NEEDHAM, Mass. ( TheStreet) -- A clerical error has cost Celldex Therapeutics ( CLDX) the opportunity to present data on its breast cancer drug CDX-011 at the upcoming American Society of Clinical Oncology (ASCO) annual meeting. This is hard to believe, but someone at Celldex clicked a wrong box on ASCO's online abstract submission form. As a result, ASCO rejected the CDX-011 abstract. Celldex appealed but ASCO refused to make an exception, the company says. Doh! With its ASCO invite revoked, Celldex has decided to hold a webcast on May 23 at which topline results from the phase II study of CDX-011 in advanced breast cancer will be made public. Dr. Linda Vahdat of Weill Cornell Medical College and the principal investigator of the CDX-011 study will speak on the Celldex call. She must be thrilled at the opportunity. Wouldn't you rather present important breast-cancer data on a company-organized webcast, rather than standing in front of hundreds of your oncology research peers at an ASCO session? Celldex shares are up 75% this year largely due to investors playing the run up into the anticipated ASCO presentation of the CDX-011 data. With CDX-011 data now coming sooner than expected, investors will have to adjust their Celldex trading strategy, including deciding whether to sell the stock once the study results are announced. (An early post-ASCO "sell the news.") Celldex shares closed Monday at $4.56. CDX-011 is a monoclonal antibody drug conjugate. The antibody portion targets cancer cells that express a protein known as GPNMB shown to correlate with poorer outcomes in breast cancer patients. When the CDX-011 antibody attaches to GPNMB-expressing tumor cells, it releases a toxic chemotherapy payload. This "drug conjugate" was licensed from Seattle Genetics ( SGEN) and is the same one used in the newly approved lymphoma drug Adcetris. The phase II "Emerge" study enrolled 124 patients with advanced breast cancer, randomizing them to treatment with CDX-011 or "investigator's choice" chemotherapy. During its May 23 webcast, Celldex is expected to release preliminary results, most notably response rate data and tumor progression data. --Written by Adam Feuerstein in Boston. >To contact the writer of this article, click here: Adam Feuerstein. >To follow the writer on Twitter, go to http://twitter.com/adamfeuerstein. >To submit a news tip, send an email to: email@example.com.