EPIX ESSA Pharma Inc

(1) Excludes 1,481,634 Shares underlying the Warrants (defined in Item 4) that are not exercisable due to the Beneficial Ownership Limitation (defined in Item 4), which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.99% of the Shares outstanding.

(1) Excludes 1,481,634 Shares underlying the Warrants (defined in Item 4) that are not exercisable due to the Beneficial Ownership Limitation (defined in Item 4), which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.99% of the Shares outstanding.

(1) Excludes 1,235,030 Shares underlying the Warrants (defined in Item 4) that are not exercisable due to the Beneficial Ownership Limitation (defined in Item 4), which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.99% of the Shares outstanding.

(1) Excludes 1,235,030 Shares underlying the Warrants (defined in Item 4) that are not exercisable due to the Beneficial Ownership Limitation (defined in Item 4), which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.99% of the Shares outstanding.

(1) Excludes 203,336 Shares underlying the Warrants (defined in Item 4) that are not exercisable due to the Beneficial Ownership Limitation (defined in Item 4), which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.99% of the Shares outstanding.

(1) Excludes 203,336 Shares underlying the Warrants (defined in Item 4) that are not exercisable due to the Beneficial Ownership Limitation (defined in Item 4), which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.99% of the Shares outstanding.

(1) Excludes 2,716,664 Shares underlying the Warrants (defined in Item 4) that are not exercisable due to the Beneficial Ownership Limitation (defined in Item 4), which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.99% of the Shares outstanding.

(1) Excludes 2,920,000 Shares underlying the Warrants (defined in Item 4) that are not exercisable due to the Beneficial Ownership Limitation (defined in Item 4), which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.99% of the Shares outstanding.

(1) Excludes 2,920,000 Shares underlying the Warrants (defined in Item 4) that are not exercisable due to the Beneficial Ownership Limitation (defined in Item 4), which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.99% of the Shares outstanding.

(1) Excludes 2,920,000 Shares underlying the Warrants (defined in Item 4) that are not exercisable due to the Beneficial Ownership Limitation (defined in Item 4), which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.99% of the Shares outstanding.

ESSA Pharma Inc., a Canada corporation (the “Issuer”).

Suite 720, 999 West Broadway

Vancouver, British Columbia,

Canada, V5Z 1K5

Biotechnology Value Fund, L.P. (“BVF”)

44 Montgomery St., 40^th Floor

San Francisco, California 94104

Citizenship: Delaware

BVF I GP LLC (“BVF GP”)

44 Montgomery St., 40^th Floor

San Francisco, California 94104

Citizenship: Delaware

Biotechnology Value Fund II, L.P. (“BVF2”)

44 Montgomery St., 40^th Floor

San Francisco, California 94104

Citizenship: Delaware

BVF II GP LLC (“BVF2 GP”)

44 Montgomery St., 40^th Floor

San Francisco, California 94104

Citizenship: Delaware

Biotechnology Value Trading Fund OS LP (“Trading Fund OS”)

PO Box 309 Ugland House

Grand Cayman, KY1-1104

Cayman Islands

Citizenship: Cayman Islands

BVF Partners OS Ltd. (“Partners OS”)

PO Box 309 Ugland House

Grand Cayman, KY1-1104

Cayman Islands

Citizenship: Cayman Islands

BVF GP Holdings LLC (“BVF GPH”)

44 Montgomery St., 40^th Floor

San Francisco, California 94104

Citizenship: Delaware

BVF Partners L.P. (“Partners”)

44 Montgomery St., 40^th Floor

San Francisco, California 94104

Citizenship: Delaware

BVF Inc.

44 Montgomery St., 40^th Floor

San Francisco, California 94104

Citizenship: Delaware

Mark N. Lampert (“Mr. Lampert”)

44 Montgomery St., 40^th Floor

San Francisco, California 94104

Citizenship: United States

Each of the foregoing is referred to as a “Reporting Person” and collectively as the “Reporting Persons.”

Common Shares, without par value (the “Shares”)

29668H708

As of the close of business on December 31, 2019, the Reporting Persons hold 2,920,000 warrants, exercisable for an aggregate of 2,920,000 Shares (the “Warrants”). Each Warrant entitles the holder thereof to acquire, for a nominal exercise price of $0.0001, one Share. The Warrants are only exercisable to the extent that the holder, together with its affiliates and any other person or entity acting as a group, would not beneficially own more than 9.99% of the outstanding Shares after giving effect to such exercise, as such percentage ownership is determined in accordance with the terms of the Warrants (the “Beneficial Ownership Limitation”). As of the close of business on December 31, 2019, the Beneficial Ownership Limitation limited the aggregate exercise of the Warrants by the Reporting Persons to zero out of the 2,920,000 Shares underlying the Warrants owned by the Reporting Persons in the aggregate. BVF holds Warrants to purchase 1,481,634 additional Shares which are excluded herein as a result of the Beneficial Ownership Limitation. BVF2 holds Warrants to purchase 1,235,030 additional Shares which are excluded herein as a result of the Beneficial Ownership Limitation. Trading Fund OS holds Warrants to purchase 203,336 additional Shares which are excluded herein as a result of the Beneficial Ownership Limitation.

