Pliant Therapeutics Provides Corporate Update and Reports First Quarter 2023 Financial Results Positive long-term data from INTEGRIS-IPF 320 mg dose group at 24-weeks demonstrated bexotegrast was well tolerated with dura

Pliant Therapeutics Provides Corporate Update and

Reports First Quarter 2023 Financial Results

Positive long-term data from INTEGRIS-IPF 320 mg dose group at 24-weeks demonstrated bexotegrast was well tolerated with durable improvement shown across multiple measures

INTEGRIS-PSC 12-week data expected in the third quarter of 2023

BEACON-IPF Phase 2b trial initiation expected in mid-2023

$577 million in cash, cash equivalents and short-term investments at end of first quarter 2023,

expected to fund operations into second half of 2026

SOUTH SAN FRANCISCO, CA., May 9, 2023 - Pliant Therapeutics, Inc. (Nasdaq PLRX), a clinical stage biotechnology company focused on discovering and developing novel therapeutics for the treatment of fibrosis, today provided a corporate update and reported first quarter 2023 financial results.

"So far in 2023 we have made significant progress in advancing the portfolio including positive 12- and 24-week data readouts from our INTEGRIS-IPF trial and a successful follow-on offering that extended our expected operating runway into the second half of 2026," said Bernard Coulie, M.D., Ph.D., President and Chief Executive Officer of Pliant Therapeutics. "With clinical data and development milestones expected throughout the remainder of 2023, including Phase 2a data from INTEGRIS-PSC and initiation of our BEACON-IPF Phase 2b and our oncology Phase 1 trials, we look forward to building upon an already productive year."

First Quarter and Recent Highlights

Bexotegrast (PLN-74809) Highlights

INTEGRIS-IPF Phase 2a 24-week 320 mg clinical data showed bexotegrast was well tolerated and demonstrated durable improvements in exploratory endpoints. This 24-week Phase 2a data from the 320 dose group showed bexotegrast was well tolerated up to 40 weeks, displayed a favorable pharmacokinetic profile and in exploratory efficacy endpoints showed improvements in forced vital capacity (FVC), Quantitative Lung Fibrosis (QLF) imaging, patient reported cough severity and biomarkers in patients with idiopathic pulmonary fibrosis (IPF) to Week 24. In January, 12-week data from the 320 mg dose group showed bexotegrast demonstrated statistically significant FVC increases at all time points, was well tolerated with no drug-related severe or serious adverse events and showed dose-proportional increases in plasma concentrations, consistent with prior dose groups.

Initiation of BEACON-IPF, a Phase 2b trial of bexotegrast in patients with IPF, expected in mid-2023. BEACON-IPF is a 52-week, multinational, randomized, placebo-controlled trial evaluating bexotegrast at doses of 160 mg or 320 mg in approximately 270 patients with IPF.

INTEGRIS-PSC Phase 2a 12-week clinical data expected in the third quarter of 2023. INTEGRIS-PSC is a 12-week randomized, dose-ranging, double-blind, placebo-controlled trial evaluating safety, tolerability and pharmacokinetics of bexotegrast at doses of 40, 80 or 160 mg in approximately 84 patients with primary sclerosing cholangitis (PSC). Exploratory efficacy endpoints include fibrosis biomarkers such as PRO-C3 and enhanced liver fibrosis (ELF) score, changes in alkaline phosphatase (ALP), and liver imaging. INTEGRIS-PSC is fully enrolled.

First patient dosed in the INTEGRIS-PSC Phase 2a 320 mg dose cohort, evaluating bexotegrast for at least 24 weeks. This cohort is evaluating the safety, tolerability and pharmacokinetics of bexotegrast at a dose of 320 mg versus placebo over at least 24 weeks of treatment in approximately 28 patients with PSC. The trial

is also evaluating exploratory efficacy endpoints including fibrosis biomarkers such as PRO-C3 and ELF score, changes in ALP and liver imaging.

Early-Stage Development Programs

Initiation of a Phase 1 first-in-human trial of PLN-101095 in oncology expected in the second quarter of 2023. PLN-101095 is an oral, small molecule, dual selective inhibitor of v 8 and v 1 integrins designed to block TGF- activation in the tumor microenvironment. Initiation of a Phase 1 trial in patients with solid tumors that are resistant to immune checkpoint inhibitors is expected in the second quarter of 2023.

Muscular dystrophy program progressing through IND enabling activities. PLN-101325 is a monoclonal antibody designed to act as an allosteric agonist of the integrin 7 1. An IND submission for Duchenne muscular dystrophy (DMD) is expected in 2023.

Corporate Highlights

Closing of underwritten public offering of $287.5 million in common stock. The Company closed a public offering in January 2023, yielding $269.9 million in net proceeds to the Company, which included the underwriter's exercise in full of their option to purchase additional shares.

First Quarter 2023 Financial Results

Research and development expenses were $29.3 million, as compared to $20.9 million for the prior-year quarter. The increase was due primarily to employee related expenses and increased clinical and manufacturing related costs associated with our lead program, bexotegrast, partially offset by a decrease in preclinical manufacturing costs for our pipeline product candidates.

General and administrative expenses were $14.2 million, as compared to $8.6 million for the prior-year quarter. The increase was due to higher personnel-related and professional services expenses.

Net loss of $37.5 million as compared to $28.1 million for the prior-year quarter due to an increase in operating expenses coupled with a slight decrease in collaboration revenues under the Novartis collaboration during the quarter.

As of March 31, 2023, the Company had cash, cash equivalents and short-term investments of $577.3 million, which the Company expects to be sufficient to fund operations into the second half of 2026.

About Pliant Therapeutics, Inc.

Forward-Looking Statements

Statements contained in this press release regarding matters that are not historical facts are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as may, will, expect, anticipate, estimate, intend, and similar expressions (as well as other words or expressions referencing future events, conditions, or circumstances) are intended to identify forward-looking statements. These statements include those regarding the safety, tolerability, pharmacodynamics and therapeutic potential of bexotegrast our plans for the future development of bexotegrast and PLN-101095 bexotegrast's potential to become a treatment for IPF the anticipated timing of data and progress from our clinical studies discussions with regulatory authorities the sufficiency of our cash runway to fund operations into the second half of 2026. Because such statements deal with future events and are based on our current expectations, they are subject to various risks and uncertainties and actual results, performance or achievements of Pliant Therapeutics could differ materially from those described in or implied by the statements in this press release. These forward-looking statements are subject to risks and uncertainties, including those related to the development and commercialization of our product candidates, including any delays in our ongoing or planned preclinical or clinical trials, the impact of the ongoing COVID-19 pandemic on our business, operations, clinical supply and plans, our reliance on third parties for critical aspects of our development operations, the risks inherent in the drug development process, the risks regarding the accuracy of our estimates of expenses and timing of development, our capital requirements and the need for additional financing, including the availability of additional term loans

under our loan facility, and our ability to obtain and maintain intellectual property protection for our product candidates. These and additional risks are discussed in the sections titled Risk Factors and Management's Discussion and Analysis of Financial Condition and Results of Operations in our Quarterly Report on Form 10-Q for the three months ended March 31, 2023 which we are filing with the SEC today, available on the SEC's website at www.sec.gov. Unless otherwise noted, Pliant is providing this information as of the date of this news release and does not undertake any obligation to update any forward-looking statements contained in this document as a result of new information, future events or otherwise.

Investor and Media Contact

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Pliant Therapeutics, Inc.

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