Exhibit (a)(1)(B)​

Letter of Transmittal to Tender Shares of Common Stock

of

Flexion Therapeutics, Inc.

at

$8.50 per share, net in cash, plus one non-transferable contingent value right for each share, which represents
the right to receive one or more contingent cash payments of up to $8.00 per share in the aggregate upon the achievement of specified milestones,
pursuant to the Offer to Purchase dated October 22, 2021

by

Oyster Acquisition Company Inc.

a wholly owned subsidiary of

Pacira BioSciences, Inc.

THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT THE END OF THE DAY,
ONE MINUTE FOLLOWING 11:59 P.M., EASTERN TIME, ON NOVEMBER 18, 2021,
UNLESS THE OFFER IS EXTENDED OR EARLIER TERMINATED.

Mail or deliver this Letter of Transmittal, or a facsimile, together with the certificate(s) representing your shares, to:

If delivering by hand, express mail, courier, or other expedited service:	By mail:
American Stock Transfer & Trust Co., LLC Operations Center Attn: Reorganization Department 6201 15th Avenue Brooklyn, New York 11219	American Stock Transfer & Trust Co., LLC Operations Center Attn: Reorganization Department 6201 15th Avenue Brooklyn, New York 11219

For assistance call (877) 248-6417 or (718) 921-8317

Delivery of this Letter of Transmittal to an address other than as set forth above will not constitute a valid
delivery to the Depositary (as defined below). You must sign this Letter of Transmittal in the appropriate
space provided therefor below, with signature guaranteed, if required, and complete the IRS Form W-9
included in this Letter of Transmittal or an applicable IRS Form W-8, if required. The instructions set forth
in this Letter of Transmittal should be read carefully before you tender any of your Shares (as defined below)
pursuant to the Offer (as defined below).

Pursuant to the offer of Oyster Acquisition Company Inc., a Delaware corporation (the “Purchaser”) to purchase all Shares of Flexion Therapeutics, Inc., the undersigned encloses herewith and surrenders the following certificate(s) representing Shares of common stock:

Name(s) and Address of Registered Holder(s)

If there is any error in the name or address shown

below, please make the necessary corrections

DESCRIPTION OF SHARES SURRENDERED
(Please fill in. Attach separate schedule if needed)

Certificate No(s)	Number of Shares
TOTAL SHARES	​

PLEASE READ THE INSTRUCTIONS ACCOMPANYING THIS LETTER OF TRANSMITTAL CAREFULLY BEFORE COMPLETING THIS LETTER OF TRANSMITTAL. CAPITALIZED TERMS USED BUT NOT DEFINED HEREIN SHALL HAVE THE MEANINGS ASCRIBED TO THEM IN THE OFFER TO PURCHASE (AS DEFINED BELOW).

IF YOU WOULD LIKE ADDITIONAL COPIES OF THIS LETTER OF TRANSMITTAL OR ANY OF THE OTHER OFFERING DOCUMENTS, YOU SHOULD CONTACT THE INFORMATION AGENT, D.F. KING & CO., INC. AT (212) 269-5550 (FOR BANKS AND BROKERS) OR (800) 578-5378 (FOR STOCKHOLDERS, WHO MAY CALL TOLL FREE).

THE OFFER IS NOT BEING MADE TO (NOR WILL TENDERS BE ACCEPTED FROM OR ON BEHALF OF) HOLDERS OF SHARES IN ANY JURISDICTION IN WHICH THE MAKING OF THE OFFER WOULD NOT BE IN COMPLIANCE WITH THE SECURITIES, BLUE SKY OR OTHER LAWS OF SUCH JURISDICTION. IN THOSE JURISDICTIONS WHERE APPLICABLE LAWS REQUIRE THE OFFER TO BE MADE BY A LICENSED BROKER OR DEALER, THE OFFER WILL BE DEEMED TO BE MADE ON BEHALF OF PURCHASER BY ONE OR MORE REGISTERED BROKERS OR DEALERS LICENSED UNDER THE LAWS OF SUCH JURISDICTION TO BE DESIGNATED BY PURCHASER.

You have received this Letter of Transmittal in connection with the offer of Purchaser, a wholly owned subsidiary of Pacira BioSciences, Inc., a Delaware corporation (“Pacira”), to purchase all of the outstanding shares of common stock, par value $0.001 per share (the “Shares”), of Flexion Therapeutics, Inc., a Delaware corporation (“Flexion”), at an offer price of (i) $8.50 per Share, in cash, net of applicable withholding taxes and without interest (the “Cash Amount”), plus (ii) one non-transferable contingent value right per Share (each, a “CVR”), which will represent the right to receive one or more contingent payments of up to $8.00 per Share in the aggregate, in cash, net of applicable withholding taxes and without interest, which amounts will become payable, if at all, if specified milestones are achieved on or prior to December 31, 2030 (the Cash Amount plus one CVR, collectively, or any higher amount per Share paid pursuant to the Offer, the “Offer Price”), upon the terms and subject to the conditions set forth in the Offer

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to Purchase, dated October 22, 2021 (the “Offer to Purchase”) and in this related Letter of Transmittal (this “Letter of Transmittal” which, together with the Offer to Purchase and other related materials, as each may be amended or supplemented from time to time, constitutes the “Offer”).