As of the close of business on December 31, 2019 (i) BVF beneficially owned 1,203,836 Shares, (ii) BVF2 beneficially owned 948,712 Shares, and (iii) Trading Fund OS beneficially owned 186,587 Shares.

BVF GP, as the general partner of BVF, may be deemed to beneficially own the 1,203,836 Shares beneficially owned by BVF.

BVF2 GP, as the general partner of BVF2, may be deemed to beneficially own the 948,712 Shares beneficially owned by BVF2.

Partners OS, as the general partner of Trading Fund OS, may be deemed to beneficially own the 186,587 Shares beneficially owned by Trading Fund OS.

BVF GPH, as the sole member of each of BVF GP and BVF2 GP, may be deemed to beneficially own the 2,152,548 Shares beneficially owned in the aggregate by BVF and BVF2.

Partners, as the investment manager of BVF, BVF2 and Trading Fund OS, and the sole member of Partners OS, may be deemed to beneficially own the 2,640,565 Shares beneficially owned in the aggregate by BVF, BVF2, Trading Fund OS, including 301,430 Shares held through certain Partners managed accounts (the “Partners Managed Accounts”).

BVF Inc., as the general partner of Partners, may be deemed to beneficially own the 2,640,565 Shares beneficially owned by Partners.

Mr. Lampert, as a director and officer of BVF Inc., may be deemed to beneficially own the 2,640,565 Shares beneficially owned by BVF Inc.

The foregoing should not be construed in and of itself as an admission by any Reporting Person as to beneficial ownership of any Shares owned by another Reporting Person. BVF GP disclaims beneficial ownership of the Shares beneficially owned by BVF. BVF2 GP disclaims beneficial ownership of the Shares beneficially owned by BVF2. Partners OS disclaims beneficial ownership of the Shares beneficially owned by Trading Fund OS. BVF GPH disclaims beneficial ownership of the Shares beneficially owned by BVF and BVF2. Each of Partners, BVF Inc. and Mr. Lampert disclaims beneficial ownership of the Shares beneficially owned by BVF, BVF2, Trading Fund OS, and held in the Partners Managed Accounts, and the filing of this statement shall not be construed as an admission that any such person or entity is the beneficial owner of any such securities.

The following percentages are based on 20,762,374 Shares outstanding as of September 30, 2019, which is the total number of Shares outstanding as reported in the Issuer’s Annual Report on Form 20-F filed with the Securities and Exchange Commission on December 20, 2019.

As of the close of business on December 31, 2019 (i) BVF beneficially owned approximately 5.8% of the outstanding Shares, (ii) BVF2 beneficially owned approximately 4.6% of the outstanding Shares, (iii) Trading Fund OS beneficially owned less than 1% of the outstanding Shares, (iv) BVF GP may be deemed to beneficially own approximately 5.8% of the outstanding Shares, (v) BVF2 GP may be deemed to beneficially own approximately 4.6% of the outstanding Shares, (vi) Partners OS may be deemed to beneficially own less than 1% of the outstanding Shares, (vii) BVF GPH may be deemed to beneficially own approximately 10.4% of the outstanding Shares, and (viii) each of Partners, BVF Inc. and Mr. Lampert may be deemed to beneficially own approximately 12.7% of the outstanding Shares (approximately 1.5% of the outstanding Shares is held in the Partners Managed Accounts).

See Cover Pages Items 5-9.

See Cover Pages Items 5-9.

See Cover Pages Items 5-9.

See Cover Pages Items 5-9.

Not Applicable.

BVF GP, BVF GPH, Partners, BVF Inc. and Mr. Lampert share voting and dispositive power over the Shares beneficially owned by BVF and BVF2. Partners, BVF Inc. and Mr. Lampert share voting and dispositive power over the Shares beneficially owned by Trading Fund OS and the Partners Managed Accounts.

Not Applicable.

See Exhibit 99.1.

Not Applicable.

By signing below each of the undersigned certifies that, to the best of its knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

SIGNATURE

After reasonable inquiry and to the best of his knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated: February 14, 2020