Rein Therapeutics Secures $15M Equity Line, Faces LTI-03 Clinical Hold

TL;DR

**Rein Therapeutics is tapping a dilutive equity line to fund operations while its lead drug faces an FDA clinical hold, making it a high-risk bet on future clinical success.**

AI Summary

Rein Therapeutics, Inc. (RNTX) is a clinical-stage biopharmaceutical company focused on orphan pulmonary and fibrosis indications. The company has two product candidates, LTI-03 and LTI-01, in clinical development. In July 2025, RNTX received a clinical hold from the FDA for its Phase 2 RENEW trial of LTI-03, pausing enrollment in the U.S., though the UK Medicines and Healthcare products Regulatory Agency authorized the trial. To secure funding, RNTX entered into a Standby Equity Purchase Agreement (SEPA) with YA II PN, Ltd. on July 29, 2025, allowing it to sell up to $15,000,000 of common stock over 36 months. Additionally, RNTX entered a Pre-Paid Advance Agreement (PPA) with Yorkville, receiving $950,000 in cash proceeds from a $1,000,000 advance. In August 2025, RNTX issued 288,209 shares of common stock at an average price of $1.06 to Yorkville, offsetting $300,000 of outstanding Pre-Paid Advances. The company's common stock closed at $1.35 on September 2, 2025, and the offering could dilute existing shareholders by up to 9,786,901 Advance Shares.

Why It Matters

This S-1 filing reveals Rein Therapeutics' strategy to secure up to $15,000,000 in funding through a Standby Equity Purchase Agreement (SEPA) with Yorkville, which is crucial for advancing its clinical pipeline, especially given the recent FDA clinical hold on its lead candidate, LTI-03. For investors, this financing mechanism, coupled with the pre-paid advance, provides a lifeline but also signals potential significant dilution as shares will be sold at a discount (96% of VWAP for SEPA shares, 95% of face value for PPA advances). The competitive landscape in orphan pulmonary and fibrosis indications is intense, and RNTX's ability to navigate the LTI-03 clinical hold and effectively utilize this capital will be critical for its long-term viability and market position against larger pharmaceutical players.

Risk Assessment

Risk Level: high — The company faces a 'high degree of risk' as stated on page 6, primarily due to the FDA clinical hold on its lead product candidate, LTI-03, which paused enrollment in the U.S. This directly impacts its ability to advance its pipeline. Furthermore, the Standby Equity Purchase Agreement (SEPA) and Pre-Paid Advance Agreement (PPA) with Yorkville, while providing up to $15,000,000 in potential funding, involve selling shares at a discount (96% of VWAP for SEPA, 95% of face amount for PPA), leading to significant dilution for existing shareholders.

Analyst Insight

Investors should exercise extreme caution and thoroughly evaluate the implications of the FDA clinical hold on LTI-03, as this is a major setback for Rein Therapeutics' lead candidate. Consider the potential for significant dilution from the $15,000,000 SEPA and PPA financing, which will likely depress share price. Await further clarity on the FDA's concerns and the company's plan to address them before considering any investment.

Financial Highlights

debt To Equity

N/A

revenue

N/A

operating Margin

N/A

total Assets

N/A

total Debt

N/A

net Income

N/A

eps

N/A

gross Margin

N/A

cash Position

N/A

revenue Growth

N/A

Key Numbers

• $15,000,000 — Aggregate gross proceeds (Maximum amount Rein Therapeutics may receive from sales of common stock to Yorkville under the SEPA over 36 months)
• 10,000,000 — Shares of common stock (Maximum number of shares offered by the Selling Stockholder in this prospectus)
• 213,099 — Commitment Shares (Shares issued to Selling Stockholder upon SEPA execution as consideration)
• 9,786,901 — Advance Shares (Additional shares that may be purchased by the Selling Stockholder under the SEPA)
• $1.35 — Closing price of common stock (Closing price on Nasdaq Capital Market on September 2, 2025)
• 96% — Purchase price discount (Advance Shares will be purchased at 96% of the lowest of three daily VWAPs)
• $6,000,000 — Aggregate pre-paid advances (Maximum amount Rein Therapeutics may request from Yorkville under the PPA)
• $950,000 — Cash proceeds received (From a $1,000,000 Pre-Paid Advance after a discount to Yorkville)
• 288,209 — Shares issued to Yorkville (In August 2025, at an average price of $1.06, offsetting $300,000 of outstanding Pre-Paid Advances)
• 23,547,429 — Shares of common stock outstanding (As of August 25, 2025, prior to this offering)

