SC 13D

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-102)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO

RULE 13d-2(a)

(Amendment No. __)*

Loxo Oncology, Inc.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

548862101

(CUSIP Number)

Lloyd Appel

Aisling Capital

888 Seventh Avenue, 12th Floor

New York, NY 10106

(212) 651-6380

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

May 17, 2016

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box . ☒

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

* 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 (the “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).

CUSIP No. 548862101 SCHEDULE 13D Page 2 of 15

1	NAME OF REPORTING PERSON OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Aisling Capital III, LP
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP	(a) ☐ (b) ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)	☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 4,028,920
	8	SHARED VOTING POWER 0
	9	SOLE DISPOSITIVE POWER 4,028,920
	10	SHARED DISPOSITIVE POWER 0

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,028,920
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES	☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 18.6% (See Item 5)
14	TYPE OF REPORTING PERSON PN

CUSIP No. 548862101 SCHEDULE 13D Page 3 of 15

1	NAME OF REPORTING PERSON OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Aisling Capital Partners III, LP
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP	(a) ☐ (b) ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)	☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 4,028,920
	8	SHARED VOTING POWER 0
	9	SOLE DISPOSITIVE POWER 4,028,920
	10	SHARED DISPOSITIVE POWER 0

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,028,920
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES	☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 18.6% (See Item 5)
14	TYPE OF REPORTING PERSON PN

CUSIP No. 548862101 SCHEDULE 13D Page 4 of 15

1	NAME OF REPORTING PERSON OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Aisling Capital Partners III LLC
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP	(a) ☐ (b) ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)	☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 4,028,920
	8	SHARED VOTING POWER 0
	9	SOLE DISPOSITIVE POWER 4,028,920
	10	SHARED DISPOSITIVE POWER 0

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,028,920
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES	☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 18.6% (See Item 5)
14	TYPE OF REPORTING PERSON OO

CUSIP No. 548862101 SCHEDULE 13D Page 5 of 15

1	NAME OF REPORTING PERSON OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Steven Elms
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP	(a) ☐ (b) ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)	☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION United States

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 0
	8	SHARED VOTING POWER 4,028,920
	9	SOLE DISPOSITIVE POWER 0
	10	SHARED DISPOSITIVE POWER 4,028,920

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,028,920
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES	☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 18.6% (See Item 5)
14	TYPE OF REPORTING PERSON IN

CUSIP No. 548862101 SCHEDULE 13D Page 6 of 15

1	NAME OF REPORTING PERSON OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Dennis Purcell
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP	(a) ☐ (b) ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)	☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION United States

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 0
	8	SHARED VOTING POWER 4,028,920
	9	SOLE DISPOSITIVE POWER 0
	10	SHARED DISPOSITIVE POWER 4,028,920

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,028,920
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES	☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 18.6% (See Item 5)
14	TYPE OF REPORTING PERSON IN

CUSIP No. 548862101 SCHEDULE 13D Page 7 of 15

1	NAME OF REPORTING PERSON OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Andrew Schiff
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP	(a) ☐ (b) ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)	☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION United States

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 0
	8	SHARED VOTING POWER 4,028,920
	9	SOLE DISPOSITIVE POWER 0
	10	SHARED DISPOSITIVE POWER 4,028,920

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,028,920
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES	☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 18.6% (See Item 5)
14	TYPE OF REPORTING PERSON IN

CUSIP No. 548862101 SCHEDULE 13D Page 8 of 15

Item 1. Security and Issuer.

This Schedule 13D (this “13D”) is filed with respect to the Common Stock, $0.0001 par value (the “Shares”), of Loxo Oncology, Inc., a Delaware corporation (the “Issuer”). The principal executive office of the Issuer is located at 281 Tresser Blvd., 9th Floor, Stamford, CT 06901.

The Reporting Persons (as defined below) have previously filed a statement on Schedule 13G in accordance with Rule 13d-1(d), dated February 2, 2015 and amended February 5, 2016.  This Schedule 13D reports the acquisition by the Reporting Persons of an aggregate of more than 2% of the Issuer’s outstanding common stock during the past 12 months.

Item 2. Identity and Background.

(a) This Schedule 13D is being filed on behalf of the following persons (each, a “Reporting Person” and collectively, the “Reporting Persons”):

(i) Aisling Capital III, LP (“Aisling”);

(ii) Aisling Capital Partners III, LP (“Aisling Partners”), the general partner of Aisling;

(iii) Aisling Capital Partners III LLC (“Aisling Partners GP”), the general partner of Aisling Partners;

(v) Mr. Dennis Purcell, a managing member of Aisling Partners GP;

(vi) Mr. Steven Elms, a managing member of Aisling Partners GP; and

(vi) Mr. Andrew Schiff, a managing member of Aisling Partners GP (together with Messrs. Purcell and Elms, the “Managers”).

(b) The principal business address for each of the Reporting Persons is 888 Seventh Avenue, 12th Floor, New York, New York 10106.

