• ALISON trial data presented at ASCO demonstrate broad immune activation and support further evaluation of vididencel in combination approaches to improve durable disease control

• Five participants of the trial remained progression-free at long-term follow-up, including two beyond 3.5 years

• Vididencel-induced immune responses correlate with long-term progression-free survival and involve multiple immune compartments

Mendus AB (publ; IMMU.ST) reported additional positive results from the Phase 1b ALISON trial in high-grade serous ovarian cancer (HGSOC) at the world’s largest cancer conference, ASCO 2026, in Chicago, USA. The data show that vididencel induces broad anti-tumor immune responses associated with improved progression-free survival, supporting its potential as a combination immunotherapy for this difficult-to-treat cancer.
 
Ovarian cancer is the deadliest gynecological cancer largely due to its high rates of recurrence and the emergence of treatment-resistant disease following initial therapy. The ALISON Phase 1b trial evaluates vididencel as an active immunotherapy in late-stage HGSOC, with the aim to improve the durability of clinical responses and prolong progression-free survival (PFS). The study enrolled 17 women diagnosed with HGSOC, who were treated with six intradermal vididencel injections following standard chemotherapy and surgery. At a median follow-up of 26.4 months, 11 patients had reached the predefined 2-year survival follow-up, 8 patients were alive of whom 5 were still in long-term PFS, including 2 beyond 3.5 years of follow-up.
 
The ALISON trial is part of an ongoing collaboration between Mendus and the University Medical Center Groningen, The Netherlands (UMCG) to study novel immunotherapies for gynecological cancers. Mendus and UMCG had previously reported stimulation of tumor-directed T cell responses following vididencel treatment, which were associated with improved PFS in HGSOC. The immune profiling data presented at ASCO reveal that vididencel-induced immune responses involve multiple compartments of the immune system, including dendritic cells, B cells and memory NK cells.
 
“After initially showing that vididencel has the potential to stimulate tumor-directed T cells, we have now taken the next steps in deciphering the immune signatures of the samples collected during the ALISON trial,” said Professor Marco de Bruyn, Head of the Immuno-oncology research group at UMCG. “B cells have been suggested to play an important role in the control of gynecological cancers and there is a growing interest in the role of other cell types such as memory NK cells. It is therefore encouraging that we observe an increase of these cell populations following vididencel treatment, which may contribute to long-term disease control.”
 
“Recurring tumors in ovarian cancer are among the hardest-to-treat cancers and new therapeutic options to prolong clinical responses and extend survival without harming health or quality of life will therefore have a major impact on prospects for women diagnosed with this fatal disease,” said Mendus Chief Medical and Scientific Officer Tariq Mughal. “The ALISON trial data presented at ASCO reveal the breadth of the immune responses following vididencel treatment, combined with an excellent safety and tolerability profile. This provides a basis to study vididencel in combination with other approved and upcoming treatment modalities, including PARP inhibitors, antibody-drug conjugates (ADCs) and bispecific antibodies.”
 
The findings of the ALISON trial confirm the proposed mechanism of action for vididencel as an active immunotherapy that stimulates immune control over residual cancer cells and extend previous observations in other tumor settings characterized by residual disease following initial treatment. The company’s clinical development strategy remains focused on myeloid blood cancers, while further clinical development of vididencel in combination with other therapeutic modalities in HGSOC will be subject to partnering.