Key Players & Entities

• Rein Therapeutics, Inc. (company) — Registrant and clinical-stage biopharmaceutical company
• RNTX (company) — Ticker symbol on Nasdaq Capital Market
• YA II PN, Ltd. (company) — Selling Stockholder and affiliate of Yorkville Advisors Global, LP
• Yorkville Advisors Global, LP (company) — Affiliate of the Selling Stockholder
• Brian Windsor, Ph.D. (person) — President and Chief Executive Officer of Rein Therapeutics, Inc.
• U.S. Food and Drug Administration (regulator) — Issued a clinical hold letter for LTI-03 Phase 2 trial
• Nasdaq Capital Market (regulator) — Listing exchange for RNTX common stock
• Daniel K. Donahue (person) — Legal counsel from Greenberg Traurig, LLP
• Greenberg Traurig, LLP (company) — Legal counsel for Rein Therapeutics, Inc.

FAQ

Risk Factors

• Dilution from Yorkville Transaction [high — financial]: The Standby Equity Purchase Agreement (SEPA) with YA II PN, Ltd. allows for the sale of up to $15,000,000 of common stock over 36 months. Upon execution, 213,099 Commitment Shares were issued. The potential sale of up to 9,786,901 Advance Shares could significantly dilute existing shareholders, and the perception of these sales may depress the stock price.
• Stock Price Volatility and Sales Pressure [high — financial]: The purchase price for Advance Shares under the SEPA will fluctuate with the market price. Sales of these shares by the Selling Stockholder, depending on market liquidity, could cause the trading price of RNTX's common stock to fall, potentially leading to a loss for investors.
• FDA Clinical Hold on LTI-03 [high — regulatory]: Rein Therapeutics received a clinical hold from the FDA for its Phase 2 RENEW trial of LTI-03 in July 2025, pausing U.S. enrollment. While the trial is authorized in the UK, this FDA action poses a significant risk to the development timeline and potential market access for this key product candidate.
• Reliance on Equity Financing [medium — financial]: The company has entered into a SEPA and a Pre-Paid Advance Agreement (PPA) with Yorkville to secure funding. The SEPA allows for up to $15,000,000 in equity sales, and the PPA has a maximum of $6,000,000. This reliance on equity financing, especially under potentially dilutive agreements, highlights financial vulnerability.
• Clinical Trial Delays and Uncertainties [high — operational]: The FDA clinical hold on the LTI-03 trial is a major setback. Further delays or complications in clinical development for both LTI-03 and LTI-01 could impact the company's ability to advance its pipeline and achieve its strategic objectives.
• Warrants and Convertible Securities [medium — financial]: As of August 25, 2025, there are 6,616,499 shares issuable upon exercise of outstanding warrants and 12,232,000 shares issuable upon conversion of Series X Preferred Stock. These represent significant potential future dilution.

Industry Context

Rein Therapeutics operates in the highly competitive biopharmaceutical industry, focusing on rare pulmonary and fibrosis indications. The development of novel therapies for these conditions is challenging, requiring significant R&D investment and navigating complex regulatory pathways. Key competitors often include larger pharmaceutical companies with established pipelines and smaller biotech firms also targeting similar unmet medical needs.

Regulatory Implications

The FDA's clinical hold on the LTI-03 trial is a critical regulatory hurdle. It signifies potential safety or data integrity concerns that must be addressed before U.S. trials can resume. This underscores the inherent regulatory risks in drug development and the importance of robust data and trial design.

What Investors Should Do

1. Monitor FDA communications regarding the LTI-03 clinical hold.
2. Evaluate the impact of potential dilution from the SEPA and PPA.
3. Assess the company's cash runway and future financing needs.
4. Analyze the scientific and clinical data supporting LTI-03 and LTI-01.

Key Dates

• 2025-07-29: SEPA and PPA entered with YA II PN, Ltd. — Secured potential future funding of up to $15,000,000 through equity sales and $6,000,000 via pre-paid advances, but introduced significant dilution risk.
• 2025-07-29: Issued 213,099 Commitment Shares — Consideration for the SEPA commitment, immediately diluting existing shareholders.
• 2025-08-01: Received $950,000 cash proceeds from $1,000,000 Pre-Paid Advance — Provided immediate cash infusion, albeit at a discount, to support operations.
• 2025-08-01: Issued 288,209 shares to Yorkville — Offset $300,000 of outstanding Pre-Paid Advances, further diluting shareholders.
• 2025-07-01: FDA issued clinical hold for LTI-03 RENEW trial — Paused U.S. enrollment for a key drug candidate, creating significant development and regulatory risk.
• 2025-09-02: Common stock closed at $1.35 — Indicates current market valuation, relevant for ongoing equity sales under the SEPA.

Glossary

Standby Equity Purchase Agreement (SEPA)

An agreement where a company can sell shares of its common stock to an investor at its discretion over a specified period, up to a certain amount. (Allows RNTX to raise capital as needed but introduces significant dilution risk and potential downward pressure on stock price.)

