Form 8-K
8-K — Spero Therapeutics, Inc.
Accession: 0001193125-26-346855
Filed: 2026-08-12
Period: 2026-08-12
CIK: 0001701108
SIC: 2834 (PHARMACEUTICAL PREPARATIONS)
Item: Results of Operations and Financial Condition
Item: Financial Statements and Exhibits
Documents
8-K — d69249d8k.htm (Primary)
EX-99.1 (d69249dex991.htm)
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8-K
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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): August 12, 2026
SPERO THERAPEUTICS, INC.
(Exact name of registrant as specified in its charter)
Delaware
001-38266
46-4590683
(State or other jurisdiction
of incorporation)
(Commission
File Number)
(I.R.S. Employer
Identification No.)
675 Massachusetts Avenue, 14th Floor
Cambridge, Massachusetts
02139
(Address of principal executive offices)
(Zip Code)
Registrant’s telephone number, including area code (857) 242-1600
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))
Title of each class
Trading
Symbol(s)
Name of each exchange
on which registered
Common Stock, $0.001 par value
SPRO
The Nasdaq Global Select Market
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 2.02
Results of Operations and Financial Condition.
On August 12, 2026, Spero Therapeutics, Inc. (the “Company”) issued a press release announcing its results for the second quarter ended June 30, 2026. A copy of the press release issued in connection with the announcement is furnished as Exhibit 99.1 to this Current Report on Form 8-K.
The information contained in this Item 2.02 and in the press release furnished as Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, or incorporated by reference in any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation language in such filing.
Item 9.01
Financial Statements and Exhibits
(d) Exhibits
Exhibit
No.
Description
99.1
Press release issued by Spero Therapeutics, Inc. on August 12, 2026
104
Cover Page Interactive Data File (embedded within the Inline XBRL document and incorporated as Exhibit 101)
SIGNATURE
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: August 12, 2026
SPERO THERAPEUTICS, INC.
By:
/s/ Esther Rajavelu
Esther Rajavelu
Chief Executive Officer and Chief Financial Officer
EX-99.1
EX-99.1
Filename: d69249dex991.htm · Sequence: 2
EX-99.1
Exhibit 99.1
Spero Therapeutics Announces Second Quarter 2026 Operating Results and Provides Business Update
•
Entered an exclusive license agreement with Innovent Biologics for SP001, a Phase 2-ready, third-generation anti-CD40L antibody for immune-mediated diseases
•
U.S. Food and Drug Administration approved
Utebzi™ (tebipenem pivoxil), the first and only oral carbapenem antibiotic for adults with complicated urinary tract infections (cUTIs), including pyelonephritis
•
Closed $105 million non-recourse, non-dilutive financing backed by a portion of future Utebzi milestones and royalties, extending cash runway into the second half of 2029
•
Appointed Debra Zack, M.D., Ph.D., as Chief Medical Officer
•
Conference call today at 5pm EDT
CAMBRIDGE, Mass., Aug 12, 2026 – Spero Therapeutics, Inc. (Nasdaq: SPRO), a clinical-stage biopharmaceutical company focused on advancing
next-generation medicines in immunology and inflammation, today announced financial results for the second quarter ended June 30, 2026, and provided a corporate update.
“During the second quarter, we achieved several defining milestones that have fundamentally strengthened Spero’s business. We entered the quarter
as a company preparing for an important regulatory milestone and have since then announced the FDA approval of Utebzi; a new Phase 2-ready immunology program with SP001; and financing that positions us to
continue executing on our mission to deliver transformative therapies to patients,” said Esther Rajavelu, President and Chief Executive Officer of Spero. “As we look to the remainder of 2026, our priorities are to advance SP001 toward a
Phase 2 study in IgG4-related disease and continue evaluating additional development opportunities in immune-mediated diseases to expand the SP001 value proposition, while maintaining our disciplined approach to execution.”
Recent Business Highlights
Exclusive License
Agreement with Innovent Biologics for SP001
•
In July 2026, Spero entered into an exclusive license agreement with Innovent Biologics, Inc. for SP001. Spero
gained exclusive rights to develop, research, manufacture, and commercialize SP001 worldwide, excluding Greater China (Mainland China, Hong Kong, Macau, and Taiwan), where Innovent retains rights.
