EX-10.3



 Exhibit 10.3 

THIRD ROCK VENTURES 

455 MISSION BAY BLVD. SOUTH 

SUITE575 
 SAN FRANCISCO, CA 94158

 June 8, 2012 
 Robert S. McDowell 

Dear Bob, 
 We are pleased to offer you
employment with MyoKardia (“the Company”) on the following terms. This employment offer is contingent upon the incorporation of MyoKardia and qualification to do business in the state of California. We anticipate these conditions being met
by July 31,2012. If these conditions are not met, the terms below will not be in force or effect. 
 1. Position. Your initial title will be
Vice President, Drug Discovery, and you will initially report to the Company’s acting Chief Executive Officer. This is a full-time position. While you render services to the Company, you will not engage in any other employment, consulting or
other business activity (whether full-time or part-time) that would create a conflict of interest with the Company. By signing this letter agreement, you confirm to the Company that you have no contractual commitments or other legal obligations that
would prohibit you from performing your duties for the Company. 
 2. Cash Compensation. The Company will pay you a starting salary at the rate of
$260,000 per year, payable in accordance with the Company’s standard payroll schedule. This salary will be subject to adjustment pursuant to the Company’s employee compensation policies in effect from time to time. It is expected that,
when an annual bonus program is approved by the Board of Directors, you will be eligible for a target bonus of 20% of your annual compensation, based upon the achievement of corporate and individual goals, as agreed by the Board of Directors. You
will be eligible to participate each year in any annual bonus plan adopted by the Company and the Company, subject to financial, business, and other circumstances and factors. 

3. Employee Benefits. As a regular employee of the Company, you will be eligible to participate in a number of Company-sponsored benefits. If the
Company does not have a health benefits program in place by the time you join, and you elect to have health insurance provided by the Company, you will be reimbursed for COBRA premiums (amount to be determined). Once the Company has a health
benefits program you will be expected to join the program if you elect to have health benefits provided by the Company. In addition, you will be entitled to 20 days of paid time off in accordance with the Company’s policy. 

4. Stock Options. Subject to the approval of the Company’s Board of Directors or its Compensation Committee, you will be granted an option to
purchase 320,000 shares of the Company’s Common Stock. The exercise price per share will be determined by the Board of Directors or the Compensation Committee when the option is granted. The option will be subject to the terms and conditions
applicable to options granted under the Company’s Stock 







 
Plan (the “Plan”), as described in the Plan and the applicable stock option agreement. You will vest in 25% of the option shares after 12 months of continuous service, and the balance
will vest in equal quarterly installments over the next 36 months of continuous service, as described in the applicable stock option agreement. 
 5.
Employee Confidentiality and Assignment Agreement. Like all Company employees, you will be required, as a condition of your employment with the Company, to sign the Company’s standard Employee Confidentiality and Assignment Agreement, a
copy of which is attached hereto as Exhibit A. 
 6. Background Check. The Company may conduct a background or reference check (or both). If so, then
you agree to cooperate fully in those procedures, and this offer is subject to the Company’s approving the outcome of those checks, in the discretion of the Company. 

7. Employment Relationship. Employment with the Company is for no specific period of time. Your employment with the Company will be “at
will,” meaning that either you or the Company may terminate your employment at any time and for any reason, with or without cause. Any contrary representations that may have been made to you are superseded by this letter agreement. This is the
full and complete agreement between you and the Company on this term. Although your job duties, title, reporting relationship, compensation and benefits, as well as the Company’s personnel policies and procedures, may change from time to time,
the “at will” nature of your employment may only be changed in an express written agreement signed by you and a duly authorized officer of the Company (other than you). 