You should use this Letter of Transmittal to deliver to American Stock Transfer & Trust Company, LLC (the “Depositary”) Shares represented by stock certificates, or held in book-entry form on the books of Flexion, for tender. If you are delivering your Shares by book-entry transfer to an account maintained by the Depositary at The Depository Trust Company (“DTC”), you must use an Agent’s Message (as defined in Instruction 2 below). In this Letter of Transmittal, stockholders who deliver certificates representing their Shares are referred to as “Certificate Stockholders,” and stockholders who deliver their Shares through book-entry transfer are referred to as “Book-Entry Stockholders.”

If certificates for your Shares are not immediately available or you cannot deliver your certificates and all other required documents to the Depositary prior to the Expiration Date or you cannot complete the book-entry transfer procedures prior to the Expiration Date, you may nevertheless tender your Shares according to the guaranteed delivery procedures set forth in Section 3 of the Offer to Purchase. See Instruction 2 below. Delivery of documents to DTC will not constitute delivery to the Depositary.

☐	CHECK HERE IF TENDERED SHARES ARE BEING DELIVERED BY BOOK-ENTRY TRANSFER TO THE ACCOUNT MAINTAINED BY THE DEPOSITARY WITH DTC AND COMPLETE THE FOLLOWING (ONLY FINANCIAL INSTITUTIONS THAT ARE PARTICIPANTS IN DTC MAY DELIVER SHARES BY BOOK-ENTRY TRANSFER):
​	Name of Tendering Institution:
​	DTC Participant Number:
​	Transaction Code Number:

☐	CHECK HERE IF TENDERED SHARES ARE BEING DELIVERED PURSUANT TO A NOTICE OF GUARANTEED DELIVERY PREVIOUSLY SENT TO THE DEPOSITARY AND COMPLETE THE FOLLOWING (PLEASE ENCLOSE A PHOTOCOPY OF SUCH NOTICE OF GUARANTEED DELIVERY):
​	Name(s) of Registered Owner(s):
​	Window Ticket Number (if any) or DTC Participant Number:
​	Date of Execution of Notice of Guaranteed Delivery:
​	Name of Institution which Guaranteed Delivery:

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NOTE: SIGNATURES MUST BE PROVIDED BELOW.
PLEASE READ THE ACCOMPANYING INSTRUCTIONS CAREFULLY.

Ladies and Gentlemen:

The undersigned hereby tenders to Oyster Acquisition Company Inc., a Delaware corporation (“Purchaser”) and wholly owned subsidiary of Pacira BioSciences, Inc., a Delaware corporation (“Pacira”), the shares of common stock, par value $0.001 per share (the “Shares”), of Flexion Therapeutics, Inc., a Delaware corporation (“Flexion”), at an offer price of (i) $8.50 per Share, in cash, net of applicable withholding taxes and without interest (the “Cash Amount”), plus (ii) one contingent value right per Share (each, a “CVR”), which will represent the right to receive one or more contingent cash payments of up to $8.00 per Share in the aggregate, in cash, net of applicable withholding taxes and without interest, which amounts will become payable, if at all, if specified milestones are achieved on or prior to December 31, 2030 (the Cash Amount plus one CVR, collectively, or any higher amount per Share paid pursuant to the Offer, the “Offer Price”), upon the terms and subject to the conditions set forth in the Offer to Purchase (as it may be amended or supplemented from time to time, the “Offer to Purchase”), receipt of which is hereby acknowledged and in this related Letter of Transmittal (as it may be amended or supplemented from time to time, this “Letter of Transmittal,” which, together with the Offer to Purchase and other related materials, as each may be amended or supplemented from time to time, constitutes the “Offer”).

On the terms and subject to the conditions of the Offer (including, if the Offer is extended or amended, the terms and conditions of such extension or amendment), subject to, and effective upon, acceptance for payment and payment for the Shares validly tendered herewith, and not validly withdrawn pursuant to the Offer, the undersigned hereby sells, assigns and transfers to, or upon the order of, Purchaser, all right, title and interest in and to all of the Shares being tendered hereby and with respect to any and all other securities or rights issued or issuable in respect of such Shares on or after the date hereof (collectively, “Distributions”). In addition, the undersigned hereby irrevocably appoints American Stock Transfer & Trust Company, LLC (the “Depositary”) the true and lawful agent and attorney-in-fact and proxy of the undersigned with respect to such Shares and any Distributions with full power of substitution (such proxy and power of attorney being deemed to be an irrevocable power coupled with an interest in the tendered shares) to the full extent of such stockholder’s rights with respect to such Shares and any Distributions (a) to deliver certificates representing Shares (the “Share Certificates”) and any Distributions, or transfer of ownership of such Shares and any Distributions on the account books maintained by DTC, together, in either such case, with all accompanying evidence of transfer and authenticity, to or upon the order of Purchaser, (b) to present such Shares and any Distributions for transfer on the books of Flexion, and (c) to receive all benefits and otherwise exercise all rights of beneficial ownership of such Shares and any Distributions, all in accordance with the terms and subject to the conditions of the Offer.