Advance Shares

Shares of common stock that the Selling Stockholder (Yorkville) may purchase from the company under the SEPA at a discount to the market price. (These are the primary shares to be sold under the SEPA, carrying substantial dilution potential for existing shareholders.)

Commitment Shares

Shares issued to the investor (Yorkville) as consideration for their commitment to purchase shares under the SEPA. (Represents immediate dilution upon the execution of the SEPA.)

Pre-Paid Advance Agreement (PPA)

An agreement where an investor provides funds upfront in exchange for the right to receive shares at a later date, often at a discount. (RNTX used this to secure immediate cash, but it involves future share issuance and potential dilution.)

VWAP

Volume Weighted Average Price, a trading benchmark representing the average price a stock has traded at throughout the day, based on volume. (The SEPA purchase price is tied to VWAP, meaning the discount is applied to a market-driven price.)

Clinical Hold

A notification from the FDA to a drug sponsor indicating that the FDA will not allow clinical trials to begin or continue. (The FDA's clinical hold on LTI-03 is a major impediment to the company's development program.)

Orphan Indications

Diseases that affect a small number of people, for which drugs may receive special incentives. (RNTX focuses on these niche areas, which can have smaller patient populations but potentially faster regulatory pathways and market exclusivity.)

Year-Over-Year Comparison

This S-1 filing reflects a significant shift in Rein Therapeutics' financial strategy and risk profile compared to previous filings. The company has moved from a more traditional financing approach to securing funds through a Standby Equity Purchase Agreement (SEPA) and Pre-Paid Advance Agreement (PPA) with Yorkville, introducing substantial dilution risks. The introduction of an FDA clinical hold on its lead candidate, LTI-03, represents a new and critical operational and regulatory risk not present in prior periods, significantly impacting the company's development trajectory and investor sentiment.

Key Financial Figures

• $0.001 — 0 shares of our common stock, par value $0.001 per share ("common stock"), by YA II PN
• $15,000,000 — rchase from us, at our direction, up to $15,000,000 of shares of our common stock (the "Adv
• $1.35 — e closing price of our common stock was $1.35. Investing in our securities involves
• $6,000,000 — -paid advances of up to an aggregate of $6,000,000 from Yorkville (each, a "Pre-Paid Advan
• $0.28 — tice to us, subject to a floor price of $0.28 per share. Yorkville shall, in each Pur
• $1,000,000 — PPA, we requested a Pre-Paid Advance of $1,000,000 from Yorkville under the PPA and receiv
• $950,000 — om Yorkville under the PPA and received $950,000 of cash proceeds after application of t
• $1 — stock, at an average price per share of $1.06, to Yorkville pursuant to Purchase N
• $300,000 — chase Notices which were offset against $300,000 of outstanding Pre-Paid Advances. Cor
• $5 — common stock, with an exercise price of $5.66, which expire on May 20, 2029, which
• $4.89 — common stock, with an exercise price of $4.89 per share, which expire on May 2, 2027,
• $4.68 — common stock, with an exercise price of $4.68 per share, which expire on May 3, 2027,
• $6.54 — at a weighted average exercise price of $6.54 per share; 1,302,066 additional share
• $15.0 million — kholder has committed to purchase up to $15.0 million of Advance Shares, upon the terms and s

Filing Documents

• d857368ds1.htm (S-1) — 260KB
• d857368dex51.htm (EX-5.1) — 7KB
• d857368dex231.htm (EX-23.1) — 1KB
• d857368dexfilingfees.htm (EX-FILING FEES) — 33KB
• g857368g75b98.jpg (GRAPHIC) — 30KB
• 0001193125-25-195041.txt ( ) — 463KB
• d857368dexfilingfees_htm.xml (XML) — 6KB

RISK FACTORS

RISK FACTORS 6 CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS 8 THE YORKVILLE TRANSACTION 10

USE OF PROCEEDS

USE OF PROCEEDS 12

DESCRIPTION OF CAPITAL STOCK

DESCRIPTION OF CAPITAL STOCK 13 SELLING STOCKHOLDER 16 PLAN OF DISTRIBUTION 18 LEGAL MATTERS 19 EXPERTS 19 INCORPORATION BY REFERENCE 19 WHERE YOU CAN FIND MORE INFORMATION 20 Table of Contents ABOUT THIS PROSPECTUS This prospectus, including information incorporated by reference herein, is part of a registration statement that we filed with the U.S. Securities and Exchange Commission ("SEC") under the Securities Act. Under this prospectus, the Selling Stockholder may, from time to time, sell shares of our common stock described in this prospectus in one or more transactions, as described herein. This prospectus provides you with a general description of the securities offered by the Selling Stockholder. Any prospectus supplement may also add, update or change information contained in this prospectus. Any statement that we make in this prospectus will be modified or superseded by any inconsistent statement made by us in a prospectus supplement. For investors outside of the United States: Neither we nor the Selling Stockholder have done anything that would permit this offering or possession or distribution of this prospectus in any jurisdiction where action for that purpose is required, other than in the United States. Persons outside of the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, the offering of our securities and the distribution of this prospectus outside of the United States. The registration statement we filed with the SEC includes exhibits that provide more detail of the matters discussed in this prospectus. This prospectus, including information incorporated by reference herein, contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of

