ImmunOs Therapeutics Reports Promising Clinical Activity of IOS-1002 in Advanced Solid Tumors

Partial remissions and complete metabolic responses in PD-1/PD-L1-resistant cancers
First-in-class multi-checkpoint inhibitor with robust efficacy and safety
Combination arm with pembrolizumab (Keytruda®) in Australia near to completion by end 2025

Schlieren, Switzerland, October 20, 2025 – ImmunOs Therapeutics AG, a clinical-stage biopharmaceutical company leveraging its unique immune system modulating HLA-based technology platform to develop first-in-class therapeutics for the treatment of cancer and inflammatory diseases, today announced encouraging preliminary results from its ongoing Phase I clinical trial evaluating IOS-1002 in patients with advanced solid tumors.

To date, 47 patients have been enrolled in the multicenter study in Australia. Nineteen patients received IOS-1002 as monotherapy, and 28 patients receive IOS-1002 in combination with MSD’s (Merck & Co., Inc., Rahway, NJ, USA) anti-PD-1 therapy, pembrolizumab (Keytruda®). The monotherapy cohort has been completed, while the combination cohort is currently enrolling the highest dose level, with the final dose group expected to be completed by December 2025.

In the monotherapy arm, 6 out of 19 patients (32%) achieved Stable Disease, highlighting a favorable disease control rate. In the combination therapy cohort, 15 out of 21 evaluable patients (71%) achieved Disease Control. In total, 13 patients (61%) so far achieved Stable Disease including 10 patients still undergoing treatment. 2 additional patients (10%) have achieved Partial Responses, including one patient who experienced a metabolic Complete Response confirmed by PET imaging.

This patient continues follow-up beyond week 40. Besides very promising clinical benefit for patients, IOS-1002 shows a very favorable safety and tolerability profile without anti-drug antibodies.

“These early signs of clinical activity, especially in a patient achieving a durable complete metabolic response, support IOS-1002’s unique mechanism of action and potential to overcome PD-1/PD-L1 resistance,” said Dr. Christoph Renner, Chief Medical Officer of ImmunOs. “We are encouraged by the compound’s activity in patients with resistance to PD-1/PD-L1 blockade.”

IOS-1002 is a novel, first-in-class stabilized HLA-B57 ‘open format’ fusion protein that targets three key immune checkpoints: LILRB1, LILRB2, and KIR3DL1, while also engaging CD64 to promote macrophage activation. This multi-targeted approach simultaneously activates NK cells, macrophages, and T cells, thereby enhancing both innate and adaptive anti-tumor responses.

Clinical results including a promising biomarker strategy for Phase Ib were recently published at the European Society for Medical Oncology (ESMO) meeting on October 19, 2025. In addition, the peer-reviewed publication in Cancers (Rafiei et al., Cancers 2024, 16(16), 2902) demonstrated IOS-1002’s preclinical efficacy in multiple tumor models and its mechanism of action involving inhibition of immunosuppressive signaling and enhancement of phagocytic and cytotoxic activity.

Identified biomarkers and patient response characteristics will guide patient stratification for the planned Phase Ib clinical trial, anticipated to start in the second half of 2026. Additional information regarding the Phase Ib study design and objectives will be communicated prior to trial initiation.

“These data underscore the potential of IOS-1002 to redefine how we target immune evasion in solid tumors,” added Dr. Reinhard Ambros, Chairman of the Board of Directors of ImmunOs. “We are looking forward to advancing this program into later-stage clinical development and exploring strategic collaborations.”

The trial is being conducted in accordance with ICH-GCP guidelines and is registered on clinicaltrials.gov. Further updates will be provided following the completion of the combination dose escalation phase and will be presented at upcoming scientific meetings.

KEYTRUDA® is a registered trademark of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.

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About ImmunOs Therapeutics AG
ImmunOs Therapeutics AG leverages its unique immune system modulating HLA-based technology platform to develop first-in-class therapeutics for the treatment of cancer and inflammatory diseases. ImmunOs’ lead program is a multi-functional HLA-fusion protein that binds specific LILRB (leukocyte immunoglobulin-like) and KIR (killer cell immunoglobulin-like) receptors and can stimulate both the innate and the adaptive immune systems of cancer patients to eliminate tumor cells. ImmunOs is also developing different modalities to agonize receptors for the modulation of the immune system in inflammatory diseases.
The Company is supported by leading international investors and is located in Schlieren, Switzerland. For more information, please visit www.immunostherapeutics.com.

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ImmunOs Therapeutics AG
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8952 Schlieren (Zurich Area), Switzerland
info@immunostherapeutics.com

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