FOLFIRINOX Versus OncoSil™ in Addition to FOLFIRINOX in Patients With Locally Advanced Pancreatic Adenocarcinoma

Inclusion Criteria: 1. Histologically or cytologically proven adenocarcinoma of the pancreas. 2. Unresectable locally advanced pancreatic adenocarcinoma according to NCCN 2021 guidelines.Staging and unresectability must be confirmed by central review of the baseline CT scan. 3. Pancreatic target tumour diameter of \< 7.0 cm (longest axis), as qualified by the central reading centre. 4. Karnofsky Performance Status ≥ 70 5. ≥ 18 years of age at screening. 6. Considered fit to commence first-line standard FOLFIRINOX chemotherapy: i) Adequate renal function: serum creatinine less than 1.5 x upper limit of normal (ULN). ii) Adequate liver function: serum liver transaminases ≤ 3 x ULN and serum bilirubin ≤ 1.5 x ULN\*. \*For study participants with recent biliary obstruction treated by drainage (e.g. stent), serum bilirubin of \> 1.5 x ULN will be accepted for study entry provided that serial levels demonstrate clear improvement. In addition, chemotherapy should not be commenced until serum bilirubin is ≤ 1.5 x ULN. iii) Adequate bone marrow function: white blood cells (WBCs) ≥ 3,000/mm3, absolute neutrophil count (ANC) ≥ 1,500/mm3, haemoglobin ≥ 9 g/dL, and platelets ≥ 100,000/mm3 iv) UGT1A1 polymorphism and DPD deficiency test performed and dose reductions applied as per local institutional practice. 7. Provide signed Informed Consent. 8. Willing and able to complete study procedures within the study timelines. 9. Life expectancy of at least 3 months at the time of screening as judged by the investigator. 10. Treated with or eligible to commence prophylactic treatment with a proton-pump inhibitor prior to implantation, and to continue to receive treatment for at least 6 months post implantation. 11. Not pregnant, and if of childbearing potential, agrees to use adequate birth control (hormonal or barrier method of birth control or abstinence) prior to study entry and during the study and agrees not to donate sperm or ova, for the duration of the study and 12 months post implantation of the investigational device. Exclusion Criteria: 1. Evidence of distant metastases, based on review of baseline CT scan. 2. More than one pancreatic tumour lesion. 3. Any prior radiotherapy or chemotherapy for pancreatic cancer. 4. Pregnant or lactating. 5. In the opinion of the investigator, EUS-directed implantation posing undue study subject risk. This includes: i) where previous EUS-FNA was considered technically too difficult to perform; ii) imaging demonstrates multiple collateral vessels surrounding or adjacent to the target tumour within the pancreas; iii) presence (or significant risk) of varices near to the target tumour. Note: The feasibility of implantation of the target tumour and assessment of risk can be repeated at any time between Screening Visit 1 and the implantation date. If any of the above risk features becomes apparent following subject screening and/or enrolment prior to and including at the time of OncoSil™ treatment, the patient should remain in the study but the implantation should be deferred or cancelled. 6. History of malignancy, treated or untreated, within the past five years whether or not there is evidence of local recurrence or metastases, with the exception of basal cell carcinoma of the skin and cervical carcinoma in situ. 7. Evidence of radiographic invasion into stomach or duodenum (if not certain, confirmation must be obtained prior to enrolment). 8. A known history of hypersensitivity to silicon or phosphorous, or any of the OncoSil™ components. 9. Any other health condition that would preclude participation in the study in the judgment of the investigator.