SELLAS Life Sciences Group, a biopharmaceutical company working to develop novel drugs to treat cancer and central nervous system (CNS) conditions, recently announced top-line results from the Phase 2 trial of its WT1 vaccine for patients with malignant pleural mesothelioma (MPM), a rare cancer often diagnosed in people who have been exposed to high levels of asbestos.
Data from the Phase 2 randomized, double-blinded clinical trial comparing a WT1 combination treatment to a control treatment revealed a clinically significant superior median overall survival rate (OS) in the WT1 vaccine group (39 months) compared to the control arm (18 months). The typical median OS in MPM patients currently receiving other treatment options ranges from 15 to 18 months. [In the trial, the WT1 analog peptides vaccine was combined with Montanide-adjuvant + Granulocyte-macrophage colony-stimulating factor (GM-CSF) in 39 patients, versus Montanide-adjuvant + GM-CSF in 39 patients; all MPM patients had previously completed combined modality therapy.]
Additionally, the WT1 cancer vaccine resulted in a median progression-free survival (PFS) of 11.5 months, more than the double of the PFS of 5.5 months observed in patients in the control arm. The researchers are continuing to track patient clinical outcomes.
As the trial was unblinded earlier than planned because the control arm was discontinued for futility, there was a smaller group of patients for the analyses as well as a shorter period for follow-up. During the study, the WT1 vaccine demonstrated a favorable tolerability and safety profile.
Marjorie G. Zauderer, MD, MS, FACP, principal study investigator and an attending physician in the Division of Thoracic Oncology at Memorial Sloan Kettering Cancer Center (MSK), stated in a press release, “MPM is a highly debilitating and often fatal disease, and patients deserve new treatments that have the potential to address current needs. These results, pending their replication in Phase 3 studies, can offer hope for patients with MPM.” Peter Maslak, MD, led the study at MSK, with the results showing that the median OS was not achieved at more than 50 months.
These and additional important data from ongoing WT1 vaccine Phase 2 clinical trials were recently presented during the 8th International WT1 Conference, held in Kyoto, Japan, by David A. Scheinberg, MD, PhD, creator of the WT1 vaccine.
Dr. Scheinberg also presented the clinical data of a recently finished Phase 2 clinical trial of the WT1 vaccine in a group of 22 adult patients with a diagnosis of acute myeloid leukemia (AML),a cancer of the myeloid line of blood cells characterized by the rapid growth of abnormal white blood cells that accumulate in the bone marrow and interfere with the production of normal blood cells. These results were presented during the 17th Annual International Congress on Chronic Myeloid Leukemia, held in Lisbon, Portugal.
Dr. Scheinberg stated, “The data being reported show strong potential for the use of the WT1 vaccine in both a solid tumor (MPM) and a hematopoietic cancer (AML) and importantly are consistent with previous data from pilot clinical studies of WT1 in similar patients. In the previous Phase 1 AML study, the WT1 vaccine resulted in a median overall survival of more than 5 years. I look forward to the further progress of this program.”
“We are grateful to the patients and their families participating in our clinical programs, and we are optimistic about the growing evidence supporting the activity and safety of our WT1 vaccine,” said Angelos M. Stergiou, MD, chairman and chief executive officer of SELLAS. “Based on these findings, we intend to commence both a pivotal Phase 3 trial in MPM patients and a pivotal Phase 3 trial in AML early next year. In addition, we also have an ongoing study in multiple myeloma with encouraging data, and we will shortly be opening a trial in combination with a PD-1 inhibitor in patients with ovarian cancer.”
The WT1 antigen is one of the most widely expressed cancer antigens in multiple malignancies. It has been ranked by the National Cancer Institute (NCI) as the No. 1 target for cancer immunotherapy. SELLAS’ WT1 vaccine is comprised of four modified peptide chains that induce a strong adaptive T-cell immune response (CD4+/CD8+ T-cells) against the WT1 antigen. Due to this immune response, the WT1 vaccine has the potential to complement currently available therapies by destroying residual tumor cells of cancers in remission and providing ongoing immune surveillance for recurrent tumors, thus keeping patients in remission and potentially having a significant survival benefit.