A Phase 1b/2 Multicenter, Open-label, Dose-escalation and Dose-expansion Study to Evaluate the Safety, Tolerability, Pharmacokinetics, Immunogenicity, and Antitumor Activity of Trastuzumab Deruxtecan (T-DXd) Monotherapy and Combinations in Adult Participants With HER2-expressing Gastric Cancer (DESTINY-Gastric-03)
DESTINY-Gastric03 will investigate the safety, tolerability, pharmacokinetics, immunogenicity, and preliminary antitumor activity of trastuzumab deruxtecan (T-DXd) alone or in combination with chemotherapy and/or immunotherapy in HER2-expressing advanced/metastatic gastric/gastroesophageal junction (GEJ) and esophageal adenocarcinoma patients. Study hypotheses: Combination of T-DXd with cytotoxic chemotherapy and/or immunotherapy administered to subjects at the recommended phase 2 dose will show manageable safety and tolerability and preliminary anti-tumor efficacy so as to permit further clinical testing. T-DXd in combination with cytotoxic chemotherapy or immune checkpoint inhibitor administered to HER2-expressing gastric, GEJ and esophageal cancer patients who have not received prior treatment for advanced/metastatic disease will show preliminary evidence of anti-tumour activity and the potential to become a therapeutic option for this patient population.
• Male and female participants must be at least 18 years of age. Other age restrictions may apply as per local regulations
• Disease Characteristics:
‣ Locally advanced, unresectable, or metastatic disease based on most recent imaging
⁃ For Part 1, 2, 3a, 4a pathologically documented adenocarcinoma of the stomach/GEJ/esophagus, HER2-positive (IHC 3+ or IHC 2+/ISH+) based on local tissue testing results
⁃ For Part 3b and 4b, pathologically documented adenocarcinoma of the stomach/GEJ/esophagus, HER2-low (IHC 2+/ISH-negative or IHC 1+) based on local tissue testing results
• For Part 1, progression on or after at least one prior trastuzumabcontaining regimen For Part 2, Part 3 and Part 4, previously untreated for unresectable or metastatic adenocarcinoma of the stomach/GEJ/ esophagus with with HER2-positive (Part 2 and Part 3 \[Arm 3A\] and Part 4 \[Arm 4A\]) or HER2-low (Part 3 \[Arm 3B\] and Part 4 \[Arm 4B\])) status
• Has measurable target disease assessed by the Investigator based on RECIST version 1.1
• Has protocol defined adequate bone marrow and organ function including cardiac, renal and hepatic function
• If of reproductive potential, agrees to use a highly effective form of contraception or avoid intercourse during and upon completion of the study.