P-285 Basket trials in upper gastrointestinal and hepato-pancreatico-biliary cancers – an emerging entity

Upper gastrointestinal (GI) and hepato-pancreatico-biliary (HPB) cancers have poor prognoses and limited therapeutic options. Basket trials are being increasingly employed in these disease groups and have led to regulatory approvals for tumour agnostic prescribing. This study aimed to explore the success of emerging basket trials including patients with upper GI and HPB cancers, assessing phase of trial, agents used, selection biomarkers and endpoints favoured. A systematic review was conducted using the combined Ovid and Medline databases, including publications released up to and including April 2022, looking for primary studies reporting the results of basket trials in which patients with upper GI and HPB cancers were eligible for enrolment. A supplementary search on ClinicalTrials.gov was conducted in July 2022. Data on trial duration, treatment used, and endpoints recorded, were collected. The literature search identified 164 studies, while ClinicalTrials.gov identified 74: 23 ineligible studies were excluded, based on irrelevance to oncology; the remaining 215 studies were assessed. Fifty-three eligible basket studies were identified; 33 (62%) industry led, 20 (38%) academic. Of the 53 trials (non-randomised), 30 (57%) were phase II, 16 (30%) combined phase I/II and 7 (13%) were phase I; conducted in multiple institutions (not mutually exclusive): USA (N=34), Asia (N=28), Europe (N=17), Australia (N=6), Africa (N=1). The commonest therapeutic agents used were immunotherapy (N=16 (30%)), followed by PARP inhibitors (N=9 (17%)), EGFR inhibitors and HER2-directed agents (N=8 (15%) each). The biomarkers for entry selection were HER2 (N=10 trials), tumour mutation burden, DNA damage repair genes and BRAF/MEK (N=5 trials each), CDKN2A, NTRK, PDL1, NF1 (N=3 each), IDH1/2 (N=2), EGFR, VEGF, FGFR, KRAS (N=1 each), other (N=6). Ten trials did not require biomarker selection for entry. Eighteen trials had either full or interim results reported: N=407 total patients had advanced, previously-treated upper GI/HPB cancers (performance status 0-2) (range 1-43 per trial). The patients had biliary tract cancer (BTC) (N=249 (61.2%)), Oesophago-gastric (OG) (N=82 (20.1%)), pancreatic (N=38 (9.3%)), small bowel (N=36 (8.8%)), and hepatocellular carcinoma (HCC) (N=2 (0.5%)). The primary endpoint for 49 of 53 trials (92%) was response rate (RR). Median RR for all upper GI and HPB cancers across all 18 reported trials was 18.2%. Upper GI cancers had a median RR of 25%, HPB cancers 17.5% and HCC 0%. Five agents (from 18 trials) (28%) have gained tumour agnostic prescribing approval in these disease groups, based on these results: Pembrolizumab, Larotrectinib, Entrectinib, Dostarlimab and Dabrafenib combined with Trametinib. The trials included in this study were early phase, conducted mainly in USA, Asia and Europe, with the most favoured therapeutic agents used being immunotherapy, likely reflecting the era of study. More patients with BTC were included, possibly due to more limited treatment options for rarer malignancies. The majority reported RR as the primary endpoint, allowing earlier read outs, with promising tumour agnostic approval in these disease groups. Evolving basket trial and statistical methodology with dedicated cohorts for these patients with emerging subgroups, will potentially lead to improved patient outcomes.