Protalix BioTherapeutics Announces Positive 12-Month Interim Data from the BRIDGE Phase III Open Label Switch-Over Study of pegunigalsidase alfa for the Treatment of Fabry Disease 12-Months On-treatment Data Indicate Sig

Protalix BioTherapeutics Announces Positive

12-Month Interim Data from the

BRIDGE Phase III Open Label Switch-Over Study of pegunigalsidase alfa

for the Treatment of Fabry Disease

12-Months On-treatment Data Indicate

Significant Improvement in Kidney Function in Patients Switched from agalsidase alfa (Replagal ) to pegunigalsidase

100% of the "progressing"

patients and 66.7% in the "fast progressing" patients achieved the proposed therapeutic goals after switching to pegunigalsidase

The switch to pegunigalsidase alfa was

CARMIEL, Israel, October 17,

2019 /PRNewswire/ -- Protalix BioTherapeutics, Inc. (NYSE American:PLX) (TASE:PLX), a biopharmaceutical company focused on the

development, production and commercialization of recombinant therapeutic proteins produced by its proprietary ProCellEx

plant cell-based protein expression system, today announced positive 12-month on-treatment data from the first 16 out of the 22

adult patients enrolled in its BRIDGE Phase III study.

"We previously announced positive preliminary results

from 16 patients after six months in the BRIDGE study in September 2018, and these new results, after 12 months of treatment, further

suggest the strong potential benefit of pegunigalsidase alfa on renal function for Fabry patients," said Raul Chertkoff,

M.D., Protalix's Vice President, Medical Affairs.

The BRIDGE study is an open label switch-over

study evaluating the safety and efficacy of pegunigalsidase alfa (PRX-102), 1 mg/kg infused every two weeks, in up to 22 Fabry

patients currently treated with agalsidase alfa (Replagal ) for at least two years and on a stable dose for at least

six months. Patients are screened and evaluated over three months while continuing agalsidase alfa treatment. Following the screening

period, each patient was enrolled and switched from Replagal treatment to receive intravenous (IV) infusions of pegunigalsidase

alfa 1 mg/kg every two weeks for 12 months. Patients have the option to receive pegunigalsidase alfa infusions in a home care setting

based on infusion tolerability and country regulation.

The 12-month interim data from the

first 16 of 22 adult patients enrolled (9 males and 7 females) demonstrate a mean improvement in kidney function, in both male

and female patients, when switched from agalsidase alfa to pegunigalsidase alfa.

One hundred percent of the progressing

patients, those with an estimated Glomerular Filtration Rate (eGFR) slope between -5 and -3 mL/min/1.73 m2/year, and

66.7% in the fast progressing group, with an eGFR slope < -5 mL/min/1.73 m2/year, achieved the proposed therapeutic

goals (eGFR slope -3 mL/min/1.73 m2/year for progressing patients, and -5 mL/min/1.73m2/year or

more than 50% decrease in progression for fast progressing patients) after switching to pegunigalsidase alfa. The majority of the

patients who completed the study rolled over to a long-term extension study, continuing to be treated with pegunigalsidase alfa.

In the study, after one year, the

mean annualized eGFR slope improved from -5.10 mL/min/1.73m2/year while on agalsidase alfa to -0.23 mL/min/1.73m2/year

on pegunigalsidase alfa. Baseline characteristics of these patients, ages 27 to 60 years, were: mean eGFR 75.45 in males and 85.78

mL/min/1.73m2 in females, annualized pre-switching eGFR slope was -5.04 and -5.18 mL/min/1.73m2/year, in

males and females respectively, mean residual leucocytes enzymatic activity 5.9% of lab normal mean in males and 27.9% in females,

and plasma lyso-Gb3 mean levels 53.6 and 13.8 nM, in males and females, respectively.

Pegunigalsidase alfa was found to be

well tolerated in the study, with all adverse events being transient in nature without sequelae. Most of the patients who were

eligible for home care therapy per country regulation were treated under a home care arrangement in which certain of the scheduled

infusions were performed at the patients' home.

Fabry disease is an X-linked inherited disease that results

from deficient activity of the lysosomal enzyme alpha galactosidase A resulting in progressive accumulation of abnormal deposits

of a fatty substance called globotriaosylceramide (Gb3) in blood vessel walls throughout a person's body. Fabry

disease occurs in one person per 40,000. Fabry patients inherit a deficiency of the enzyme alpha-galactosidase-A, which is normally

responsible for the breakdown of Gb3. The abnormal storage of Gb3 increases with time and, accordingly, Gb3

accumulates, primarily in the blood and in the blood vessel walls. The ultimate consequences of Gb3 deposition range

from episodes of pain and impaired peripheral sensation to end-organ failure - particularly of the kidneys, but also of the

heart and the cerebrovascular system.

