Clinical Results Summary
A clinical study to understand the effect of probenecid on the bloodlevels of pexidartinib in healthy participantsProtocol number: PL3397-A-U122

Thank You!

Daiichi Sankyo, Inc., the sponsor of this study, would like to thank the participants who
took part in this study for pexidartinib, also known PLX3397. Each participant helped toadvance medical research. Their contribution to medicine and healthcare is greatlyappreciated.

Important note: This summary only shows the results of a single study. Other studies may have different
findings. Researchers and health authorities look at the results of many studies to understand which
treatments work and how they work. It takes a lot of people in many studies around the world to advance
medical science and healthcare.
Do not use the results of this study to make health decisions. Please talk to a doctor before changing any
treatment you are taking or if you have any questions about these study results.

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What was the main purpose of this study?
Pexidartinib, also known as PLX3397, is a study drug that is being tested for its ability to stop the growth oftumor cells. A tumor is a type of cancer or abnormal growth of cells in the body, which can spread to otherparts of the body.
Probenecid is a drug already available in the market for treating conditions like a type of arthritis (gout) andexcess blood uric levels (hyperuricemia). Probenecid also blocks certain proteins that break down pexidartinibin the body. This may help to slow the breakdown of pexidartinib in the body.
In this study, researchers wanted to understand the effect of probenecid on the blood levels of pexidartinib
and its breakdown product ZAAD-1006a in healthy participants.

Treatments given in this study

Main goal of this study
The main question the researchers wanted to answer in this study was:

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Other goal of this study
Researchers also wanted to answer the following question:•Was there a difference in the blood levels of ZAAD-1006a, when given pexidartinib with probenecid
versus when given alone?

Researchers also monitored the health of the participants throughout the study.

How long was this study?
An individual participant could have been in this study forabout 1 month. The study started in February 2017 andended in March 2017.
This study was completed as planned. When the study
ended, the results were collected and a study report wascreated. This summary is based on that report.

Who was in this study?
This study included 16 participants from a single site in
the United States.
Healthy men and women could take part in this study ifthey were:•between 18 years and 60 years of age,•

not underweight,•

using effective birth control methods during thestudy or were unable to have children.

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What happened during this study?
This was a Phase 1 study done in a small number of participants to learn what happens to the study drug inthe body. This was an “open label” study. This means that both the researchers and participants knew which
treatment was given to which participant.
Participants were screened to find out if they could take part in the study. Researchers then randomlyassigned participants equally to 2 treatment groups using a computer system. This process is calledrandomization. It means that each participant could be assigned to any group to make sure the groups aredistributed fairly.
Participants in each treatment group went through 2 treatment periods: Period 1 and Period 2. Eachtreatment period lasted for 15 days. Participants were given both the treatments based on the order shown in
the figure below:•Treatment A: Pexidartinib 600 milligram (mg) as capsules on Day 2.

•Treatment B: Probenecid 500 mg tablet 4 times a day for 14 days. Pexidartinib 600 mg as capsules on
Day 2.

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There was a washout period of 3 to 4 days between treatment periods. Participants were given no drugs
during this time to allow drugs given during Period 1 to leave their body.
Researchers took blood samples at defined time points and monitored the participants’ health throughout thestudy.
A total of 16 participants were enrolled in this study, but 1 participant in Treatment B (treatment sequence BA)
discontinued the study due to the side effect of rash. So, 15 participants received Treatment A and16 participants received Treatment B.

What were the key results of this study?
Key results from this study are shown for the total group of participants as average results. This summary does
not show the results from each individual participant. An individual participant’s results could be different
from the total group of participants. A full list of the questions the researchers wanted to answer, and adetailed presentation of the results can be found on the website listed at the end of this summary.

Was there a difference in the blood levels of pexidartinib when given withprobenecid versus when given alone?
The total blood level of pexidartinib measured over time was 60% higher when given with probenecid
compared with when given alone. This means that probenecid reduced the breakdown of pexidartinib in thebody as expected.
iHow was this measured?

Researchers took blood samples from participants at defined time points. They then measured the total levelsof pexidartinib in participants’ blood over time in units, nanograms hours per milliliter (ng•h/mL). This shows
how much of pexidartinib in nanogram (one thousand-millionth of a gram) was found in each milliliter ofblood over time.

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What were the other results of this study?
Was there a difference in the blood levels of ZAAD-1006a, when pexidartinib wasgiven with probenecid versus when given alone?
The total blood level of ZAAD-1006a measured over time was 2 times higher, when pexidartinib was given
with probenecid compared with when given alone. This means that probenecid reduced the breakdown ofZAAD-1006a in the body as expected.
iHow was this measured?

Researchers took blood samples from participants at defined time points. They then measured the total levels
of ZAAD-1006a in participants’ blood over time in units, nanograms hours per milliliter (ng•h/mL).

What medical problems did the study participants have?
Side effects are medical problems (such as feeling tired) that happened during the study which the study
doctor (investigator) thought could be related to the treatments in the study. This section provides a summaryof side effects related to pexidartinib. The website listed at the end of this summary has more information
about the medical problems that happened in this study.
Side effects are considered serious if they cause death, are life-threatening, cause lasting problems, or require
hospitalization. Some participants stop study treatment because of side effects.

How many participants had serious side effects?
No participant had a serious side effect during this study. No deaths were reported due to side effects.
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How many participants had side effects during the study?
The side effects that happened during any treatment are presented below:

How many participants had to stop treatment because of side effects?
No participant stopped the study treatment due to a side effect related to pexidartinib.

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How was this study useful for patients and researchers?
This study helped researchers understand the effect of probenecid on the blood levels of pexidartinib and its
breakdown product ZAAD-1006a in healthy participants.
Findings from this study may be used in other studies. Other studies for pexidartinib are ongoing.
Please remember, this summary only shows the results of a single study. Other studies may have different
findings. Please talk to a doctor before changing any treatment you are taking or if you have any questions
about these study results.

Where can I learn more about this study?
You can find more information about this study on the following website:www.clinicaltrials.gov: Use the NCT identifier NCT03138759 in the search field.
Please remember that the results on this website may be presented in a different way. If you were a study
participant and have questions about the results of this study, please speak with the doctor or staff at your study
site.
Full study title: An Open-Label, Randomized, 2Treatment, 2-Period, Crossover Study to Evaluate
the Effect of Probenecid on the Pharmacokineticsof Pexidartinib in Healthy Subjects.

Sponsor: Daiichi Sankyo, Inc.
Sponsor contact information:
211 Mount Airy Road, Basking Ridge, NJ 07920
Email: CTRInfo@dsi.com
Phone number: 1-908-992-6640Date of this summary: 11 March 2021

This summary was prepared by Kinapse Ltd, a Syneos Health® company.

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