•
SP001 is a third-generation, fully humanized, Fc-silent IgG1 monoclonal
antibody targeting CD40L, an upstream immune activation signal involved in T-cell, B-cell, antigen-presenting cell, and platelet biology. Innovent completed two healthy
volunteer Phase 1 trials, a single ascending dose (“SAD”) study and a multiple ascending dose (“MAD”) study, as well as a Phase 1b MAD study in patients with primary Sjögren’s disease (“SjD”). Data from
the Phase 1b SjD study were presented in a poster session at the EULAR 2026 Congress.
•
Spero plans to advance SP001 into a Phase 2 study in IgG4-related disease
(IgG4-RD), a serious, rare chronic fibroinflammatory disease with significant treatment burden and limited therapeutic options.
Utebzi (tebipenem pivoxil) U.S. FDA Approval
•
In June 2026, Spero and GSK announced that the U.S. Food and Drug Administration (FDA) approved Utebzi for the
treatment of complicated urinary tract infections (cUTIs), including pyelonephritis, caused by certain susceptible pathogens in adult patients who have limited or no alternative oral treatment options. Utebzi is the first and only oral carbapenem
antibiotic approved for these patients. The product is expected to be made available by GSK to U.S. patients by the end of 2026. GSK holds commercialization rights in the U.S. and Europe.
$105 Million Non-Recourse, Non-Dilutive Royalty Financing
•
In July 2026, Spero announced a non-recourse, non-dilutive royalty financing with affiliates of HealthCare Royalty Partners, a business of KKR (HCRx), for $105 million in gross proceeds, in exchange for rights to a portion of the anticipated payments from
sales of Utebzi owing from GSK (GSK Proceeds).
•
The transaction is structured as a non-recourse Note Purchase and
Guaranty Agreement (NPA) generally payable solely from the GSK proceeds, and a Royalty and Milestone Payment Interest Purchase and Sale Agreement (RPA) under which the Company may retain 35% interest in the GSK Proceeds arising after required
payments under the NPA, preserving potential long-term upside from the asset.
•
The proceeds will primarily support advancement of SP001.
Corporate
•
In July 2026, Spero announced the appointment of Debra Jeske Zack, M.D., Ph.D., as Chief Medical Officer.
Dr. Zack is a board-certified rheumatologist with a Ph.D. in immunology and brings more than 25 years of leadership in developing therapeutics for immune-mediated diseases. She will oversee Spero’s clinical development strategy and
organization as the Company advances its immunology program.
Second Quarter 2026 Financial Results
•
Spero reported a net loss of $9.6 million for the second quarter of 2026 compared to a net loss of
$1.7 million for the second quarter of 2025, or a diluted net loss per share of common stock of $0.16 and $0.03, respectively.
•
No revenue was recognized for the second quarter of 2026, compared to total revenue of $14.2 million for the
second quarter of 2025, as all deferred revenue under the collaboration agreements was recognized in prior periods and all grant revenue has been fully recognized, and the awards have been completed and closed out.
•
Research and development expenses for the second quarter of 2026 were $3.4 million, compared to
$10.7 million of research and development expenses for the same period in 2025. The decrease in research and development expenses was a result of decreased clinical activities related to our pivotal Phase 3 clinical trial of Utebzi, which was
stopped early for efficacy in the first half of 2025, and a decrease in personnel related costs.
•
General and administrative expenses for the second quarter of 2026 were $6.5 million, compared to
$5.9 million of general and administrative expenses for the same period in 2025. The increase was a result of increased legal and business development costs, offset partially by a decrease in personnel related costs.
•
As of June 30, 2026, cash and cash equivalents were $50.8 million. This balance does not reflect the
proceeds from the royalty financing completed in July 2026.
•
The company expects that its cash and cash equivalents at June 30, 2026, together with the proceeds of the
royalty financing, will be sufficient to fund operating expenses and capital expenditure into the second half of 2029.
For further
details on Spero’s financials, refer to Spero’s Quarterly Report on Form 10-Q, filed with the U.S. Securities and Exchange Commission (SEC) today.
