A Phase IB Study of PRS-343 and Atezolizumab in Patients with HER2-Positive Digestive Cancers


Full Title

A Phase 1B, Open-Label, Dose Escalation Study of PRS-343 in Combination with Atezolizumab in Patients with Specific HER2-Positive Advanced or Metastatic Solid Tumors


The purpose of this study is to find the highest dose of the investigational drug PRS-343 that can be given safely with atezolizumab immunotherapy in patients with recurrent or persistent digestive cancers that are positive for the HER2 protein. PRS-343 is a protein that targets HER2 and an immune receptor called CD137. PRS-343 tells CD137 cells to group together and attach to HER2-containing tumor cells. This may allow CD137 to stimulate the immune system to attack HER2-positive cancer cells and slow or stop the growth of tumors.

Atezolizumab is an antibody that boosts the immune system’s ability to find and destroy cancer cells. Atezolizumab is thought to be most effective when an anticancer immune response has already begun, like the one triggered by CD137. PRS-343 and atezolizumab are both given intravenously (by vein).


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

  • Patient must have a HER2-positive inoperable or metastatic digestive cancer that has come back or continued to grow despite prior treatment.
  • At least 3 weeks must pass between the completion of previous therapies and entry into the study.
  • Patients must be able to walk and do routine activities for more than half of their normal waking hours.
  • This study is for patients age 18 and older.

For more information about this study and to inquire about eligibility, please contact Dr. Geoffrey Ku at 646-888-4588.





Disease Status

Relapsed or Refractory