A Phase II Study of Immunotherapy with Atezolizumab plus Cobimetinib versus Atezolizumab Alone in Patients with Advanced Bile Duct Cancer

Full Title

A Randomized Phase 2 Study of Atezolizumab in Combination with Cobimetinib Versus Atezolizumab Monotherapy in Participants with Unresectable Cholangiocarcinoma (CIRB)


The purpose of this study is to assess the safety and effectiveness of combining two drugs in patients with advanced bile duct cancer (cholangiocarcinoma) that has grown or come back despite prior therapy and which cannot be surgically removed. The drugs are cobimetinib and atezolizumab. Patients will be randomly assigned to receive both cobimetinib and atezolizumab or atezolizumab alone.

Cobimetinib works by inhibiting MEK, a protein which fuels cancer growth. It may also strengthen the immune system’s ability to fight cancer. It is used to treat melanoma; its use in this study is considered investigational. Cobimetinib is taken orally (by mouth).

Atezolizumab is an immunotherapy drug designed to improve the immune system’s ability to recognize and destroy cancer cells by blocking PD-L1, a protein made by some cancers. It is approved for treating bladder and lung cancers; its use in this study is investigational. Atezolizumab is given intravenously (by vein).


To be eligible for this study, patients must meet several criteria, including but not limited to the following:

  • Patients must have metastatic or inoperable bile duct cancer that has grown or came back despite at least one prior regimen of therapy. Patients may have had up to two regimens of treatment for metastatic disease.
  • At least 3 weeks must pass since the completion of prior therapy and entry into the study.
  • Patients may not have previously received a MEK inhibitor nor immunotherapy with a PD-1 or PD-L1 inhibitor.
  • Patients must be physically well enough that they are fully ambulatory, capable of all self care, and are capable of all but physically strenuous activities. As an example, patients must be well enough that they would be able to carry out office work or light housework.
  • This study is for patients age 18 and older.

For more information and to inquire about eligibility for this study, please contact Dr. Ghassan Abou-Alfa at 646-888-4184.