How DPX-Survivac works
DPX-Survivac is composed of survivin-based synthetic peptide antigens and an adjuvant (a therapy applied together with another cancer treatment to increase its activity) encapsulated in nanoscale lipid particles. Survivin is a tumor-associated antigen (TAA) or protein that is found in tumors at much higher levels than normal.
When administrated, DPX-Survivac creates a depot at the injection site from which the survivin antigens and adjuvant are released and exposed to the immune system for an extended period of time. This provokes a strong immune response against cancer cells that make survivin, and ultimately results in the decrease of tumor cell proliferation and induces the death of tumor cells.
Immune system cells called T-cells that are exposed to survivin have been shown to specifically target and kill cancer cells that express survivin while not having any effect on normal cells.
Survivin is found in high levels in a variety of human cancers including ovarian, breast, colon and lung cancers, while absent in most normal adult cells. DPX-Survivac could therefore potentially benefit patients with these types of cancer.
DPX-Survivac in clinical trials
The safety and immunogenicity (the ability to trigger an immune response) of DPX-Survivac was tested in 30 patients with ovarian cancer in a Phase 1/1B clinical trial (NCT01416038) with or without an accompanying low dose of oral Cytoxan (cyclophosphamide). The results showed that DPX-Survivac was well-tolerated and led to a sustained and high immune response against tumor cells when combined with a low dose of Cytoxan.
A Phase 2 study (NCT02323230) assessed the efficacy and safety of DPX-Survivac plus low-dose Cytoxan in patients with recurrent diffuse large B-cell lymphoma (DLBCL) who were not eligible for a transplant.
Early results from the trial suggested that the two-drug combo did increase the number of T-cells in the tumors, suggesting a stronger immune response. However, the team also discovered high levels of another protein in tumor cells that was likely limiting the anti-tumor activity of the vaccine. Another compound was added to the combo therapy to prevent this result, and the trial is now investigating the effectiveness and safety of the three-drug combo therapy.
Another Phase 1B trial (NCT02785250) is assessing the safety, tolerability, and effectiveness of DPX-Survivac, combined with epacadostat and low-dose Cytoxan in patients with progressive recurrent ovarian cancer.
Preliminary results showed that the combination therapy appears to have an acceptable safety profile. The researchers observed signs of increased T-cell activity in the tumors in three patients and stable disease with signs of tumor shrinkage in one patient. The trial is currently recruiting patients in the U.S. and Canada.
Finally, a Phase 2 trial (NCT03029403) will test the combination of DPX-Survivac plus Keytruda and Cytoxan in patients with advanced epithelial ovarian, fallopian tube, or primary peritoneal cancer. The study is not yet open for recruitment, but aims to enroll 40 patients in Canada.
DPX-Survivac has been granted fast track designation by the U.S. Food and Drug Administration (FDA) as a maintenance therapy in individuals with advanced ovarian, fallopian tube, and peritoneal cancers. The vaccine has also received orphan drug status from the FDA and the European Medicines Agency (EMA).
Fast track designation accelerates the review of therapies for serious conditions with unmet medical needs.
Orphan drug designation helps companies develop products for rare diseases (those that affect fewer than 200,00 people in the U.S.) by giving them incentives such as tax credits or exemption from FDA user fees, assistance in clinical trial design, and potential market exclusivity for up to seven years, if the drug is approved.
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