The undersigned hereby irrevocably appoints each of the designees of Purchaser the attorneys-in-fact and proxies of the undersigned, each with full power of substitution, to the full extent of such stockholder’s rights with respect to the Shares tendered hereby which have been accepted for payment by Purchaser and any Distributions. The designees of Purchaser will, with respect to the Shares and any other securities or rights for which the appointment is effective, be empowered to exercise all voting and any other rights of such stockholder, as they, in their sole discretion, may deem proper at any annual, special, adjourned or postponed meeting of Flexion’s stockholders, by written consent in lieu of any such meeting or otherwise. This proxy and power of attorney shall be irrevocable and coupled with an interest in the tendered Shares. Such appointment is effective when, and only to the extent that, Purchaser accepts the Shares tendered with this Letter of Transmittal for payment pursuant to the Offer. Upon the effectiveness of such appointment, all prior powers of attorney, proxies and consents given by such stockholder with respect to such Shares or other securities or rights will, without further action, be revoked and no subsequent powers of attorney, proxies, consents or revocations may be given by such stockholder (and, if given, will not be deemed effective). Purchaser reserves the right to require that, in order for Shares to be deemed validly tendered, immediately upon Purchaser’s acceptance for payment of such Shares, Purchaser must be able to exercise full voting, consent and other rights, with respect to such Shares and any other related securities or rights.

The undersigned hereby represents and warrants that the undersigned has full power and authority to tender, sell, assign and transfer the Shares and any Distributions tendered hereby and, when the same are accepted for payment by Purchaser, Purchaser will acquire good, marketable and unencumbered title thereto,

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free and clear of all liens, restrictions, charges and encumbrances and the same will not be subject to any adverse claim. The undersigned hereby represents and warrants that the undersigned is the registered owner of the Shares, or the Share Certificate(s) have been endorsed to the undersigned in blank, or the undersigned is a participant in DTC whose name appears on a security position listing as the owner of the Shares. The undersigned will, upon request, execute and deliver any additional documents deemed by the Depositary or Purchaser to be necessary or desirable to complete the sale, assignment and transfer of the Shares and any Distributions tendered hereby. In addition, the undersigned shall promptly remit and transfer to the Depositary for the account of Purchaser any and all Distributions in respect of the Shares tendered hereby, accompanied by appropriate documentation of transfer and, pending such remittance or appropriate assurance thereof, Purchaser shall be entitled to all rights and privileges as owner of any such Distributions and may withhold the entire Offer Price or deduct from the Offer Price the amount or value thereof, as determined by Purchaser in its sole discretion.

It is understood that the undersigned will not receive payment for the Shares unless and until the Shares are accepted for payment and until the Share Certificate(s) owned by the undersigned are received by the Depositary at the address set forth above, together with such additional documents as the Depositary may require, or, in the case of Shares held in book-entry form, ownership of Shares is validly transferred on the account books maintained by DTC, and until the same are processed for payment by the Depositary.

IT IS UNDERSTOOD THAT THE METHOD OF DELIVERY OF THE SHARES, THE SHARE CERTIFICATE(S) AND ALL OTHER REQUIRED DOCUMENTS (INCLUDING DELIVERY THROUGH DTC) IS AT THE OPTION AND RISK OF THE UNDERSIGNED AND THAT THE RISK OF LOSS OF SUCH SHARES, SHARE CERTIFICATE(S) AND OTHER DOCUMENTS SHALL PASS ONLY AFTER THE DEPOSITARY HAS ACTUALLY RECEIVED THE SHARES OR SHARE CERTIFICATE(S) (INCLUDING, IN THE CASE OF A BOOK-ENTRY TRANSFER, BY BOOK-ENTRY CONFIRMATION (AS DEFINED BELOW)). IF DELIVERY IS BY MAIL, IT IS RECOMMENDED THAT ALL SUCH DOCUMENTS BE SENT BY PROPERLY INSURED REGISTERED MAIL WITH RETURN RECEIPT REQUESTED. IN ALL CASES, SUFFICIENT TIME SHOULD BE ALLOWED TO ENSURE TIMELY DELIVERY.

All authority herein conferred or agreed to be conferred pursuant to this Letter of Transmittal shall not be affected by, and shall survive, the death or incapacity of the undersigned and any obligation of the undersigned hereunder shall be binding upon the heirs, executors, administrators, trustees in bankruptcy, personal representatives, successors and assigns of the undersigned. Except as stated in the Offer to Purchase, this tender is irrevocable.

