A Safety and Efficacy Study of ZW25 (Zanidatamab) Plus Combination Chemotherapy in HER2-expressing Gastrointestinal Cancers, Including Gastroesophageal Adenocarcinoma, Biliary Tract Cancer, and Colorectal Cancer

Inclusion:

Disease diagnosis:

Part 1:
GEA: Unresectable, locally advanced, recurrent or metastatic HER2-expressing GEA (IHC 3+ or 2+ with or without gene amplification based upon local assessment or central assessment)
BTC: Unresectable, locally advanced, recurrent or metastatic HER2-expressing BTC (including intrahepatic cholangiocarcinoma [ICC], extrahepatic cholangiocarcinoma [ECC], or gallbladder cancer [GBC]) (IHC 3+ with or without gene amplification; or IHC 0, 1+ or 2+ with gene amplification, based upon central assessment)
CRC: Unresectable, locally advanced, recurrent or metastatic HER2-expressing CRC (IHC 3+ with or without gene amplification; or IHC 0, 1+ or 2+ with gene amplification, based upon central assessment). Patients will be required to be extended RAS (KRAS and NRAS) and BRAF wild-type based upon central assessment.
Part 2:
GEA: Unresectable, locally advanced, recurrent or metastatic HER2-expressing GEA (IHC 3+, or IHC 2+ and FISH+ by central assessment)
BTC: Same as Part 1
CRC: Same as Part 1

Tumor measurements as per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1:

Part 1: Measurable or non-measurable disease
Part 2: Measurable disease
An Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0 or 1
Adequate organ function
Adequate cardiac left ventricular function, as defined by a LVEF >/= institutional standard of normal

Exclusion:

Prior treatment with a HER2-targeted agent

Prior systemic anti-cancer therapy (including investigational products) except prior adjuvant/neoadjuvant therapy, which must be completed at least 6 months prior to first study treatment dosing. For subjects with BTC and CRC the following additional exceptions apply:

BTC: patients may have started therapy for advanced disease but may not have received more than one cycle of any standard gemcitabine-based chemotherapy regimen.
CRC: patients may have started therapy for advanced disease but may not have received more than one cycle of 5-FU-based chemotherapy (< 1 month of therapy).
Patients with certain contraindications to bevacizumab cannot be enrolled on the mFOLFOX6-2 with bevacizumab arm.
Palliative radiotherapy is allowed if completed at least 2 weeks prior to first study treatment dosing
Untreated known brain metastases (patients with treated brain metastases who are off steroids, off antiseizure medications, and stable for at least 1 month at the time of screening are eligible)
Clinically significant cardiac disease, such as ventricular arrhythmia requiring therapy, uncontrolled hypertension or any history of symptomatic congestive heart failure (CHF). Patients with known myocardial infarction or unstable angina within 6 months prior to randomization are also excluded.
QTc Fridericia (QTcF) > 470 ms. For patients with longer QTcF on initial electrocardiogram (ECG), follow-up ECG may be performed in triplicate to determine eligibility
Peripheral neuropathy > Grade 1 per NCI-CTCAE v5.0
Clinically significant interstitial lung disease
Prior or concurrent malignancy whose natural history or treatment has the potential to interfere with the safety or efficacy assessment of the investigational regimen
Active hepatitis B or hepatitis C infection or infection with Human Immunodeficiency Virus (HIV)-1 or HIV-2 (Exception: patients with well controlled HIV [e.g., CD4 > 350/mm3 and undetectable viral load] are eligible)