# EDGAR Filing Document

**Accession Number:** 0001664710
**File Stem:** 0001664710-26-000024
**Filing Date:** 2026-3
**Character Count:** 21380
**Document Hash:** e0dce01e4f4a977726b383ff8f9cba7a
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001664710-26-000024.hdr.sgml**: 20260309

**ACCESSION NUMBER**: 0001664710-26-000024

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 15

**CONFORMED PERIOD OF REPORT**: 20260309

**ITEM INFORMATION**: Other Events

**ITEM INFORMATION**: Financial Statements and Exhibits

**FILED AS OF DATE**: 20260309

**DATE AS OF CHANGE**: 20260309

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Keros Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0001664710
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 811173868
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 8-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-39264
- **FILM NUMBER:** 26733247

**BUSINESS ADDRESS:**
- **STREET 1:** 1050 WALTHAM STREET, SUITE 302
- **CITY:** LEXINGTON
- **STATE:** MA
- **ZIP:** 02421
- **BUSINESS PHONE:** 617-314-6297

**MAIL ADDRESS:**
- **STREET 1:** 1050 WALTHAM STREET, SUITE 302
- **CITY:** LEXINGTON
- **STATE:** MA
- **ZIP:** 02421

?xml version='1.0' encoding='ASCII'? kros-20260309

**UNITED STATES** 

**SECURITIES AND EXCHANGE COMMISSION** 

**Washington, D.C. 20549** 

**FORM 8-K** 

**CURRENT REPORT** 

**Pursuant to Section 13 or 15(d)** 

**of the Securities Exchange Act of 1934** 

**Date of Report (Date of earliest event reported): March 9, 2026**

**Keros Therapeutics, Inc.** 

**(Exact name of registrant as specified in its charter)** 

---

| | | |
|:---|:---|:---|
| **Delaware** | **001-39264** | **81-1173868** |
| **(state or other jurisdiction**<br>**of incorporation)** | **(Commission**<br>**File Number)** | **(I.R.S. Employer**<br>**Identification No.)** |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**1050 Waltham Street**, **Suite 302** <br>**Lexington**, **Massachusetts** | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**1050 Waltham Street**, **Suite 302** <br>**Lexington**, **Massachusetts** | **02421** |
| **(Address of principal executive offices)** | **(Address of principal executive offices)** | **(Zip Code)** |

---

**Registrant's telephone number, including area code: (617) 314-6297**

**Not applicable**

**(Former name or former address, if changed since last report.)** 

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

------

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

---

| | | |
|:---|:---|:---|
| **Title of each class** | **Trading**<br>**Symbol** | **Name of each exchange**<br>**on which registered** |
| **Common Stock, $0.0001 par value per share** | **KROS** | **The Nasdaq Stock Market LLC** |
| **Preferred Share Purchase Rights** | **N/A** | **The Nasdaq Stock Market LLC** |

---

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

------

**Item 8.01 Other Events.**

On March 9, 2026, Keros Therapeutics, Inc. (the "Company") issued a press release announcing that it has entered into an agreement with the Massachusetts General Hospital for the design of a Phase 2 clinical trial evaluating rinvatercept in patients with amyotrophic lateral sclerosis ("ALS") within the HEALEY ALS MyMatch program, led by the Sean M. Healey & AMG Center for ALS at Mass General Brigham. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and, other than the quotes contained therein, is incorporated herein by reference.

On March 9, 2026, the Company also issued a press release announcing that it presented additional data from its Phase 1 clinical trial of rinvatercept in healthy volunteers at the 2026 Muscular Dystrophy Association Clinical & Scientific Conference. A copy of the press release is attached as Exhibit 99.2 to this Current Report on Form 8-K and, other than the quotes contained therein, is incorporated herein by reference.