(c) Aisling was formed in order to engage in the acquiring, holding and disposing of investments in various companies. Aisling Partners is the general partner of Aisling and was formed to act as the general partner of Aisling, to make investments through Aisling and to fulfill such other purposes as may be determined by Aisling from time to time. Aisling Partners GP is the general partner of Aisling Partners and was formed to act as the general partner of Aisling Partners. The principal occupation of each of Messrs. Purcell, Elms and Schiff are as the Managers of Aisling Partners GP. Accordingly, pursuant to the regulations promulgated under Section 13(d) of the Act, Aisling Partners, Aisling GP, Messrs. Elms, Purcell and Schiff each may be deemed to be a beneficial owner of the Common Stock held for the account of Aisling.

CUSIP No. 548862101 SCHEDULE 13D Page 9 of 15

(d) None of the Reporting Persons has, during the last five years, been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).

(e) None of the Reporting Persons has, during the last five years, been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding were or are subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, Federal or state securities laws or finding any violation with respect to such laws.

(f) Each of Aisling and Aisling Partners is a Delaware limited partnership. Aisling Partners GP is a Delaware limited liability company. Each of Steven Elms, Dennis Purcell and Andrew Schiff is a United States citizen.

Item 3. Source and Amount of Funds or Other Consideration.

As of the date hereof, each of the Reporting Persons may be deemed to beneficially own 4,028,920 Shares, consisting of (i) 2,850,709 Shares issued upon the conversion of (x) 2,343,749 shares of Series A Convertible Preferred Stock of the Issuer and (y) 506,960 shares of Series B Convertible Preferred Stock of the Issuer at the closing of the Issuer’s initial public offering of Common Stock (“IPO”) on August 6, 2014, (ii) 188,707 Shares, which were acquired on July 3, 2013 and (iii) 989,504 Shares, which were acquired at various times following the IPO at various prices. The source of the purchase price for the Common Stock was capital contributions from the partners of Aisling. No borrowed funds were used in the purchase of the Common Stock.

Item 4. Purpose of Transaction.

Each Reporting Person expects to evaluate on an ongoing basis the Issuer’s financial condition and prospects and its interest in, and intentions with respect to, the Issuer and their investment in the securities of the Issuer, which review may be based on various factors, including the Issuer’s business and financial condition, results of operations and prospects, general economic and industry conditions, the securities markets in general and those for the Issuer’s securities in particular, as well as other developments and other investment opportunities, which, if effected, could result in, among other things, any of the matters identified in Items 4(a)-(j) of Schedule 13D.

CUSIP No. 548862101 SCHEDULE 13D Page 10 of 15

Accordingly, each Reporting Person reserves the right to change its intentions and develop plans or proposals at any time, as it deems appropriate. In particular, each Reporting Person may at any time and from time to time, (i) in the open market, in privately negotiated transactions or otherwise, acquire additional Common Stock or other securities of the Issuer, including acquisitions from affiliates of the Reporting Persons; (ii) dispose or transfer of all or a portion of the securities of the Issuer, including the Common Stock that the Reporting Persons now own or may hereafter acquire, to any person or entity, including dispositions to affiliates of the Reporting Persons; (iii) enter into derivative transactions with institutional counterparties with respect to the Issuer’s securities; (iv) cause or seek to cause the Issuer or any of its subsidiaries to acquire all or a portion of another person’s assets or business, including acquisitions from affiliates of the Reporting Persons; (v) cause or seek to cause the Issuer or any of its subsidiaries to enter into one or more acquisitions, business combinations or mergers or to sell, transfer or otherwise dispose of all or any portion of its assets or business to any person or entity, including acquisitions, business combinations, mergers, sales, transfers and other dispositions with or to affiliates of the Reporting Persons; (vi) restructure the Issuer’s or any of its subsidiaries’ capitalization, indebtedness or holding company arrangements; (vii) make personnel changes to the present management of the Issuer deemed necessary or desirable; (viii) change the identity of the directors of the Issuer, including Mr. Elms, who is a director of the Issuer; (ix) make or propose any other material change in the Issuer’s or any of its subsidiaries’ corporate structure or business; or (x) engage in communications with one or more stockholders, officers or directors of the Issuer and other persons regarding any of the matters described in clauses (i) through (ix) above.

Item 5. Interest in Securities of the Issuer.

(a) The aggregate percentage of Shares reported as owned by each Reporting Person is based on 21,616,960 Shares of the Issuer’s Common Stock issued and outstanding immediately following the May 2016 Offering, as reported in the Issuer’s prospectus filed with the Securities and Exchange Commission (the “SEC”) on May 12, 2016, assuming exercise in full by the underwriters in such offering of their option to purchase 251,250 Shares. Based on calculations made in accordance with Rule 13d-3(d), each Reporting Person may be deemed to beneficially own 4,028,920 Shares, constituting approximately 18.6% of the outstanding Shares.

CUSIP No. 548862101 SCHEDULE 13D Page 11 of 15

(b) (i) Each of Aisling, Aisling Partners and Aisling Partners GP may be deemed to have sole power to direct the voting and disposition of the 4,028,920 Shares of Common Stock that may be deemed to be beneficially owned by the Reporting Persons.

