Form 8-K

8-K — Armata Pharmaceuticals, Inc.

Accession: 0001104659-26-107253

Filed: 2026-09-14

Period: 2026-09-14

CIK: 0000921114

SIC: 2836 (BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES))

Item: Regulation FD Disclosure

Item: Financial Statements and Exhibits

Documents

8-K — tm2625289d1_8k.htm (Primary)

EX-99.1 — EXHIBIT 99.1 (tm2625289d1_ex99-1.htm)

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UNITED STATES

SECURITIES AND

EXCHANGE COMMISSION

Washington, DC

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):

September 14, 2026

ARMATA PHARMACEUTICALS, INC.

(Exact name of Registrant as specified in

its charter)

Washington

001-37544

91-1549568

(State or other jurisdiction

of incorporation or

organization)

(Commission File Number)

(IRS Employer Identification No.)

5005 McConnell Avenue

Los Angeles, California

90066

(Address of principal executive offices)

(Zip Code)

(310) 665-2928

(Registrant’s Telephone number)

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 (see General Instruction A.2. below):

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))

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. ¨

Securities registered pursuant to Section 12(b) of

the Act:

Title

of Each Class

Trading

Symbol(s)

Name

of Each Exchange on Which Registered

Common Stock

ARMP

NYSE American

Item 7.01

Regulation FD Disclosure.

On September 14, 2026, Armata Pharmaceuticals, Inc.

(the “Company”) issued a press release announcing that the U.S. Food and Drug Administration has granted Breakthrough Therapy

designation to AP-SA02, the Company’s intravenously administered Staphylococcus aureus (“S. aureus”) multi-phage

product candidate, for the adjunct treatment of complicated bacteremia caused by methicillin-sensitive S. aureus or methicillin-resistant

S. aureus. The full text of the press release issued in connection with this announcement is furnished as Exhibit 99.1 to

this Current Report on Form 8-K.

The information in this Item 7.01 and the attached

Exhibit 99.1 is being furnished and shall not be deemed “filed” for the purposes of Section 18 of the Securities

Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section. The information in this Item 7.01 and the attached

Exhibit 99.1 shall not be incorporated by reference into any registration statement or other document pursuant to the Securities

Act of 1933, as amended.

Item 9.01

Financial Statements and Exhibits.

(d) Exhibits.

Exhibit

No.

Description

99.1

Press Release, dated September 14,

2026.

104

Cover Page Interactive

Data File (embedded within Inline XBRL document).

- 2 -

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.

Date: September 14, 2026

Armata Pharmaceuticals, Inc.

By:

/s/ David House

Name:

David House

Title:

Chief Financial Officer

- 3 -

EX-99.1 — EXHIBIT 99.1

EX-99.1

Filename: tm2625289d1_ex99-1.htm · Sequence: 2

Exhibit 99.1

Armata Pharmaceuticals Receives U.S. FDA Breakthrough

Therapy Designation for AP-SA02

Designation is driven by compelling Phase 2 clinical data in patients

with complicated Staphylococcus aureus bacteremia showing AP-SA02 may offer substantial improvement over available therapies

Potentially accelerating the path to market

for this innovative antibacterial treatment

AP-SA02 now holds Breakthrough Therapy, Fast Track and QIDP designations,

providing strong regulatory validation

LOS ANGELES,

Calif., September 14, 2026 - Armata Pharmaceuticals, Inc. (NYSE American: ARMP) (“Armata” or the “Company”),

a late clinical-stage biotechnology company focused on the development of high-purity and potency, pathogen-specific bacteriophage therapeutics

for the treatment of antibiotic-resistant and difficult-to-treat bacterial infections, today announced that the U.S. Food and Drug Administration

(the “FDA”) has granted Breakthrough Therapy designation to AP-SA02, the Company’s intravenously administered Staphylococcus

aureus (“S. aureus”) multi-phage product candidate, for adjunct treatment of complicated bacteremia caused by methicillin-sensitive

S. aureus (“MSSA”) or methicillin-resistant S. aureus (“MRSA”). Breakthrough Therapy designation

is intended to expedite the review of medicines that treat a serious or life-threatening condition and have shown preliminary clinical

evidence indicating the potential for substantial improvement over available therapies.

“The decision by the FDA to grant

Breakthrough Therapy designation to AP-SA02, in addition to Qualified Infectious Disease Product (“QIDP”) and Fast Track designations,

recognizes the urgent need for new treatment options for patients with complicated S. aureus bacteremia (“SAB”), including

MRSA, where many outcomes remain poor despite current standard-of-care,” said Dr. Deborah Birx, Chief Executive Officer of

Armata. “Based on the Phase 2 clinical trial data, we believe AP-SA02 has the potential to represent an important advancement in

the treatment of complicated SAB, a serious bloodstream infection that continues to be associated with significant relapse rate, morbidity

and mortality. If ultimately confirmed in Phase 3 and approved, AP-SA02 has the potential to become the first antibacterial therapy approved

based on superiority to current standard-of-care treatment in this patient population. We are grateful for the FDA’s enhanced engagement

and are committed to working closely with the Agency to efficiently advance the development and review of AP-SA02, with the goal of bringing

this potential new treatment option to patients as quickly as possible.”

