Asher Biotherapeutics Announces Two Presentations at the ASCO 2026 Annual Meeting Highlighting Clinical Progress Across Its CD8-Targeted Cytokine Pipeline
SAN MATEO, Calif., May 21, 2026 (GLOBE NEWSWIRE) -- Asher Biotherapeutics (Asher Bio), a clinical-stage biotechnology company developing precisely-targeted immunotherapies for cancer, today announced two upcoming presentations at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting from May 29 – June 2, 2026 in Chicago.
The presentations will include updated clinical data from the phase 1A/B study of AB248, Asher Bio’s investigational CD8+ T cell targeted interleukin-2 (IL-2) immunotherapy, alone and in combination with pembrolizumab in patients with advanced solid tumor malignancies, as well as a trials-in-progress report from the ongoing phase 1 study of AB821, Asher Bio’s CD8-targeted interleukin-21(IL-21) immunotherapy candidate, in patients with locally advanced or metastatic melanoma and other solid tumor malignancies.
“AB248 and AB821 were each designed to address historical limitations of cytokine therapy by selectively activating CD8+ T cells while avoiding the broader immune activation associated with conventional cytokines,” said Ivana Djuretic, Ph.D., chief executive officer and co-founder of Asher Bio. “Together, these programs are designed to selectively deliver complementary IL-2 and IL-21 biology to CD8+ T cells, with the goal of providing the proliferative and functional signals needed to drive potent antitumor immunity. Updated data to be presented at ASCO continue to support the differentiated profile of AB248, with robust and selective CD8+ T-cell expansion, encouraging antitumor activity in a heavily pretreated melanoma population and a tolerability profile that supports further evaluation. In addition, the evaluation and trial design for AB821 highlight the broader potential of our CD8-targeted cytokine platform, including the potential to use these drugs in combination with each other.”
AB248 (Etakafusp alfa)
As of the most recent data cutoff, AB248 demonstrates robust and dose-dependent pharmacologic activity, including preferential CD8+ T cell expansion of approximately 20-fold at higher dose levels. Importantly, this magnitude of CD8+ T cell expansion was achieved without vascular leak or a capillary leak-driven toxicity pattern, a key distinction from high-dose systemic IL-2, where capillary leak syndrome is a recognized dose-limiting toxicity. Across the phase 1A/B study, the most common treatment-emergent adverse events were predominantly grade 1 or 2 and self-limited.
Additionally, AB248 demonstrates anti-tumor activity in patients with immune checkpoint inhibitor-refractory melanoma. In the monotherapy arm, deep and durable responses were observed in two out of 11 patients with cutaneous melanoma treated at higher dose levels (0.3 – 0.5 mg/kg), representing an 18% objective response rate (ORR). In the combination arm with pembrolizumab, seven of 30 patients with IO doublet-refractory melanoma treated with 0.15 – 0.3 mg/kg AB248 achieved an objective response, including 30% of patients treated at 0.3 mg/kg. Activity was observed across melanoma subtypes, including cutaneous melanoma and more difficult-to-treat forms of the disease, such as mucosal and acral melanoma. A maximum tolerated dose (MTD) was not reached with step-up dosing, supporting further evaluation of dose optimization, including the potential to evaluate higher doses.
“These data are particularly encouraging given that patients enrolled in the melanoma cohorts had received extensive prior immunotherapy, including prior checkpoint inhibitor doublets,” said Harriet Kluger, M.D., Harvey and Kate Cushing Professor of Medicine (Oncology) and of Dermatology at Yale School of Medicine and chief of the Skin and Kidney Cancer Program at Smilow Cancer Hospital at Yale New Haven. “The observation of responses across cutaneous, mucosal and acral melanoma supports continued development of AB248 in combination with anti-PD-1 therapy, including additional dose optimization and expansion.”
AB821
Asher Bio will also present the trial design from the ongoing phase 1 study of AB821, an investigational CD8-targeted IL-21 immunotherapy candidate designed to selectively deliver IL-21 activity to CD8+ T cells. The ongoing study is evaluating AB821 as monotherapy in patients with recurrent locally advanced or metastatic melanoma and other immune-responsive solid tumors. Preliminary findings from approximately 10 patients enrolled to date suggest promising pharmacokinetic, pharmacodynamic, tolerability and clinical activity. Emerging results are consistent with preclinical data, including evidence of cis-targeting and pharmacodynamic effects on CD8+ T cells. An amendment evaluating AB821 in combination with AB248 is in development.
