LIMITED POWER OF ATTORNEY

The undersigned hereby constitutes and appoints Julia M. Eastland, as long as
she is providing services to Cascadian Therapeutics, Inc. (the "Company"), the
undersigned's true and lawful attorney-in-fact to:
(1)	execute for and on behalf of the undersigned, in the undersigned's capacity
as an officer and/or director of the Company, Forms 3, 4s and 5s in accordance
with Section 16(a) of the Securities Exchange Act of 1934, as amended, and the
rules and regulations thereunder;
(2)	do and perform any and all acts for and on behalf of the undersigned that
may be necessary or desirable to complete and execute any such Forms 3, 4s and
5s and timely file such forms with the Securities and Exchange Commission and
any stock exchange or similar authority; and
(3)	take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of benefit to,
in the best interest of, or legally required by, the undersigned, it being
understood that the documents executed by such attorney-in-fact on behalf of the
undersigned pursuant to this Power of Attorney shall be in such form and shall
contain such terms and conditions as such attorney-in-fact may approve in such
attorney-in-fact's discretion.

The undersigned hereby grants to such attorney-in-fact full power and authority
to do and perform each and every act and thing whatsoever requisite, necessary
or proper to be done in the exercise of any of the rights and powers herein
granted, as fully to all intents and purposes as the undersigned might or could
do if personally present, with full power of substitution and revocation, hereby
ratifying and confirming all that such attorney-in-fact, or such
attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be
done by virtue of this power of attorney and the rights and powers herein
granted.  The undersigned acknowledges that such attorney-in-fact, in serving in
such capacity at the request of the undersigned, is not assuming, nor is the
Company assuming, any of the undersigned's responsibilities to comply with
Section 16 of the Exchange Act.

The undersigned agrees that such attorney-in-fact may rely entirely on
information furnished orally or in writing by the undersigned to such
attorney-in-fact.  The undersigned also agrees to indemnify and hold harmless
the Company and such attorney-in-fact against any losses, claims, damages or
liabilities (or actions in these respects) that arise out of or are based on any
untrue statement or omission of necessary facts in the information provided by
the undersigned to such attorney-in-fact for purposes of executing,
acknowledging, delivering and filing Forms 3, 4s or 5s (including amendments
thereto) and agrees to reimburse the Company and such attorney-in-fact for any
legal or other expenses reasonably incurred in connection with investigating or
defending against any such loss, claim, damage, liability or action.

	This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4s and 5s with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorney-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of March 24, 2017.

/s/ Robert Azelby
Robert W. Azelby