Initial Statement of Beneficial Ownership (3)

FORM 3	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0104 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * PERCEPTIVE ADVISORS LLC	2. Date of Event Requiring Statement (MM/DD/YYYY) 3/9/2020	3. Issuer Name and Ticker or Trading Symbol LEAP THERAPEUTICS, INC. [LPTX]
(Last)        (First)        (Middle) 51 ASTOR PLACE, 10TH FLOOR,	4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director                          ___X___ 10% Owner _____ Officer (give title below)        _____ Other (specify below)
(Street) NEW YORK, NY 10003       (City)              (State)              (Zip)	5. If Amendment, Date Original Filed(MM/DD/YYYY)	6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	6726496	I	See footnote (1)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 4)	2. Date Exercisable and Expiration Date (MM/DD/YYYY)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Warrants (right to buy)	(2)	(2)	Common Stock	6726496	$2.11	I	See footnote (1)

Explanation of Responses:
(1)	The securities are directly held by Perceptive Life Sciences Master Fund Ltd. (the "Master Fund"). Perceptive Advisors LLC (the "Advisor") serves as the investment manager of Master Fund. Joseph Edelman is the managing member of the Advisor. Each of Mr. Edelman and the Advisor disclaims, for purposes of Section 16 of the Securities Exchange Act of 1934, beneficial ownership of such securities, except to the extent of his/its indirect pecuniary interest therein, and this report shall not be deemed an admission that either Mr. Edelman or the Advisor is the beneficial owner of such securities for purposes of Section 16 or for any other purposes.
(2)	The Warrants are exercisable at any time on or after the issuance date until January 7, 2027. The Warrants cannot be exercised to the extent that, after giving effect to such exercise, the Reporting Persons would beneficially own in excess of 9.9% of the Issuer's voting shares. Accordingly, the Warrants cannot currently be exercised.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
PERCEPTIVE ADVISORS LLC 51 ASTOR PLACE, 10TH FLOOR NEW YORK, NY 10003		X
PERCEPTIVE LIFE SCIENCES MASTER FUND LTD C/O PERCEPTIVE ADVISORS LLC 51 ASTOR PLACE, 10TH FLOOR NEW YORK, NY 10003		X
EDELMAN JOSEPH C/O PERCEPTIVE ADVISORS LLC 51 ASTOR PLACE, 10TH FLOOR NEW YORK, NY 10003		X

Signatures
/s/ Perceptive Life Sciences Master Fund Ltd., By: Perceptive Advisors LLC, its investment manager By: Joseph Edelman, its managing member		4/20/2020
**Signature of Reporting Person		Date
/s/ Perceptive Advisors LLC, By: Joseph Edelman, its managing member		4/20/2020
**Signature of Reporting Person		Date
/s/ Joseph Edelman		4/20/2020
**Signature of Reporting Person		Date