Exhibit 10.21


 


AKARI THERAPEUTICS PLC


75/76 Wimpole Street

London W1G 9RT UK


 


19 October 2018


 


Clive Richardson


c/o Akari Therapeutics plc


75/76 Wimpole Street


London
W1G 9RT UK


 


Re: Option and Bonus Letter


 


Dear Clive:


 


We appreciate your
continued service as acting chief executive officer of Akari Therapeutics plc (the “Company”). This will
confirm the following agreement made today between you and the Company respecting an option grant and a potential bonus paid
to you by the Company, subject to your continued employment with the company and the other terms and conditions herein set
forth, to demonstrate such appreciation.


 


For valid consideration, the receipt of which is hereby
acknowledged, the parties hereby agree as follows:


 


		1.	The Company will deliver to you a Stock Option Grant Notice
respecting the grant of 20,000,000 additional ordinary shares under option in the capital of the Company (as American Depositary
Shares) (the “Additional Options”), subject to the terms and conditions of the grant notice and the Company’s
2014 Equity Incentive Plan (as amended from time to time). The Additional Options will vest over a period of four years and have
a strike price as set forth in the grant notice.



 


		2.	In the event a Sale Transaction (as defined below) is completed
while you are (i) employed by the Company (and you have not given notice to terminate your employment) and (ii) acting chief executive
officer of the Company or in the six month period after you are no longer acting in such capacity, the Company shall pay you a
bonus (the “Bonus”) equal to (x) (1) your then base salary plus the Company’s then annual contribution
to your pension multiplied by (y) three, as determined by the Company. The Bonus will be subject to deductions and withholdings
as required by law. An example of the Bonus calculation is set forth on Exhibit A hereto. For purposes of the foregoing,
“Sale Transaction” means the first occurrence of one of the following: a merger, consolidation or similar transaction
(directly or indirectly) involving the Company if, immediately after the consummation of such merger, consolidation or similar
transaction, the shareholders of the Company immediately prior thereto do not own, directly or indirectly, outstanding equity
securities representing more than fifty percent (50%) of the combined outstanding voting power of the surviving entity (or the
parent of the surviving entity) (but not including any bona fide financing of the Company), or the sale of all or substantially
all of the assets of the Company.









 




     


     


    

 


		3.	Receipt of the Bonus (and/or, to avoid doubt, any severance
payment under Clause 7.11 of your Service Agreement/Employment Contract) shall be conditioned upon your execution of a customary
settlement agreement, release and non-disparagement satisfactory to and in favor of the Company and its subsidiaries, affiliates
and shareholders and their respective officers, directors, employees, stockholders, attorneys, accountants, consultants and other
agents.






 


		4.	You agree to keep the terms and existence of this letter
agreement confidential, except for disclosure for purposes of obtaining legal or accounting advice. Notwithstanding the foregoing,
you shall not be restricted from: (i) disclosing information that is required to be disclosed by law, court order or other valid
and appropriate legal process; provided, however, that in the event such disclosure is required by law, you shall provide the
Company with prompt notice of such requirement so that the Company may seek an appropriate protective order prior to any such
required disclosure by you; or (ii) reporting possible violations of federal, state, or local law or regulation to any governmental
agency or entity, or from making other disclosures that are protected under the whistleblower provisions of federal, state, or
local law or regulation, and you shall not need the prior authorization of the Company to make any such reports or disclosures
and shall not be required to notify the Company that you has made such reports or disclosures.



 


		5.	You agree to cooperate with the Company and its shareholders
as they seek, negotiate and pursue any potential Sale Transaction or strategic transaction involving the Company. You also agree
to maintain an acceptable level of performance consistent with your past performance.



 


		6.	This letter agreement shall
not create any obligation on the part of the Company to establish or continue any other compensation programs, plans or policies
of any kind. This letter agreement shall not give you any right with respect to continuance of your employment by the Company
or of any specific aggregate amount of compensation, nor shall there be a limitation in any way on the right of the Company to
terminate your employment at any time for any reason or for no reason whatsoever, nor shall this letter agreement create a contract
respecting your employment by the Company. All amounts payable pursuant to the terms of this letter agreement shall be paid from
the general assets of the Company. Payments will be paid under this letter agreement only if the Company determines, in its complete
and sole discretion, that you are entitled to them. If, on termination of your employment, for whatever reason, whether lawfully
or in breach of contract, you lose any rights in relation to the Additional Options or Bonus (including, to avoid doubt, any rights
which you would not have lost had your employment not been terminated) you will not be entitled, by way of compensation for unlawful
termination of employment, loss of employment or office or otherwise, to any compensation for loss of any rights or loss
of profits in respect of either the Additional Options or Bonus.



 




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		7.	This letter agreement constitutes the full understanding
and entire agreement between you and the Company and supersedes any other agreements of any kind, whether oral or written, formal
or informal, with respect to the subject matter herein set forth; provided however, that you shall remain bound by any continuing
obligations to preserve the Company’s trade secrets, intellectual property, and confidential information, and non-solicitation
and non-competition, if any, and of course, your Service Agreement/Employment Contract with the Company (which remain otherwise
unchanged). You represent and acknowledge that in signing this letter agreement, you have not relied upon any representation or
statement not set forth in this letter agreement. This letter agreement may only be amended by the written agreement of you and
the Company. This letter agreement may not be assigned or transferred in whole or in part by you. This letter agreement and any
dispute or claim arising out of or in connection with it or its subject matter or formation (including non-contractual disputes
or claims) shall be governed by and construed in accordance with the law of England and Wales.



 


Very truly yours,


 


AKARI THERAPEUTICS PLC


 


	By: 	/s/ Ray Prudo	 
	 	Name:	Ray Prudo	 
	 	Title:	Chairman	 


 


	ACCEPTED AND AGREED:	 
	 	 	 
	By: 	/s/ Clive Richardson	 
	Name: 	Clive Richardson	 


 




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Exhibit A


 


Sale Transaction Bonus Calculation


 


This calculation illustrates the Bonus payable should
the Sale Transaction take place in fiscal year 2018 and be payable as hereunder provided.


 


	Current Base
 Salary	 	 	Annual
 Pension
 Contribution	 	 	Combined
 Annual Total	 	 	Multiplier	 	 	Bonus	 
	£	259,560	 	 	£	25,956	 	 	£	285,516	 	 	 	3X		 	£	856,548	*



 


In the event the Sale Transaction
takes place after fiscal year 2018, the Bonus calculation will be calculated by the Company on the basis of the fiscal year in
which the Sale Transaction takes place.


 


 






* Subject to deductions and withholdings as required
by law.


 




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