**Item 9.01 &nbsp;&nbsp;&nbsp;&nbsp;Financial Statements and Exhibits.** 

(d) Exhibits

---

| | |
|:---|:---|
| **Exhibit**<br>**No.** |<br>**Description** |
| <u>[99.1](exhibit991als3426pr.htm)</u> | <u>[Press Release, dated March 9, 2026.](exhibit991als3426pr.htm)</u> |
| <u>[99.2](exhibit992mda3426pr.htm)</u> | <u>[Press Release, dated March 9, 2026.](exhibit992mda3426pr.htm)</u> |
| 104 | Cover Page Interactive Data File (the cover page XBRL tags are embedded within the Inline XBRL document) |

---

------

**SIGNATURES** 

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

---

| | |
|:---|:---|
| **KEROS THERAPEUTICS, INC.** | **KEROS THERAPEUTICS, INC.** |
| By: | /s/ Jasbir Seehra |
|  | Jasbir Seehra, Ph.D.<br>Chief Executive Officer  |

---

Dated: March 9, 2026

## Exhibit 99.1

**Exhibit 99.1**

**Keros Therapeutics Announces Collaboration with Sean M. Healey & AMG Center for ALS** 

**LEXINGTON, Mass., Mar. 9, 2026 (GLOBE NEWSWIRE)** -- Keros Therapeutics, Inc. ("Keros" or the "Company") (Nasdaq: KROS), a clinical-stage biopharmaceutical company focused on developing and commercializing novel therapeutics to treat a wide range of patients with disorders that are linked to dysfunctional signaling of the transforming growth factor-beta ("TGF-ß") family of proteins, today announced that it has entered into an agreement with the Massachusetts General Hospital ("MGH") for the design of a Phase 2 clinical trial evaluating rinvatercept in patients with amyotrophic lateral sclerosis ("ALS") within the Healey ALS MyMatch program ("ALS MyMatch"), led by the Sean M. Healey & AMG Center for ALS at Mass General Brigham.

The collaboration is in response to the Healey & AMG Center's call for applications for the ALS MyMatch program. The ALS MyMatch program is accelerating the development of new therapies for ALS by harnessing the power of biomarker-driven personalized trial approaches. By integrating comprehensive genetic and biofluid markers, the program matches subgroups of ALS individuals to various experimental therapies based on their disease markers. ALS MyMatch is an ongoing series of early-stage Phase 1b/2a clinical trials aimed at deepening the understanding of biological effects of experimental products and identifying the optimal population for future later-stage Phase 2/3 clinical trials.

"We are proud to be selected to the ALS MyMatch program to collaborate with the Healey & AMG Center at Mass General," said Jasbir S. Seehra, Ph.D., President and Chief Executive Officer of Keros. "Rinvatercept represents a potentially novel approach to treat patients with ALS. Based on the data we have generated to date, we believe there is a strong scientific rationale for the potential of rinvatercept to preserve muscle strength and function and improve quality of life in patients with ALS."

"ALS is a serious, progressive disorder with need of additional treatment options," said Merit Cudkowicz, M.D., M.Sc., director of the Sean M. Healey & AMG Center for ALS, executive director of the Neuroscience Institute at Mass General Brigham, and the Julieanne Dorn Professor of Neurology at Harvard Medical School. "We look forward to partnering with Keros to evaluate rinvatercept within the ALS MyMatch program, bringing us closer to our goal of finding additional treatments for those battling ALS."

**About Healey ALS MyMatch** 

Healey ALS MyMatch is a multi-site, collaborative initiative that currently brings together four trial-ready, high enrolling ALS research centers and is a Network of Excellence for ALS (NEALS) affiliated program. Research centers include Mass General in Boston; University of Minnesota in Minneapolis, Minn.; Northwestern University in Evanston, Ill.; and Nova Southeastern University in Fort Lauderdale, Fla. ALS MyMatch has partnered with the Acceleration Centers of Enrollment (ACE) program, a community-driven philanthropic partnership program focused on expediting start up and recruitment at study centers. Additional trials and high performing sites will be added as the program grows.

**About the Sean M. Healey & AMG Center for ALS at Mass General Brigham** 

The Sean M. Healey & AMG Center for ALS at Mass General Brigham, launched in 2018, brings together a global network of scientists, physicians, nurses, foundations, federal agencies and people living with ALS, their loved ones, and caregivers to accelerate the pace of ALS therapy discovery and development.

**About Rinvatercept**

------

Rinvatercept is a novel ligand trap comprised of a modified ligand-binding domain derived from activin receptor type IIA and activin receptor type IIB that is fused to the portion of the human antibody known as the Fc domain. Rinvatercept is designed to act as a ligand trap and inhibit the biological effects of myostatin and activin A, which are negative regulators of muscle and bone mass and strength, to improve skeletal muscle regeneration, increase muscle size and strength, inhibit and reduce fibrosis, inhibit inflammation, reduce fat accumulation and improve bone health through bone anabolic mechanisms. We are developing rinvatercept for the treatment of Duchenne muscular dystrophy and for the treatment of ALS.

