Key Inclusion Criteria:  Willing and able to give written informed consent Male or female patients, ≥18 years of age Histological or cytological confirmation of a locally advanced (unresectable) and/or metastatic pancreatic, CRC, NSCLC, SCCHN, ovarian, breast, soft tissue sarcoma and bladder cancer, who have either relapsed or progressed on SoC treatment or are intolerant or nonamenable to SoC treatment In Phase 1b part of the study only: At least 1 lesion, not previously irradiated, that can be accurately measured at baseline as ≥10mm in the largest diameter (except lymph nodes, which must have a short axis ≥15 mm) with CT or MRI scan and that is suitable for accurate repeated measurements. Life expectancy of greater than 12 weeks, in the opinion of the investigator Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1 Recovered from all acute toxic effects of any prior radiotherapy, chemotherapy, or surgical procedure (must have resolved to CTCAE grade ≤1 or returned to baseline, except alopecia and peripheral neuropathy, which can be up to CTCAE grade 2)  Adequate haematological function (applies only to patients not receiving therapeutic anticoagulation; patients receiving therapeutic anticoagulation should be on a stable dose):  Neutrophil count of ≥1.5× 10^9 cells/L Haemoglobin ≥9g/dL (with or without transfusion support) Platelet count of ≥75,000/μL (without transfusion within 2 weeks prior to Cycle 1, Day 1) International normalised ratio (INR) and activated partial thromboplastin time (aPTT) ≤1.5 times the upper limit of normal (ULN)  Adequate liver function:  Total bilirubin ≤1.5 × ULN (in patients with Gilbert's Syndrome, <3 × ULN is allowed) Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤2.5 × ULN (in patients with liver metastases, <5 × ULN is allowed) Alkaline phosphatase (ALP) <5 × ULN (patients with documented liver or bone metastases only)  Adequate renal function:  a. Serum creatinine ≤1.5 × ULN (in patients for whom, in the Investigator's judgment, serum creatinine levels do not adequately reflect renal function, creatinine clearance by Cockcroft-Gale formula ≥ 50 mL/min may be used)  Women of childbearing potential (WOCBP) and women who have ≤ 2 years amenorrhea after start of menopause: has a negative serum pregnancy test within 7 days prior to Cycle 1, Day 1  Contraception requirements:  Female patients of childbearing potential must agree to remain abstinent (refrain from heterosexual intercourse) or use a highly effective contraceptive method (Pearl Index failure rate <1% per year) during the treatment period and for at least 6 months after the last dose of study drug Male patients with female partners of childbearing potential must agree to use 2 acceptable methods of contraception (Pearl Index failure rate <1% per year), including a barrier method (with or without spermicide) during the treatment period and for at least 6 months after the last dose of study drug  Key Exclusion Criteria:  Received trastuzumab within 7 months of the planned Cycle 1, Day 1 AVA6000 infusion Received a prior total cumulative anthracycline dose of >350mg/m^2 doxorubicin hydrochloride (or equivalent anthracycline dose) Clinically significant or untreated central nervous system (CNS) metastases requiring treatment, as determined by the Investigator. Has leptomeningeal disease Any history of an active (requiring treatment) other malignancy (except any in-situ carcinoma, non-melanoma skin carcinoma and early prostate cancer with a normal PSA) within 2 years of study entry Has a significant, uncontrolled, concomitant disease that could affect compliance with the protocol Has uncontrolled hypertension (systolic blood pressure [SBP] >150 mmHg and/or diastolic [DBP] >100 mm Hg), unstable angina, congestive heart failure (New York Heart Association (NYHA) Class >II), left ventricular ejection fraction (LVEF) <55% or the low limit of institutional normal limit (whichever is lower) by echocardiogram (ECHO), serious cardiac arrhythmia requiring treatment (exceptions include atrial fibrillation, paroxysmal supraventricular tachycardia), history of myocardial infarction within 6 months prior to Cycle 1, Day 1; history of uncontrolled cardiovascular disease or high-sensitivity troponin above normal at baseline Screening baseline mean QTcF interval (Fridericia's) of >470 msec, obtained from 3 electrocardiograms (ECGs). Has any clinically significant abnormalities in rhythm, conduction, or morphology of resting ECG (e.g., complete left bundle branch block, third-degree heart block, second-degree heart block, PR interval >250msec). Has any factors that increase the risk of QTc prolongation or risk of arrhythmic events such as heart failure, hypokalaemia, congenital long QT syndrome, known family history of long QT syndrome or unexplained sudden death under 40 years of age in first degree relatives or any concomitant medication known to prolong the QT interval, a baseline resting bradycardia <45 beats/min or a baseline resting tachycardia of >100 beats/min Known uncontrolled HIV infection  Active hepatitis B (HBV) or hepatitis C (HCV) infection:  Positive hepatitis B surface antigen (HBsAG) test at Screening. Patients with a past or resolved HBV infection (defined as having a negative HBsAG test and a positive antibody to hepatitis B core antigen [antiHBc] antibody test) are eligible. Patients positive for HCV antibody are eligible only if PCR is negative for HCV RNA Severe infection(requiring IV treatment)within 21 days prior to Cycle 1, Day 1 including, but not limited to, hospitalisation for complications of infection, bacteraemia, or severe pneumonia Any other clinically significant active disease, metabolic dysfunction, physical examination finding, clinical laboratory finding, or reasonable suspicion of a disease or condition that would contraindicate the use of an investigational drugin the opinion of the investigator. Major surgery within 21 days prior to Cycle 1, Day 1 (excluding biopsies) or anticipates the need for major surgery during study treatment Has dementia or altered mental status that in the opinion of the investigator would preclude providing informed consent Pregnant or breastfeeding woman Known hypersensitivity to any of the components of AVA6000 or any excipient related to the product Received prior investigational therapy (defined as a treatment for which there is no Regulatory Authority-approved indication) within 21 or 42 days of Cycle 1 Day 1, for small molecule and biologic investigational therapies, respectively.  Received any approved anticancer therapy, including chemotherapy or hormonal therapy, within 28 days prior to Cycle 1, Day 1, with the following exceptions:  Hormone-replacement therapy or oral contraceptives Tyrosine kinase inhibitors (TKIs) that have been discontinued more than 7 days prior to Cycle1, Day 1 Is planned for on study treatment or has received within 21 days prior to Cycle 1, Day 1: St John's Wort, any strong inhibitor or inducer of CYP3A4, CYP2D6, narrow therapeutic index CYP1A2, CYP2B6, or P-glycoprotein (PGP) ̧ or any moderate OATP1B3 inhibitor (will include statins) Received systemic immunosuppressive medication (for any indication) at doses of >10mg prednisolone (or equivalent) within 28 days prior to Cycle 1, Day 1. Received radiotherapy within 28 days prior to Cycle 1, Day 1, except for limited field palliative radiotherapy. Patients who have received prior or concomitant radiotherapy to the mediastinal area are also excluded.