Zenas BioPharma and Royalty Pharma Enter into Obexelimab Funding Agreement for up to $300 Million - Initial $75 million to fund the potential U.S. commercial launch of obexelimab for the treatment of IgG4-Related Disease

Zenas BioPharma and Royalty Pharma Enter into

Obexelimab Funding Agreement for up to $300 Million

- Initial $75 million to fund the potential

U.S. commercial launch of obexelimab for the treatment of IgG4-Related Disease -

- Additional $150 million associated with the

upcoming results of the obexelimab Phase 3 INDIGO trial and FDA approval for the treatment of IgG4-Related Disease -

WALTHAM, Mass and New York, September 2, 2025

(GLOBE NEWSWIRE) - Zenas BioPharma, Inc. (Nasdaq: ZBIO), and Royalty Pharma plc (Nasdaq: RPRX) today announced that Royalty Pharma

will provide up to $300 million in funding in exchange for a royalty on sales of obexelimab.

"We are very pleased to partner with Royalty

Pharma as we rapidly advance our broad obexelimab program through late-stage development and into global commercialization. This transaction

underscores our conviction in the potential of obexelimab as a franchise molecule and provides us with financial flexibility to rapidly

advance our clinical programs and fund the commercial launch of obexelimab if approved for the treatment of IgG4-RD," said Lonnie

Moulder, Founder and Chief Executive Officer of Zenas. "We are committed to bringing obexelimab to as many patients living with

autoimmune diseases as possible and look forward to our upcoming key milestones, including the topline results from our pivotal Phase

3 trial in IgG4-RD expected around year-end, our Phase 2 trial in Relapsing Multiple Sclerosis expected early in the fourth quarter of

this year and our Phase 2 trial in Systemic Lupus Erythematosus expected in mid-2026."

"We are delighted to partner with Zenas

as they develop obexelimab in IgG4-RD and other autoimmune diseases," said Pablo Legorreta, founder and CEO of Royalty Pharma. "There

is clear unmet need in IgG4-RD where obexelimab, with its exciting novel B cell modulating mechanism of action, has demonstrated compelling

proof-of-concept. IgG4-RD represents a potential blockbuster opportunity for obexelimab. This agreement builds on an already record year

for Royalty Pharma in announced value of synthetic royalty transactions, reflecting the compelling advantages this funding paradigm offers

to innovative biotech companies. We look forward to supporting the Zenas team as they advance their broad development program to bring

this important new treatment to patients in need."

Obexelimab is an investigational bifunctional

monoclonal antibody designed to inhibit B cell function by binding to both CD19 and Fc RIIb and is in Phase 3 development for the

treatment of Immunoglobulin G4-Related Disease (IgG4-RD), and Phase 2 development for Relapsing Multiple Sclerosis (RMS) and Systemic

Lupus Erythematosus (SLE). This financing will support obexelimab development and a potential IgG4-RD commercial launch in the first half

of 2027, subject to approval by the U.S. Food and Drug Administration (FDA). With the receipt of the initial $75 million payment under

the agreement with Royalty Pharma, the Company expects to have cash to fund its operations through the first quarter of 2027.

Under the agreement Zenas will receive up to $300

million, consisting of an upfront payment of $75 million, and three additional payments of $75 million each upon 1) achievement of defined

success criteria in the Phase 3 INDIGO trial of obexelimab in IgG4-RD (expected around the end of this year), 2) U.S. FDA approval of

obexelimab for IgG4-RD, and 3) U.S. FDA approval of obexelimab for SLE. In exchange, Royalty Pharma will receive a 5.5% royalty on worldwide

net sales of obexelimab by Zenas and its affiliates and certain other payments associated with the commercialization of obexelimab in

partnered geographies.

Evercore acted as exclusive financial advisor

and Ropes & Gray LLP acted as legal advisor to Zenas BioPharma. Goodwin Procter LLP and Maiwald GmbH acted as legal advisors to Royalty

Obexelimab is a bifunctional monoclonal antibody

designed to bind both CD19 and Fc RIIb, which are broadly present across B cell lineage, to inhibit the activity of cells that are

implicated in many autoimmune diseases without depleting them. This unique mechanism of action and self-administered, subcutaneous injection

regimen may broadly and effectively address the pathogenic role of B cell lineage in chronic autoimmune disease.

Obexelimab has been evaluated in five completed

clinical trials in a total of 198 subjects who received obexelimab either as an intravenous infusion or as a subcutaneous injection. Obexelimab

was well tolerated and demonstrated pharmacologic activity across these five clinical trials, providing the Company an initial clinical

proof of concept for obexelimab as a potent B cell inhibitor for the treatment of patients living with certain autoimmune diseases. Currently,

Zenas is conducting multiple Phase 2 and Phase 3 trials of obexelimab in several autoimmune diseases including Immunoglobulin G4-Related

Disease, Relapsing Multiple Sclerosis and Systemic Lupus Erythematosus.