(ii) By virtue of the relationships between and among the Reporting Persons described in Item 2 of this Schedule 13D, each of the Messrs. Elms, Purcell and Schiff may be deemed to share the power to direct the voting and disposition of the 4,028,920 Shares beneficially owned by the Reporting Persons.

(c) On May 17, 2016, Aisling acquired 232,558 Shares in an underwritten offering (the “May 2016 Offering”) at a price of $21.50 per Share.

(d) The partners of Aisling have the right to participate in the receipt of dividends from, or proceeds from the sale of, the Shares held for the account of Aisling in accordance with their ownership interests in Aisling.

(e) Not applicable.

Item 6. Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer.

Mr. Elms, a managing member of Aisling Partners GP, has been a member of the board of directors of the Issuer since July 2013.  In addition, Dr. Joshua Bilenker, the president, chief executive officer and director of the Company is an operating partner of Aisling GP.

Lock-up Agreement

In connection with the May 2016 Offering, Citigroup Global Markets Inc. (“Citigroup”) and Cowen and Company, LLC (“Cowen”, and together with Cowen, the “Representatives”) and each of Mr. Elms and Aisling entered into Lock-Up Agreements (the “Lock-Up Agreement”). Each of the Lock-Up Agreements provides that, subject to limited exceptions, without the prior written consent of the Representatives, neither Elms nor Aisling will, for a period of 90 days from the date of the Underwriting Agreement dated May 11, 2016 between the Issuer and the Representatives (the “Lock-Up Period”), (1) offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, including the filing of a registration statement with the Securities and Exchange Commission in respect of, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position with respect to, any Shares or securities convertible into or exercisable or exchangeable for Shares, (2) enter into any swap or other similar agreement or arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the Shares or other securities of the Issuer described in clause (1) above, whether now owned or hereafter acquired by Mr. Elms or Aisling or with respect to which Mr. Elms or Aisling has or hereafter acquires the power of disposition.

The foregoing description of the Lock-Up Agreements does not purport to be complete and is qualified in its entirety by reference to the full text of each of the Lock-Up Agreements, a copy of which is filed as Exhibits 1 and 2 and are incorporated herein by reference.

CUSIP No. 548862101 SCHEDULE 13D Page 12 of 15

Amended and Restated Investor Rights Agreement

Aisling and certain other stockholders of the Issuer entered into an amended and restated investor rights agreement with the Issuer (“Investor Rights Agreement”), dated as of July 21, 2014. Pursuant to the Investor Rights Agreement and subject to the terms and conditions therein, the parties agreed that:

Demand Registration Rights

After the expiration of the 180-day period following the registration statement effective date with respect to the IPO, the holders of a majority of the Shares covered by the Investor Rights Agreement, or their transferees, can, on not more than three occasions, request that the Issuer register all or a portion of their Shares. Such request for registration must cover a number of Shares with an anticipated aggregate offering price, net of selling expenses, of at least $10.0 million. The Issuer will not be required to effect a demand registration during the period that is 60 days before the Issuer’s good faith estimate of the date of filing of, and ending on a date that is 180 days after the effective date of, a company-initiated registration statement relating to an initial public offering of its securities, provided that the Issuer is actively employing in good faith commercially reasonable efforts to cause such registration statement to become effective.

Piggyback Registration Rights

The Investor Rights Agreement further provides that, in the event that the Issuer determines to register any of its securities under the Securities Act, either for its own account or for the account of other security holders, the stockholders who are party to the Investor Rights Agreement, including Aisling, will be entitled to certain “piggyback” registration rights allowing the holders to include their Shares in such registration, subject to certain marketing and other limitations. These rights do not apply with respect to a registration related to employee benefit plans, the offer and sale of debt securities, or corporate reorganizations or certain other transactions.

 Form S-3 Registration Rights

The stockholders who are party to the Investor Rights Agreement, including Aisling, will be entitled to make a written request that the Issuer register their Shares on Form S-3 (an “S-3 Demand Request”) if the Issuer is eligible to file a registration statement on Form S-3 and if the aggregate price to the public, net of selling expenses, is at least $750,000. These stockholders may make an unlimited number of S-3 Demand Requests; provided however, the Issuer will not have to effect a registration pursuant to an S-3 Demand Request if the Issuer has effected two (2) registrations pursuant to S-3 Demand Requests within the twelve (12) month period immediately preceding the date of such S-3 Demand Request. The Issuer will also not be required to effect an S-3 Demand Request during the period that is 30 days before the Issuer’s good faith estimate of the date of filing of, and ending on a date that is 90 days after the effective date of, a company-initiated registration statement relating to an initial public offering of its securities, provided that the Issuer is actively employing in good faith commercially reasonable efforts to cause such registration statement to become effective.

CUSIP No. 548862101 SCHEDULE 13D Page 13 of 15

Expenses of Registration

The Issuer will pay the registration expenses of the holders of the Shares registered pursuant to the demand, piggyback and Form S-3 registration rights described above.

Indemnification

The Investor Rights Agreement contains customary cross-indemnification provisions, pursuant to which the Issuer is obligated to indemnify the selling stockholders in the event of material misstatements or omissions in the registration statement attributable to the Issuer, and the selling stockholders are obligated to indemnify the Issuer for material misstatements or omissions attributable to them.

