Paclitaxel protein bound (A) plus gemcitabine (G) plus cisplatin (C), and paricalcitol (P)neoadjuvant therapy for localized pancreatic ductal adenocarcinoma (PDAC).

Abstract

4631 Background: Localized PDAC management has recently evolved. Due to concerns over micro metastases at diagnosis the use of neoadjuvant chemotherapy for PDAC has become more common. Typical therapies involve the use of multiagent systemic chemotherapies with or without radiation therapy. In retrospective studies, Cancer Antigen 19-9 (CA 19-9) normalization in borderline resectable (BR) and locally advanced (LA) PDAC has been associated with greater OS. The addition of cisplatin (C) to gemcitabine (G) and paclitaxel protein bound (A), has shown promising clinical data in a previously reported study in advanced PDAC [JAMA Oncol. 2020;6(1):125-132]. We conducted a prospective, phase 2 clinical trial of patients with resectable (R), BR, and LA PDAC utilizing a regimen combining A + G + C + paricalcitol (P) with the primary endpoint of CA 19-9 normalization (NCT03138720). Methods: Eligibility criteria include patients with histologically confirmed R, BR, or LA PDAC, elevated CA 19-9, and a KPS ≥ 70% with normal end organ function. Doses are A 125 mg/m2, G 1000 mg/m2, C 25 mg/ m2, P at a fixed dose of 25 µg on days 1, 8 of a 21-day cycle (all treatment IV). Primary objective is to evaluate CA 19-9 normalization with the neoadjuvant chemotherapy. Secondary objectives are to assess R0 rate, pathologic complete response (pCR), safety and tolerability, radiologic response rate, and 2 year overall survival (OS) from date of study entry. Exploratory objectives include evaluating imaging biomarkers and vascular involvement by tumor in relation to therapy. Results: To date 24 of the planned 24 patients have been enrolled. 13 male, 11 female; age range 49 to 84 yo. Patient classifications is 8 R; 7 BR; 9 LAPC. Median baseline CA 19-9 156 (range 45-3674). Most common drug related grade (gr) 3-4 adverse events (AEs) are: thrombocytopenia gr 3 29%, gr 4 25%, anemia gr 3 45.8%, gr 4 4.2%, and hypophosphatemia gr 3 8.3%. CA 19-9 normalization occurred in 50% (12/24) who have completed at least 1 cycle of treatment. To date, 14 individuals went to surgery, with 13/14 achieving R0, (1 pCR). Overall response rate in measurable patients is 38% (1 CR, 8 PR). Median OS and 2-year survival data are not yet matured. Conclusions: In patients with non-metastatic PDAC, the use of A+G+C+P resulted in a CA 19-9 normalization rate in 50% of individuals. The study is ongoing and OS data is maturing. Clinical trial information: NCT03138720 .