Exhibit 99.1 

FORM OF
INSTRUCTIONS AS TO USE OF SUBSCRIPTION RIGHTS CERTIFICATES
ENZON PHARMACEUTICALS, INC.

Please consult Georgeson LLC, the Information Agent, or Continental Stock Transfer & Trust Company, the Subscription Agent, or your bank or broker as to any questions.

The following instructions relate to a distribution in a rights offering (the “Rights Offering”) by Enzon Pharmaceuticals, Inc., a Delaware corporation (the “Company”), to holders of record of its common stock, $0.01 par value per share (the “Common Stock”), as described in the Company’s prospectus dated [            ], 2020 (the “Prospectus”). Each holder of Common Stock as of 5:00 PM, New York City Time, on [            ], 2020 (the “Record Date”) will receive, at no charge, transferable subscription rights (the “Subscription Rights”) to subscribe for and purchase units (the “Units”). Each Unit consists of one share of newly designated Series C Preferred Stock, par value $0.01 per share (the “Preferred Stock”), and 750 shares of Common Stock. For every 1,105 Subscription Rights held, the holder is entitled to purchase one Unit at a subscription price per Unit of $1,090 (the “Subscription Price”). The Subscription Rights, Units and Preferred Stock are described in the Prospectus.

The Subscription Rights may be exercised at any time during the subscription period, which commences on [            ], 2020 and ends at 5:00 p.m., New York City Time, on [            ], 2020, unless extended in the sole discretion of the Company; provided, however, that the Company may not extend the expiration date of the Rights Offering by more than 30 days past the original expiration date (as it may be extended, the “Expiration Date”). If you do not exercise your Subscription Rights before that time, your Subscription Rights will expire and will no longer be exercisable. The Company will not be required to issue Units to you if the Subscription Agent receives your Subscription Rights Certificate or your subscription payment after that time. The Company has the option to extend the Rights Offering by giving oral or written notice to the Subscription Agent before the Rights Offering expires in the Company’s sole discretion; provided, however, that the Company may not extend the Expiration Date of the Rights Offering by more than 30 days past the original Expiration Date. If the Company elects to extend the Rights Offering, the Company will issue a press release announcing the extension no later than 9:00 a.m., New York City Time, on the next business day after the most recently announced expiration date of the Rights Offering.

As described in the Prospectus, holders will receive one Subscription Right for every share of Common Stock owned on the Record Date, evidenced by transferable Subscription Rights certificates (the “Subscription Rights Certificates”). For every 1,105 Subscription Rights held, the holder is entitled to purchase one Unit at the Subscription Price.

The Company will not issue fractional Subscription Rights or fractional Units in the Rights Offering. Accordingly, if you hold shares of Common Stock in an amount other than a whole multiple of 1,105 shares and wish to acquire a certain number of Units in the Rights Offering, you will need to either acquire (i) additional shares of Common Stock in the open market prior to the Record Date or (ii) additional Subscription Rights during the offering period of the Rights Offering, in each case in an amount sufficient to increase your ownership of Subscription Rights to allow you to participate at a level you desire to participate.

PAYMENT OF THE SUBSCRIPTION PRICE FOR ALL UNITS, INCLUDING FINAL CLEARANCE OF ANY CHECKS, MUST BE RECEIVED ON OR BEFORE THE EXPIRATION DATE. SUBSCRIPTION RIGHTS NOT VALIDLY EXERCISED PRIOR TO THE EXPIRATION DATE OF THE RIGHTS OFFERING WILL EXPIRE. IN CASE YOU HOLD SUBSCRIPTION RIGHTS THROUGH A BROKER OR OTHER NOMINEE, YOU SHOULD VERIFY WITH YOUR BROKER OR NOMINEE BY WHEN YOU MUST DELIVER YOUR INSTRUCTION.

If you are a beneficial owner of Common Stock that is registered in the name of a broker, dealer, bank or other nominee, you will need to coordinate exercises of Subscription Rights through your broker, dealer, bank or other nominee in order for them to transmit payment to the Subscription Agent.

If you are a beneficial owner of Common Stock that is registered in the name of a broker, dealer, bank or other nominee, you will need to coordinate payments through your broker, dealer, bank or other nominee.

7.                Execution.

To be effective, a written notice of revocation must be received by the Subscription Agent at its address identified above prior to the Expiration Date of the Rights Offering, as may be extended. Any notice of revocation must specify the name of the person who exercised the Subscription Rights for which such exercises are to be revoked and the number of Subscription Rights to be revoked. Any funds received by the Subscription Agent will be promptly returned to such holder following a revocation. Revocations of Subscription Rights may not be cancelled; however, you may exercise your Subscription Rights again by following one of the procedures described above at any time prior to the expiration of the Rights Offering. All questions as to the form and validity (including time of receipt) of any notice of revocation will be determined by the Company, in its sole discretion, which determination shall be final and binding, subject to the judgments of any courts with jurisdiction over the Company that might provide otherwise. Neither the Company nor any other person will be under any duty to give notification of any defect or irregularity in any notice of revocation or incur any liability for failure to give any such notification, subject to the judgment of any court with jurisdiction over the Company.