Exploring external validity of chemotherapy for pancreatic ductal adenocarcinoma in real life

Introduction: Cisplatin, nab-paclitaxel, capecitabine, and gemcitabine (PAXG) regimen activity was assessed in a single institution phase II trial (PACT-19) on pancreatic ductal adenocarcinoma (PDAC). The PACT-31 study explored the external validity of PACT-19 results. Materials and methods: Patients aged ≥18 and ≤75 years with KPS ≥70, and PDAC diagnosis receiving PAXG in the participating institutions were eligible and categorized as follows: A) PACT-19; B) PACT-31-HSR; C) PACT-31-non-HSR. With a sample of 175 patients, assuming a target 1-year overall survival of 60 % for metastatic and of 80 % for non-metastatic patients, the trial will be considered successful with the 1-year OS falling into the 95 % CI. Results: Data from 68 PACT-19 and 168 PACT-31 patients were retrieved. After 124 events, 1yOS was 52.5 % (95 %CI: 44.6-60.4 %) for metastatic and 80.5 % (95 %CI: 71.9-89.1 %) for non-metastatic patients. Survival overlapped between PACT-19 and PACT-31-HSR (median 17.6 and 17.4 months, p = 0.21) and was significantly shorter in PACT-31-non-HSR (median 11.3 months; p = 0.03). Differences of dose-intensity, use of maintenance therapy, and treatment after progression between PACT-31-HSR and non-HSR were evidenced. Discussion: PACT-19 results have external validity. The outcome difference between HSR and non-HSR centers endorses the need of creating a hub-and-spoke network aimed at sharing the expertise on rare-diseases.