About pegunigalsidase alfa (PRX-102)

The Company's proprietary pegunigalsidase

alfa is an investigational, plant cell culture expressed enzyme, and a chemically modified stabilized version of, the recombinant

alpha-Galactosidase-A protein. Protein sub-units are covalently bound via chemical cross-linking using short PEG moeity, resulting

in a more stable molecule with different pharmacokinetic parameters compared to the current available versions of the enzyme. In

clinical studies, pegunigalsidase alfa has been observed to have a favorable circulatory half-life of approximately 80 hours. In

addition, in a Fabry mouse model, pegunigalsidase alfa was observed to have favorable levels of enzyme activity in target organs

affected by Fabry disease. The Company designed pegunigalsidase alfa to potentially address the continued unmet clinical need in

Fabry patients of continuous disease progression, infusion reaction and immunogenicity.

About Protalix BioTherapeutics,

Protalix is a biopharmaceutical company focused on the development and commercialization of recombinant

therapeutic proteins expressed through its proprietary plant cell-based expression system, ProCellEx . Protalix

was the first company to gain FDA approval of a protein produced through plant cell-based in suspension expression system. Protalix's

unique expression system represents a new method for developing recombinant proteins in an industrial-scale manner. Protalix's

pipeline consists of proprietary, potentially clinically superior versions of recombinant therapeutic proteins that target established

pharmaceutical markets.

Protalix's first product manufactured

by ProCellEx, taliglucerase alfa, was approved for marketing by the U.S. Food and Drug Administration (FDA) in May 2012 and,

subsequently, by the regulatory authorities of other countries. Protalix has licensed to Pfizer Inc. the worldwide development

and commercialization rights for taliglucerase alfa, excluding Brazil, where Protalix retains full rights.

Protalix's development pipeline

includes the following product candidates: pegunigalsidase alfa, a modified version of the recombinant human alpha-GAL-A protein

for the treatment of Fabry disease, in Phase III clinical trials (BALANCE, BRIDGE and BRIGHT studies); and OPRX-106, an orally

delivered anti-inflammatory treatment, and alidornase alfa for the treatment of Cystic Fibrosis, both in Phase II clinical

trials. Protalix has partnered with Chiesi Farmaceutici S.p.A., both in the United States and outside the United States, for the

development and commercialization of pegunigalsidase alfa.

Forward-Looking Statements

To the extent that statements in this

press release are not strictly historical, all such statements are forward-looking, and are made pursuant to the safe-harbor provisions

of the Private Securities Litigation Reform Act of 1995. The terms "expect," "anticipate," "believe,"

"estimate," "project," "plan," "should" and "intend," and other words

or phrases of similar import are intended to identify forward-looking statements. These forward-looking statements are subject

to known and unknown risks and uncertainties that may cause actual future experience and results to differ materially from the

statements made. These statements are based on our current beliefs and expectations as to such future outcomes. Drug discovery

and development involve a high degree of risk and the final results of a clinical trial may be different than the preliminary findings

for the clinical trial. Factors that might cause material differences include, among others: risks related to our ability to identify

and complete strategic alternatives on attractive terms or at all within the time period required to regain compliance with the

continued listing standards of the NYSE American; risks related to our ability to continue as a going concern absent a refinancing

or restructuring; risks related to any transactions we may effect in the public or private equity markets to raise capital to finance

future activities; failure or delay in the commencement or completion of our preclinical and clinical trials which may be caused

by several factors, including: risks that the FDA will not accept an application for accelerated approval of PRX--102 with the

data generated to date or will request additional data or other conditions of our submission of any application for accelerated

approval of PRX-102; risks related to our ability to continue as a going concern absent access to sources of capital we will need

to finance future research and development activities, general and administrative expenses and working capital; risks related to

any capital raising transactions we may effect in the public or private equity markets to raise capital to finance future research

and development activities, general and administrative expenses and working capital; slower than expected rates of patient recruitment;

unforeseen safety issues; determination of dosing issues; lack of effectiveness during clinical trials; inability to monitor patients

adequately during or after treatment; inability or unwillingness of medical investigators and institutional review boards to follow