On February 2, 2022 Medigene AG ( View Source) (Medigene, FSE: MDG1, Prime Standard), a clinical-stage immuno-oncology company focusing on the development of T-cell-based cancer therapies, reported that promising preliminary efficacy and immune monitoring data from the Phase I part of the Phase I/II clinical trial of Medigene’s T cell receptor-modified T cell (TCR-T) therapy MDG1011 in patients with advanced-stage blood cancers (ClinicalTrials.gov Identifier: NCT03503968 ( View Source)) (Press release, MediGene, FEB 3, 2022, View Source [SID1234607703]). Data demonstrating safety and tolerability, with no cases of dose-limiting toxicity (DLT) associated with MDG1011, were published in December 2021.
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MDG1011 is a TCR-T immunotherapy directed against the tumor antigen PRAME (PReferentially expressed Antigen in MElanoma). Patients with relapsed or refractory acute myeloid leukemia (AML), myelodysplastic syndrome (MDS) or multiple myeloma (MM) were included in the open-label, dose-escalation Phase I part of the study that was conducted at nine clinical centers in Germany. Following standard pre-conditioning, patients received MDG1011 as a single intravenous infusion at specified dose levels of 0.5, 1 or 5 million TCR-transduced T cells per kg body weight. The primary study objectives were to evaluate safety, tolerability, and feasibility to manufacture autologous MDG1011 TCR-T cells for heavily pretreated patients. In addition, preliminary signs of clinical efficacy and immune monitoring data were investigated.
Clinical and biological data analysis
MDG1011 contained CD8+ TCR-T cells showing recognition and killing of specific standardized target cells in vitro and was successfully manufactured for 13 patients. The group of patients included ten with AML, two with MM and one with MDS. Four patients succumbed to disease before treatment could be administered, in line with the severity of the underlying condition of study patients. Thus, nine patients received MDG1011 at one of the three specified dose levels.
Patient immune monitoring included detection of PRAME-specific T cells (MDG1011 TCR-T cells) in blood to determine persistence over time and biomarker tracking of PRAME in bone marrow and/or blood (as an indicator for remaining cancer cells) by qPCR.
* One patient with AML treated at the lowest dose experienced complete remission at week 4 after treatment; however, this clinical response was not sustained, and the patient’s disease progressed 8 weeks thereafter. PRAME expression was slightly increased from baseline at week 4 whereas MDG1011 TCR-T cells were below the detection level.
* Two patients with AML, treated at the intermediate and highest dose respectively, experienced transient grade 1 or 2 cytokine release syndrome (CRS) within 3 days of drug administration, providing evidence of biological activity of MDG1011 therapy in vivo. MDG1011 TCR-T cells were still detectable in both patients at week 4.
* One patient with multilineage MDS and myeloproliferative neoplasm (MPN) treated at the highest dose, remained without apparent progression to secondary AML 3 and 6 months after MDG1011 administration and is still monitored. MDG1011 TCR-T cells were found at weeks 4, 8 and 12 and were still present at lower levels at month 6 after treatment. Bone marrow could not be evaluated in this patient. PRAME signals in blood were no longer detected at week 4 but gradually increased thereafter at 2, 3 and 6 months, remaining clearly below the baseline level. In concordance, blast counts both in blood and bone marrow remained well below baseline.
* MDG1011 TCR-T cells were detected in six of eight evaluable patients at one or more time points within four weeks after administration. TCR-T cells were also present in two patients at later time points, albeit at decreased levels.
* The biomarker PRAME was assessed in bone marrow samples from five patients four weeks after MDG1011 administration compared to baseline. PRAME decreases occurred in three AML and one MM patient while a slight increase was noted in another patient with MM. PRAME decreased in blood at week 4 for two patients treated at the highest dose but increased thereafter.
The preliminary clinical observations in two patients and occurrence of CRS in a further two of the nine heavily pretreated cancer patients are both encouraging and consistent with expectations of an adoptive T cell therapy. These observations are corroborated by the immune monitoring data.
Prof. Simone Thomas, from the Department of Internal Medicine III of the University Hospital Regensburg and Leibniz Institute for Immunotherapy, Principal Investigator of the study: "No immune effector cell-associated neurotoxicity syndrome (ICANS) or DLTs were detected, so MDG1011 appears to be safe and well-tolerated at all three doses. The aforementioned clinical observations taken together with the effect on PRAME levels and the persistence of MDG1011 strongly support the hypothesis of biological activity of MDG1011."
Prof. Dolores Schendel, Chief Executive Officer and Chief Scientific Officer at Medigene: "We are very pleased that all MDG1011 TCR-T drug products manufactured from such heavily pre-treated patients with a substantial disease burden showed strong functional activity in vitro, leading to detectable biological and/or clinical activity in four patients.
The effects of PRAME-specific TCR-T immunotherapy on cancer cells should be further investigated based on this safe and well-tolerated treatment. The use of higher cell numbers as well as the treatment of patients with less advanced disease stages could further increase the clinical benefit in the future. Based on our strategic shift to development of TCR-T immunotherapy for solid cancer, Medigene has announced previously that the Phase II part of this study will only be conducted with or by a partner; based on overall results from the Phase I part of the study.
Our current development programs in solid cancer concentrate on TCR discovery for novel tumor-specific antigens and implementation of innovative tools to enhance efficacy and improve safety of T-cell-based immunotherapies."