Stemline Therapeutics Inc. has announced trial results of two clinical studies of direct injection synthetic peptide vaccine, now being developed as SL-701, in both adults and children with advanced brain cancer. SL-701 is comprised of synthetic peptides corresponding to epitopes of targets overexpressed on glioblastoma multiforme (GBM) and other high-grade and low-grade gliomas and administered via direct subcutaneous injection. The data were presented by investigators at the University of Pittsburgh (Pitt), who developed the direct injection synthetic peptide vaccine. In 2009, the University of Pittsburgh licensed patent rights relating to the vaccine to Stemline.
In the pediatric study conducted by the Pitt team and led by Dr. Ian Pollack, 27 children were enrolled, including 16 with newly diagnosed brainstem glioma (BSG), five with newly diagnosed cerebral high grade glioma (HGG), and six with recurrent gliomas. Children were treated with the Pitt synthetic peptide vaccine, administered via direct subcutaneous injection, every three weeks for up to eight courses. Among 22 evaluable children who were HLA-A2-positive, three had sustained partial responses (PRs) including one exceeding 15 months, one had prolonged disease free status following surgery, and 14 had stable disease lasting longer than three months. In addition, the results of ELISPOT immunological assays revealed specific T-cell responses to the intended targets in six of seven children evaluated. Systemic side effects were minimal. Tumor pseudoprogression, which is transient tumor enlargement due to inflammation followed by tumor stabilization or shrinkage, occurred in four children. The research team concluded that the direct injection synthetic peptide vaccine, now being developed by Stemline as SL-701, demonstrated both immunological and clinical activity in children with malignant glioma.
In the adult study, conducted at the University of Pittsburgh and other centers, adult patients with low-grade glioma (LGG) were treated with the Pitt vaccine via direct subcutaneous injection every three weeks for eight courses. Twenty-four HLA-A2-positive patients were enrolled, including 13 with newly diagnosed high-risk LGG without prior radiotherapy, one with newly diagnosed high-risk LGG with prior radiotherapy, and 10 with recurrent LGG. Side effects were minimal with one grade 3 fever. Sustained and specific immune responses, as assessed by ELISPOT assays, were observed in the majority of evaluable patients. The research team on the adult study led by Dr. Hideho Okada at Pitt, reported that, although a thorough evaluation of progression-free survival would require a longer observation period, among 17 patients who completed eight courses, 10 had stable disease. The team concluded that the Pitt vaccine, now being developed by Stemline as SL-701, was well tolerated and demonstrated immune responses in high risk adult patients with LGG.
Date: April 18, 2012
Source: Stemline Therapeutics Inc.
Filed Under: Drug Discovery