Conference call and webcast
Management will host a
conference call and live audio webcast at 5:00 pm EDT today, August 12, to discuss the results and provide a business and pipeline update. To access the call, please dial 1-877-407-0789 (domestic) or 1-201-689-8562 (international) and refer to
conference ID 13762082, or click on this link to request a return call. The webcast for the event can be accessed live on this link, or on the Investor Relations page of the Spero Corporate website at https://www.sperotx.com/.
The archived webcast will be available for 30 days following the call.
About SP001
SP001 is a third-generation, potential best-in-class, fully humanized, Fc-silent IgG1 monoclonal antibody targeting CD40L, an upstream immune activation signal involved in T-cell, B-cell, antigen-presenting
cell, and platelet biology. By blocking CD40L, SP001 has the potential to provide a targeted non-B-cell-depleting treatment across multiple immune-mediated diseases
where immune-cell interactions drive chronic inflammation, relapse, and tissue damage. SP001 is designed to address platelet activation concerns associated with earlier anti-CD40L antibodies, while preserving key monoclonal antibody properties,
including FcRn interaction that supports IgG-like half-life.
About Spero Therapeutics
Spero Therapeutics is a clinical-stage biopharmaceutical company focused on advancing next-generation medicines for patients with serious immune-mediated
diseases. The company’s lead program, SP001, is a third-generation, Fc-silent anti-CD40L monoclonal antibody being advanced first in IgG4-related disease, with potential for development in additional
immunological & inflammatory diseases. For more information, visit www.sperotx.com.
Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. Forward-looking
statements include, but are not limited to, statements relating to Spero’s plans to advance SP001 into a Phase 2 study in IgG4-related disease; Spero’s plans to explore the use of SP001, and the role of CD40L inhibition, in additional
autoimmune and inflammatory diseases; the anticipated benefits of the non-dilutive royalty-backed transaction, including the anticipated use of proceeds; Spero’s expectation that Utebzi will be made
available to U.S. patients by the end of 2026; anticipated cash runway, and future milestones. Forward-looking statements are based on Spero’s current expectations and assumptions and are subject to risks and uncertainties that could cause
actual results to differ materially from those expressed or implied by such statements. These risks and uncertainties include, among others, risks related to the completion and integration of the Innovent transaction; Spero’s ability to
successfully develop SP001; the timing and outcome of clinical trials and regulatory interactions; the ability to obtain and maintain regulatory approvals; potential safety, efficacy, manufacturing, supply, intellectual property, financing,
competitive, and market risks; and other risks described in Spero’s filings with the Securities and Exchange Commission. Spero undertakes no obligation to update any forward-looking statements, except as required by law.
Investor Relations Contact:
Shai Biran, PhD
Spero Therapeutics
IR@Sperotherapeutics.com
Media Inquiries:
media@sperotherapeutics.com
Spero Therapeutics, Inc.
Condensed Consolidated Balance Sheet Data
(in thousands)
(unaudited)
June 30,
December 31,
2026
2025
Cash and cash equivalents
$
50,774
$
40,265
Other assets
1,992
28,654
Total assets
$
52,766
$
68,919
Total liabilities
8,562
9,898
Total stockholder’s equity
44,204
59,021
Total liabilities and stockholders’ equity
$
52,766
$
68,919
Spero Therapeutics, Inc.
Condensed Consolidated Statements of Operations
(in thousands, except share and per share data)
(unaudited)
Three Months Ended June 30,
Six Months Ended June 30,
2026
2025
2026
2025
Revenues:
Grant revenue
$
—
2,387
$
—
3,150
Collaboration revenue - related party
—
11,802
258
16,901
Collaboration revenue
—
—
—
12
Total revenues
—
14,189
258
20,063
Operating expenses:
Research and development
3,434
10,672
6,343
24,278
General and administrative
6,492
5,878
11,379
12,702
Restructuring
—
83
—
258
Total operating expenses
9,926
16,633
17,722
37,238
Loss from operations
(9,926
)
(2,444
)
(17,464
)
(17,175
)
Total other income, net
374
744
709
1,609
Net loss
$
(9,552
)
$
(1,700
)
$
(16,755
)
$
(15,566
)
Net loss per share attributable to common shareholders per share, basic and diluted
$
(0.16
)
$
(0.03
)
$
(0.29
)
$
(0.28
)
Weighted average shares outstanding, basic and diluted:
57,968,608
56,026,767
57,626,986
55,703,275
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