Press release

Stockholm, Sweden, June 17, 2024

ALL PATIENTS WITH CONFIRMED TUMOR ANTIGEN-SPECIFIC T CELL REPONSES FOLLOWING VIDIDENCEL TREATMENT REMAIN ALIVE IN LONG-TERM FOLLOW-UP

Mendus AB ("Mendus" publ; IMMU. ST), a biopharmaceutical company focused on immunotherapies targeting tumor recurrence, announces that it has presented data from the ADVANCE II phase 2 trial with its lead product vididencel in acute myeloid leukemia (AML) during the annual European Hematology Association conference (EHA). The data confirm the potential of vididencel to stimulate functional immune responses in AML patients, comprising T cell and B cells. All patients with confirmed T cell responses against tumor antigens following vididencel treatment were alive in long-term follow-up at the time of read-out.

AML is an aggressive blood-borne tumor which is characterized by a high relapse rate and low overall survival. The ADVANCE II Phase 2 trial focuses on AML patients in first complete remission following intensive induction chemotherapy, who are diagnosed with measurable residual disease (MRD), which is associated with an increased relapse risk. At a median follow-up for the total study population of 31.6 months, the majority of patients (14/20) were alive and relapse-free survival stood at 30.4 months. Immune responses against at least one tumor antigen were observed in the majority of patients following vididencel treatment. The data presented at EHA specifically addressed which type of immune responses were most strongly associated with survival outcomes. The data showed significantly better survival in patients with a confirmed tumor antigen-specific T cell response, versus patients without such a confirmed T cell response. All of the patients with a confirmed T cell response remained alive in long-term follow-up at the time of read-out. Durable clinical remissions were also associated with increased levels of circulating B cells. The data indicate that functional immune responses following vididencel treatment involve both T cells and B cells and that the breadth of the immune response contributes to long-term disease control and survival in AML.
“The data presented at EHA deepen our understanding of vididencel as an immunotherapy for AML patients in need of maintenance treatment to prevent or delay disease relapse,” said Jeroen Rovers, CMO of Mendus. “The observation that functional immune responses occur in AML patients following vididencel treatment, despite the nature of the disease and preceding treatment with intensive induction chemotherapy, is encouraging. The date strongly supports the use of vididencel as a maintenance immunotherapy for AML, based on long-term survival benefit related to active immunity against residual disease.”

Please see below for abstract details:

Abstract Number:  P1437 (poster presentation)

Abstract Title: Long term survival in AML patients after immunotherapy with vididencel correlates with functional T and B-cell responses

Authors: Arjan van de Loosdrecht, Hester van Zeeburg, Jeroen Rovers, Jacqueline Cloos, Eva Wagner-Drouet, Uwe Platzbecker, Tobias Holderried, Catharina van Elssen, Aristoteles Giagounidis, Bjørn T. Gjertsen

Session Date & Time: Friday, 14 June 2024 between 18:00 – 19:00 CEST

Peripheral blood samples were collected at baseline and different time points up to 32 weeks following start of vididencel treatment. IFNg ELISPOT assays were used to detect functional T cell responses against well-documented AML antigens (WT-1, RHAMM and PRAME).
The majority of patients (17/20) showed at least one vaccine-induced T-cell response. A significantly better overall survival (OS) was observed in patients with two or more T-cell responses at different time points toward at least one of the antigens tested (confirmed T cell response), versus patients without such a confirmed response (p = 0.005, log rank statistical test between groups). In addition, detailed analysis using multiparametric flow cytometry was performed, to distinguish > 100 immune cell subsets for each patient at each timepoint. Distinct differences were observed between patients with durable clinical remissions and patients who relapsed. Overall survival was associated with increased B-cell levels, suggesting an important role for vididencel-induced B-cell responses in the control of residual disease. The data substantiate a link between the use of vididencel and the potential to induce a functional T cell and B cell-mediated immune response, leading to long-term survival in AML.
The poster presented at EHA can be viewed on the Mendus website.