Termination of Registration Rights.

Aisling’s demand, piggyback and Form S-3 registration rights described above generally will terminate upon the earlier of: (i) the date seven years following the Issuer’s initial public offering; (ii) a Deemed Liquidation Event (as defined in the Issuer’s Restated Certificate of Incorporation) or Stock Sale (as defined in the Investor Rights Agreement); or (iii) such time as all of the Registrable Securities (as defined in the Investor Rights Agreement) of the Issuer held by Aisling may be sold without any restriction on volume or manner of sale in any three-month period pursuant to Rule 144.

The foregoing description of the Investor Rights Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Investor Rights Agreement, a copy of which is filed as Exhibit 3 and incorporated herein by reference.

Other than as described in this Schedule 13D, to the best of the Reporting Persons’ knowledge, there are no other contracts, arrangements, understandings or relationships (legal or otherwise) among the persons named in Item 2 and between such persons and any person with respect to any securities of the Issuer. 

CUSIP No. 548862101 SCHEDULE 13D Page 14 of 15

On May 30, 2014, each of the Reporting Persons entered into an agreement (the “Joint Filing Agreement”) in which the parties agreed to the joint filing on behalf of each of them of statements on Schedule 13D with respect to the securities of the Issuer to the extent required by applicable law. The Joint Filing Agreement is attached as Exhibit 4 to this Schedule 13D and is incorporated herein by reference.

Item 7. Material to be Filed as Exhibits.

Exhibit 1: Lock-Up Agreement dated May 11, 2016, by and among Citigroup Global Market Inc, Cowen and Company LLC and Ailsing Capital III, LP.

Exhibit 2: Lock-Up Agreement dated May 11, 2016, by and among Citigroup Global Market Inc, Cowen and Company LLC and Mr, Steven Elms

Exhibit 3: Amended and Restated Investors’ Rights Agreement, dated July 21, 2014, by and among the Registrant and certain of its stockholders, as amended (incorporated herein by reference to Exhibit 4.2 to the Form S-1/A filed by the Issuer on July 21, 2014 (File No. 333-197123)).

Exhibit 4: Joint Filing Agreement dated as of May 27, 2016, as required by Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended.

CUSIP No. 548862101 SCHEDULE 13D Page 15 of 15

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: May 27, 2016

	AISLING CAPITAL III, LP
By:	Aisling Capital Partners III, LP General Partner
By:	Aisling Capital Partners III LLC General Partner
	By:	/s/ Dennis Purcell
		Name: Dennis Purcell
		Title: Managing Member

	AISLING CAPITAL PARTNERS III, LP
By:	Aisling Capital Partners III LLC General Partner
	By:	/s/ Dennis Purcell
		Name: Dennis Purcell
		Title: Managing Member

	AISLING CAPITAL PARTNERS III LLC
By:	/s/ Dennis Purcell
	Name: Dennis Purcell Title: Managing Member
	/s/ Steven Elms
	Steven Elms
	/s/ Dennis Purcell
	Dennis Purcell
	/s/ Andrew Schiff
	Andrew Schiff

Attention. Intentional misstatements or omissions of fact constitute Federal criminal violations (see 18 U.S.C. 1001).

EX-99.1

EXHIBIT 1

LOXO ONCOLOGY, INC.

May 11, 2016

Citigroup Global Markets Inc.Cowen and Company, LLCAs Representatives of the several Underwriters

c/o Citigroup Global Markets Inc.388 Greenwich StreetNew York, New York 10013

c/o Cowen and Company, LLC599 Lexington AvenueNew York, New York 10022

Ladies and Gentlemen:

This letter is being delivered to you in connection with the proposed Underwriting Agreement (the “Underwriting Agreement”), between Loxo Oncology, Inc., a Delaware corporation (the “Company”), and each of you as representatives (together, the “Representatives”) of a group of Underwriters named therein, relating to an underwritten public offering (the “Offering”) of Common Stock, $0.0001 par value (the “Common Stock”), of the Company.

In order to induce you and the other Underwriters to enter into the Underwriting Agreement, the undersigned will not, without the prior written consent of Citigroup Global Markets Inc. and Cowen and Company, LLC, (i) offer, sell, contract to sell, pledge or otherwise dispose of, (or enter into any transaction which is designed to, or might reasonably be expected to, result in the disposition (whether by actual disposition or effective economic disposition due to cash settlement or otherwise) by the undersigned or any affiliate of the undersigned or any person in privity with the undersigned or any affiliate of the undersigned), directly or indirectly, including the filing (or participation in the filing) of a registration statement with the Securities and Exchange Commission in respect of, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the rules and regulations of the Securities and Exchange Commission promulgated thereunder with respect to, or (ii) enter into any swap or any other agreement or any transaction that transfers, in whole or in part, directly or indirectly, the economic consequence of ownership of, any shares of capital stock of the Company or any securities convertible into or exercisable or exchangeable for such capital stock, whether now owned or hereafter acquired by the undersigned or with respect to which the undersigned has or hereafter acquires the power of disposition, or publicly announce an intention to effect any such transaction, for a period from the date hereof through and including 90 days after the date of the Underwriting Agreement (the “Lock-Up Period”).