**About Keros Therapeutics, Inc.**

Keros is a clinical-stage biopharmaceutical company focused on developing and commercializing novel therapeutics to treat a wide range of patients with disorders that are linked to dysfunctional signaling of the TGF-ß family of proteins. Keros is a leader in understanding the role of the TGF-ß family of proteins, which are master regulators of the growth, repair and maintenance of a number of tissues, including skeletal muscle, bone, adipose, heart tissue and blood. By leveraging this understanding, Keros has discovered and is developing protein therapeutics that have the potential to provide meaningful and potentially disease-modifying benefit to patients. Keros' lead product candidate, rinvatercept, is being developed for the treatment of Duchenne muscular dystrophy and for the treatment of ALS. Keros' most advanced product candidate, elritercept, is being developed for the treatment of cytopenias, including anemia and thrombocytopenia, in patients with myelodysplastic syndrome and in patients with myelofibrosis.

**Cautionary Note Regarding 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, as amended. Words such as "aim," "believe," "forward," "goal," "potential" or similar expressions are intended to identify forward-looking statements. Examples of these forward-looking statements include statements concerning: the potential of rinvatercept to preserve muscle strength and function and improve quality of life in patients with ALS. Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. These risks and uncertainties include, among others: Keros' limited operating history and historical losses; Keros' ability to raise additional funding to complete the development and any commercialization of its product candidates; Keros' dependence on the success of its product candidates, rinvatercept and elritercept; that Keros may be delayed in initiating, enrolling or completing any clinical trials; competition from third parties that are developing products for similar uses; Keros' ability to obtain, maintain and protect its intellectual property; and Keros' dependence on third parties in connection with manufacturing, clinical trials and preclinical studies.

These and other risks are described more fully in Keros' filings with the Securities and Exchange Commission ("SEC"), including the "Risk Factors" section of the Company's Annual Report on Form 10-K, filed with the SEC on March 4, 2026, and its other documents subsequently filed with or furnished to the SEC. All forward-looking statements contained in this press release speak only as of the date on which they were made. Except to the extent required by law, Keros undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made.

**Contacts**

Investor Contact:

------

Justin Frantz

<u>jfrantz@kerostx.com</u>

617-221-6042

Media Contact:

Mahmoud Siddig / Adam Pollack / Viveca Tress

Joele Frank, Wilkinson Brimmer Katcher

(212) 355-4449

## Exhibit 99.2

**Exhibit 99.2**

Keros Therapeutics Presents Additional Clinical Data from Its Rinvatercept Program at the 2026 MDA Clinical & Scientific Conference

**LEXINGTON, Mass., Mar. 9, 2026 (GLOBE NEWSWIRE)** -- Keros Therapeutics, Inc. ("Keros" or the "Company") (Nasdaq: KROS), a clinical-stage biopharmaceutical company focused on developing and commercializing novel therapeutics to treat a wide range of patients with disorders that are linked to dysfunctional signaling of the transforming growth factor-beta ("TGF-ß") family of proteins, today announced that it presented additional data from its Phase 1 clinical trial of rinvatercept (KER-065) in healthy volunteers at the 2026 Muscular Dystrophy Association Clinical & Scientific Conference.

"We are pleased to present additional data that further underscore the wide-ranging therapeutic potential of rinvatercept," said Jasbir S. Seehra, President and Chief Executive Officer of Keros. "These data continue to reinforce the potential of rinvatercept to treat neuromuscular diseases, and our focus remains on advancing the rinvatercept program into two Phase 2 clinical trials, one in Duchenne muscular dystrophy ("DMD") and one in amyotrophic lateral sclerosis ("ALS")."

<u>Clinical Presentation</u>

*Proteome Analysis in a Phase 1 Trial of KER-065, a Modified Activin Receptor Ligand Trap, Confirmed Target Engagement and Guides Clinical Development in Neuromuscular Diseases* 

This Phase 1 clinical trial was a randomized, double-blind, placebo-controlled, two-part dose escalation (single and multiple ascending dose) trial in healthy adult male volunteers. The primary objectives of this trial were to assess safety, tolerability and pharmacokinetics of rinvatercept. Exploratory proteomic analysis was performed on serum samples. Differential expression analysis was used to compare protein levels in serum samples from volunteers who received rinvatercept or placebo over 71 days. Initial topline data from this trial was reported in March 2025.

