Oncopeptides – Study confirms use of Pepaxti in a broader population, with strong data in the 50% of RRMM patients that suffer from reduced kidney function

Stockholm – May 20, 2026 – Oncopeptides AB (publ) (Nasdaq Stockholm: ONCO), a biotech company focused on difficult-to-treat cancers, today announces the publication of the results from the Phase 2 BRIDGE (OP-107) clinical study in the peer-reviewed journal Clinical Lymphoma, Myeloma and Leukemia.

The prospective, open-label study evaluated the pharmacokinetics (PK), safety, and efficacy of Pepaxti (melflufen) plus dexamethasone in relapsed, refractory multiple myeloma (RRMM) patients with moderate-to-severe renal impairment (RI). Patients with renal insufficiency represent roughly half of all myeloma diagnoses and typically suffer from poorer long-term outcomes and limited clinical options.

“The findings are highly significant for everyday clinical practice because they demonstrate that with proper renal function-based dose adjustments, we can maintain strong disease control and survival outcomes without compromising safety or worsening kidney function in a very fragile patient segment,” says Dr. Ludek Pour, Ph.D., Clinic of Internal Medicine – Hematology and Oncology, University Hospital Brno, Czech Republic, and lead author of the study.

The final analyses demonstrate that while systemic exposure to the active metabolite melphalan varies based on baseline kidney function, a reduced melflufen starting dose of 30 mg in patients with moderate renal impairment delivers a consistent safety profile, treatment responses, and survival measures aligned with prior trials conducted in less selected populations.

Furthermore, exploratory data gathered across the treatment cycles showed that renal function remained stable or slightly improved during therapy, suggesting that Pepaxti does not adversely impact the kidneys at the studied doses.

Key study highlights:

• Validated dose optimization: The PK data directly validate the clinical use and efficacy of a 30 mg Pepaxti starting dose for patients with moderate renal impairment (eGFR ≤30 to <45 mL/min/1.73 m²).
• Sustained efficacy in fragile populations: Patients with moderate renal impairment achieved an Overall Response Rate (ORR) of 47.6% in Cohort 1a (40 mg starting dose) and 70.0% in Cohort 1b (30 mg starting dose), with a median progression-free survival (PFS) of 8.6 months and 7.7 months, respectively.
• No new safety signals: Despite advanced renal impairment and high treatment exposure, the safety profile was well-characterized and manageable. The most frequently reported treatment-emergent adverse events were hematological (thrombocytopenia, anemia, and neutropenia), which is consistent with previous clinical trials.

“This publication adds critical scientific peer-reviewed validation to the treatment algorithm of Pepaxti, specifically strengthening our data footprint in patient subgroups with renal impairment,” says Stefan Norin, Chief Medical Officer at Oncopeptides. “By demonstrating that Pepaxti can be safely administered at an optimized 30 mg dose, BRIDGE gives healthcare professionals the clinical confidence they need to confidently utilize this therapy in a broader patient population.”

The full article, titled “BRIDGE (OP-107): A Phase 2 Pharmacokinetic Study of Melflufen Plus Dexamethasone in Patients with Relapsed/Refractory Multiple Myeloma and Impaired Renal Function,” is available online via Clinical Lymphoma, Myeloma and Leukemia.

For more information, including a Q&A for investors, please visit www.oncopeptides.com.

For more information, please contact:
David Augustsson, Director of IR and Communications, Oncopeptides AB (publ)
E-mail: ir@oncopeptides.com
Cell phone: +46 76 229 38 68

About Oncopeptides
Oncopeptides is a Swedish biotech company focusing on research, development and commercialization of targeted therapies for difficult-to-treat cancers.

The company uses its proprietary Peptide Drug Conjugate platform (PDC) to develop compounds that rapidly and selectively deliver cytotoxic agents into cancer cells. Its flagship drug is currently being commercialized in Europe with partnership agreements for South Korea, the Middle East and Africa and elsewhere.

Oncopeptides is also developing several new compounds based on its two proprietary technology platforms PDC and SPiKE.

The company was founded in 2000, has about 80 employees with operations in Sweden, Germany, Austria, Spain and Italy. Oncopeptides is listed on Nasdaq Stockholm with the ticker ONCO.

For more information see: www.oncopeptides.com

About Pepaxti
Pepaxti® (melphalan flufenamide, also called melflufen) has been granted Marketing Authorization, in the European Union, the EEA-countries Iceland, Lichtenstein and Norway, as well as in the UK. Pepaxti is indicated in combination with dexamethasone for the treatment of adult patients with multiple myeloma who have received at least three prior lines of therapies, whose disease is refractory to at least one proteasome inhibitor, one immunomodulatory agent, and one anti-CD38 monoclonal antibody, and who have demonstrated disease progression on or after the last therapy. For patients with a prior autologous stem cell transplantation, the time to progression should be at least 3 years from transplantation.