The restrictions set forth in the preceding paragraphs shall not apply to:

(1)if the undersigned is a natural person, any transfers made by the undersigned (a) as a bona fide gift to any member of the immediate family (as defined below) of the undersigned or to a trust the direct or indirect beneficiaries of which are exclusively the undersigned or members of the undersigned’s immediate family, (b) by will or intestate succession upon the death of the undersigned or (c) as a bona fide gift to a charity or educational institution, provided that if the undersigned is required to file a report under Section 16(a) of the Exchange Act, reporting any transfer pursuant to this clause (1), the undersigned shall include a statement in such report to the effect that such transfer is being made as a gift or by will or intestate succession, provided, further that no filing under Section 16(a) of the Exchange Act shall be voluntarily made during the Lock-Up Period,

(2)if the undersigned is a corporation, partnership, limited liability company or other business entity, any transfers to any current or former stockholder, partner (which, for additional clarity, includes limited partners) or member of, or owner of a similar equity interest in, the undersigned or to any investment fund or other entity that controls or manages the undersigned (including, for the avoidance of doubt, a fund managed by the same manager or managing member or general partner or management company or by an entity controlling, controlled by, or under common control with such manager or managing member or general partner or management company as the undersigned or who shares a common investment advisor with the undersigned), as the case may be, if, in any such case, such transfer is not for value,

(3)if the undersigned is a corporation, partnership, limited liability company or other business entity, any transfer made by the undersigned (a) in connection with the sale or other bona fide transfer in a single transaction of all or substantially all of the undersigned’s capital stock, partnership interests, membership interests or other similar equity interests, as the case may be, or all or substantially all of the undersigned’s assets, in any such case not undertaken for the purpose of avoiding the restrictions imposed by this agreement or (b) to another corporation, partnership, limited liability company or other business entity so long as the transferee is an affiliate (as defined below) of the undersigned and such transfer is not for value,

(4)if the undersigned is a trust, transfers to the beneficiary of such trust and such transfer is not for value,

(5)transactions relating to shares of Common Stock or other securities convertible into or exercisable or exchangeable for Common Stock acquired in open market transactions after completion of the Offering, provided that no filing under Section 16(a) of the Exchange Act shall be required or shall be voluntarily made in connection with subsequent sales of Common Stock or other securities acquired by you in such open market transactions,

2

(6)to the Company pursuant to agreements under which the Company has the option to repurchase such shares or a right of first refusal with respect to transfers of such shares upon termination of service of the undersigned,

(7)the entry, by the undersigned, at any time on or after the date of the Underwriting Agreement, of any trading plan providing for the sale of Common Stock by the undersigned, which trading plan meets the requirements of Rule 10b5-1(c) under the Exchange Act, provided, however, that such plan does not provide for, or permit, the sale of any Common Stock during the Lock-Up Period and no public announcement or filing is voluntarily made or required regarding such plan during the Lock-Up Period,

(8)any transfers made by the undersigned to the Company to satisfy tax withholding obligations pursuant to the Company’s equity incentive plans or arrangements existing as of the date of the Underwriting Agreement, and

(9)the transfer of shares of Common Stock or any security convertible into or exercisable or exchangeable for Common Stock pursuant to a bona fide third-party tender offer, merger, consolidation or other similar transaction made to all holders of the Company’s securities involving a change of control of the Company, provided that in the event that such tender offer, merger, consolidation or other such transaction is not completed, such securities held by the undersigned shall remain subject to the restrictions on transfer set forth in this letter;

provided, however, that (A) in the case of any transfer described in clause (1), (2), (3) or (4) above, it shall be a condition to the transfer that the transferee executes and delivers to the Representatives, acting on behalf of the Underwriters, not later than one business day prior to such transfer, a written agreement, in substantially the form of this agreement (it being understood that any references to “immediate family” in the agreement executed by such transferee shall expressly refer only to the immediate family of the undersigned and not to the immediate family of the transferee) and otherwise satisfactory in form and substance to the Representatives; (B) in the case of any transfer described in clause (2), (3) or (4) above, it shall be a condition to the transfer or distribution that no filing under Section 16(a) of the Exchange Act shall be required or voluntarily made during the Lock-Up Period; and (C) in the case of any transfer described in clause (6) or (8) above, if the undersigned is required to file a report under Section 16(a) of the Exchange Act reporting a reduction in beneficial ownership of shares of Common Stock or Common Stock which may be deemed to be beneficially owned by the undersigned in accordance with the rules and regulations promulgated under the Exchange Act, as the same may be amended or supplemented from time to time (such shares, the “Beneficially Owned Shares”) or any securities convertible into or exercisable or exchangeable for Common Stock or Beneficially Owned Shares during the Lock-Up Period, the undersigned shall include a statement in such report to the effect that, in the case of any transfer pursuant to clause (6) above, such transfer is being made pursuant to a right of repurchase or right of first refusal by the Company or, in the case of any transfer pursuant to clause (8), that such transfer is being made to satisfy tax withholding obligations pursuant to the Company’s equity incentive plans.  For the purposes of clause (9), “change of control” shall mean the transfer (whether by tender offer, merger,

