Leap Therapeutics and BeiGene Announce First Patient Dosed in Study of DKN-01 in Combination with Tislelizumab for the Treatment of Metastatic Gastric or Gastroesophageal Junction Cancer Cambridge, MA and Beijing, China

Cambridge, MA and Beijing, China

- September 21, 2020 - Leap Therapeutics, Inc. (Nasdaq:LPTX), a biotechnology company focused on

developing targeted and immuno-oncology therapeutics, and BeiGene, Ltd., (Nasdaq:BGNE; HKEX: 06160), a commercial-stage

biotechnology company focused on developing and commercializing innovative medicines worldwide, today announced that the

first patient has been dosed in the DisTinGuish study, a Phase 2a clinical trial evaluating Leap's investigational

anti-Dickkopf-1 antibody (DKK1), DKN-01, in combination with tislelizumab, BeiGene's anti-PD-1 antibody, with or without

chemotherapy, in patients with gastric or gastroesophageal junction cancer (G/GEJ).

"Dosing of the first patient in the

DisTinGuish study is a key milestone for the DKN-01 development program," said Cynthia Sirard, M.D., Chief Medical Officer

of Leap Therapeutics. "We are excited to have the opportunity to combine DKN-01 with tislelizumab due to the promising signals

in a DKK1 biomarker-defined population of esophagogastric cancer patients. We look forward to working closely alongside BeiGene

to evaluate this potential new combination therapy for a patient population with a high global unmet medical need."

The DisTinGuish trial (NCT04363801)

is a Phase 2a, nonrandomized, open-label, multicenter study of DKN-01 in combination with tislelizumab with or without chemotherapy

as first-line or second-line therapy in adult patients with inoperable, locally advanced G/GEJ adenocarcinoma. The study, which

will be conducted in two parts, is expected to enroll up to 72 patients.

Part A will enroll up to 24

patients with G/GEJ adenocarcinoma who have received no prior systemic treatment in the locally advanced/metastatic setting

(first-line treatment), and Part B will enroll up to 48 patients with previously treated, inoperable, locally advanced

or metastatic DKK1-high G/GEJ adenocarcinoma (second-line treatment). The study is designed to evaluate safety, tolerability,

and efficacy of the combination therapy of intravenous DKN-01 and tislelizumab CAPOX (capecitabine + oxaliplatin) in

G/GEJ adenocarcinoma patients. Treatment will be conducted in repeating 21-day cycles until the patient meets pre-established

criteria for discontinuation or is no longer deriving clinical benefit. Part A and Part B of the study will be

conducted concurrently.

Leap is conducting this combination study

in the United States as part of an exclusive option and license agreement with BeiGene for the development of DKN-01 in Asia (excluding

Japan), Australia and New Zealand. Leap retains exclusive rights for the development, manufacturing and commercialization of

DKN-01 for the rest of the world.

DKN-01 is a humanized monoclonal antibody

that binds to and blocks the activity of the Dickkopf-1 (DKK1) protein, a modulator of Wnt/Beta-catenin signaling, a signaling

pathway frequently implicated in tumorigenesis and suppressing the immune system. DKK1 has an important role in tumor cell signaling

and in mediating an immuno-suppressive tumor microenvironment through enhancing the activity of myeloid-derived suppressor cells

and downregulating NK ligands on tumor cells. DKN-01 has received Orphan Drug Designation for the treatment of gastric and gastroesophageal

junction cancer from the U.S. Food and Drug Administration.

Tislelizumab is a humanized IgG4 anti-PD-1

monoclonal antibody specifically designed to minimize binding to Fc R on macrophages. In pre-clinical studies, binding to

Fc R on macrophages has been shown to compromise the anti-tumor activity of PD-1 antibodies through activation of antibody-dependent

macrophage-mediated killing of T effector cells. Tislelizumab is approved by the China National Medical Products Administration

(NMPA) as a treatment for patients with classical Hodgkin's lymphoma who received at least two prior therapies and for patients

with locally advanced or metastatic urothelial carcinoma (UC) with PD-L1 high expression whose disease progressed during or following

platinum-containing chemotherapy or within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy.

In addition, three supplemental new

drug applications (sNDAs) for tislelizumab have been accepted by the Center for Drug Evaluation (CDE) of the NMPA and are

under review - for first-line treatment of patients with advanced squamous non-small cell lung cancer (NSCLC) in

combination with chemotherapy, for first-line treatment of patients with advanced non-squamous NSCLC in combination with

chemotherapy, and for previously treated unresectable hepatocellular carcinoma.

