FDA Grants Orphan Drug Designation to Eidos Therapeutics’ Product Candidate, AG10, for Treatment of Transthyretin Amyloidosis

SAN FRANCISCO, Oct. 03, 2018 (GLOBE NEWSWIRE) — Eidos Therapeutics, Inc. (Eidos) (Nasdaq:EIDX), a clinical stage biopharmaceutical company focused on addressing the large and growing unmet need in diseases caused by transthyretin (TTR) amyloidosis (ATTR), announced today that the U.S. Food and Drug Administration (FDA) has granted the company Orphan Drug Designation for AG10 for the treatment of ATTR.

TTR normally circulates in the blood as a four-part molecule or tetramer, but in ATTR the tetramer destabilizes and dissociates into individual monomers which aggregate as amyloid fibrils. AG10, Eidos’ lead product candidate, is designed to target ATTR at its source by stabilizing tetrameric TTR in the blood. Eidos is investigating AG10 for the treatment of ATTR cardiomyopathy (ATTR-CM) and ATTR polyneuropathy (ATTR-PN), both of which are progressive, fatal diseases. The company plans to initiate Phase 3 studies in each indication in the first half of 2019.

“The granting of Orphan Drug status to Eidos’ lead development candidate, AG10, for treating transthyretin amyloidosis is an important step forward for the product and our company,” said Jonathan Fox, M.D., Ph.D., president and chief medical officer of Eidos. “We believe that AG10 holds great promise as a disease-modifying therapy for patients with ATTR, and Orphan status will help us develop it as quickly as possible.”

Orphan Drug Designation provides incentives and support for the development of drugs for patients with rare diseases, specifically to drugs that are intended for the treatment of diseases or conditions that affect fewer than 200,000 people in the United States. Orphan Drug Designation provides certain benefits, including seven years of market exclusivity upon regulatory approval, exemption from FDA application user fees and tax credits for qualified clinical trial expenses.

About AG10

AG10 is an investigational, orally-administered small molecule designed to potently stabilize tetrameric transthyretin, or TTR, thereby halting at its outset the series of molecular events that give rise to amyloidosis, or ATTR. AG10 is currently being examined in a Phase 2 clinical trial in patients with ATTR cardiomyopathy. Top-line results from this trial are expected to be reported by the end of 2018.

AG10 was designed to mimic a naturally-occurring variant of the TTR gene (T119M) that is considered a “rescue mutation” because it has been shown to prevent ATTR in individuals carrying pathogenic, or disease-causing, mutations in the TTR gene. To our knowledge, AG10 is the only TTR stabilizer in development that has been observed to mimic the “super-stabilizing” properties of this rescue mutation.

About Eidos Therapeutics

Eidos Therapeutics is a clinical stage biopharmaceutical company focused on addressing the large and growing unmet need in diseases caused by transthyretin (TTR) amyloidosis (ATTR). For more information, please visit www.eidostx.com.

Forward-Looking Statements

This release includes forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act. All statements other than statements of historical facts, including the statements about the clinical and therapeutic potential and future clinical milestones of AG10, including the initiation of Phase 3 clinical trials, the potential for AG10 to capture any expected benefits from Orphan Drug Designation, the indications we intend to pursue and our possible clinical or other business strategies, and the timing of these events, are forward- looking statements. Forward-looking statements can be identified by terms such as “believes,” “expects,” “plans,” “potential,” “would” or similar expressions and the negative of those terms. These forward-looking statements are based on our management’s current beliefs and assumptions about future events and on information currently available to management.

Forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. These risks include, but are not limited to, risks and uncertainties related to: our limited operating history and historical losses, our liquidity to fund the development of our other product candidates through current and future milestones, our ability to raise additional funding to complete the development and any commercialization of our product candidates, our dependence on the success of our lead product candidate, AG10, results from our clinical trials and pre-clinical studies and those of third parties working in the same area as our product candidate and our dependence on third parties in connection with our manufacturing, clinical trials and pre-clinical studies. Additional risks and uncertainties that could affect our future results are included in the section 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 quarter ended June 30, 2018, which is available on the SEC’s website at www.sec.gov and our website at eidostx.com. Additional information on potential risks will be made available in other filings that we make from time to time with the SEC. In addition, any forward-looking statements contained in this press release are based on assumptions that we believe to be reasonable as of this date. Except as required by law, we assume no obligation to update these forward-looking statements, or to update the reasons if actual results differ materially from those anticipated in the forward-looking statements.

Media Contact:

Carolyn Hawley, Canale Communications, (619) 849-5382, carolyn@canalecomm.com

Investor Contact:

Alex Gray, Burns McClellan, (212) 213-0006, agray@burnsmc.com

Eidos Therapeutics Presents Data from its Phase 1 Clinical Trial of AG10 at the 22nd Annual Scientific Meeting of the Heart Failure Society of America

SAN FRANCISCO, Sept. 17, 2018 (GLOBE NEWSWIRE) — Eidos Therapeutics, Inc. (Eidos) (Nasdaq:EIDX) announced the presentation of results from its Phase 1 clinical trial of AG10 during a poster session at the 22nd Annual Scientific Meeting of the Heart Failure Society of America (HFSA). The poster, entitled “AG10, A Novel, Potent, and Selective Transthyretin Stabilizer, Is Well-Tolerated at Doses Resulting in Target Therapeutic Blood Levels, and Demonstrates Clinical Proof-of-Concept in Healthy Volunteers,” was presented on Saturday, September 15, and is accessible through the science section of the company’s website.

In this initial Phase 1 study in healthy adult volunteers, AG10 was well-tolerated with no safety signals of potential clinical concern identified. At the highest tested dose, AG10 achieved 100% transthyretin (TTR) stabilization at peak concentration and over 95% TTR stabilization on average at steady state. Serum TTR concentrations, an in vivo indicator of TTR stability, were increased to a greater degree in AG10-treated patients than placebo-treated patients from baseline to Day 12.

“We believe that maximizing the level of TTR stabilization will lead to optimal clinical benefit for TTR Amyloidosis (ATTR) patients. This initial human trial demonstrated that AG10 stabilized TTR in established ex vivo assays and increased circulating TTR concentrations,” noted Jonathan C. Fox, M.D., Ph.D., president and chief medical officer of Eidos. “Given that below normal levels of serum TTR are associated with poorer prognosis in ATTR patients, and stabilization of TTR by protective mutations or small molecule stabilizers increase serum TTR concentrations, we believe that these data provide clinical proof of concept. We are rapidly moving forward with additional studies of AG10 and have already completed enrollment in our Phase 2 trial in patients with symptomatic ATTR cardiomyopathy (ATTR-CM).”

TTR normally circulates in the blood as a four-part molecule, or tetramer. In ATTR, the tetramer is destabilized by inherited mutation or age-related factors and dissociates into individual monomers, which can aggregate and are deposited as amyloid fibrils in various tissues. AG10, Eidos’ lead product candidate, is designed to target ATTR at its source by stabilizing tetrameric TTR in the blood. Eidos is pursuing AG10 for the treatment of ATTR-CM and ATTR polyneuropathy (ATTR-PN), both of which are progressive, fatal diseases. The company plans to initiate Phase 3 studies in each indication in the first half of 2019.

About AG10

AG10 is an orally-administered small molecule designed to potently stabilize tetrameric transthyretin, or TTR, thereby halting at its outset the series of molecular events that give rise to transthyretin amyloidosis, or ATTR. AG10 is currently being tested in a Phase 2 clinical trial in patients with symptomatic ATTR cardiomyopathy. Top-line results from this trial are expected to be reported in the fourth quarter of 2018.

AG10 was designed to mimic a naturally-occurring variant of the TTR gene (T119M) that is considered a “rescue mutation” because it has been shown to prevent ATTR in individuals carrying pathogenic, or disease-causing, mutations in the TTR gene. To our knowledge, AG10 is the only TTR stabilizer in development that has been observed to mimic the “super-stabilizing” properties of this rescue mutation.

