Dual Erb B Inhibition in Oesophago-gastric Cancer (DEBIOC): A phase I dose escalating safety study and randomised dose expansion of AZD8931 in combination with oxaliplatin and capecitabine chemotherapy in patients with oesophagogastric adenocarcinoma

Background
AZD8931 has equipotent activity against epidermal growth factor receptor, erbB2, and erbB3. Primary objectives were to determine the recommended phase II dose (RP2D) of AZD8931 + chemotherapy, and subsequently assess safety/preliminary clinical activity in patients with operable oesophagogastric cancer (OGC).

Methods
AZD8931 (20 mg, 40 mg or 60 mg bd) was given with Xelox (oxaliplatin + capecitabine) for eight 21-day cycles, continuously or with intermittent schedule (4 days on/3 off every week; 14 days on/7 off, per cycle) in a rolling-six design. Subsequently, patients with OGC were randomised 2:1 to AZD8931 + Xelox at RP2D or Xelox only for two cycles, followed by radical oesophagogastric surgery. Secondary outcomes were safety, complete resection (R0) rate, six-month progression-free survival (PFS) and overall survival.

Results
During escalation, four dose-limiting toxicities were observed among 24 patients: skin rash (1) and failure to deliver 100% of Xelox because of treatment-associated grade III-IV adverse events (AEs) (3: diarrhoea and vomiting; vomiting; fatigue). Serious adverse events (SAE) occurred in 15 of 24 (63%) patients. RP2D was 20-mg bd with the 4/3 schedule. In the expansion phase, 2 of 20 (10%) patients in the Xelox + AZD8931 group and 5/10 (50%) patients in the Xelox group had grade III–IV AEs. Six-month PFS was 85% (90% CI: 66%–94%) in Xelox + AZD8931 and 100% in Xelox alone. Seven deaths (35%) occurred with Xelox + AZD8931 and one (10%) with Xelox. R0 rate was 45% (9/20) with Xelox + AZD8931 and 90% (9/10) with Xelox-alone (P = 0.024).

Conclusion
Xelox + AZD8931 (20 mg bd 4/3 days) has an acceptable safety profile administered as neoadjuvant therapy in operable patients with OGC.