Tislelizumab is not approved for use outside

/ gastroesophageal junction cancer

adenocarcinoma (gastric cancer) remains one of the most common and deadly cancers worldwide, especially among older

malesi. Based on GLOBOCAN 2018 data, stomach cancer is the 5th most common neoplasm and the

3rd most deadly cancer, with an estimated 783,000 deaths globally in 2018i. Ninety-five percent of

cancers of the stomach are adenocarcinomas i. Gastric cancer incidence and mortality are highly variable by region

and highly dependent on diet and Helicobacter pylori infectioni. The gastroesophageal junction (GEJ) is

the area where the esophagus and stomach join together. Given its anatomic location, GEJ adenocarcinomas have often been

grouped together with either esophageal or gastric cancers in clinical trials.

About Leap Therapeutics

Leap Therapeutics (Nasdaq:LPTX) is focused

on developing targeted and immuno-oncology therapeutics. Leap's most advanced clinical candidate, DKN-01, is a humanized monoclonal

antibody targeting the Dickkopf-1 (DKK1) protein, a Wnt pathway modulator. DKN-01 is in clinical trials in patients with esophagogastric,

hepatobiliary, gynecologic, and prostate cancers. Leap has entered into a collaboration with BeiGene, Ltd. for the rights

to develop DKN-01 in Asia (excluding Japan), Australia, and New Zealand. For more information about Leap Therapeutics, visit http://www.leaptx.com

or view our public filings with the SEC that are available via EDGAR at http://www.sec.gov

or via https://investors.leaptx.com/.

BeiGene is a global,

commercial-stage biotechnology company focused on discovering, developing, manufacturing, and commercializing innovative medicines

to improve treatment outcomes and access for patients worldwide. Our 4,200+ employees in China, the United States, Australia, Europe,

and elsewhere are committed to expediting the development of a diverse pipeline of novel therapeutics. We currently market two

internally discovered oncology products: BTK inhibitor BRUKINSA (zanubrutinib) in the United States and China, and anti-PD-1

antibody tislelizumab in China. We also market or plan to market in China additional oncology products licensed from Amgen Inc.,

Celgene Logistics S rl, a Bristol Myers Squibb (BMS) company, and EUSA Pharma. To learn more about BeiGene, please visit

LEAP FORWARD-LOOKING STATEMENTS

This press release contains forward-looking

statements within the meaning of Section 27A of the Securities Act of 1933, Section 21E of the Securities Exchange Act

of 1934 and the Private Securities Litigation Reform Act of 1995, which involve risks and uncertainties. These statements include

statements relating to Leap's expectations with respect to the development and advancement of DKN-01, including the initiation,

timing and design of future studies, enrollment in future studies, potential for the receipt of future option exercise, milestones

or royalty payments from BeiGene, and other future expectations, plans and prospects. Although Leap believes that the expectations

reflected in such forward-looking statements are reasonable as of the date made, forward-looking statements are subject to known

and unknown risks, uncertainties and other factors that could cause actual results to differ materially from our expectations.

Such risks and uncertainties include, but are not limited to: that the initiation, conduct, and completion of clinical trials,

laboratory operations, manufacturing campaigns, and other studies may be delayed, adversely affected, or impacted by COVID-19 related

issues, the accuracy of our estimates regarding expenses, future revenues, capital requirements and needs for financing; the outcome,

cost, and timing of our product development activities and clinical trials; the uncertain clinical development process, including

the risk that clinical trials may not have an effective design or generate positive results; our ability to obtain and maintain

regulatory approval of our drug product candidates; the size and growth potential of the markets for our drug product candidates;

our ability to continue obtaining and maintaining intellectual property protection for our drug product candidates; and other risks.

Detailed information regarding factors that may cause actual results to differ materially will be included in Leap Therapeutics'

periodic filings with the SEC, including Leap's Annual Report on Form 10-K for the fiscal year ended December 31, 2019,

as filed with the SEC on March 16, 2020 and as may be updated by Leap's Quarterly Reports on Form 10-Q and the other

reports we file from time to time with the SEC. Any forward-looking statements contained in this release speak only as of its date.

We undertake no obligation to update any forward-looking statements contained in this release to reflect events or circumstances

occurring after its date or to reflect the occurrence of unanticipated events.

BEIGENE FORWARD-LOOKING STATEMENTS

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and

other federal securities laws, including statements regarding plans for the advancement of, anticipated clinical development and regulatory

milestones, and the potential opportunity of DKN-01 and tislelizumab as a combination therapy. Actual results may differ materially from

those indicated in the forward-looking statements as a result of various important factors, including BeiGene's ability to demonstrate

the efficacy and safety of its drug candidates; the clinical results for its drug candidates, which may not support further development

or marketing approval; actions of regulatory agencies, which may affect the initiation, timing and progress of clinical trials and marketing