The undersigned understands that the acceptance for payment by Purchaser of Shares tendered pursuant to one of the procedures described in Section 3 of the Offer to Purchase and in the instructions hereto will constitute a binding agreement between the undersigned and Purchaser upon the terms and subject to the conditions of the Offer.

The undersigned understands that the CVRs will not be transferable except (a) upon death of a holder by will or intestacy; (b) pursuant to a court order; (c) by operation of law (including by consolidation or merger) or without consideration in connection with the dissolution, liquidation or termination of any corporation, limited liability company, partnership or other entity; (d) in the case of CVRs held in book-entry or other similar nominee form, from a nominee to a beneficial owner and, if applicable, through an intermediary, as allowable, by DTC; (e) if the holder is a partnership or limited liability company, a distribution by the transferring partnership or limited liability company to its partners or members, as applicable; (f) by instrument to an inter vivos or testamentary trust in which the CVRs are to be passed to beneficiaries upon the death of the trustee; or (g) to Pacira or any of its affiliates in connection with the abandonment of such CVR by the applicable holder. The undersigned further understands that the CVRs will not have any voting or dividend rights, will not represent any equity or ownership interest in Pacira, Purchaser or Flexion and will not be evidenced by a certificate or other instrument, and that no interest will accrue or be payable in respect of any of the amounts that may be payable on CVRs. The undersigned further understands that the CVRs will be governed by the terms and conditions of the CVR Agreement (as defined in the Offer to Purchase), and that holders of CVRs will have no greater rights against Pacira than those accorded to general, unsecured creditors under applicable law. The undersigned understands that the CVRs will be registered in the name of the undersigned.

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Unless otherwise indicated herein under “Special Payment Instructions,” please issue the check for the Cash Amount in the name(s) of, and/or return any Share Certificates representing Shares not validly tendered or accepted for payment to, the registered owner(s) appearing under “Description of Shares Tendered.” Similarly, unless otherwise indicated under “Special Delivery Instructions,” please mail the check for the Cash Amount and/or return any Share Certificates representing Shares not validly tendered or accepted for payment (and accompanying documents, as appropriate) to the address(es) of the registered owner(s) appearing under “Description of Shares Tendered.” Subject to the terms of the CVR Agreement, please make all payments regarding the CVRs as directed herein for payment of the Cash Amount and enter in the CVR register to be maintained by the Rights Agent (as defined in the Offer to Purchase) pursuant to the CVR Agreement the name(s) and address(es) appearing on the cover page of this Letter of Transmittal for each registered holder. The undersigned recognizes that Purchaser has no obligation, pursuant to the Special Payment Instructions, to transfer any Shares from the name(s) of the registered holder(s) thereof if Purchaser does not accept for payment any of the Shares so tendered.

In the event that both the Special Delivery Instructions and the Special Payment Instructions are completed, please issue the check for the Cash Amount and/or issue any Share Certificates representing Shares not validly tendered or accepted for payment (and any accompanying documents, as appropriate) in the name of, and deliver such check and/or return such Share Certificates (and any accompanying documents, as appropriate) to, the person or persons so indicated. Unless otherwise indicated herein in the box titled “Special Payment Instructions,” please credit any Shares tendered hereby or by an Agent’s Message and delivered by book-entry transfer, but which are not purchased, by crediting the account at DTC designated above. The undersigned recognizes that Purchaser has no obligation pursuant to the Special Payment Instructions to transfer any Shares from the name of the registered owner thereof if Purchaser does not accept for payment any of the Shares so tendered.

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SPECIAL PAYMENT INSTRUCTIONS (See Instructions 1, 4, 5, 6 and 7)
To be completed ONLY if Share Certificate(s) not validly tendered or not accepted for payment and/or the check for the Cash Amount in consideration of Shares accepted for payment are to be issued in the name of someone other than the undersigned or if Shares tendered by book-entry transfer which are not accepted for payment are to be returned by credit to an account maintained at DTC other than that designated above.
Issue Check and/or Share Certificates to:	​
Name:	​
​	(Please Print)
Address:	​
​	(Include Zip Code)
​	(Tax Identification or Social Security Number)
​	Credit Shares tendered by book-entry transfer that are not accepted for payment to the DTC account set forth below.
​	(DTC Account Number)

SPECIAL DELIVERY INSTRUCTIONS (See Instructions 1, 4, 5, 6 and 7)
To be completed ONLY if Share Certificate(s) not validly tendered or not accepted for payment and/or the check for the Cash Amount in consideration of Shares accepted for payment are to be sent to someone other than the undersigned or to the undersigned at an address other than that shown in the box titled “Description of Shares Tendered” above.
Deliver Check and/or Share Certificates to:	​
Name:	​
​	(Please Print)
Address:	​
​	(Include Zip Code)

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IMPORTANT — SIGN HERE
(U.S. Holders Please Also Complete the Enclosed IRS Form W-9)
(Non-U.S. Holders Please Obtain and Complete IRS Form W-8BEN or Other Applicable IRS Form W-8)

(Signature(s) of Stockholder(s))

Dated:                       , 2021

(Must be signed by registered owner(s) exactly as name(s) appear(s) on Share Certificate(s) or on a security position listing or by person(s) authorized to become registered owner(s) by certificates and documents transmitted herewith. If signature is by trustees, executors, administrators, guardians, attorneys-in-fact, officers of corporations or others acting in a fiduciary or representative capacity, please set forth full title and see Instruction 5. For information concerning signature guarantees, see Instruction 1.)

