Exhibit 10.21

FOURTH AMENDMENT

TO

LOAN AND SECURITY AGREEMENT

This Fourth Amendment to Loan and Security Agreement (the “Amendment”), is
entered into as of November 9, 2015, by and between PACIFIC WESTERN BANK, a
California state chartered bank (“Bank”), and ALDEYRA THERAPEUTICS, INC.
(“Borrower”).

RECITALS

Borrower and Bank (as successor in interest by merger to Square 1 Bank) are
parties to that certain Loan and Security Agreement dated as of April 12, 2012
(as amended from time to time, the “Agreement”). The parties desire to amend the
Agreement in accordance with the terms of this Amendment.

NOW, THEREFORE, the parties agree as follows:

 

1) The following defined terms in Exhibit A to the Agreement are hereby amended
and restated, as follows:

“Availability End Date” means October 24, 2016.

“Term Loan Maturity Date” means October 24, 2019.

 

2) Unless otherwise defined, all initially capitalized terms in this Amendment
shall be as defined in the Agreement. The Agreement, as amended hereby, shall be
and remain in full force and effect in accordance with its respective terms and
hereby is ratified and confirmed in all respects. Except as expressly set forth
herein, the execution, delivery, and performance of this Amendment shall not
operate as a waiver of, or as an amendment of, any right, power, or remedy of
Bank under the Agreement, as in effect prior to the date hereof. Borrower
ratifies and reaffirms the continuing effectiveness of all agreements entered
into in connection with the Agreement.

 

3) Borrower represents and warrants that the representations and warranties
contained in the Agreement are true and correct as of the date of this
Amendment.

 

4) This Amendment may be executed in two or more counterparts, each of which
shall be deemed an original, but all of which together shall constitute one
instrument.

 

5) As a condition to the effectiveness of this Amendment, Bank shall have
received, in form and substance satisfactory to Bank, the following:

 

  a) this Amendment, duly executed by Borrower;

 

  b) payment of a $2,500 facility fee, which may be debited from any of
Borrower’s accounts;

 

  c)

payment of all Bank Expenses, including Bank’s expenses for the documentation of
this Amendment and any related documents, and any UCC, good standing or
intellectual

 

Aldeyra Therapeutics – 4th Amendment to LSA

--------------------------------------------------------------------------------

  property search or filing fees, which may be debited from any of Borrower’s
accounts; and

 

  d) such other documents and completion of such other matters, as Bank may
reasonably deem necessary or appropriate.

[Remainder of page intentionally left blank]

 

Aldeyra Therapeutics – 4th Amendment to LSA

--------------------------------------------------------------------------------

IN WITNESS WHEREOF, the undersigned have executed this Amendment as of the first
date above written.

 

ALDEYRA THERAPEUTICS, INC.     PACIFIC WESTERN BANK By:  

/s/ Stephen Tulipano

    By:  

/s/ Lisa Foussianes

Name:   Stephen Tulipano     Name:   Lisa Foussianes Title:   CFO     Title:  
SVP

[Signature Page to Fourth Amendment to Loan and Security Agreement]

 

Aldeyra Therapeutics – 4th Amendment to LSA