Vaccine Promotes Immune Response in Ovarian Cancer

Jeffrey C. Goh, MBBS

Interim data from a phase II clinical study of the dendritic cell vaccine CVac in patients with epithelial ovarian cancer showed promising signs of improving progression- free survival (PFS) compared with the observational standard of care, according to results presented at the 14th Biennial International Gynecologic Cancer Society (IGCS) meeting in Vancouver, Canada.

The CAN-003 trial is seeking to assess the safety and efficacy of CVac in patients with stage III or IV cancers who were in complete remission after surgical intervention followed by first- or second-line chemotherapy, with PFS among its primary endpoints and overall survival and immunologic response as secondary objectives.

CVac is made by harvesting the patient’s autologous dendritic cells and then pulsing the cells with mucin 1 (MUC1)- glutathione S-transferase, a recombinant human fusion protein. The charged dendritic cells are then reinjected intradermally into the patient to stimulate a T-cell response targeting MUC1-overexpressing cells. The treatment regimen in the CAN-003 trial consisted of seven doses four weeks apart, followed by three doses eight weeks apart.

In all, 63 patients were enrolled in the trial, including 42 who were in first remission and 21 in second remission. The first seven patients were treated with CVac without randomization, while the next 56 patients were randomized to receive either CVac or observation without treatment.

As of the data cutoff, the median PFS was 365 days for patients who received CVac, 421 days for the initial nonrandomized vaccine recipients, and 321 days for the observation arm. A further breakdown indicates the median PFS for patients in first remission was 326 days in the CVac arm but not yet defined for the observation group; by contrast, the median PFS had not yet been reached for those in second remission who took CVac, while the observation arm had a median PFS of 145 days.

In addition, three patients whose immune response was analyzed after their first three doses displayed a MUC1-specific T-cell response, measured as a percentage of CD4-positive or CD8-positive cells.

Researchers said the vaccine was “very well-tolerated,” with only one of seven serious adverse events (SAEs) related to treatment. Five SAEs in the vaccine arm included disease progression, abdominal pain, small bowel obstruction, and febrile neutropenia. In the observation arm, two SAEs consisting of one abdominal pain and one hematoma/ respiratory failure leading to death occurred.

“The initial immune monitoring data are representative of the type of response necessary to mount an effective immune response against cancer,” lead author Jeffrey C. Goh, MBBS, of the Royal Brisbane and Women’s Hospital in Queensland, Australia, said in a press release as the data were presented on October 15. “And the trends in progression-free survival are very encouraging. This interim dataset is consistent with expectations for a potentially effective immune therapy to treat ovarian cancer.”

Prima BioMed Ltd, based in Sydney, Australia, is developing the vaccine. Patients currently are being recruited for the CAN-004 (CANVAS) study, an international phase III trial that will seek to accrue 1000 patients in nearly a dozen countries, including the United States.

Goh JC, Gray H, Berek JS, et al. Clinical study of autologous dendritic cell therapy targeting mucin-1 for treatment of ovarian cancer in first or second remission. Poster presented at: 14th Biennial International Gynecologic Cancer Society (IGCS); Vancouver, Canada; October 13-16, 2012. A-473-0008-00583.