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consolidation or other similar transaction), in one transaction or a series of related transactions, to a person or group of affiliated persons (other than an Underwriter pursuant to the Offering), of the Company’s voting securities if, after such transfer, such person or group of affiliated persons would hold more than 50% of the outstanding voting securities of the Company (or the surviving entity).  For purposes of this paragraph, “immediate family” shall mean a spouse, child, grandchild or other lineal descendant (including by adoption), father, mother, brother or sister of the undersigned; and “affiliate” shall have the meaning set forth in Rule 405 under the Securities Act of 1933, as amended.

In the event that the Representatives on behalf of the Underwriters, release, in full or in part, any officer, director or holder of at least one percent (1%) or more of the then outstanding Common Stock (measured as of the date of the Triggering Release (as defined below)) (a ‘Triggering Shareholder”) from the restrictions of any lock-up agreement similar to this Agreement signed by such Triggering Shareholder for the benefit of the Underwriters (a “Triggering Release”), then, subject to the restrictions below, the undersigned shall be concurrently released to the same extent with respect to the same percentage of the then outstanding Common Stock of the undersigned as the percentage of the then outstanding Common Stock being released in the Triggering Release represent with respect to the then outstanding Common Stock held by the Triggering Shareholder at the time of the request of the Triggering Release.  In the event of a Triggering Release, the Company shall use commercially reasonable efforts to notify the undersigned within five (5) business days of the occurrence of such Triggering Release, which notification obligation may be satisfied by the issuance of a press release through a major news service announcing such Triggering Release; provided that the failure by the Company to give such notice shall not give rise to any claim or liability against the Company, the Representatives, or any Underwriter except, in respect of the Company, in the case of bad faith on the part of the Company.  The provisions of this paragraph will not apply if (a) the release or waiver is effected solely to permit a transfer not for consideration and (b) the transferee has agreed in writing to be bound by the same terms described in this letter to the extent and for the duration that such terms remain in effect at the time of the transfer.  Notwithstanding the foregoing, no release by the Representatives of any Common Stock will constitute a Triggering Release if the amount of such release granted to any Triggering Shareholder requesting a release does not exceed $1,000,000.

For avoidance of doubt, nothing in this Agreement prohibits the undersigned from exercising any options or warrants to purchase Common Stock (which exercises may be effected on a cashless basis to the extent the instruments representing such options or warrants permit exercises on a cashless basis), it being understood that any Common Stock issued upon such exercises will be subject to the restrictions of this Agreement.

In order to enable this covenant to be enforced, the undersigned hereby consents to the placing of legends or stop transfer instructions with the Company’s transfer agent with respect to any Common Stock or securities convertible into or exercisable or exchangeable for Common Stock.

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The undersigned further agrees that it will not, during the Lock-Up Period, make any demand or request for or exercise any right with respect to the registration under the Securities Act of 1933, as amended, of any shares of Common Stock or other Beneficially Owned Shares or any securities convertible into or exercisable or exchangeable for Common Stock or other Beneficially Owned Shares.

The undersigned hereby represents and warrants that the undersigned has full power and authority to enter into this agreement and that this agreement has been duly authorized (if the undersigned is not a natural person), executed and delivered by the undersigned and is a valid and binding agreement of the undersigned.  This agreement and all authority herein conferred are irrevocable and shall survive the death or incapacity of the undersigned (if a natural person) and shall be binding upon the heirs, personal representatives, successors and assigns of the undersigned.

This Agreement shall be governed by and construed in accordance with the internal laws of the State of New York applicable to agreements made and to be performed in such state.

If (i) the Company notifies the Representatives in writing that it does not intend to proceed with the Offering, (ii) the Underwriting Agreement is not executed by July 1, 2016, or (iii) the Underwriting Agreement (other than the provisions thereof which survive termination) shall terminate or be terminated for any reason prior to payment for and delivery of any Common Stock to be sold thereunder, then this Agreement shall immediately be terminated and the undersigned shall automatically be released from all of his or her obligations under this Agreement.  The undersigned acknowledges and agrees that whether or not any public offering of Common Stock actually occurs depends on a number of factors, including market conditions.

Yours very truly,
AISLING CAPITAL III, LP
By:	/s/ Lloyd Appel
Name:	Lloyd Appel
Title:	Chief Financial Officer

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EX-99.2

EXHIBIT 2

LOXO ONCOLOGY, INC.

May 11, 2016

Citigroup Global Markets Inc.Cowen and Company, LLCAs Representatives of the several Underwriters

c/o Citigroup Global Markets Inc.388 Greenwich StreetNew York, New York 10013

c/o Cowen and Company, LLC599 Lexington AvenueNew York, New York 10022

Ladies and Gentlemen:

This letter is being delivered to you in connection with the proposed Underwriting Agreement (the “Underwriting Agreement”), between Loxo Oncology, Inc., a Delaware corporation (the “Company”), and each of you as representatives (together, the “Representatives”) of a group of Underwriters named therein, relating to an underwritten public offering (the “Offering”) of Common Stock, $0.0001 par value (the “Common Stock”), of the Company.

