UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

(Rule 13d-102)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO RULES 13d-1(b), (c), AND (d) AND AMENDMENTS THERETO FILED

PURSUANT TO RULE 13d-2(b)

(Amendment No. 1)¹

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

1              The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

 (1) Excludes 355,077 Common 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 9.9% of the Common Shares outstanding.

(1) Excludes 235,562 Common Shares underlying the Warrants that are not exercisable due to the Beneficial Ownership Limitation, which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.9% of the Common Shares outstanding.  

(1) Excludes 61,020 Common Shares underlying the Warrants that are not exercisable due to the Beneficial Ownership Limitation, which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.9% of the Common Shares outstanding.

(1) Excludes 61,020 Common Shares underlying the Warrants that are not exercisable due to the Beneficial Ownership Limitation, which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.9% of the Common Shares outstanding.

(1) Excludes 749,998 Common Shares underlying the Warrants that are not exercisable due to the Beneficial Ownership Limitation, which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.9% of the Common Shares outstanding.

(1) Excludes 749,998 Common Shares underlying the Warrants that are not exercisable due to the Beneficial Ownership Limitation, which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.9% of the Common Shares outstanding. 

(1) Excludes 749,998 Common Shares underlying the Warrants that are not exercisable due to the Beneficial Ownership Limitation, which provides that the Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own more than 9.9% of the Common 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

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

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 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 “Common Shares”)

29668H708

As of the close of business on October 17, 2018, the Reporting Persons hold 749,998 warrants, exercisable for an aggregate of 749,998 Common Shares (the “Warrants”). Each Warrant entitles the holder thereof to acquire, for a nominal exercise price, one Common 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 9.9% of the outstanding Common 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 October 17, 2018, the Beneficial Ownership Limitation limits the aggregate exercise of the Warrants by the Reporting Persons to zero out of the 749,998 Common Shares underlying the Warrants owned by the Reporting Persons in the aggregate. BVF holds Warrants to purchase 355,077 additional Common Shares which are excluded herein as a result of the Beneficial Ownership Limitation. BVF2 holds Warrants to purchase 235,562 additional Common Shares which are excluded herein as a result of the Beneficial Ownership Limitation. BVTOS holds Warrants to purchase 61,020 additional Common Shares which are excluded herein as a result of the Beneficial Ownership Limitation. The Reporting Persons through certain Partners managed accounts (the “Partners Managed Accounts”) hold Warrants to purchase 98,339 additional Common Shares which are excluded herein as a result of the Beneficial Ownership Limitation.

As of the close of business on October 17, 2018 (i) BVF beneficially owned 237,757 Common Shares, (ii) BVF2 beneficially owned 236,371 Common Shares, and (iii) Trading Fund OS beneficially owned 40,680 Common Shares.

Partners OS, as the general partner of Trading Fund OS, may be deemed to beneficially own the 40,680 Common Shares beneficially owned by Trading Fund OS.

Partners, as the general partner of BVF, BVF2, the investment manager of Trading Fund OS, and the sole member of Partners OS, may be deemed to beneficially own the 580,367 Common Shares beneficially owned in the aggregate by BVF, BVF2, Trading Fund OS, and the Partners Managed Accounts, including 65,559 Common Shares held in the Partners Managed Accounts.

BVF Inc., as the general partner of Partners, may be deemed to beneficially own the 580,367 Common Shares beneficially owned by Partners.

Mr. Lampert, as a director and officer of BVF Inc., may be deemed to beneficially own the 580,367 Common 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 Common Shares owned by another Reporting Person. Partners OS disclaims beneficial ownership of the Common Shares beneficially owned by Trading Fund OS. Each of Partners, BVF Inc. and Mr. Lampert disclaims beneficial ownership of the Common Shares beneficially owned by BVF, BVF2, Trading Fund OS, and 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 5,776,098 Common Shares outstanding, as of June 30, 2018, which is the total number of Common Shares outstanding as reported in Exhibit 99.1 to the Issuer’s Report of foreign issuer on Form 6-K filed with the Securities and Exchange Commission on August 14, 2018.

As of the close of business on October 17, 2018 (i) BVF beneficially owned approximately 4.1% of the outstanding Common Shares, (ii) BVF2 beneficially owned approximately 4.1% of the outstanding Common Shares, (iii) Trading Fund OS beneficially owned less than 1% of the outstanding Common Shares, (iv) Partners OS may be deemed to beneficially own less than 1% of the outstanding Common Shares, and (v) each of Partners, BVF Inc. and Mr. Lampert may be deemed to beneficially own approximately 10.1% of the outstanding Common Shares (approximately 1.1% of the outstanding Common 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.

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

Not Applicable.

See Exhibit 99.1 to the Schedule 13G filed with the Securities and Exchange Commission on January 16, 2018.

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: October 17, 2018