8. Taxes. All forms of compensation referred to in this letter agreement are subject to reduction to reflect applicable withholding and payroll taxes
and other deductions required by law. You agree that the Company does not have a duty to design its compensation policies in a manner that minimizes your tax liabilities, and you will not make any claim against the Company or its Board of Directors
related to tax liabilities arising from your compensation. 
 9. Interpretation, Amendment and Enforcement. This letter agreement and Exhibit A
constitute the complete agreement between you and the Company, contain all of the terms of your employment with the Company and supersede any prior agreements, representations or understandings (whether written, oral or implied) between you and the
Company. This letter agreement may not be amended or modified, except by an express written agreement signed by both you and a duly authorized officer of the Company. The terms of this letter agreement and the resolution of any disputes as to the
meaning, effect, performance or validity of this letter agreement or arising out of, related to, or in any way connected with, this letter agreement, your employment with the Company or any other relationship between you and the Company will be
governed by California law, excluding laws relating to conflicts or choice of law. 
 * * * * * 

We hope that you will accept our offer to join the Company. You may indicate your agreement with these terms and accept this offer by signing
and dating both the enclosed duplicate original of this letter agreement and the enclosed Proprietary Information and Inventions Agreement and returning them to me. This offer, if not accepted, will expire at the


  
 2 








 
close of business on June 12, 2012. As required by law, your employment with the Company is contingent upon your providing legal proof of your identity and authorization to work in the
United States. Your employment is also contingent upon you being able to start working with the Company upon its incorporation and qualification to do business in California. 

If you have any questions, please call me at 415 766 3637. 

 

	
	 Very truly yours,

	
	 THIRD ROCK VENTURES

	
	 /s/ Charles Homcy

	 By: Charles Homcy

	 Title: Venture Partner



 I have read and accept this employment offer: 
  


	
	 /s/ Robert S. McDowell

	Robert S. McDowell

 Attachment 
 Exhibit A:
Employee Confidentiality and Assignment Agreement 

  
 3 








 MyoKardia, Inc. 

Employee Confidentiality and Assignment Agreement 

In consideration and as a condition of my employment or continued employment by MyoKardia, Inc. (the
“Company”), I agree as follows: 

 

 1. Proprietary Information. I agree that all information, whether or not in writing, concerning
the Company’s business, technology, business relationships or financial affairs which the Company has not released to the general public (collectively, “Proprietary Information”) is and will be the exclusive property of the Company.
By way of illustration, Proprietary Information may include information or material which has not been made generally available to the public, such as: (a) corporate information, including plans, strategies, methods, policies,
resolutions, negotiations or litigation; (b) marketing information, including strategies, methods, customer identities or other information about customers, prospect identities or other information about prospects, or market analyses or
projections; (c) financial information, including cost and performance data, debt arrangements, equity structure, investors and holdings, purchasing and sales data and price lists; and (d) operational and technological
information, including plans, specifications, manuals, forms, templates, software, designs, methods, procedures, formulas, discoveries, inventions, improvements, concepts and ideas; and (e) personnel information, including personnel
lists, reporting or organizational structure, resumes, personnel data, compensation structure, performance evaluations and termination arrangements or documents. Proprietary Information also includes information received in confidence by the Company
from its customers or suppliers or other third parties. 
 2. Recognition of Company’s Rights. I will not, at any time, without the
Company’s prior written permission, either during or after my employment, disclose any Proprietary Information to anyone outside of the Company, or use or permit to be used any Proprietary Information for any purpose other than the performance
of my duties as an employee of the Company. I will cooperate with the Company and use my best efforts to prevent the unauthorized disclosure of all Proprietary Information. I will deliver to the Company all copies of Proprietary Information in my
possession or control upon the earlier of a request by the Company or termination of my employment. 
 3. Rights of Others. I understand that
the Company is now and may hereafter be subject to non-disclosure or confidentiality agreements with third persons which require the Company to protect or refrain from use of proprietary information. I agree to be bound by the terms of such
agreements in the event I have access to such proprietary information. 
 4. Commitment to Company; Avoidance of Conflict of Interest. While
an employee of the Company, I will devote my full-time efforts to the Company’s business and I will not engage in any other business activity that conflicts with my




 
duties to the Company. I will advise the chief executive officer of the Company or his or her nominee at such time as any activity of either the Company or another business presents me with a
conflict of interest or the appearance of a conflict of interest as an employee of the Company. I will take whatever action is requested of me by the Company to resolve any conflict or appearance of conflict which it finds to exist. 

