Exhibit 16.1
NovemberĀ 15, 2023
Securities and Exchange Commission
100 F Street, N.E.
Washington, DC 20549
Commissioners:
We have read Item 4.01 of Form 8-K dated NovemberĀ 15, 2023, of Day One Biopharmaceuticals, Inc. and are in agreement with the statements contained in the first, second, third and fourth paragraphs included in Item 4.01(a) therein. We have no basis to agree or disagree with other statements of the registrant contained therein.
/s/ ErnstĀ & Young LLP
San Mateo, California