Impressive early anti-tumour activity and a therapy-leading safety profile seen in heavily pretreated patients across multiple B-cell lymphoma subtypes

Objective response rate of 53% in 17 efficacy evaluable patients, including responses in patients previously treated with CD19-directed CAR-T cell therapy

Iksuda Therapeutics (Iksuda), the developer of class leading, antibody drug conjugates (ADCs), today announces the presentation of preliminary data from the dose escalation portion of its Phase 1 study of IKS03, a CD19-directed ADC, in patients with advanced B-cell non-Hodgkin lymphoma (B-NHL), at the 68th American Society of Hematology (ASH) Annual Meeting, December 12–15, 2026, New Orleans, Louisiana.

As of 8 July 2026, 21 patients (median age 67 years) with a median of four prior lines of therapy (range 2-8) have been treated with IKS03 across five dose levels up to 3.1 mg/m²(approximately 84µg/kg). A maximum tolerated dose (MTD) has not been reached.

IKS03 showed a highly differentiated and manageable safety profile, with treatment-related adverse events (TRAEs) affecting only seven of 21 patients. Compared with other treatments across modalities, there was a markedly lower frequency of high-grade neutropenia and thrombocytopenia and an absence of peripheral neuropathy. A single Grade 4 neutropenia (4.8%), a dose-limiting toxicity, was observed in the fourth dose cohort in a patient with follicular lymphoma and bone marrow involvement, and who had previously received six prior regimens including CAR-T. On resolution, the patient remained on therapy and in response. There were only two Grade 3 neutropenia events, and all remaining TRAEs were mild or moderate (Grade 1–2). No patient experienced a Grade 5 event or a treatment-related serious adverse event, and none stopped treatment because of an adverse event. Non-haematological toxicity was both limited and low-grade.

Responses to treatment were observed from the lowest dose level (around 20 µg/kg) and across all dose cohorts. Of 17 patients evaluable for efficacy (those who had completed two treatment cycles across the first four dose levels), nine responded, giving an overall objective response rate (ORR) of 53%, with two patients achieving stable disease. Five patients (29%) achieved a complete metabolic response: two with follicular lymphoma and one each with diffuse large B-cell lymphoma, marginal zone lymphoma and T cell/histiocyte-rich large B-cell lymphoma. Four patients (24%) achieved a partial metabolic response, two each with follicular lymphoma and marginal zone lymphoma.

Responses were seen in patients who were CAR-T naïve, as well as in those who had received prior CAR-T (3 of 4 patients), including a durable complete response in a patient who had received 8 prior regimens which included failed responses to CAR-T and allogeneic transplantation. Of the eight patients who did not respond, five were being treated for Richter-transformed diffuse large B-cell lymphoma, well known to be highly aggressive and difficult to treat.

Responses have lasted up to 14 months. Currently, six of the nine responders eligible for efficacy assessment at the time of writing remain on treatment. Dose escalation is ongoing and updated results will be presented at the convention.

Dr. Dave Simpson, Chief Executive Officer, Iksuda Therapeutics, commented: “These first clinical data for IKS03 are incredibly exciting. To see responses in patients treated from the lowest dose level and across all cohorts, in heavily pretreated patients including those who had previously received CD19-directed CAR-T therapy, is immensely rewarding, whilst the safety profile is distinct from all other therapies in use for these cancers. These results support the design strategy of tumour-selective payload release, and we look forward to onward progression of this exciting program.”

Prof. Enrico Derenzini, European Institute of Oncology IRCCS, Milan, added: “Patients with relapsed or refractory B-cell lymphoma who have already received several lines of treatment have limited options. To see responses at this early stage, alongside a manageable safety profile, is encouraging and supports further evaluation of IKS03.”

The Phase 1 study (NCT05365659) is a first-in-human, multicentre trial of IKS03 in patients with relapsed or refractory B-NHL who have received at least two prior systemic therapies. Part I (dose escalation) uses a 3+3 design to determine the MTD and recommended Phase 2 dose in patients with CD19-positive follicular, marginal zone, mantle cell, large B-cell (including Richter-transformed) or high-grade B-cell lymphoma. Part II will assess efficacy in disease-specific expansion cohorts. Around 140 patients are expected to be enrolled across the study.

Presentation details
Abstract number: 5456
Title: First-in-human phase 1 trial to determine safety and preliminary antineoplastic activity of IKS03, a CD19-targeting PBD prodrug antibody drug conjugate, in advanced B-cell non-Hodgkin lymphomas
Presenter: Prof. Enrico Derenzini
Session Name: 629. Aggressive Lymphomas, Non-Cellular Immunotherapy including Bispecific Antibodies: Poster III
Session Date: December 14, 2026
Session Time: 12/14/2026 6:00:00 PM - 12/14/2026 8:00:00 PM
Presentation Time: 12/14/2026 6:00:00 PM - 12/14/2026 8:00:00 PM
Room: MCCNO - Hall F

About IKS03

IKS03 is a best-in-class CD19-targeting ADC delivering a tumour-activated prodrug pyrrolobenzodiazepine (PBD) which was licensed from LigaChem Biosciences (formerly LegoChem Biosciences). Preclinical testing demonstrated best-in-class efficacy (vs in-clinic and marketed CD19-targeted therapies) in in vivo xenograft models and significantly raised maximum tolerated dose (MTD) in non-human primate disease models, demonstrating its potential to be the leading anti-CD19 therapy in B-cell cancers.

About Iksuda Therapeutics: www.iksuda.com

Iksuda Therapeutics is a clinical stage, UK-based biotechnology company focussed on the development of class leading ADCs targeting difficult-to-treat haematological and solid tumours. Iksuda’s pipeline of ADCs is centred on a portfolio of prodrug ADCs which utilise tumour-selective release and activation of payloads, incorporating proprietary and in-licensed (from LigaChem Biosciences) prodrug and linker technologies in combination with stable conjugation chemistries including its proprietary PermaLink® platform. The early pipeline incorporates Iksuda’s proprietary, first-in-class protein alkylating payload class, ‘ProAlk™. The Company’s design concepts for ADCs are now clinically validated to significantly improve the therapeutic index of this important modality and improve the outcomes for patients living with cancer.

View source version on businesswire.com: https://www.businesswire.com/news/home/20261104379955/en/

Iksuda Therapeutics
Dave Simpson, Chief Executive Officer
Tel: +44 (0) 191 6031680
info@iksuda.com

FTI Consulting (Financial Media and IR)
Simon Conway / Natalie Garland Collins / Amy Byrne
Tel: +44 (0) 020 3727 1000
Iksuda@fticonsulting.com

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