Shares of cancer drug developer, Celldex Therapeutics, Inc. (Nasdaq: CLDX) were up as much as 22 percent from Monday’s closing price, in morning trading on Tuesday after the company announced positive data for its cancer therapy CDX-1401.

“CDX-1401 represents a new generation of off-the-shelf dendritic cell targeted vaccines built upon excellent preclinical activity data,” said Tom Davis, M.D., Chief Medical Officer of Celldex Therapeutics in a statement. ““The initial data from this ongoing study confirm safety and immunogenicity even in patients with advanced cancer who have received multiple prior therapies. CDX-1401 has passed the initial Phase 1 hurdles and we look forward to forthcoming cohorts that will include additional TLR agonists in combination regimens.”

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CDX-1401 is a cancer vaccine designed to activate a patient’s immune system against cancers including melanoma and other cancers that are known to express the tumor antigen NY-ESO-1. The product consists of a fully human monoclonal antibody with specificity for the dendritic cell receptor, DEC-205, genetically linked to the NY-ESO-1 tumor antigen. Celldex has accessed NY-ESO-1 through a multi-year clinical research collaboration with the international Ludwig Institute for Cancer Research. By selectively delivering the NY-ESO-1 antigen to dendritic cells in the body, this product is intended to induce robust immune responses against the antigen-expressing cancer cells.

Here’s Forbes’ report on the data:

The data presented were from a Phase 1/2 dose-escalating clinical trial evaluating three different doses of the vaccine in combination with resiquimod , which is an activator of toll-like receptors 7 and 8 (TLR7/8) and stimulator of immune cells. The study has enrolled 20 patients with advanced cancer, of which 35% had confirmed NY-ESO-1 expression. Six patients maintained stable disease and were eligible for multiple cycles of the treatment regimen, including 4 patients who have received 3 or more cycles (6 weeks of treatment followed by a 6 week rest), with stable disease of up to 11.5+ months. The treatment was well tolerated and there were no dose-limiting toxicities. Robust anti-NY-ESO-1 immunity was induced with the majority of the patients developing anti-NY-ESO-1 antibody responses and 39% of the patients having increases in NY-ESO-1 specific T cell responses, including both CD4 and CD8 responses. Importantly, the T cell responses were directed against multiple regions of the NY-ESO-1 antigen.

Last month, Celldex’s partner Pfizer Inc (NYSE: PFE) pulled out of a strategic partnership to develop the vaccine, and the company said it now plans to develop it on its own.

The finding is yet another example of the potential of cancer immunotherapies — treatments that recruit the immune system to fight cancer.

Earlier this year, the U.S. Food and Drug Administration approved Dendreon Corp’s (Nasdaq: DNDN) prostate cancer therapy Provenge, the first cancer vaccine. Bristol-Myers Squibb Co’s (NYSE: BMY) immune system treatment ipilimumab also helped to extend the lives of patients with aggressive melanoma, the deadliest form of skin cancer for which there are few treatment options.