Phase 1b/II study of durvalumab (D) and tremelimumab (T) plus PET-adjudicated chemoradiation (CRT) in patients (Pts) with esophageal adenocarcinoma.

Abstract

355 Background: We previously evaluated adding D, an anti-PD-L1 antibody, to PET-directed CRT and found the combination to be safe and promising in terms of pathologic response and survival outcomes.1 Here, we add T to the combination. Methods: Pts with locally advanced esophageal/GEJ adenocarcinoma were enrolled. Pts received 2 cycles of mFOLFOX6 prior to repeat PET/CT. PET responders (≥35% reduction in SUV (PETr)) received 5-FU/capecitabine and oxaliplatin with RT, while induction PET non-responders (PETnr) received carboplatin/paclitaxel with RT. All Pts received T 300 mg ×1 and D 1,500 mg q4W ×2 starting 2 weeks prior to CRT. Esophagectomy was planned 6-8 weeks after CRT. Pts with R0 resections received adjuvant T 300 mg ×1 and D 1,500mg q4W ×6. The primary endpoint was the pathologic complete response (pCR) rate. Initially, 6 Pts were enrolled to evaluate for toxicity; they received RT to 50.4 Gy. Subsequently, RT was lowered to 41.4 Gy to decrease the length of preop treatment (tx). Results: 16 pts have been enrolled. All Pts had clinical ≥T3 and/or N+ disease. PD-L1 CPS was ≥1 in 9 (60%) of 15 tested. 1 Pt (6%) had a microsatellite unstable (MSI) tumor. 9 (56%) Pts were PETr; 3 Pts (19%) were PETnr but had improved clinical symptoms and other PET parameters (MTV/TLG) and also continued with 5-FU/capecitabine and oxaliplatin during RT. Significant tx-related adverse events (AEs) are shown in the Table. Immune-related AEs (irAEs) were: gd 3 enterocolitis (1 Pt), gd 3/4 colitis (2 Pts, 12%), gd 1 diarrhea (1 Pt), gd 2 pruritis (1 Pt), gd 1 and gd 3 dermatitis (1 Pt each) and gd 2 arthralgias in 1 Pt. 1 Pt died of aspiration pneumonia while being treated for gd 4 colitis during CRT; 1 Pt developed gd 3 enterocolitis and cholecystitis during CRT, achieved a clinical CR and did not undergo surgery. He developed local recurrence and had surgery off-study 16 months after start of tx; 1 Pt developed a bone metastasis after CRT. 4 Pts are awaiting restaging post-CRT. Of 9 Pts who had surgery, 4 achieved a pCR (44%, including the MSI Pt) and 3 (33%) had ypN0 tumors and ³90% tx response. All 9 Pts have initiated/completed adjuvant D+T. Conclusions: The addition of D+T to induction FOLFOX and PET-directed CRT prior to surgery is feasible, although irAEs seem numerically higher than in our prior study of D and CRT. Pathologic response data are promising. Accrual is ongoing and updated data will be presented. 1. Ann Surg 2023;278:e511. Clinical trial information: NCT02962063 . [Table: see text]