Filed pursuant to Rule 424(b)(5)
Registration No. 333-257428
Prospectus Supplement
(To Prospectus Supplement dated November 9,
2021)

Up to $17,000,000
Common Stock
This prospectus supplement amends and supplements the information
in the prospectus supplement, dated November 9, 2021, filed
with the Securities and Exchange Commission as a part of our
registration statement on Form S-3 (File No. 333-257428) (the “Prior
Prospectus”), relating to the offer and sale of up to
$25,000,000 of shares of our common stock, $0.01 par value per
share, pursuant to the Controlled Equity
OfferingSM Sales Agreement
dated as of August 18, 2020 (the “Sales Agreement”) we
previously entered into with Cantor Fitzgerald & Co. (the
“Agent”). This prospectus supplement should be read in conjunction
with the Prior Prospectus, and is qualified by reference
thereto, except to the extent that the information herein amends or
supersedes the information contained in the Prior
Prospectus. This prospectus supplement is not complete
without, and may only be delivered or utilized in connection with,
the Prior Prospectus and any future amendments or supplements
thereto.
Through February 27, 2023, we have sold an aggregate of
515,000 shares of our common stock in accordance with the Sales
Agreement under the Prior Prospectus for aggregate gross proceeds
of approximately $4 million. We are filing this prospectus
supplement to amend the Prior Prospectus because we are now subject
to General Instruction I.B.6 of Form S-3, which limits the amounts that we
may sell under the registration statement of which this prospectus
supplement and the Prior Prospectus are a part. After giving effect
to these limitations and the current public float of our common
stock, and after giving effect to the terms of the Sales Agreement,
we currently may offer and sell shares of our common stock having
an aggregate offering price of up to $17,000,000 under the Sales
Agreement, which amount is in addition to the shares of common
stock that we have sold to date in accordance with the Sales
Agreement under the Prior Prospectus. If our public float
increases such that we may sell additional amounts under the Sales
Agreement and the registration statement of which this prospectus
supplement and the Prior Prospectus are a part, we will file
another prospectus supplement prior to making additional sales.
Our common stock is listed on The Nasdaq Capital Market under the
symbol “DCTH.” On February 24, 2023, the last report sale
price of our common stock on The Nasdaq Capital Market was $4.91
per share.
The aggregate market value of our common stock held by non-affiliates as of February 27,
2023 pursuant to General Instruction I.B.6 of Form S-3 is $51,156,403 which was calculated
based on 9,386,496 shares of our common stock outstanding held by
non-affiliates and at a
price of $5.45 per share, the closing price of our common stock on
February 9, 2023. As of the date hereof, we have not offered
or sold any securities pursuant to General Instruction I.B.6 of
Form S-3 during the prior
12 calendar month period that ends on and includes the date hereof.
As a result of the limitations of General Instruction I.B.6 of Form
S-3, and in accordance with
the terms of the Sales Agreement, we are registering the offer and
sale of shares of our common stock having an aggregate offering
price of up to $17,000,000 from time to time through the Agent.
Investing in our securities involves risks. See “Risk Factors”
on page S-6 of the Prior
Prospectus and in the documents incorporated by reference into the
Prior Prospectus and in our most recent Annual Report on Form
10-K and in our most recent
Quarterly Reports on Form 10-Q, and any amendments thereto, which
are incorporated by reference into the Prior Prospectus, and under
similar headings in the other documents that are filed after the
date hereof and incorporated by reference into this prospectus
supplement and the Prior Prospectus for a discussion of the factors
you should carefully consider before deciding to purchase our
common stock.
Neither the Securities and Exchange Commission nor any state
securities commission has approved or disapproved of these
securities or passed upon the adequacy or accuracy of the Prior
Prospectus, this prospectus supplement or the accompanying
prospectus. Any representation to the contrary is a criminal
offense.

The date of this prospectus supplement is
February 27, 2023.