“Together, these presentations highlight an important step in advancing our CD8-targeted cytokine portfolio from platform biology into clinical translation,” said Edward Garmey, M.D., interim chief medical officer of Asher Bio. “The AB248 data continue to inform dose optimization and combination strategies for CD8-targeted IL-2, while the initial AB821 findings provide an early clinical view of CD8-targeted IL-21. Looking ahead, we are particularly interested in exploring how these complementary cytokine signals may be used individually and potentially together to deepen and extend antitumor responses while maintaining tolerability.”
ASCO 2026 Presentation Details
Title: Phase 1A/B study of AB248, a CD8+ selective IL-2 mutein fusion protein, alone or in combination with pembrolizumab, in patients with advanced solid tumor malignancies
Abstract Number: 2616
Poster Session: Developmental Therapeutics – Immunotherapy
Poster Board: 406
Date and Time: Saturday, May 30, 2026, 1:30 – 4:30 p.m. CDT
Title: Phase 1 clinical trial investigating the safety, pharmacokinetics, pharmacodynamics and antitumor activity of AB821 in adult patients with locally advanced or metastatic melanoma and other solid tumor malignancies
Abstract Number: TPS2687
Poster Session: Developmental Therapeutics – Immunotherapy
Poster Board: 466a
Date and Time: Saturday, May 30, 2026, 1:30 – 4:30 p.m. CDT
For more information on these and other abstracts, please visit the ASCO 2026 Annual Meeting website.
About AB248
AB248 is a novel CD8+ T cell selective IL-2, generated by fusing a reduced potency IL-2 mutein to an anti-CD8β antibody. It was specifically engineered to selectively and potently activate CD8+ T cells, which are the immune cells that drive antitumor efficacy, while avoiding natural killer cells, which can act as a pharmacological sink and contribute to toxicity, and regulatory T cells, which are immunosuppressive. Asher Bio is evaluating AB248 in a phase 1A/B clinical trial, AB248-101. The trial consists of a dose escalation and expansion phase to investigate the safety, pharmacokinetics, pharmacodynamics and antitumor activity of AB248 alone and in combination with pembrolizumab in subjects with locally advanced/metastatic solid tumors who failed prior therapies. AB248 is also being evaluated in combination with IMDELLTRA® (tarlatamab), Amgen’s DLL3-targeting Bispecific T-cell Engager (BiTE®) therapy, in an Amgen-sponsored phase 1b trial in patients with extensive-stage small cell lung cancer (ES-SCLC). Please refer to ClinicalTrials.gov, NCT05653882 and NCT07037758, for additional details related to these clinical trials.
About AB821
AB821 is a CD8-targeted IL-21 immunotherapy candidate designed to selectively activate CD8+ T cells, the immune cell type driving antitumor response. AB821 is a fusion protein combining a CD8+ T-cell targeting antibody with a modified IL-21 cytokine designed to prevent binding to other cell types that may drive toxicity or act as a pharmacological sink. In preclinical studies, AB821 enhanced CD8+ T-cell cytotoxicity and memory formation, with potential to reinvigorate exhausted immune responses and generate new antitumor activity, both as monotherapy and in combination with checkpoint inhibitors. AB821 is being evaluated in an ongoing phase 1 clinical trial in patients with recurrent locally advanced or metastatic melanoma and other immune-responsive solid tumors.
About Asher Bio
Asher Bio is a biotechnology company developing therapies to precisely engage specific immune cells to fight cancer. We utilize our proprietary cis-targeting platform to develop therapies engineered to overcome limitations of other immune-based treatments by selectively activating specific immune cell types with validated disease fighting functionality. Our candidates feature an antibody connected to a modified immunomodulatory protein, such as a cytokine. Our candidate design is intended to enable our candidates to selectively activate the desired immune cells and not other cells that contribute to toxicity or immune suppression. Our lead program, AB248, also known as etakafusp alfa, is an IL-2 fusion protein, and our second clinical program, AB821, is an IL-21 fusion protein. Both are designed to selectively activate CD8+ T cells through distinct and potentially complementary pathways and are currently being evaluated in phase 1 oncology trials.
Asher Bio is located in South San Francisco. For more information, please visit www.asherbio.com.
Source: Asher Biotherapeutics
Investors & Media Contact Noopur Batsha Liffick, MPH CFO / CBO noopur@asherbio.com
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