Vaccine May Slow Advance of Breast, Ovarian Cancers

This report is part of a 12-month Clinical Context series.

By Kurt Ullman, Contributing Writer, MedPage Today
Published: November 08, 2011
Reviewed by Vandana G. Abramson, MD; Assistant Professor of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee.

â–*Note that in this pilot study of 26 patients with advanced breast or ovarian cancer, a recombinant poxviral vaccine resulted in a decrease in serum tumor markers and/or stable disease in a subset of patients.

Ovarian and breast cancer patients with limited tumor burden and minimal prior chemotherapy may benefit from a recombinant poxviral vaccine, according to researchers with the National Cancer Institute (NCI).

Among 12 patients with breast cancer who were given the vaccine, median time to progression was 2.5 months (range: 1 to 37+ months) with a median overall survival of 13.7 months (range: 2.7 to 42.9), reported James L. Gulley, MD, and colleagues from the Laboratory of Tumor Immunology and Biology at NCI.

For 14 ovarian cancer patients who received the vaccine, median time to progression was two months (range: 1 to 6 months) with median overall survival of 15.0 months (range: 1.5 to 57+ months), the authors wrote in the Nov. 15 edition of Clinical Cancer Research.

The 26 patients in the trial had either metastatic breast (n=12) or ovarian cancer (n=14) which had progressed following standard therapy, or they were patients who were not candidates for standard therapies. Enrollees also were required to have an Eastern Cooperative Oncology Group performance status of 0 or 1.

Participants were given monthly injections with PANVAC vaccines expressing tumor-associated antigens (TAA) for carcinoembryonic antigen (CEA) and mucin-1 along with three T-cell costimulatory molecules.

These patients were also heavily pretreated. Of the 26 patients, 21 had three or more previous rounds of chemotherapy.

Side effects were generally mild. Injection-site reactions were most commonly reported.

Among the breast cancer patients, five started the trial with elevated serum CEA levels, with two showing a decrease. Four of the patients had stable disease.

Among the ovarian cancer patients, two showed declines in serum CA-125, an antigen found on the surface of many ovarian cancer cells,

"In the study reported here, some patients who had limited tumor burden and whose immune system was not compromised by multiple rounds of chemotherapy seemed to benefit from the vaccine," the authors wrote.

They also noted that some patients showed good clinical responses to subsequent therapies following the study. This suggests that once a vaccine triggers a response from the immune system, it may start a "prolonged, dynamic process" that could lead to increased responses to any following therapy.

Many of the patients had already progressed by their first scheduled restaging. The researchers pointed out that previous studies have shown a lag of at least a few months before an optimal immune response.

Therefore, they theorized, reported progression may not reflect the effect of the vaccine, but an ongoing process before the immune system has had an adequate time to ramp up a response. They suggested that overall survival may be a better endpoint than time to progression or tumor shrinkage.

Gulley and colleagues stressed that this was a pilot study, but did say that their results confirm that other studies are warranted.

http://www.medpagetoday.com/clinical-co ... ncer/29538