5. Developments. I will make full and prompt disclosure to the Company of all inventions, discoveries, designs, developments, methods,
modifications, improvements, processes, algorithms, databases, computer programs, formulae, techniques, trade secrets, mask works, graphics or images, and audio or visual works and other works of authorship (collectively “Developments”),
whether or not patentable or copyrightable, that are created, made, conceived or reduced to practice by me (alone or jointly with others) or under my direction during the period of my employment. I acknowledge that all work performed by me is on a
“work for hire” basis, and I hereby do assign and transfer and, to the extent any such assignment cannot be made at present, will assign and transfer, to the Company and its successors and assigns all my right, title and interest in all
Developments that (a) relate to the business of the Company or any customer of or supplier to the Company or any of the products or services being researched, developed, manufactured or sold by the Company or which may be used with such
products or services; or (b) result from tasks assigned to me by the Company; or (c) result from the use of premises or personal property (whether tangible or intangible) owned, leased or contracted for by the Company
(“Company-Related Developments”), and all related patents, patent applications, trademarks and trademark applications, copyrights and copyright applications, and other intellectual property rights in all countries and territories worldwide
and under any international conventions (“Intellectual Property Rights”). 
 To preclude any possible uncertainty, I have set forth on
Exhibit A attached hereto a complete list of Developments that I have, alone or jointly with others, conceived, developed or reduced to practice prior to the commencement of my employment with the Company that I consider to be my
property or the property of third parties and that I wish to have excluded from the scope of this Agreement (“Prior Inventions”). If disclosure of any such Prior Invention would cause me to violate any prior confidentiality agreement, I
understand that I am not to list such Prior Inventions in Exhibit A but am only to disclose a cursory name for each such invention, a listing of the party(ies) to whom it belongs and the fact that full disclosure as to such inventions
has not been made for that reason. I have also listed on Exhibit A all patents and patent applications in which I am named as an inventor, other than those which have been assigned to the


 









 
Company (“Other Patent Rights”). If no such disclosure is attached, I represent that there are no Prior Inventions or Other Patent Rights. If, in the course of my employment with
the Company, I incorporate a Prior Invention into a Company product, process or machine or other work done for the Company, I hereby grant to the Company a nonexclusive, royalty-free, paid-up, irrevocable, worldwide license (with the full right to
sublicense) to make, have made, modify, use, sell, offer for sale and import such Prior Invention. Notwithstanding the foregoing, I will not incorporate, or permit to be incorporated, Prior Inventions in any Company-Related Development without the
Company’s prior written consent. 
 As required pursuant to Section 2872 of the California Labor Code (a copy of which is attached as
Exhibit B), I acknowledge that the Company has notified me that the provisions of this paragraph 5 do not apply to an invention which qualifies fully under the provisions of Section 2870 of the California Labor Code. Specifically,
such provisions do not apply to, and I am not required to transfer to the Company, any invention developed entirely on my own time without using the Company’s equipment, supplies, facilities, or trade secret information except for those
inventions that either (a) relate at the time of conception or reduction to practice of the invention to the Company’s business, or actual or demonstrably anticipated research or development of the Company; or (b) result from any work
performed by me for the Company. However, I will also promptly disclose to the Company any such Developments for the purpose of determining whether they qualify for such exclusion. I understand that to the extent this Agreement is required to be
construed in accordance with the laws of any state which precludes a requirement in an employee agreement to assign certain classes of inventions made by an employee, this paragraph 5 will be interpreted not to apply to any invention which a court
rules and/or the Company agrees falls within such classes. I also hereby waive all claims to any moral rights or other special rights which I may have or accrue in any Company-Related Developments. 