Use of Proceeds

Use of Proceeds We will not receive any of the proceeds from the resale of the Advance Shares by the Selling Stockholder. We may receive up to $15,000,000 in aggregate gross proceeds under the SEPA from any sales of Advance Shares we make to the Selling Stockholder pursuant to the SEPA, assuming that we sell the full amount of our common stock that we have the right, but not the obligation, to sell to the Selling Stockholder under the SEPA. Any proceeds that we receive from sales of shares of our common stock to the Selling Stockholder under the SEPA will be used for advancing our clinical development pipeline, business development activities, working capital and other general corporate purposes. See " Use of Proceeds ." Market for Our Shares of Common Stock Our common stock is listed on the Nasdaq Capital Market under the symbol "RNTX."

Risk Factors

Risk Factors Any investment in our common stock offered hereby is speculative and involves a high degree of risk. You should carefully consider the information set forth under " Risk Factors " commencing on page 6 of this prospectus, as well as all other information contained and incorporated by reference in this prospectus. The number of shares of common stock to be outstanding is based on 23,547,429 shares of common stock outstanding as of August 25, 2025 (which includes the 213,099 Commitment Shares and 288,209 PPA shares sold in August 2025) and excludes: 12,232,000 shares of our common stock issuable upon conversion of 12,232 shares of Series X Preferred Stock outstanding as of August 25, 2025; 4 Table of Contents 6,616,499 shares of our common stock reserved for issuance upon exercise of outstanding warrants, which consist of (i) 726,437 shares of our common stock, with an exercise price of $5.66, which expire on May 20, 2029, which were issued in October 2023, (ii) 255,000 shares of our common stock, with an exercise price of $4.89 per share, which expire on May 2, 2027, which were issued in November 2023, (iii) 3,383,367 shares of our common stock, with an exercise price of $4.68 per share, which expire on May 3, 2027, which were issued in May 2024; (iv) 1,939,000 of our common stock, with an exercise price of $0.001 per share, which were issued in April 2025; and (v) 312,695 shares of our common stock, with an exercise price of $0.001 per share, which were issued in April 2025; 2,053,779 shares of our common stock issuable upon the exercise of stock options outstanding as of August 25, 2025, at a weighted average exercise price of $6.54 per share; 1,302,066 additional shares of our common stock available for future issuance as of August 25, 2025 under our 2021 Stock Incentive Plan, as amended, or the 2021 Plan; and 7,500 shares of our common stock available for future issuance as of August 25, 2025 under our 2017 Employee Stock Purchase Pl

RISK FACTORS

RISK FACTORS An investment in our common stock involves a high degree of risk. You should consider carefully the risks below and the risk and uncertainties described under the heading " Risk Factors " in Item 1A of Part I of our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, which is incorporated by reference in this prospectus, including our audited financial statements and the related notes, before you decide whether to purchase our common stock. If any of such risks actually occur, our business, financial condition, results of operations, cash flow and prospects could be materially and adversely affected. As a result, the trading price of our common stock could decline and you could lose all or part of your investment in our common stock. Risks Related to this Offering The issuance and sale of our common stock to the Selling Stockholder may cause dilution to our other stockholders and the sale of the shares of common stock acquired by the Selling Stockholder, or the perception that such sales may occur, could cause the price of our common stock to fall. On July 29, 2025, we entered into the SEPA with the Selling Stockholder, pursuant to which the Selling Stockholder has committed to purchase up to $15.0 million of Advance Shares, upon the terms and subject to the conditions set forth in the SEPA. Upon the execution of the SEPA, we issued 213,099 Commitment Shares to the Selling Stockholder as consideration for its commitment to purchase our Advance Shares at our direction under the SEPA. The remaining shares of our common stock that may be issued under the SEPA may be sold by us to the Selling Stockholder at our discretion from time to time over a 36-month period following the date of the SEPA. The purchase price for the shares that we may sell to the Selling Stockholder under the SEPA will fluctuate based on the market price of our common stock. Depending on demand and market liquidity at the time, sales of such shares by the Sel

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