Study of an Immunotherapeutic, DPX-Survivac, in Combination With Low Dose Cyclophosphamide & Pembrolizumab, in Subjects With Selected Advanced & Recurrent Solid Tumors

Key Inclusion Criteria: * Subjects with advanced or metastatic solid tumours who have completed treatment with first line therapy: 1. Epithelial ovarian, fallopian tube, or peritoneal cancer 2. Hepatocellular carcinoma 3. Non-small cell lung cancer 4. Urothelial cancer 5. Microsatellite instability high solid tumours, other than the above indications * Radiologic and/or biochemical evidence of disease progression * Completion of pre-treatment tumour biopsy * Must have measurable disease by RECIST v1.1 * Ambulatory with an ECOG 0-1 * Life expectancy ≥ 6 months * Meet protocol-specified laboratory requirements Key Exclusion Criteria: * Chemotherapy or immunotherapy within treatment within 28 days of start of study treatment * Radiotherapy within treatment within 2 weeks of start of study treatment * Prior therapy with an anti-PD-1, anti-PD-L1, or anti PD L2 agent or with an agent directed to another stimulatory or co-inhibitory T cell receptor where subject was discontinued from that treatment due to a Grade 3 or higher immune-related toxicity * For NSCLC subjects: Known EGFR mutations or ALK rearrangements * Prior receipt of survivin-based vaccine(s) and/or immunotherapies * Concurrent second malignancy other than non-melanoma skin cancer, cervical carcinoma in situ, or controlled bladder cancer * Clinical ascites or pleural fluid that cannot be managed * Malignant bowel obstruction or recent history of bowel obstruction * For OvCa, subjects with any single lesion greater than 5 cm * Autoimmune disease requiring treatment within the last two years (except replacement therapy) * Recent history of thyroiditis * Any history of (non-infectious) pneumonitis that required steroid therapy or current pneumonitis * Presence of a serious acute or chronic infection * Active CNS metastases and/or carcinomatous meningitis * GI condition that might limit absorption of oral agents * Allogenic tissue/solid organ transplant * Other serious intercurrent chronic or acute illness, including myocardial infarction or cerebrovascular event within 6 months * Ongoing treatment with steroid therapy or other immunosuppressive * Receipt of live attenuated vaccines * Acute or chronic skin and/or microvascular disorders * Edema or lymphedema in the lower limbs \> grade 2 * Severe hypersensitivity (≥ Grade 3) to pembrolizumab