About Eidos Therapeutics

Eidos Therapeutics is a clinical stage biopharmaceutical company focused on addressing the large and growing unmet need in diseases caused by transthyretin (TTR) amyloidosis (ATTR). For more information, please visit www.eidostx.com.

Forward-Looking Statements

This release includes forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act. All statements other than statements of historical facts, including the statements about future clinical milestones of AG10, including the completion of our ongoing Phase 2 clinical trial and availability of top-line data therefrom, the initiation of Phase 3 clinical trials, the timing of these events, the indications we intend to pursue and our possible clinical or other business strategies, are forward-looking statements. Forward-looking statements can be identified by terms such as “believes,” “expects,” “plans,” “potential,” “would” or similar expressions and the negative of those terms.

These forward-looking statements are based on our management’s current beliefs and assumptions about future events and on information currently available to management.

Forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. These risks include, but are not limited to, risks and uncertainties related to: our limited operating history and historical losses, our liquidity to fund the development of our other product candidates through current and future milestones, our ability to raise additional funding to complete the development and any commercialization of our product candidates, our dependence on the success of our lead product candidate, AG10, results from our clinical trials and pre-clinical studies and those of third parties working in the same area as our product candidate and our dependence on third parties in connection with our manufacturing, clinical trials and pre-clinical studies. Additional risks and uncertainties that could affect our future results are included in the section titled “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in the final

prospectus for our initial public offering filed with the SEC on June 21, 2018, and our Quarterly Report on Form 10-Q for the quarter ended June 30, 2018, which are available on the SEC’s website at www.sec.gov and our website at eidostx.com. Additional information on potential risks will be made available in other filings that we make from time to time with the SEC. In addition, any forward-looking statements contained in this press release are based on assumptions that we believe to be reasonable as of this date. Except as required by law, we assume no obligation to update these forward- looking statements, or to update the reasons if actual results differ materially from those anticipated in the forward-looking statements.

Media Contact:

Carolyn Hawley, Canale Communications, (619) 849-5382, carolyn@canalecomm.com

For Investors

Alex Gray, Burns McClellan, (212) 213-0006, agray@burnsmc.com

Eidos Therapeutics Announces Publication of AG10 Molecular Design in Journal of Medicinal Chemistry

SAN FRANCISCO, Aug. 23, 2018 (GLOBE NEWSWIRE) — Eidos Therapeutics, Inc. (Eidos) (Nasdaq:EIDX) today announced publication of the design and preclinical characterization of its lead product candidate, AG10, in the Journal of Medicinal Chemistry.

AG10 is designed to prevent progression of transthyretin (TTR) amyloidosis (ATTR) by stabilizing tetrameric TTR in the blood. AG10 is currently being evaluated in a Phase 2 study in patients with symptomatic ATTR cardiomyopathy (NCT03458130).

“Stabilizing transthyretin has been validated as an approach for treating ATTR based on the correlation of genetic mutations with disease progression and the success of previous clinical trials in the disease. A comparison of various TTR stabilizers and their potency based on structural evidence has not been previously conducted,” said Mamoun Alhamadsheh, PhD, co-founder of Eidos and associate professor at the University of the Pacific (Stockton, CA). “We believe our results provide strong evidence that AG10’s potentially superior stabilizing activity is driven by its unique ability to mimic the disease-protective T119M mutation and its selectivity for binding TTR in the plasma.”

The published paper demonstrates that AG10’s binding to TTR is driven by molecular interactions that mimic the structure of the T119M TTR variant that is known to protect carriers from developing ATTR and leads to prolonged lifespan in otherwise healthy individuals. Using in vitro and ex vivo assays, the data indicated that:

  • AG10 demonstrated more potent activity than other clinical candidates in binding and stabilizing the TTR tetramer at clinically relevant concentrations,
  • the binding of AG10 to TTR was not significantly affected by the presence of additional plasma proteins such as albumin, and
  • AG10 exhibited a predictable relationship between pharmacokinetics and pharmacodynamics in animal studies.

