• Updated DOC1021 data in newly diagnosed glioblastoma show 90% 12-month overall survival in a predominantly MGMT-unmethylated population, accompanied by immune analyses suggesting immune memory.
• DOC1021 is now also enrolling in a refractory melanoma clinical study, targeting a population with limited options after anti-PD-1 failure.

HOUSTON, June 5, 2026 /PRNewswire/ -- Diakonos Oncology Corp., a clinical-stage biotechnology company developing a new generation of immunotherapies to treat challenging and aggressive cancers, today announced the presentation of two posters at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, Illinois. The presentations feature updated pooled data from the Company's Phase 1 study and expanded access protocol with DOC1021 (dubodencel) in glioblastoma (GBM), as well as the initiation of a Phase 1/2 study (DOC-RM) evaluating DOC1021 in patients with refractory melanoma.

"ASCO provides an important opportunity to share the continued clinical development of DOC1021 across multiple difficult-to-treat cancers," said Jay Hartenbach, President and Chief Operating Officer of Diakonos Oncology. "The pooled GBM data reinforce our confidence in the program, with strong 12‑month survival in a predominantly MGMT unmethylated population, a subgroup associated with poorer outcomes and limited treatment responsiveness. We're also pleased to introduce our melanoma program, where DOC1021 may offer a differentiated approach to re-engaging the immune system in patients who progress after anti‑PD‑1 treatments."

ASCO Poster Presentations Key Highlights:

Glioblastoma
Abstract Title: Pooled Analysis of Phase I and Expanded Access Study Cohorts of DOC1021 (dubodencel) in Combination with Chemoradiation for Glioblastoma

Updated results combine patients from the Phase 1 study and expanded access protocol, evaluating DOC1021 together with standard therapy in both newly diagnosed and recurrent GBM.

• In newly diagnosed patients, overall survival is 18.5 months (8.7 to 38.4 months), with a 90% 12-month survival rate. In recurrent GBM, survival ranged from 10.2 to 22 months post-second surgery. Survival continues to be monitored.
• There were no dose-limiting toxicities, with a similar safety profile between studies.
• Immune analyses showed consistent activation of memory T cells, supporting a sustained immune response.
• A randomized Phase 2 trial is currently enrolling at over 15 clinical sites to further evaluate DOC1021 plus standard of care versus standard of care alone in newly diagnosed GBM.

"This pooled dataset provides important insights into the clinical outcomes and immune responses observed with DOC1021 in glioblastoma," said Dr. Jay-Jiguang Zhu, MD, PhD, Study Investigator at UTHealth Houston (Department of Neurosurgery). "The findings, including the 12-month survival outcomes observed in a predominantly MGMT-unmethylated patient population, support continued investigation of this approach. The ongoing randomized Phase 2 study builds directly on these results and represents an important next step in further evaluating the safety and efficacy of DOC1021 in newly diagnosed glioblastoma."

Refractory Melanoma
Abstract Title: A Phase I/II Clinical Study of DOC1021 (dubodencel) Dendritic Cell Immunotherapy for Refractory Melanoma: Trial in Progress

The Trial-in-Progress poster describes the rationale and design for DOC-RM, an ongoing multi-center Phase 1/2 study evaluating DOC1021 in patients with unresectable or metastatic melanoma who have progressed after prior therapies, including anti‑PD‑1. The study is supported by Diakonos Oncology and a Product Development Research Grant from CPRIT.

• The trial includes an initial safety cohort followed by an expansion phase to evaluate tumor response, where patients will receive two courses of DOC1021 with pegylated interferon, and an optional booster approximately six months later.
• Preclinical data showed improved tumor responses in multiple models, including B16F10 melanoma, supporting exploration in PD‑1 refractory disease.
• The clinical study is now actively enrolling at leading cancer centers, including City of Hope, the University of Alabama at Birmingham, and Massachusetts General Hospital.

"Patients with unresectable or metastatic melanoma who progress after anti-PD-1 therapy have limited treatment options, highlighting the need for continued investigation of new immunotherapy approaches," said Alexandra (Lexi) Haugh, MD, MPH, Principal Investigator at Massachusetts General Hospital Cancer Center for the DOC-RM study. "DOC1021 utilizes an individualized dendritic cell-based strategy designed to present a broad range of patient-specific tumor antigens, and avoids the need for myeloablative chemotherapy and IL-2. We're excited to begin and help evaluate the safety and feasibility of this approach for patients with refractory melanoma."

About DOC1021

DOC1021 is a first-in-class, patient-derived double-loaded dendritic cell therapy that combines tumor lysate and amplified tumor-derived mRNA. The immunotherapy is made with a patient's own dendritic cells combined with mRNA and proteins prepared from freshly obtained patient tumor specimens.

The unique double-loading approach, a physiologic mimic of viral infection, unlocks a synergistic and exponentially more powerful tumor killing response that permits complete targeting of the total cancer antigen pool. Moreover, the approach does not require any molecular modification or genetic engineering of the patient's immune cells and does not require preconditioning chemotherapy or high dose IL-2 for administration. DOC1021 is designed for outpatient administration and broad access via community cancer centers.

Diakonos currently has three actively enrolling clinical trials evaluating DOC1021, including a Phase 1 pancreatic cancer study (NCT04157127), a Phase 2 glioblastoma (GBM) study (NCT06805305) and a Phase 1/2 study in refractory melanoma (NCT07288112) supported by the Cancer Prevention and Research Institute of Texas (CPRIT). The U.S. Food and Drug Administration (FDA) has granted Fast Track designation to DOC1021 for the treatment of pancreatic cancer, GBM, and unresectable or metastatic cutaneous melanoma, reflecting the significant unmet medical need across these indications. Diakonos also received Orphan Drug Designation for the GBM program in January 2024.

About Diakonos Oncology Corp.
Based in Houston, TX, Diakonos Oncology Corp. is a clinical-stage biotechnology company dedicated to revolutionizing cancer immunotherapy with its proprietary double-loaded patient-derived dendritic cell therapeutic platform. The company is focused on addressing critical, unmet medical needs in late-stage, aggressive, and lethal cancers. For more information visit: https://www.diakonosoncology.com

Media Contact:
David Schull
Russo Partners
858-717-2310
david.schull@russopartnersllc.com

Jay Hartenbach
Diakonos Oncology
pr@diakonosoncology.com

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SOURCE Diakonos Oncology