In order to induce you and the other Underwriters to enter into the Underwriting Agreement, the undersigned will not, without the prior written consent of Citigroup Global Markets Inc. and Cowen and Company, LLC, (i) offer, sell, contract to sell, pledge or otherwise dispose of, (or enter into any transaction which is designed to, or might reasonably be expected to, result in the disposition (whether by actual disposition or effective economic disposition due to cash settlement or otherwise) by the undersigned or any affiliate of the undersigned or any person in privity with the undersigned or any affiliate of the undersigned), directly or indirectly, including the filing (or participation in the filing) of a registration statement with the Securities and Exchange Commission in respect of, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the rules and regulations of the Securities and Exchange Commission promulgated thereunder with respect to, or (ii) enter into any swap or any other agreement or any transaction that transfers, in whole or in part, directly or indirectly, the economic consequence of ownership of, any shares of capital stock of the Company or any securities convertible into or exercisable or exchangeable for such capital stock, whether now owned or hereafter acquired by the undersigned or with respect to which the undersigned has or hereafter acquires the power of disposition, or publicly announce an intention to effect any such transaction, for a period from the date hereof through and including 90 days after the date of the Underwriting Agreement (the “Lock-Up Period”).

The restrictions set forth in the preceding paragraphs shall not apply to:

(1)if the undersigned is a natural person, any transfers made by the undersigned (a) as a bona fide gift to any member of the immediate family (as defined below) of the undersigned or to a trust the direct or indirect beneficiaries of which are exclusively the undersigned or members of the undersigned’s immediate family, (b) by will or intestate succession upon the death of the undersigned or (c) as a bona fide gift to a charity or educational institution, provided that if the undersigned is required to file a report under Section 16(a) of the Exchange Act, reporting any transfer pursuant to this clause (1), the undersigned shall include a statement in such report to the effect that such transfer is being made as a gift or by will or intestate succession, provided, further that no filing under Section 16(a) of the Exchange Act shall be voluntarily made during the Lock-Up Period,

(2)if the undersigned is a corporation, partnership, limited liability company or other business entity, any transfers to any stockholder, partner (which, for additional clarity, includes limited partners) or member of, or owner of a similar equity interest in, the undersigned, as the case may be, if, in any such case, such transfer is not for value,

(3)if the undersigned is a corporation, partnership, limited liability company or other business entity, any transfer made by the undersigned (a) in connection with the sale or other bona fide transfer in a single transaction of all or substantially all of the undersigned’s capital stock, partnership interests, membership interests or other similar equity interests, as the case may be, or all or substantially all of the undersigned’s assets, in any such case not undertaken for the purpose of avoiding the restrictions imposed by this agreement or (b) to another corporation, partnership, limited liability company or other business entity so long as the transferee is an affiliate (as defined below) of the undersigned and such transfer is not for value,

(4)if the undersigned is a trust, transfers to the beneficiary of such trust and such transfer is not for value,

(5)transactions relating to shares of Common Stock or other securities convertible into or exercisable or exchangeable for Common Stock acquired in open market transactions after completion of the Offering, provided that no filing under Section 16(a) of the Exchange Act shall be required or shall be voluntarily made in connection with subsequent sales of Common Stock or other securities acquired by you in such open market transactions,

(6)to the Company pursuant to agreements under which the Company has the option to repurchase such shares or a right of first refusal with respect to transfers of such shares upon termination of service of the undersigned,

(7)the entry, by the undersigned, at any time on or after the date of the Underwriting Agreement, of any trading plan providing for the sale of Common Stock by the undersigned, which trading plan meets the requirements of Rule 10b5-1(c) under the

2

Exchange Act, provided, however, that such plan does not provide for, or permit, the sale of any Common Stock during the Lock-Up Period and no public announcement or filing is voluntarily made or required regarding such plan during the Lock-Up Period,

(8)any transfers made by the undersigned to the Company to satisfy tax withholding obligations pursuant to the Company’s equity incentive plans or arrangements existing as of the date of the Underwriting Agreement, and

(9)the transfer of shares of Common Stock or any security convertible into or exercisable or exchangeable for Common Stock pursuant to a bona fide third-party tender offer, merger, consolidation or other similar transaction made to all holders of the Company’s securities involving a change of control of the Company, provided that in the event that such tender offer, merger, consolidation or other such transaction is not completed, such securities held by the undersigned shall remain subject to the restrictions on transfer set forth in this letter;