“This newly published paper describes the preclinical support for AG10 and further validates AG10’s mechanism to potently and selectively stabilize TTR,” said Uma Sinha, PhD, chief scientific officer of Eidos. “As a result, AG10 has the potential to be a disease-modifying therapy for ATTR, which we are evaluating in our ongoing Phase 2 study in symptomatic ATTR cardiomyopathy patients.”

About AG10

AG10 is an orally-administered small molecule designed to potently stabilize tetrameric transthyretin, or TTR, thereby halting at its outset the series of molecular events that give rise to amyloidosis, or ATTR. AG10 is currently being examined in a Phase 2 clinical trial in patients with ATTR cardiomyopathy. Top-line results from this trial are expected to be reported by the end of 2018.

AG10 was designed to mimic a naturally-occurring variant of the TTR gene (T119M) that is considered a “rescue mutation” because it has been shown to prevent ATTR in individuals carrying pathogenic, or disease-causing, mutations in the TTR gene. To our knowledge, AG10 is the only TTR stabilizer in development that has been observed to mimic the “super-stabilizing” properties of this rescue mutation.

About Eidos Therapeutics

Eidos Therapeutics is a clinical stage biopharmaceutical company focused on addressing the large and growing unmet need in diseases caused by transthyretin (TTR) amyloidosis (ATTR). For more information, please visit www.eidostx.com.

Forward-Looking Statements

This release includes forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act. All statements other than statements of historical facts, including statements about the clinical and therapeutic potential of AG10, the completion of our ongoing Phase 2 clinical trial of AG10 in patients with symptomatic ATTR cardiomyopathy and availability of top-line data therefrom, the timing of these events, the indications we intend to pursue and our possible clinical or other business strategies, are forward-looking statements.

Forward-looking statements can be identified by terms such as “believes,” “expects,” “plans,” “potential,” “would” or similar expressions and the

negative of those terms. These forward-looking statements are based on our management’s current beliefs and assumptions about future events and on information currently available to management.

Forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. These risks include, but are not limited to, risks and uncertainties related to: our limited operating history and historical losses, our liquidity to fund the development of AG10 through current and future milestones, our ability to raise additional funding to complete the development and any commercialization of any of our product candidates, our dependence on the success of our current product candidate, AG10, results from our clinical trials and pre-clinical studies and those of third parties working in the same area as our product candidate and our dependence on third parties in connection with our manufacturing, clinical trials and pre-clinical studies. Additional risks and uncertainties that could affect our future results are

included in the section 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 quarter ended June 30, 2018, which is available on the SEC’s website at www.sec.gov and our website at eidostx.com. Additional information on potential risks will be made available in other filings that we make from time to time with the SEC. In addition, any forward-looking statements contained in this press release are based on assumptions that we believe to be reasonable as of this date. Except as required by law, we assume no obligation to update these forward-looking statements, or to update the reasons if actual results differ materially from those anticipated in the forward-looking statements.

Media Contact:

Carolyn Hawley, Canale Communications, (619) 849-5382, carolyn@canalecomm.com

For Investors

Alex Gray, Burns McClellan, (212) 213-0006, agray@burnsmc.com

Eidos Therapeutics Announces Closing of Initial Public Offering and Exercise in Full of the Underwriters’ Option to Purchase Additional Shares

SAN FRANCISCO, June 22, 2018 /PRNewswire/ — Eidos Therapeutics, Inc. (Nasdaq: EIDX), a clinical stage biopharmaceutical company focused on addressing the large and growing unmet need in diseases caused by transthyretin (TTR) amyloidosis (ATTR), today announced the closing of its initial public offering of 7,187,500 shares of common stock, including the exercise in full of the underwriters’ option to purchase 937,500 additional shares of common stock, at a public offering price of $17.00 per share. The aggregate gross proceeds to Eidos from the offering were approximately

$122.2 million, before deducting underwriting discounts and other offering expenses. All of the shares in the offering were offered by Eidos. Eidos’ common stock is listed on The NASDAQ Global Select Market under the ticker symbol “EIDX.”