Name(s):

Capacity (full title):

Address:

Area Code and Telephone Number:

GUARANTEE OF SIGNATURE(S)
(For use by Eligible Institutions only;
see Instructions 1 and 5)

Name of Firm:

                                 (Include Zip Code)

Authorized Signature:

Name:

Area Code and Telephone Number:

Dated:                       , 2021

Place medallion guarantee in space below:

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INSTRUCTIONS
Forming Part of the Terms and Conditions of the Offer

1.   Guarantee of Signatures.   Except as otherwise provided below, all signatures on this Letter of Transmittal must be guaranteed by a financial institution (including most commercial banks, savings and loan associations and brokerage houses) that is a participant in the Security Transfer Agent Medallion Signature Program or other “eligible guarantor institution,” as such term is defined in Rule 17Ad-15 under the Exchange Act (each, an “Eligible Institution” and, collectively, “Eligible Institutions”). Signatures on this Letter of Transmittal need not be guaranteed (a) if this Letter of Transmittal is signed by the registered owner(s) (which term, for purposes of this document, includes any participant in any of DTC’s systems whose name appears on a security position listing as the owner of the Shares) of Shares tendered herewith and such registered owner has not completed the box titled “Special Payment Instructions” or the box titled “Special Delivery Instructions” on this Letter of Transmittal or (b) if such Shares are tendered for the account of an Eligible Institution. See Instruction 5.

2.   Delivery of Letter of Transmittal and Certificates or Book-Entry Confirmations.   This Letter of Transmittal is to be completed by stockholders if Share Certificates are to be forwarded herewith. If tenders are to be made pursuant to the procedures for tender by book-entry transfer set forth in Section 3 of the Offer to Purchase, an Agent’s Message must be utilized. A manually executed facsimile of this document may be used in lieu of the original. Share Certificates representing all physically tendered Shares, or confirmation of any book-entry transfer into the Depositary’s account at DTC of Shares tendered by book-entry transfer (“Book-Entry Confirmation”), as well as this Letter of Transmittal properly completed and duly executed with any required signature guarantees, or an Agent’s Message in the case of a book-entry transfer, and any other documents required by this Letter of Transmittal, must be received by the Depositary at its address set forth herein prior to the Expiration Date (as defined in the Offer to Purchase). Please do not send your Share Certificates directly to Purchaser, Pacira or Flexion.

Stockholders whose Share Certificates are not immediately available or who cannot deliver all other required documents to the Depositary prior to the Expiration Date or who cannot complete the procedures for book-entry transfer prior to the Expiration Date may nevertheless tender their Shares by properly completing and duly executing a Notice of Guaranteed Delivery pursuant to the guaranteed delivery procedure set forth in Section 3 of the Offer to Purchase. Pursuant to such procedure: (a) such tender must be made by or through an Eligible Institution, (b) a properly completed and duly executed Notice of Guaranteed Delivery substantially in the form provided by Purchaser must be received by the Depositary prior to the Expiration Date, and (c) Share Certificates representing all tendered Shares, in proper form for transfer (or a Book-Entry Confirmation with respect to such Shares), this Letter of Transmittal (or facsimile thereof), properly completed and duly executed with any required signature guarantees (or, in the case of a book-entry transfer, an Agent’s Message), and all other documents required by this Letter of Transmittal, if any, must be received by the Depositary within two Nasdaq Global Select Market trading days after the date of execution of such Notice of Guaranteed Delivery.

A properly completed and duly executed Letter of Transmittal (or facsimile thereof) must accompany each such delivery of Share Certificates to the Depositary.

The term “Agent’s Message” means a message, transmitted through electronic means by DTC in accordance with the normal procedures of DTC and the Depositary, to, and received by, the Depositary and forming a part of a Book-Entry Confirmation, which states that DTC has received an express acknowledgment from the participant tendering the Shares that are the subject of Book-Entry Confirmation that such participant has received and agrees to be bound by the terms of the Letter of Transmittal and that Purchaser may enforce such agreement against the participant. The term “Agent’s Message” also includes any hard copy printout evidencing such message generated by a computer terminal maintained at the Depositary’s office.