As previously reported, treatment with rinvatercept was generally well-tolerated at all dose levels evaluated. No dose-limiting toxicities or serious adverse events were reported.

Administration of rinvatercept led to changes in body composition consistent with activin and myostatin inhibition. An increase in muscle mass, decrease in fat mass and an increase in bone mineral density were observed.

Proteomic data further demonstrated the mechanism of action of rinvatercept, including its observed effects on mitigating fibrosis and inflammation by inhibiting activins, consistent with the anti-fibrotic and anti-inflammatory effects observed preclinically. Changes in serum markers of energy metabolism indicated a shift in macronutrient requirements for muscle growth, which aligned with the observed increases in muscle mass. These data provide multiple lines of evidence that rinvatercept may potentially achieve sufficient activin inhibition across tissues of interest, at drug exposures that we anticipate targeting in DMD and ALS.

<u>Preclinical Presentations</u>

Additionally, the Company presented the following preclinical presentations from its rinvatercept program that continue to support the further development of rinvatercept in DMD and ALS:

------

• *RKER-065 Improved Muscle and Bone Mass and Strength in the D2.mdx Mouse Model of Duchenne Muscular Dystrophy* 

• *RKER-065 Exhibited Beneficial Effects in an Amyotrophic Lateral Sclerosis Mouse Model*

**About Rinvatercept**

Rinvatercept is a novel ligand trap comprised of a modified ligand-binding domain derived from activin receptor type IIA and activin receptor type IIB that is fused to the portion of the human antibody known as the Fc domain. Rinvatercept is designed to act as a ligand trap and inhibit the biological effects of myostatin and activin A, which are negative regulators of muscle and bone mass and strength, to improve skeletal muscle regeneration, increase muscle size and strength, inhibit and reduce fibrosis, inhibit inflammation, reduce fat accumulation and improve bone health through bone anabolic mechanisms. We are developing rinvatercept for the treatment of DMD and for the treatment of ALS.

**About Keros Therapeutics, Inc.**

Keros is a clinical-stage biopharmaceutical company focused on developing and commercializing novel therapeutics to treat a wide range of patients with disorders that are linked to dysfunctional signaling of the TGF-ß family of proteins. Keros is a leader in understanding the role of the TGF-ß family of proteins, which are master regulators of the growth, repair and maintenance of a number of tissues, including skeletal muscle, bone, adipose, heart tissue and blood. By leveraging this understanding, Keros has discovered and is developing protein therapeutics that have the potential to provide meaningful and potentially disease-modifying benefit to patients. Keros' lead product candidate, rinvatercept, is being developed for the treatment of DMD and for the treatment of ALS. Keros' most advanced product candidate, elritercept, is being developed for the treatment of cytopenias, including anemia and thrombocytopenia, in patients with myelodysplastic syndrome and in patients with myelofibrosis.

**Cautionary Note Regarding 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, as amended. Words such as "potential" or similar expressions are intended to identify forward-looking statements. Examples of these forward-looking statements include statements concerning: Keros' expectations regarding its strategy and timing of its two Phase 2 clinical trials for rinvatercept; and the potential of rinvatercept to treat neuromuscular diseases, including DMD and ALS. Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. These risks and uncertainties include, among others: Keros' limited operating history and historical losses; Keros' ability to raise additional funding to complete the development and any commercialization of its product candidates; Keros' dependence on the success of its product candidates, rinvatercept and elritercept; that Keros may be delayed in initiating, enrolling or completing any clinical trials; competition from third parties that are developing products for similar uses; Keros' ability to obtain, maintain and protect its intellectual property; and Keros' dependence on third parties in connection with manufacturing, clinical trials and preclinical studies.

These and other risks are described more fully in Keros' filings with the Securities and Exchange Commission ("SEC"), including the "Risk Factors" section of the Company's Annual Report on Form 10-K, filed with the SEC on March 4, 2026, and its other documents subsequently filed with or furnished to the SEC. All forward-looking statements contained in this press release speak only as of the date on which they were made. Except to the extent required by law, Keros undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made.

**Contacts**

------

Investor Contact:

Justin Frantz

<u>jfrantz@kerostx.com</u>

617-221-6042

Media Contact:

Mahmoud Siddig / Adam Pollack / Viveca Tress

Joele Frank, Wilkinson Brimmer Katcher

(212) 355-4449

<br>