provided, however, that (A) in the case of any transfer described in clause (1), (2), (3) or (4) above, it shall be a condition to the transfer that the transferee executes and delivers to the Representatives, acting on behalf of the Underwriters, not later than one business day prior to such transfer, a written agreement, in substantially the form of this agreement (it being understood that any references to “immediate family” in the agreement executed by such transferee shall expressly refer only to the immediate family of the undersigned and not to the immediate family of the transferee) and otherwise satisfactory in form and substance to the Representatives; (B) in the case of any transfer described in clause (2), (3) or (4) above, it shall be a condition to the transfer or distribution that no filing under Section 16(a) of the Exchange Act shall be required or voluntarily made during the Lock-Up Period; and (C) in the case of any transfer described in clause (6) or (8) above, if the undersigned is required to file a report under Section 16(a) of the Exchange Act reporting a reduction in beneficial ownership of shares of Common Stock or Common Stock which may be deemed to be beneficially owned by the undersigned in accordance with the rules and regulations promulgated under the Exchange Act, as the same may be amended or supplemented from time to time (such shares, the “Beneficially Owned Shares”) or any securities convertible into or exercisable or exchangeable for Common Stock or Beneficially Owned Shares during the Lock-Up Period, the undersigned shall include a statement in such report to the effect that, in the case of any transfer pursuant to clause (6) above, such transfer is being made pursuant to a right of repurchase or right of first refusal by the Company or, in the case of any transfer pursuant to clause (8), that such transfer is being made to satisfy tax withholding obligations pursuant to the Company’s equity incentive plans.  For the purposes of clause (9), “change of control” shall mean the transfer (whether by tender offer, merger, consolidation or other similar transaction), in one transaction or a series of related transactions, to a person or group of affiliated persons (other than an Underwriter pursuant to the Offering), of the Company’s voting securities if, after such transfer, such person or group of affiliated persons would hold more than 50% of the outstanding voting securities of the Company (or the surviving entity).  For purposes of this paragraph, “immediate family” shall mean a spouse, child, grandchild or other lineal descendant (including by adoption), father, mother, brother or sister of the undersigned; and

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“affiliate” shall have the meaning set forth in Rule 405 under the Securities Act of 1933, as amended.

For avoidance of doubt, nothing in this Agreement prohibits the undersigned from exercising any options or warrants to purchase Common Stock (which exercises may be effected on a cashless basis to the extent the instruments representing such options or warrants permit exercises on a cashless basis), it being understood that any Common Stock issued upon such exercises will be subject to the restrictions of this Agreement.

In order to enable this covenant to be enforced, the undersigned hereby consents to the placing of legends or stop transfer instructions with the Company’s transfer agent with respect to any Common Stock or securities convertible into or exercisable or exchangeable for Common Stock.

The undersigned further agrees that it will not, during the Lock-Up Period, make any demand or request for or exercise any right with respect to the registration under the Securities Act of 1933, as amended, of any shares of Common Stock or other Beneficially Owned Shares or any securities convertible into or exercisable or exchangeable for Common Stock or other Beneficially Owned Shares.

The undersigned hereby represents and warrants that the undersigned has full power and authority to enter into this agreement and that this agreement has been duly authorized (if the undersigned is not a natural person), executed and delivered by the undersigned and is a valid and binding agreement of the undersigned.  This agreement and all authority herein conferred are irrevocable and shall survive the death or incapacity of the undersigned (if a natural person) and shall be binding upon the heirs, personal representatives, successors and assigns of the undersigned.

This Agreement shall be governed by and construed in accordance with the internal laws of the State of New York applicable to agreements made and to be performed in such state.

If (i) the Company notifies the Representatives in writing that it does not intend to proceed with the Offering, (ii) the Underwriting Agreement is not executed by July 1, 2016, or (iii) the Underwriting Agreement (other than the provisions thereof which survive termination) shall terminate or be terminated for any reason prior to payment for and delivery of any Common Stock to be sold thereunder, then this Agreement shall immediately be terminated and the undersigned shall automatically be released from all of his or her obligations under this Agreement.  The undersigned acknowledges and agrees that whether or not any public offering of Common Stock actually occurs depends on a number of factors, including market conditions.

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Yours very truly,
/s/ Steven A. Elms
Name:	Steven A. Elms
Address:

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EX-99.4

EXHIBIT 4

JOINT FILING AGREEMENT

Each of the undersigned hereby acknowledges and agrees, in compliance with the provisions of Rule 13d-1(k)(1) promulgated under the Securities Exchange Act of 1934, as amended, that the Schedule 13D to which this Agreement is attached as an Exhibit (the “Schedule 13D”), and any amendments thereto, will be filed with the Securities and Exchange Commission jointly on behalf of the undersigned. This Agreement may be executed in one or more counterparts.

Date: May 27, 2016

	AISLING CAPITAL III, LP
By:	Aisling Capital Partners III, LP General Partner
By:	Aisling Capital Partners III LLC General Partner
	By:	/s/ Dennis Purcell
		Name: Dennis Purcell
		Title: Managing Member

	AISLING CAPITAL PARTNERS III, LP
By:	Aisling Capital Partners III LLC General Partner
	By:	/s/ Dennis Purcell
		Name: Dennis Purcell
		Title: Managing Member

	AISLING CAPITAL PARTNERS III LLC
By:	/s/ Dennis Purcell
	Name: Dennis Purcell Title: Managing Member
	/s/ Steven Elms
	Steven Elms
	/s/ Dennis Purcell
	Dennis Purcell
	/s/ Andrew Schiff
	Andrew Schiff