About Zenas BioPharma, Inc.

Zenas is a clinical-stage global biopharmaceutical

company committed to becoming a leader in the development and commercialization of transformative therapies for patients with autoimmune

diseases. Our core business strategy combines our experienced leadership team with a disciplined product candidate acquisition approach

to identify, acquire and develop product candidates globally that we believe can provide superior clinical benefits to patients living

with autoimmune diseases. Zenas' lead product candidate, obexelimab, is a bifunctional monoclonal antibody designed to bind both

CD19 and Fc RIIb, which are broadly present across B cell lineage, to inhibit the activity of cells that are implicated in many

autoimmune diseases without depleting them. We believe that obexelimab's unique mechanism of action and self-administered, subcutaneous

injection regimen may broadly and effectively address the pathogenic role of B cell lineage in chronic autoimmune disease. For more information

About Royalty Pharma

Founded in 1996, Royalty Pharma is the largest

buyer of biopharmaceutical royalties and a leading funder of innovation across the biopharmaceutical industry, collaborating with innovators

from academic institutions, research hospitals and non-profits through small and mid-cap biotechnology companies to leading global pharmaceutical

companies. Royalty Pharma has assembled a portfolio of royalties which entitles it to payments based directly on the top-line sales of

many of the industry's leading therapies. Royalty Pharma funds innovation in the biopharmaceutical industry both directly and indirectly

- directly when it partners with companies to co-fund late-stage clinical trials and new product launches in exchange for future

royalties, and indirectly when it acquires existing royalties from the original innovators. Royalty Pharma's current portfolio includes

royalties on more than 35 commercial products, including Vertex's Trikafta, GSK's Trelegy, Roche's Evrysdi, Johnson

& Johnson's Tremfya, Biogen's Tysabri and Spinraza, Servier's Voranigo, AbbVie and Johnson & Johnson's

Imbruvica, Astellas and Pfizer's Xtandi, Pfizer's Nurtec ODT, and Gilead's Trodelvy, and 17 development-stage product

Zenas BioPharma Forward looking statements

This press release contains "forward-looking

statements" which involve risks, uncertainties and contingencies, many of which are beyond the control of the Company, which may

cause actual results, performance, or achievements to differ materially from anticipated results, performance, or achievements. All statements

other than statements of historical facts contained in this press release are forward-looking statements. In some cases, forward-looking

statements can be identified by terms such as "may," "will," "should," "expect," "plan,"

"anticipate," "could," "intend," "target," "project," "contemplate,"

"believe," "estimate," "predict," "potential" or "continue" or the negative

of these terms or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements

include, but are not limited to, statements concerning the timing and results of ongoing and future clinical trials, including expectations

on the timing of reporting INDIGO trial topline results, our Phase 2 trial in RMS and our Phase 2 trial in SLE; the timing of the potential

commercial launch of obexelimab for the treatment of IgG4-RD, subject to favorable Phase 3 data and receipt of FDA approval; and cash

runway guidance. The forward-looking statements in this press release speak only as of the date of this press release and are subject

to a number of known and unknown risks, uncertainties and assumptions that could cause the Company's actual results to differ materially

from those anticipated in the forward-looking statements, including, but not limited to: the Company's limited operating history,

incurrence of substantial losses since the Company's inception and anticipation of incurring substantial and increasing losses for

the foreseeable future; the Company's need for substantial additional financing to achieve the Company's goals; the uncertainty

of clinical development, which is lengthy and expensive, and characterized by uncertain outcomes, and risks related to additional costs

or delays in completing, or failing to complete, the development and commercialization of the Company's current product candidates

or any future product candidates; delays or difficulties in the enrollment and dosing of patients in clinical trials; the impact of any

significant adverse events or undesirable side effects caused by the Company's product candidates; potential competition, including

from large and specialty pharmaceutical and biotechnology companies, many of which already have approved therapies in the Company's

current indications; the Company's ability to realize the benefits of the Company's current or future collaborations or licensing

arrangements and ability to successfully consummate future partnerships; the Company's ability to obtain regulatory approval to

commercialize any product candidate in the United States or any other jurisdiction, and the risk that any such approval may be for a more

narrow indication than the Company seeks; the Company's dependence on the services of the Company's senior management and

other clinical and scientific personnel, and the Company's ability to retain these individuals or recruit additional management

or clinical and scientific personnel; the Company's ability to grow the Company's organization, and manage the Company's

growth and expansion of the Company's operations; risks related to the manufacturing of the Company's product candidates,

which is complex, and the risk that the Company's third-party manufacturers may encounter difficulties in production; the Company's

ability to obtain and maintain sufficient intellectual property protection for the Company's product candidates or any future product

candidates the Company may develop; the Company's reliance on third parties to conduct the Company's preclinical studies and