (PT) Activated partial thromboplastin time (aPTT) ≤1.5 × ULN unless participant is receiving anticoagulant therapy as long as PT or aPTT is within therapeutic range of intended use of anticoagulants ALT (SGPT)=alanine aminotransferase (serum glutamic pyruvic transaminase); AST (SGOT) =aspartate aminotransferase (serum glutamic oxaloacetic transaminase); GFR=glomerular filtration rate; ULN=upper limit of normal. 1 Criteria must be met without erythropoietin dependency and without packed red blood cell (pRBC) transfusion within last 2 weeks. 2 Creatinine clearance (CrCl) should be calculated per institutional standard. Note: This table i ncludes eligibility -defining laboratory value requirements for treatment; laboratory value requirements should be adapted according to local regulations and guidelines for the administration of specific chemotherapies. 16. Patients should be willing and able to return to the clinical site for adequate follow-up, as required by this protocol. Additional Inclusion Criteria for Selected Tumor Types: (i). CRC (third/fourth line) a. Histologically or cytologically documented adenocarcinoma of colon or rectum at the time of initial presentation. b. Metastatic CRC with documented disease progression (per standard criteria) after the last administration of standard therapies or intolerance to standard therapies (and approved SELLAS Life Sciences Group Galinpepimut -S Protocol : SLS17 -201/MK3475 -770 Protocol v1.1 (Amendment 1.0) 12 April 2019 Page 123 therapies must have included all the following a fluoropyrimidine, oxaliplatin , irinotecan, bevacizumab, and, if KRAS wild-type, cetuximab or panitumumab). Prior use of (and failure after) regorafenib or trifluridine/tipiracil is allowed , but not mandated. (ii).