La Jolla Pharmaceutical Company Announces Proposed Underwritten Public Offering of Common Stock

SAN DIEGO–(BUSINESS WIRE)–La Jolla Pharmaceutical Company (Nasdaq: LJPC) (“La Jolla” or the
Company), a leader in the development of innovative therapies intended
to significantly improve outcomes in patients suffering from
life-threatening diseases, today announced its intention to offer and
sell $100,000,000 of its common stock in an underwritten public offering
pursuant to its existing shelf registration statement. All of the shares
to be sold in the proposed public offering are being offered by La Jolla.

J.P. Morgan Securities LLC and Cowen and Company, LLC are acting as
joint book-running managers for the offering. La Jolla intends to grant
the underwriters a 30-day option to purchase additional shares of its
common stock. The offering is subject to market conditions, and there
can be no assurance as to whether or when the offering may be completed,
or the actual size or terms of the offering.

La Jolla intends to use the net proceeds from the underwritten offering
for general corporate purposes, including funding its ongoing and future
clinical trials of its drug candidates, for expenses relating to the
potential regulatory approval of LJPC-501, potential future acquisitions
and for general and administrative expenses.

The securities described above are being offered pursuant to a shelf
registration statement (File No. 333-214721), including a base
prospectus, which was declared effective by the United States Securities
and Exchange Commission (the “SEC”) on December 8, 2016. The specific
terms of the offering are described in a prospectus supplement to be
filed with the SEC in connection with the offering. The offering will be
made only by means of the prospectus supplement and accompanying
prospectus, copies of which may be obtained at the SEC’s website at www.sec.gov,
or by request at J.P. Morgan Securities LLC c/o Broadridge Financial
Solutions, 1155 Long Island Ave, Edgewood, NY 11717, (tel: +1 866 803
9204) or Cowen and Company, LLC, c/o Broadridge Financial Services, 1155
Long Island Avenue, Edgewood, NY 11717, Attn: Prospectus Department, or
by calling 631-274-2806, or by faxing 631-254-7140.

This press release shall not constitute an offer to sell or the
solicitation of an offer to buy these securities, nor shall there be any
sale of these securities in any state or other jurisdiction in which
such offer, solicitation or sale would be unlawful prior to the
registration or qualification under the securities laws of any such
state or other jurisdiction.

About La Jolla Pharmaceutical Company

La Jolla Pharmaceutical Company is a biopharmaceutical company focused
on the discovery, development and commercialization of innovative
therapies intended to significantly improve outcomes in patients
suffering from life-threatening diseases. The company has several
product candidates in development. LJPC-501 is La Jolla’s proprietary
formulation of synthetic human angiotensin II for the potential
treatment of catecholamine resistant hypotension. LJPC-401 is La Jolla’s
proprietary formulation of synthetic human hepcidin for the potential
treatment of conditions characterized by iron overload, such as
hereditary hemochromatosis, beta thalassemia, sickle cell disease and
myelodysplastic syndrome. LJPC-30S is La Jolla’s next-generation
gentamicin derivative program that is focused on the potential treatment
of serious bacterial infections as well as rare genetic disorders, such
as cystic fibrosis and Duchenne muscular dystrophy.

Forward Looking Statements

This press release contains “forward-looking” statements within the
meaning of the Private Securities Litigation Reform Act of 1995. These
forward-looking statements are based on our current expectations and
beliefs, speak only as of the date of this press release and involve
risks and uncertainties, many of which are outside of our control, that
can cause actual results to differ materially from those anticipated in
the forward-looking statements. Potential risks and uncertainties
include, but are not limited to: the uncertainties related to market
conditions, the timing and size of the public offering and the
completion of the public offering on the anticipated terms or at all,
the intended use of the net proceeds raised during the public offering,
and the expected duration of the Company’s operating runway based on
current cash resources. Further information regarding these and other
risks that could affect our future results of operations are included in
La Jolla’s most recently filed Annual Report on Form 10-K and subsequent
Quarterly Reports on Form 10-Q under the caption “Risk Factors,” as
filed with the U.S. Securities and Exchange Commission at www.sec.gov.
We disclaim any intent to update any forward-looking statements to
reflect actual events that occur after the date of this press release.

Contacts

La Jolla Pharmaceutical Company
Sandra Vedrick
Associate
Director, Investor Relations & Human Resources

858-256-7910
svedrick@ljpc.com
and
Dennis
M. Mulroy
Chief Financial Officer
858-433-6839
dmulroy@ljpc.com