THE METHOD OF DELIVERY OF THE SHARES, THIS LETTER OF TRANSMITTAL AND ALL OTHER REQUIRED DOCUMENTS, INCLUDING DELIVERY THROUGH DTC, IS AT THE ELECTION AND RISK OF THE TENDERING STOCKHOLDER. DELIVERY OF ALL SUCH DOCUMENTS WILL BE DEEMED MADE AND RISK OF LOSS OF THE SHARE CERTIFICATES SHALL PASS ONLY WHEN ACTUALLY RECEIVED BY THE DEPOSITARY (INCLUDING, IN THE

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CASE OF A BOOK-ENTRY TRANSFER, BY BOOK-ENTRY CONFIRMATION). IF SUCH DELIVERY IS BY MAIL, IT IS RECOMMENDED THAT ALL SUCH DOCUMENTS BE SENT BY PROPERLY INSURED REGISTERED MAIL WITH RETURN RECEIPT REQUESTED. IN ALL CASES, SUFFICIENT TIME SHOULD BE ALLOWED TO ENSURE TIMELY DELIVERY.

No alternative, conditional or contingent tenders will be accepted, and no fractional Shares will be purchased. All tendering stockholders, by execution of this Letter of Transmittal (or facsimile thereof), waive any right to receive any notice of the acceptance of their Shares for payment.

All questions as to validity, form and eligibility (including time of receipt) of the surrender of any Share Certificate hereunder, including questions as to the proper completion or execution of any Letter of Transmittal, Notice of Guaranteed Delivery or other required documents and as to the proper form for transfer of any certificate of Shares, will be determined by Purchaser in its reasonable discretion (which may delegate power in whole or in part to the Depositary) which determination will be final and binding, subject to the rights of the tendering holders of Shares to challenge Purchaser’s determination in a court of competent jurisdiction. Purchaser’s interpretation of the terms and conditions of the Offer (including the Letter of Transmittal and the instructions thereto) will be determined by it in its reasonable judgement. Purchaser reserves the absolute right to reject any and all tenders determined by it not to be in proper form or the acceptance for payment of or payment for which may be unlawful. Purchaser also reserves the absolute right to waive any defect or irregularity in the surrender of any Shares or Share Certificate(s) whether or not similar defects or irregularities are waived in the case of any other stockholder. A surrender will not be deemed to have been validly made until all defects and irregularities have been cured or waived.

3.   Inadequate Space.   If the space provided herein is inadequate, the certificate numbers and/or the number of Shares should be listed on a separate schedule attached hereto and separately signed on each page thereof in the same manner as this Letter of Transmittal is signed.

4.   Partial Tenders (Applicable to Certificate Stockholders Only).   If fewer than all the Shares evidenced by any Share Certificate delivered to the Depositary are to be tendered, fill in the number of Shares which are to be tendered in the column titled “Number of Shares Surrendered” in the box titled “Description of Shares Surrendered.” In such cases, new certificate(s) for the remainder of the Shares that were evidenced by the old certificate(s) but not validly tendered will be sent to the registered owner, unless otherwise provided in the appropriate box on this Letter of Transmittal, as soon as practicable after the Expiration Date. All Shares represented by Share Certificates delivered to the Depositary will be deemed to have been tendered unless otherwise indicated.

5.   Signatures on Letter of Transmittal; Stock Powers and Endorsements.   If this Letter of Transmittal is signed by the registered owner(s) of the Shares tendered hereby, the signature(s) must correspond with the name(s) as written on the face of the Share Certificate(s) without alteration or any other change whatsoever.

If any Shares tendered hereby are owned of record by two or more joint owners, all such owners must sign this Letter of Transmittal.

If any tendered Shares are registered in the names of different holder(s), it will be necessary to complete, sign and submit as many separate Letters of Transmittal (or facsimiles thereof) as there are different registrations of such Shares.

If this Letter of Transmittal or any certificates or stock powers are signed by trustees, executors, administrators, guardians, attorneys-in-fact, officers of corporations or others acting in a fiduciary or representative capacity, such persons should so indicate when signing, and proper evidence satisfactory to Purchaser of their authority so to act must be submitted.

If this Letter of Transmittal is signed by the registered owner(s) of the Shares listed and transmitted hereby, no endorsements of Share Certificates or separate stock powers are required unless payment is to be made to, or Share Certificates representing Shares not validly tendered or accepted for payment are to be issued in the name of, a person other than the registered owner(s), in which case the Share Certificates representing the Shares tendered by this Letter of Transmittal must be endorsed or accompanied by appropriate stock powers, in either case, signed exactly as the name(s) of the registered owner(s) or holder(s)

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appear(s) on the Share Certificates. Signatures on such Share Certificates or stock powers must be guaranteed by an Eligible Institution.

If this Letter of Transmittal is signed by a person other than the registered owner(s) of the Share(s) listed, the Share Certificate(s) must be endorsed or accompanied by the appropriate stock powers, in either case, signed exactly as the name or names of the registered owner(s) or holder(s) appear(s) on the Share Certificate(s). Signatures on such Share Certificates or stock powers must be guaranteed by an Eligible Institution.