6. Documents and Other Materials. I will keep and maintain adequate and current records of all Proprietary Information and Company-Related
Developments developed by me during my employment, which records will be available to and remain the sole property of the Company at all times. 
 All
files, letters, notes, memoranda, reports, records, data, sketches, drawings, notebooks, layouts, charts, quotations and proposals, specification sheets, program listings, blueprints, models, prototypes, or other written, photographic or other
tangible material containing Proprietary Information, whether created by me or others, which come into my custody or possession, are the exclusive property of the Company to be used by me only in the performance of my duties for the Company. Any
property situated on the Company’s premises and owned by the Company, including without limitation computers, disks and other storage media, filing cabinets or other work areas, is subject to inspection by the Company at any time with or
without notice. In the event of the termination of my employment for any reason, I will deliver to the Company all files, letters, notes, memoranda, reports, records, data, sketches, drawings, notebooks, layouts, charts,




 
quotations and proposals, specification sheets, program listings, blueprints, models, prototypes, or other written, photographic or other tangible material containing Proprietary Information, and
other materials of any nature pertaining to the Proprietary Information of the Company and to my work, and will not take or keep in my possession any of the foregoing or any copies. 

7. Enforcement of Intellectual Property Rights. I will cooperate fully with the Company, both during and after my employment with the Company,
with respect to the procurement, maintenance and enforcement of Intellectual Property Rights in Company-Related Developments. I will sign, both during and after the term of this Agreement, all papers, including without limitation copyright
applications, patent applications, declarations, oaths, assignments of priority rights, and powers of attorney, which the Company may deem necessary or desirable in order to protect its rights and interests in any Company-Related Development. If the
Company is unable, after reasonable effort, to secure my signature on any such papers, I hereby irrevocably designate and appoint each officer of the Company as my agent and attorney-in-fact to execute any such papers on my behalf, and to take any
and all actions as the Company may deem necessary or desirable in order to protect its rights and interests in any Company-Related Development. 
 8.
Non-Solicitation. 
 During my employment and for a period of one year following the termination of my employment for any reason (the
“Restricted Period”), I will not directly or indirectly solicit, entice or attempt to persuade any other employee or consultant of the Company to leave the Company for any reason or otherwise participate in or facilitate the hire, directly
or through another entity, of any person who is employed or engaged by the Company or who was employed or engaged by the Company within six months of any attempt to hire such person. I acknowledge and agree that if I violate any of the provisions of
this paragraph 8, the running of the Restricted Period will be extended by the time during which I engage in such violation(s). 
 9. Government
Contracts. I acknowledge that the Company may have from time to time agreements with other persons or with the United States Government or its agencies which impose obligations or restrictions on the Company regarding inventions made during
the course of work under such agreements or regarding the confidential nature of such work. I agree to comply with any such obligations or restrictions upon the direction of the Company. In addition to the rights assigned under paragraph 5, I also
assign to the Company (or any of its nominees) all rights which I have or acquired in any Developments, full title to which is required to be in the United States under any contract between the Company and the United States or any of its agencies.

 10. Prior Agreements. I hereby represent that, except as I have fully disclosed previously in writing to the Company, I am not bound by the
terms of any agreement with any previous employer or other party to refrain from using or disclosing any trade secret or confidential or proprietary


 









 
information in the course of my employment with the Company or to refrain from competing, directly or indirectly, with the business of such previous employer or any other party. I further
represent that my performance of all the terms of this Agreement as an employee of the Company does not and will not breach any agreement to keep in confidence proprietary information, knowledge or data acquired by me in confidence or in trust prior
to my employment with the Company. I will not disclose to the Company or induce the Company to use any confidential or proprietary information or material belonging to any previous employer or others. 

11. Remedies Upon Breach. I understand that the restrictions contained in this Agreement are necessary for the protection of the business and
goodwill of the Company and I consider them to be reasonable for such purpose. Any breach of this Agreement is likely to cause the Company substantial and irrevocable damage and therefore, in the event of such breach, the Company, in addition to
such other remedies which may be available, will be entitled to specific performance and other injunctive relief, without the posting of a bond. I further agree that if any action at law or in equity is necessary to enforce or interpret the terms of
this Agreement, the prevailing party shall be entitled to reasonable attorney’s fees, costs, and disbursements in addition to any other relief to which such party may be entitled. 

