Spero Therapeutics — Third Quarter 2026 Earnings Summary

Financial Performance:

• Reported no revenue for the third quarter of 2026, compared to $5.4 million in the same period of 2025.
• Research and development expenses were $38.2 million for Q3 2026, an increase from $8.6 million in Q3 2025, primarily driven by a $35 million upfront payment to Innovent Biologics.
• General and administrative expenses were $3.7 million for Q3 2026, a decrease from $4.2 million in Q3 2025, attributed to reduced personnel costs.
• Reported a net loss of $44.3 million for Q3 2026, compared to a net loss of $7.4 million in Q3 2025.
• Diluted net loss per share was $0.76 for Q3 2026, compared to $0.13 in Q3 2025.
• Cash and cash equivalents totaled $107.9 million as of September 30, 2026, reflecting proceeds from the July 2026 royalty financing.

Guidance and Future Outlook:

• Cash and cash equivalents are expected to fund operating expenses and capital expenditures into the second half of 2029.
• Plans to initiate a Phase 2 study for SP001 in IgG4-related disease in the second quarter of 2027.
• Management intends to continue evaluating additional indications where CD40L inhibition may benefit patients.

Business Segments and Product Lines:

• In July 2026, Spero in-licensed SP001 from Innovent Biologics affiliates, securing exclusive worldwide rights (excluding Greater China) to research, develop, manufacture, and commercialize the antibody.
• SP001 is a third-generation, fully humanized, Fc-silent IgG1 monoclonal antibody targeting CD40L.
• Innovent completed Phase 1 single and multiple ascending dose studies in healthy volunteers and a Phase 1b study in patients with primary Sjögren's disease in China, with results presented at EULAR 2026.
• The company holds a 35% interest in GSK payments (Utebzi) remaining after required note payments to HealthCare Royalty Partners are satisfied.

Market and Competitive Landscape:

• IgG4-related disease is characterized as a serious, rare, chronic fibroinflammatory disease with significant treatment burden and limited therapeutic options.
• SP001 is designed to address platelet activation concerns associated with earlier anti-CD40L antibodies while preserving IgG-like half-life properties.

Risks and Challenges:

• Forward-looking statements are subject to risks including the completion and integration of the Innovent transaction.
• Risks include the ability to successfully develop SP001, timing and outcomes of clinical trials, regulatory interactions, and obtaining regulatory approvals.
• Potential risks encompass safety, efficacy, manufacturing, supply, intellectual property, financing, competitive, and market uncertainties.

Management Commentary and Tone:

• CEO Esther Rajavelu stated the company believes SP001 represents a compelling opportunity to address unmet medical needs and that the company is well-positioned to execute its clinical development strategy.
• Management emphasized a focus on execution as they advance SP001 toward a Phase 2 study in IgG4-RD.
• The tone reflects confidence in the strong financial position and recent team additions supporting the next stage of development.

Other Key Points:

• Closed a $105 million non-recourse, non-dilutive milestone and royalty financing in July 2026 with affiliates of HealthCare Royalty Partners (a business of KKR).
• Appointed Debra Jeske Zack, M.D., Ph.D., as Chief Medical Officer in July 2026.
• Appointed Amy Rock, Ph.D., as Chief Regulatory and Quality Officer to lead global regulatory strategy and quality functions.
• Appointed William Ho, M.D., Ph.D., to the Board of Directors and Development Committee effective November 10, 2026.
• Dr. Patrick Vink stepped down from the Board after eleven years of service.