6.   Transfer Taxes.   If payment of the Offer Price is to be made to, or (in the circumstances permitted hereby) if Share Certificates not validly tendered or accepted for payment are to be registered in the name of, any person other than the registered owner(s), or if tendered Share Certificates are registered in the name of any person other than the person signing this Letter of Transmittal, it will be a condition to payment that the person requesting such payment shall have paid any transfer taxes (whether imposed on the registered owner(s) or such person) payable on account of the transfer to such person or such person shall have established that such transfer taxes have been paid or are not applicable.

Except as provided in this Instruction 6, it will not be necessary for transfer tax stamps to be affixed to the Share Certificates listed in this Letter of Transmittal.

7.   Special Payment and Delivery Instructions.   If a check for the Cash Amount is to be issued, and/or Share Certificates representing Shares not validly tendered or accepted for payment are to be issued or returned to, a person other than the signer(s) of this Letter of Transmittal or to an address other than that shown in the box titled “Description of Shares Tendered” above, the appropriate boxes on this Letter of Transmittal should be completed. Stockholders delivering Shares tendered hereby or by Agent’s Message by book-entry transfer may request that Shares not purchased be credited to an account maintained at DTC as such stockholder may designate in the box titled “Special Payment Instructions” herein. If no such instructions are given, all such Shares not purchased will be returned by crediting the same account at DTC as the account from which such Shares were delivered.

8.   Requests for Assistance or Additional Copies.   Questions or requests for assistance may be directed to the Information Agent at its address and telephone numbers set forth below or to your broker, dealer, commercial bank or trust company. Additional copies of the Offer to Purchase, this Letter of Transmittal, the Notice of Guaranteed Delivery and other tender offer materials may be obtained from the Information Agent as set forth below, and will be furnished at Purchaser’s expense.

9.   Tax Forms:   Under U.S. federal income tax law, failure to provide a properly completed and signed Internal Revenue Service (“IRS”) Form W-9 or applicable IRS Form W-8 may result in backup withholding on any consideration paid pursuant to the Offer or the Merger and may result in a penalty imposed by the IRS. Each “U.S. person” ​(as defined in the instructions accompanying the enclosed IRS Form W-9) receiving consideration pursuant to the Offer or the Merger is generally required to provide a correct Taxpayer Identification Number (“TIN”) on IRS Form W-9, and to indicate whether the holder is subject to backup withholding. If a stockholder or payee that is a “U.S. person” does not have a TIN, such stockholder or payee should consult the instructions to the IRS Form W-9 on how to on apply for a TIN and should apply for a TIN immediately. If the stockholder or payee does not provide such stockholder’s or payee’s TIN to the Depositary by the time of payment, backup withholding may apply. Certain stockholders or payees (including, among others, certain corporations, non-resident foreign individuals and foreign entities) may not be subject to these backup withholding and reporting requirements. A stockholder or payee who is not a “U.S. person” is required to provide a properly executed IRS Form W-8BEN (or other applicable IRS Form W-8). Please see “IMPORTANT TAX INFORMATION”.

NOTE: FAILURE TO COMPLETE AND RETURN THE IRS FORM W-9 MAY RESULT IN BACKUP WITHHOLDING OF A PORTION OF ANY PAYMENTS MADE TO YOU PURSUANT TO THE OFFER. PLEASE REVIEW THE “IMPORTANT TAX INFORMATION” SECTION BELOW.

10.   Lost, Destroyed, Mutilated or Stolen Share Certificates.   If any Share Certificate has been lost, destroyed, mutilated or stolen, the stockholder should promptly notify Flexion’s stock transfer agent, Computershare Trust Company, N.A. at 150 Royall St, Canton, MA 02021. The stockholder will then be instructed as to the steps that must be taken in order to replace the Share Certificate. This Letter of Transmittal

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and related documents cannot be processed until the procedures for replacing lost, mutilated, destroyed or stolen Share Certificates have been followed.

11.   Waiver of Conditions.   Subject to the terms and conditions of the Merger Agreement (as defined in the Offer to Purchase) and the applicable rules and regulations of the Securities and Exchange Commission, the conditions of the Offer (other than the Minimum Tender Condition, the Termination Condition and the Order Condition (each as defined in the Offer to Purchase)) may be waived by Purchaser in whole or in part at any time and from time to time in its sole discretion.

IMPORTANT: THIS LETTER OF TRANSMITTAL (OR A MANUALLY EXECUTED FACSIMILE COPY THEREOF) OR AN AGENT’S MESSAGE, TOGETHER WITH SHARE CERTIFICATE(S) OR BOOK-ENTRY CONFIRMATION OR A PROPERLY COMPLETED AND DULY EXECUTED NOTICE OF GUARANTEED DELIVERY AND ALL OTHER REQUIRED DOCUMENTS, MUST BE RECEIVED BY THE DEPOSITARY PRIOR TO THE EXPIRATION DATE.