12. Use of Voice, Image and Likeness. I give the Company permission to use any and all of my voice, image and likeness, with or without using my
name, in connection with the products and/or services of the Company, for the purposes of advertising and promoting such products and/or services and/or the Company, and/or for other purposes deemed appropriate by the Company in its reasonable
discretion, except to the extent expressly prohibited by law. 
 13. Publications and Public Statements. I will obtain the Company’s
written approval before publishing or submitting for publication any material that relates to my work at the Company and/or incorporates any Proprietary Information. To ensure that the Company delivers a consistent message about its products,
services and operations to the public, and further in recognition that even positive statements may have a detrimental effect on the Company in certain securities transactions and other contexts, any statement about the Company which I create,
publish or post during my period of employment and for six (6) months thereafter, on any media accessible by the public, including but not limited to electronic bulletin boards and Internet-based chat rooms, must first be reviewed and approved
by an officer of the Company before it is released in the public domain. 
 14. No Employment Obligation. I understand that this Agreement
does not create an obligation on the Company or any other person to continue my employment. I acknowledge that, unless otherwise agreed in a formal written employment agreement signed on behalf of the Company by an authorized officer, my employment
with the Company is at will and therefore may be terminated by the Company or me at any time and for any reason, with or without cause.



 15. Survival and Assignment by the Company. I understand that my obligations under this Agreement
will continue in accordance with its express terms regardless of any changes in my title, position, duties, salary, compensation or benefits or other terms and conditions of employment. I further understand that my obligations under this Agreement
will continue following the termination of my employment regardless of the manner of such termination and will be binding upon my heirs, executors and administrators. The Company will have the right to assign this Agreement to its affiliates,
successors and assigns. I expressly consent to be bound by the provisions of this Agreement for the benefit of the Company or any parent, subsidiary or affiliate to whose employ I may be transferred without the necessity that this Agreement be
resigned at the time of such transfer. 
 16. Disclosure to Future Employers. I will provide a copy of this Agreement to any prospective
employer, partner or coventurer prior to entering into an employment, partnership or other business relationship with such person or entity. 
 17.
Severability. In case any provisions (or portions thereof) contained in this Agreement shall, for any reason, be held invalid, illegal or unenforceable in any respect, such invalidity, illegality or unenforceability shall not affect
the other provisions of this Agreement, and this Agreement shall be construed as if such invalid, illegal or unenforceable provision had never been contained herein. If, moreover, any one or more of the provisions contained in this Agreement shall
for any reason be held to be excessively broad as to duration, geographical scope, activity or subject, it shall be construed by limiting and reducing it, so as to be enforceable to the extent compatible with the applicable law as it shall then
appear. 
 18. Interpretation. This Agreement will be deemed to be made and entered into in the State of California, and will in all respects
be interpreted, enforced and governed under the laws of the State of California, without regard to conflict of law principles. 

 








 I UNDERSTAND THAT THIS AGREEMENT AFFECTS IMPORTANT RIGHTS. BY SIGNING BELOW, I CERTIFY THAT I HAVE READ IT
CAREFULLY AND AM SATISFIED THAT I UNDERSTAND IT COMPLETELY. 
 IN WITNESS WHEREOF, the undersigned has executed this agreement as a
sealed instrument as of the date set forth below. 
  

			
	Signed:	 	  

		
	Date:	 	  









 EXHIBIT A 

MyoKardia, Inc. 
 333 Allerton Avenue 

South San Francisco, CA 94080 USA 
 Attention: Board of Directors

 Directors: 
 The following is a complete list of all Prior
Inventions (as defined in paragraph 5 of the attached Employee Confidentiality and Assignment Agreement): 
  

					
	  
	 	No Prior Inventions or Patent Rights	  	
			
	  
	 	Prior Inventions (listed below)	  	

  

	
	  

	
	  

	
	  

	
	  



 

					
	  
	 	Number of additional sheets attached	  	

  

			
	Very truly yours,
	
	  

	Employee Signature
	
	  

	Employee Name
	
	  

	Date









 EXHIBIT B 

California Labor Code – CAL. CIV. Code 2872 
 If an
employment agreement entered into after January 1, 1980, contains a provision requiring the employee to assign or offer to assign any of his or her rights in any invention to his or her employer, the employer must also, at the time the
agreement is made, provide a written notification to the employee that the agreement does not apply to an invention which qualifies fully under the provisions of Section 2870. In any suit or action arising thereunder, the burden of proof shall
be on the employee claiming the benefits of its provisions.