Ligand Signs Global License Agreement with TG Therapeutics for IRAK-4 Inhibitor Program

  Ligand Signs Global License Agreement with TG Therapeutics for IRAK-4
  Inhibitor Program

Ligand Receives $1 million of TGTX Common Stock as Upfront License Fee and is
         Eligible for Tiered Royalties and $207 million in Milestones

Business Wire

SAN DIEGO -- June 24, 2014

Ligand Pharmaceuticals Incorporated (NASDAQ:LGND) announced the signing of an
exclusive global license agreement with TG Therapeutics, Inc. (NASDAQ: TGTX)
for the development and commercialization of Ligand’s Interleukin-1 Receptor
Associated Kinase-4 (IRAK-4) inhibitors. The IRAK-4 program is in preclinical
development for potential use in certain cancers and autoimmune diseases.

Under the terms of the agreement, Ligand is entitled to receive 125,000 shares
of TG Therapeutics common stock, valued at approximately $1 million at date of
signing, and is eligible to receive $207 million in potential milestone
payments. Ligand is also eligible to receive tiered royalties of 6% to 9.5% on
future net sales of licensed products containing patented IRAK-4 inhibitors.

“Through this partnership we are combining our IRAK-4 inhibitors program with
the promising clinical portfolio of an oncology-focused company capable of
efficiently advancing this asset,” commented John Higgins, President and Chief
Executive Officer of Ligand Pharmaceuticals. “TG Therapeutics has a proven
ability in transitioning preclinical compounds into best-in-class clinical
programs and IRAK-4 is an ideal complement to their two clinical-stage
hematology products, namely TG-1101, or ublituximab, and TGR-1202, a PI3K
delta inhibitor. Given the evolution of these areas of research, there may be
opportunities for treatment synergies between IRAK-4 inhibitors and these
other programs.”

Higgins continued, “This transaction is a clear illustration of our business
model, which is focused on selecting promising drugtargets, generating
answers to key questions in the early research phase and then licensing the
asset to a strong partner for further development. Our agreement with TG
Therapeutics is structured such that bothcompanies will behighly
rewardedshould thisprogram be successfulin generating a commercial product,
and builds upon our portfolio of more than 90 fully-funded partnerships.”

About Interleukin-1 Receptor Associated Kinase-4 (IRAK-4)

IRAK-4 is a serine/threonine protein kinase that is a key downstream signaling
component of the interleukin-1 receptor and multiple toll-like receptors.
Signaling through IRAK-4 is important for both innate immunity and
inflammation. Recent pre-clinical studies suggest a potential that IRAK-4
plays an important role in certain b-cell lymphomas. Ligand has discovered
novel compounds that selectively and potently inhibit IRAK-4 activity. IRAK-4
inhibitors may have therapeutic potential in oncology and a number of
autoimmune diseases. Ligand originally acquired the rights to the IRAK-4
program at a discovery stage via its 2008 acquisition of Pharmacopeia.

About TG Therapeutics

TG Therapeutics is an innovative, clinical-stage biopharmaceutical company
focused on the acquisition, development and commercialization of medically
important pharmaceutical products for the treatment of cancer and other
underserved therapeutic needs. Currently, the company is developing two
therapies targeting hematological malignancies. TG-1101 (ublituximab) is a
novel, glycoengineered monoclonal antibody that targets a specific and unique
epitope on the CD20 antigen found on mature B-lymphocytes. TG Therapeutics is
also developing TGR-1202, an orally available PI3K delta inhibitor. The delta
isoform of PI3K is strongly expressed in cells of hematopoietic origin and is
believed to be important in the proliferation and survival of B-lymphocytes.
Both TG-1101 and TGR-1202 are in clinical development for patients with
hematologic malignancies. TG Therapeutics is headquartered in New York City
and its common stock is traded on NASDAQ under the ticker symbol "TGTX".

About Ligand Pharmaceuticals

Ligand is a biopharmaceutical company that develops and acquires assets it
believes will generate royalty revenues and, under its lean corporate cost
structure, produce sustainable profitability. Ligand has a diverse asset
portfolio addressing the unmet medical needs of patients for a broad spectrum
of diseases including thrombocytopenia, multiple myeloma, diabetes, hepatitis,
muscle wasting, dyslipidemia, anemia and osteoporosis. Ligand’s Captisol
platform technology is a patent-protected, chemically modified cyclodextrin
with a structure designed to optimize the solubility and stability of drugs.
Ligand has established multiple alliances with the world's leading
pharmaceutical companies including GlaxoSmithKline, Onyx Pharmaceuticals (now
Amgen), Merck, Pfizer, Baxter International, Bristol-Myers Squibb, Celgene,
Lundbeck Inc., Eli Lilly & Co., Spectrum Pharmaceuticals and The Medicines
Company. Please visit for more information on Captisol or for more information on Ligand.

Follow Ligand on Twitter @Ligand_LGND.

Forward-Looking Statements

This news release contains certain forward-looking statements by Ligand that
involve risks and uncertainties and reflect Ligand's judgment as of the date
of this release. These statements include those related to the IRAK-4 program
profile, market size and possibility of commercial success, efficacy, potency,
competitiveness and the strength of Ligand's out-licensed product portfolio.
Actual events or results may differ from our expectations. For example, there
can be no assurance that the IRAK-4 program or other potential drugs that
Ligand has partnered will progress through clinical development or receive
required regulatory approvals within the expected timelines or at all, that
further clinical trials will confirm any safety or other characteristics or
profile described or assumed in this press release, that there will be a
market of any size for IRAK-4 inhibitor containing products, or that any such
products will be beneficial to patients or successfully marketed. In addition,
there can be no assurance that Ligand will achieve any of its guidance or
forecasts. The failure to meet expectations with respect to any of the
foregoing matters may have a negative effect on Ligand's stock price.
Additional information concerning these and other risk factors affecting
Ligand's business can be found in prior press releases available via as well as in Ligand's public current and periodic filings with
the Securities and Exchange Commission at Ligand disclaims any
intent or obligation to update these forward-looking statements beyond the
date of this release. This caution is made under the safe harbor provisions of
the Private Securities Litigation Reform Act of 1995.


Ligand Pharmaceuticals Incorporated
John Higgins, President and CEO
Bruce Voss, 310-691-7100
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