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IMPORTANT TAX INFORMATION

PLEASE COMPLETE AND SUBMIT THE ACCOMPANYING IRS FORM W-9 IF YOU ARE A U.S. PERSON (AS DEFINED IN THE INSTRUCTIONS TO THE IRS FORM W-9) OR THE APPROPRIATE IRS FORM W-8 IF YOU ARE NOT A U.S. PERSON, WHICH IRS FORM W-8 CAN BE OBTAINED FROM THE IRS WEBSITE AT WWW.IRS.GOV. Please note that a failure to properly complete and return an IRS Form W-9 or the appropriate IRS Form W-8, as applicable, may subject any payments made to you in connection with the Offer of the Merger to backup withholding (at the applicable statutory rate (currently 24%)).

Under current U.S. federal income tax law, a stockholder or payee that is a non-exempt “U.S. person” (as defined in the instructions accompanying the enclosed IRS Form W-9) whose tendered Shares are accepted for payment in the Offer or whose Shares are converted in the Merger (each, a “Payee”) may be subject to backup withholding. In order to avoid such backup withholding, a Payee must provide the Depositary with such Payee’s correct TIN and certify under penalties of perjury that such TIN is correct, that such Payee is not subject to such backup withholding and that such Payee is a U.S. person by completing the IRS Form W-9 provided herewith. In general, if a Payee is an individual, such Payee’s TIN is generally its, his or her Social Security number. If the Depositary is not provided with the correct TIN, a Payee may be subject to penalties imposed by the IRS and any consideration such Payee receives in the Offer or the Merger may be subject to backup withholding at the applicable rate (currently 24%). Failure to comply with the backup withholding requirements also may result in the imposition of criminal and/or civil fines and penalties. For further information concerning backup withholding and instructions for completing the IRS Form W-9 (including how to obtain a TIN if you do not have one and how to complete the IRS Form W-9 if Share Certificates are held in more than one name), consult the instructions on the IRS Form W-9.

Certain Payees that are U.S. persons (including, among others, certain corporations) are exempt recipients not subject to these backup withholding requirements. See the enclosed copy of the IRS Form W-9 and the General Instructions to Form W-9for more information. To avoid possible erroneous backup withholding, exempt Payees should indicate their exempt status on the enclosed IRS Form W-9 by furnishing their TIN, entering the appropriate “exempt payee code” box(es) on the form, and signing and dating the form. Each Payee is urged to consult his, her or its tax advisor for more information.

To prevent backup withholding, Payees that are not U.S. persons should (i) submit a properly completed, appropriate IRS Form W-8 to the Depositary, certifying under penalties of perjury to such Payee’s non-U.S. person status or (ii) otherwise establish an exemption from backup withholding. The appropriate IRS Form W-8 may be obtained from the Depositary or from the IRS website at www.irs.gov. Each Payee that is not a U.S. person is urged to consult his, her or its tax advisor for more information.

If backup withholding applies, the Depositary is required to withhold and pay over to the IRS a portion of any payment otherwise payable to such Payee. Backup withholding is not an additional tax. Rather, the U.S. federal income tax liability of a Payee subject to backup withholding will be reduced by the amount of tax withheld. If backup withholding results in an overpayment of taxes, a refund may be obtained from the IRS, provided that the required information is timely furnished to the IRS.

Please consult your tax advisor for further guidance, including regarding the completion of IRS Form W-9 or the appropriate version of IRS Form W-8, as applicable, to claim exemption from backup withholding, and which version of IRS Form W-8 you should provide to the Depositary.

NOTE: FAILURE TO COMPLETE AND RETURN THE IRS FORM W-9 MAY RESULT IN BACKUP WITHHOLDING OF A PORTION OF ANY PAYMENTS MADE TO YOU PURSUANT TO THE MERGER. PLEASE REVIEW THE ENCLOSED “GENERAL INSTRUCTIONS” ON IRS FORM W-9 FOR ADDITIONAL DETAILS.

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The Depositary for the Offer is:

If delivering by mail:	If delivering by hand, express mail, courier or any other expedited service:
American Stock Transfer & Trust Company, LLC Operations Center Attn: Reorganization Department 6201 15th Avenue Brooklyn, New York 11219 Phone: Toll-free (877) 248-6417 (718) 921-8317 Fax: 718 234-5001	American Stock Transfer & Trust Company, LLC Operations Center Attn: Reorganization Department 6201 15th Avenue Brooklyn, New York 11219

DELIVERY OF THIS LETTER OF TRANSMITTAL TO AN ADDRESS OTHER THAN AS SET FORTH ABOVE WILL NOT CONSTITUTE A VALID DELIVERY TO THE DEPOSITARY.

Any questions or requests for assistance may be directed to the Information Agent at its telephone number and location listed below. Requests for additional copies of the Offer to Purchase and the Letter of Transmittal may be directed to the Information Agent at the telephone number and location listed below. You may also contact your broker, dealer, commercial bank or trust company or other nominee for assistance concerning the Offer.

The Information Agent for the Offer is:

D.F. King & Co., Inc.
48 Wall Street, 22nd Floor
New York, New York 10005
Banks and Brokers may call: (212) 269-5550
Stockholders may call toll free: (800) 578-5378
FLXN@dfking.com