J.P. Morgan Securities LLC and BofA Merrill Lynch acted as joint book-running managers for the offering. Barclays Capital Inc. also participated as a joint book-running manager.

The shares were offered by Eidos pursuant to a registration statement that was declared effective by the Securities and Exchange Commission (“SEC”) on June 19, 2018. A prospectus relating to and describing the terms of the offering has been filed with the SEC and is available on the SEC’s website at www.sec.gov.

This offering was made only by means of a prospectus. Copies of the final prospectus relating to this offering can be obtained from (1) J.P. Morgan Securities LLC, Attention: c/o Broadridge Financial Solutions, Attn: Prospectus Department, 1155 Long Island Avenue, Edgewood, NY 11717, telephone: (866) 803-9204, or by emailing prospectus-eq_fi@jpmchase.com; (2) BofA Merrill Lynch, NC1-004-03-43, 200 North College Street, 3rd Floor, Charlotte, NC 28255-0001, Attention: Prospectus Department, or by emailing dg.prospectus_requests@baml.com; and (3) Barclays Capital Inc., c/o Broadridge Financial Solutions, Attn: Prospectus Department, 1155 Long Island Avenue, Edgewood, NY 11717, telephone: (888) 603-5847, or by emailing barclaysprospectus@broadridge.com.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About Eidos Therapeutics

Eidos Therapeutics is a clinical stage biopharmaceutical company focused on addressing the large and growing unmet need in diseases caused by transthyretin (TTR) amyloidosis (ATTR).

Eidos Therapeutics Announces Pricing of Initial Public Offering

SAN FRANCISCO, June 19, 2018 /PRNewswire/ — Eidos Therapeutics, Inc. (Nasdaq: EIDX), a clinical stage biopharmaceutical company focused on addressing the large and growing unmet need in diseases caused by transthyretin (TTR) amyloidosis (ATTR), today announced the pricing of its initial public offering of 6,250,000 shares of common stock at a public offering price of $17.00 per share. All of the shares are being offered by Eidos. The shares are expected to begin trading on the Nasdaq Global Select Market on June 20, 2018 under the ticker symbol “EIDX.” The gross proceeds from the offering, before deducting underwriting discounts and commissions and other offering expenses payable by Eidos, are expected to be approximately $106.3 million. The offering is expected to close on June 22, 2018, subject to the satisfaction of customary closing conditions. In addition, Eidos has granted the underwriters a 30-day option to purchase up to an additional 937,500 shares of common stock at the initial public offering price.

J.P. Morgan Securities LLC and BofA Merrill Lynch are acting as joint book-running managers for the offering. Barclays Capital Inc. is also participating as a joint book-running manager.

A registration statement relating to these securities was declared effective by the Securities and Exchange Commission on June 19, 2018. The offering will be made only by means of a prospectus, copies of which may be obtained from J.P. Morgan Securities LLC, Attention: Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY 11717, telephone: (866) 803-9204, or by emailing prospectus-eq_fi@jpmchase.com; BofA Merrill Lynch, NC1-004-03-43, 200 North College Street, 3rd Floor, Charlotte, NC 28255-0001, Attention: Prospectus Department, or by emailing dg.prospectus_requests@baml.com; or Barclays Capital Inc., c/o Broadridge Financial Solutions, Attn: Prospectus Department, 1155 Long Island Avenue, Edgewood, NY 11717, telephone: (888) 603-5847 or by emailing barclaysprospectus@broadridge.com.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About Eidos Therapeutics

Eidos Therapeutics is a clinical stage biopharmaceutical company focused on addressing the large and growing unmet need in diseases caused by transthyretin (TTR) amyloidosis (ATTR).