Vaccine Response With NT-I7

* INCLUSION CRITERIA: * Age greater than or equal to 60 years * Documentation of positive diagnosis based on pathology/histology report (no need for archival tissue or new biopsy) for any of the following: * Stage I-III breast carcinoma following neo-adjuvant/adjuvant chemotherapy and appropriate surgery and/or radiotherapy. * Stage II or III gastrointestinal cancer following appropriate surgery and adjuvant chemotherapy or following appropriate neoadjuvant chemoradiation/surgery and adjuvant chemotherapy. * Stage II or III bladder carcinoma following neo-adjuvant chemotherapy and appropriate surgery or following adjuvant chemotherapy. * Stage IV breast, gastrointestinal, or prostate cancer, following surgery and chemotherapy, or chemotherapy alone NOTE: "Appropriate therapy" for each disease must be consistent with NCCN Clinical Practice Guidelines in Oncology available at the time of treatment in the opinion of the investigator (http://www.nccn.org/professionals/physician\_gls/f\_guidelines.asp) * Completed cancer specific therapy (including surgery, radiotherapy and/or systemic therapy) at least 4 weeks and no more than 12 months prior to registration. (Subjects with hormone receptor positive breast carcinoma maintained on hormonal therapy following chemotherapy and radiation are eligible. Subjects with HER2 positive breast carcinoma maintained on anti-HER2 agents after definitive therapies are also eligible). * Reasonable expectation that no cancer-specific therapy, with the exception noted in the previous criteria, will be given in the subsequent 6 months (PI's discretion). * Adequate organ function, as follows: * AST/ALT: \< 3 times upper limit of normal (ULN) * Bilirubin: \< 1.5 times ULN * Absolute Neutrophil Count: \> 1000/mm3 * Platelet count: \> 75,000/mm3 * INR/PTT: \<1.5 times ULN * Serum Creatinine: \<1.5 times ULN * CPK: \<2.5 times ULN * Serum albumin: greater than or equal to 3g/dL * Serum electrolytes: within normal limits * Karnofsky performance status greater or equal to 70% * Effects of NT-I7 on the developing human fetus are unknown. For these reasons the following measures apply: * Subjects enrolled on the study must not be planning to father children within the projected duration of the trial, starting with the pre-screening/screening visit through 120 days after the administration of NT-I7. * Men with partners of childbearing potential (defined as any female who has experienced menarche and who has not undergone successful surgical sterilization or who is not postmenopausal (i.e., amenorrheic for greater than or equal to 12 months without alternative medical cause) must use effective contraception prior to study entry, and for 120 days after the administration of NT-I7. * Should a woman become pregnant or suspect she is pregnant while her partner is participating in this study, the study participants' treating physician should be informed immediately. EXCLUSION CRITERIA: * Subjects who are receiving any other investigational agents * Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements * Significant heart disease defined as: * Significant coronary arterial disease * Myocardial infarction in the last 6 months, angina in the previous 3 months * Troponin elevation above reference range set by each institution where the troponin measurement was performed. * Ischemic changes on ECG * Atrio-ventricular block greater than 1st degree, in absence of pacemaker * QTc (using Fridericia and Framingham correction formula) greater than 480ms (CTCAE 5.0 grade 1 abnormality is acceptable) * History of ventricular arrhythmia * Left Ventricular Ejection Fraction of less than 50% determined by echocardiography * Positive serology for HTLV-I or HIV, or serology findings indicative of ongoing infection with hepatitis A, hepatitis B, or hepatitis C. Subjects with serology findings indicative of previous exposure to hepatitis A or B vaccination will not be excluded from Phase 1 part of the study but will be excluded from Phase 1b part of the study (see below for additional exclusion criteria for the Phase-1b part of the study only). * History of autoimmune disease EXCEPT for the following: subjects with vitiligo or endocrine disease controlled by replacement therapy including diabetes, thyroid, and adrenal disease may be enrolled * Subjects requiring chronic immunosuppressive therapy (including corticosteroids above physiologic replacement dosage) for any medical condition. We will permit 1) systemic corticosteroids at physiologic replacement dosage which are not to exceed 10 mg/day of prednisone or an equivalent, 2) intranasal or inhaled corticosteroids, 3) intraarticular injection of corticosteroids, 4) topical corticosteroids, 5) or a short-term use of systemic corticosteroids greater than 10 mg/day of prednisone or an equivalent for 10 days or less. * Splenomegaly or history of proliferative hematologic disease * Prior allogeneic hematopoietic stem cell transplantation or solid organ transplantation * History of medical or psychiatric disease, or cognitive impairment, which, in the view of the principal investigator would preclude safe treatment * Serious bleeding diathesis based on clinical history of significant bleeding attributed to coagulation/bleeding disorders, documentation of abnormal coagulation factors/platelet function studies at the discretion of PI, or those who are on therapeutic anticoagulation * Inability to give informed consent * Subjects who have received immune checkpoint inhibitors in the previous 12 months, or subjects who have received immunomodulatory drugs in the previous 4 weeks for any medical indications. Subjects who have received intravesical BCG administration for non-muscle invasive bladder cancer will be included in this study (i.e., not one of exclusion criteria). * Additional exclusion criteria for the Phase-1b part of the study only are as follows: * Known hypersensitivity to any of the following: diphtheria toxoid, neomycin, polymixin B, streptomycin, 2 phenoxyethanol, formaldehyde, aluminum hydroxide, yeast * Previous exposure to Hepatitis A or B vaccines or history of hepatitis A or B infection * Subjects who received a Td or Tdap immunization in the previous 5 years * History of anaphylaxis or serious allergic reactions to previous administration of any of the vaccines * Subjects who had received one or more doses of the PPSV23 vaccine in the previous 12 months * Latex allergy * A history of Guillain-Barre syndrome within six weeks of administration of previous tetanus toxoid containing vaccines.