13D Filing: Caxton Corp and Strongbridge Biopharma PLC (SBBP)

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Exhibit A

AGREEMENT

Pursuant to Rule 13d-1(k)(1) under the Securities
Exchange Act of 1934, as amended, each of the undersigned hereby agrees that only one statement containing the information required
by Schedule 13D need be filed with respect to the ownership by each of the undersigned of Ordinary Shares, $0.01 par value of Strongbridge
Biopharma plc.

This Agreement may be executed in any
number of counterparts, each of which shall be deemed an original.

Date: 10/10/2017 Caxton Corporation*
/s/ Heath N. Weisberg
Heath N. Weisberg, as General Counsel and Chief Compliance Officer of Caxton Corporation
Date: 10/10/2017 CDK Associates, L.L.C.
By: Caxton Corporation,
Manager of CDK Associates, L.L.C.
/s/ Heath N. Weisberg
Heath N. Weisberg, as General Counsel and Chief Compliance Officer of Caxton Corporation
Date: 10/10/2017 Bruce S. Kovner*
/s/ Heath N. Weisberg
Heath N. Weisberg, as attorney
in fact for Bruce Kovner

* The Reporting Persons disclaim beneficial ownership
over the securities reported herein except to the extent of the reporting persons’ pecuniary interest therein.

 

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