Critically, the Breakthrough Therapy designation is supported by data

from the successful Phase 1b/2a diSArm study in adults with complicated SAB. Armata’s proprietary purification process yielded the

production of a high-purity, high-titer AP-SA02 drug product formulation enabling repetitive dose intravenous administration every six

hours for five days. This dosing regimen was well tolerated with no serious adverse events attributed to AP-SA02, and, when added to best

available antibiotic therapy (“BAT”) demonstrated higher and earlier clinical cure rates than placebo plus BAT. At the end-of-study

assessment, 28 days after completion of BAT, 100% of patients treated with AP-SA02 maintained clinical response without relapse, compared

with 75% of patients receiving placebo. Patients treated with AP-SA02 also demonstrated favorable trends across multiple measures of disease

resolution, including more rapid normalization of C-reactive protein (CRP) and Interleukin-10 (IL-10), biomarkers associated with mortality

risk and complications in SAB.

About Breakthrough Therapy Designation

Breakthrough

Therapy designation is a program designed by the FDA to expedite the development and review of therapies that are intended to treat a

serious or life-threatening condition where preliminary clinical evidence indicates potential substantial improvement over available

therapies on a clinically significant endpoint. A Breakthrough Therapy is eligible for all features of Fast Track designation,

in addition to comprehensive, cross-disciplinary collaboration with the FDA to design the most efficient clinical development program,

and organizational commitment from senior FDA managers to expedite development and review.

About AP-SA02

Armata

is developing AP-SA02, a fixed multi-phage cocktail, for the adjunct treatment of complicated Staphylococcus aureus

bacteremia caused by methicillin-sensitive S. aureus (MSSA) or methicillin-resistant S. aureus (MRSA). AP-SA02 has

received Qualified Infectious Disease Product (QIDP) designation, Fast

Track designation, and Breakthrough Therapy designation from the FDA. The diSArm study (NCT05184764) was a Phase 1b/2a,

multicenter, randomized, double-blind, placebo-controlled, multiple ascending dose escalation study of the safety, tolerability, and

efficacy of intravenous AP-SA02 in addition to best available antibiotic therapy (“BAT”) compared to BAT alone (placebo)

for the treatment of adults with complicated S. aureus bacteremia. Positive results from the Phase 2a diSArm study

were highlighted in a late-breaking oral presentation at IDWeek 2025™ in October 2025. The Phase 1b/2a clinical

development of AP-SA02, and activities related to End-of-Phase 2 and Armata’s preparation and readiness for its planned Phase

3 clinical study, is partially supported by a $28.7 million Department of War (DoW) award, received through the Medical Technology

Enterprise Consortium (MTEC) and managed by the Naval Medical Research Command (NMRC) – Naval Advanced Medical Development

(NAMD) with funding from the Defense Health Agency and Joint Warfighter Medical Research Program. The Company plans to advance

AP-SA02 into a Phase 3 superiority study in complicated SAB, anticipated to initiate in the second half of 2026.

About Armata Pharmaceuticals, Inc.

Armata is a late clinical-stage biotechnology company focused on the

development of high-purity and potency, pathogen-specific bacteriophage therapeutics for the treatment of antibiotic-resistant and difficult-to-treat

bacterial infections using its proprietary bacteriophage-based technology. Armata is developing and advancing a broad pipeline of natural

and synthetic phage candidates, including clinical candidates for Pseudomonas aeruginosa, Staphylococcus aureus, and other important

pathogens. Armata is committed to advancing phage therapy with drug development expertise that spans bench to clinic including in-house

phage-specific current Good Manufacturing Practices (“cGMP”) manufacturing to support full commercialization.

Forward Looking Statements

This communication

contains “forward-looking” statements as defined by the Private Securities Litigation Reform Act of 1995. These statements

relate to future events, results or to Armata’s future financial performance and involve known and unknown risks, uncertainties

and other factors which may cause Armata’s actual results, performance or events to be materially different from any future results,

performance or events expressed or implied by the forward-looking statements. In some cases, you can identify these statements by terms

such as “anticipate,” “believe,” “could,” “estimate,” “expect,” “intend,”

“may,” “plan,” “potential,” “predict,” “project,” “should,” “will,”

“would” or the negative of those terms, and similar expressions. These forward-looking statements reflect management’s

beliefs and views with respect to future events and are based on estimates and assumptions as of the date of this communication and are

subject to risks and uncertainties including risks related to Armata’s development of bacteriophage-based therapies; Armata’s

planned clinical trials; ability to staff and maintain its production facilities under fully compliant cGMP; ability to meet anticipated

milestones in the development and testing of the relevant product; ability to be a leader in the development of phage-based therapeutics;

ability to achieve its vision, including improvements through engineering and success of clinical trials; ability to successfully complete

preclinical and clinical development of, and obtain regulatory approval of its product candidates and commercialize any approved products

on its expected timeframes or at all; and Armata’s estimates regarding anticipated operating losses, capital requirements and needs

for additional funds. Additional risks and uncertainties relating to Armata and its business can be found under the caption “Risk

Factors” and elsewhere in Armata’s filings and reports with the U.S. Securities and Exchange Commission (the “SEC”),

including in Armata’s Annual Report on Form 10-K, filed with the SEC on March 25, 2026, and in its subsequent filings

with the SEC.

Armata expressly disclaims any obligation or undertaking to release

publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in Armata’s expectations

with regard thereto or any change in events, conditions or circumstances on which any such statements are based.

Media Contacts:

At Armata:

Pierre Kyme

ir@armatapharma.com

310-665-2928

Investor Relations:

Joyce Allaire

LifeSci Advisors, LLC

jallaire@lifesciadvisors.com

212-915-2569

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