What is the BESTOW Study?

When patients receive a transplanted kidney, they also receive medicines as part of routine care to help prevent rejection of the transplanted kidney. The main medicine used to prevent rejection is tacrolimus, which has some unwanted side effects.

The BESTOW Study is researching the safety and effectiveness of an investigational drug called tegoprubart that could replace tacrolimus in preventing rejection of the transplanted kidney. Tegoprubart is considered an investigational drug because it is still being tested and has not been approved by any regulatory agencies.

The BESTOW Study is designed to compare tegoprubart with tacrolimus, the current standard of care medicine, to test whether tegoprubart is safer and/or more effective than tacrolimus, as measured by kidney function.

Some of the points the study will look at include:

Icon of the kidneys, function of the transplanted kidney, BESTOW Study

Function of the transplanted kidney

Icon of a blood sugar monitor, risk of diabetes, BESTOW Study

Risk of diabetes

Icon of a checklist with icons of different types of medicine, prevention of rejection, BESTOW Study

Prevention of rejection

Click here to learn more about the study and study site locations

Who can participate?

Icon of a person, Age, first-time kidney transplant recipient, BESTOW Study


Adults 18 years of age or older

Icon of the kidneys, Status, first-time kidney transplant recipient, BESTOW Study


Recipients of their first kidney transplant

Additional study inclusion and exclusion criteria apply.

Icons of a clipboard with a medicine checklist, Medicine, first-time kidney transplant recipient, BESTOW Study


Willing and able to comply with the trial requirements, including avoiding prohibited medicine

What happens during the study?

The BESTOW Study has 4 periods—screening, transplant, post-transplant treatment, and follow-up—and will last up to 13 months (not including screening). There will be up to 26 study visits. 

Screening Period

Up to 28 days before transplant

If you choose to participate, the study staff will perform tests to see if you meet the participation criteria—this is called “screening.”


Day 0

On kidney transplant day you will undergo study-related tests. A physical exam and the collection of blood and urine samples will be done.

Study participants will be randomly selected (like tossing a coin) to 1 of 2 treatment groups: a study group to receive tegoprubart and a study group to receive tacrolimus. You and your study doctor will know which treatment group you are assigned to.

Post-transplant treatment

12 months

After the kidney transplant you will be monitored closely and will begin your study treatment. Some study visits will take place in the clinic and others will occur while you are in the hospital. After completion of this study, you may be eligible to enroll in a long-term extension study. 


1 month

After study treatment is completed, there will be 1 month of safety follow-up and a final clinic visit.


What kind of tests and health checks can I expect during the study?

Some of the tests included in the study are:

Icon of a pregnancy test represents one of the tests, if applicable, you can expect during the BESTOW Study

Pregnancy test*

Icon of a urine collection cup represents one of the tests you can expect during in the BESTOW Study

Urine tests

Icon of a clipboard represents the questionnaires you can expect to complete when participating in the BESTOW Study


Icon of a blood pressure cuff represents one of the health checks you can expect during the BESTOW Study

Vital signs

Icon of a heart and heartbeat line represents a heart activity test, or ECG test, you can expect during the BESTOW Study

Heart activity (ECG)

Icon of a blood collection tube represents the blood tests you can expect during the BESTOW Study for kidney transplants

Blood tests

Icon of a biopsy needle represents the kidney biopsy you can expect during the BESTOW Study for kidney transplants

Kidney biopsy

*If applicable

You will not have all tests at every visit. This list is not inclusive of all tests.