Castle Biosciences (CSTL) SC 13G Castle Biosciences Inc

CUSIP No. 1483C-105 13G Page 7 of 7 Pages

Exhibit 99.1

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k) promulgated under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree to the joint filing with all other Reporting Persons (as such term is defined in the Schedule 13G referred to below) on behalf of each of them of a statement on Schedule 13G (including amendments thereto) with respect to the common stock of Castle Biosciences, Inc., a Delaware corporation, and that this Agreement may be included as an Exhibit to such joint filing. This Agreement may be executed in any number of counterparts all of which, taken together, shall constitute one and the same instrument.

Dated: February 12, 2020

/s/ Daniel Bradbury
Daniel Bradbury
BioBrit LLC
By:	/s/ Daniel Bradbury
Name:	Daniel Bradbury, Managing Member