Pfizer has been demonstrating its credentials in cancer at the American Society of Clinical Oncology meeting in Chicago but the treatment that has most caught the eye is the brain cancer vaccine being developed by partner Avant Immunotherapeutics.

The firms presented data from two Phase II studies at ASCO on CDX-110, an experimental vaccine targeting a growth factor specific to tumours in patients with glioblastoma multiforme (GBM), the most common and aggressive form of brain cancer. There are an estimated 10,000 new cases of GBM annually in the USA, and the most high-profile potential patient for the vaccine is the Democratic senator Edward Kennedy who was diagnosed with a malignant glioma last month and has just undergone surgery.

In a ACT II study of 23 patients with GBM, patients receiving the vaccine lived an average of 33.1 months, compared with 14.3 months for patients receiving standard therapy. The time it took for tumours to recur also more than doubled to 16.6 months for patients treated with CDX-110. The jab was generally well-tolerated in the ACT II study, with side effects mainly reported as injection site reactions.

Avant is due to begin a mid-to-late-stage clinical trial, ACT III, to evaluate the vaccine in 90 patients at over 20 cancer centres in North America. However the firm noted that the Phase III portion of the trial will not open until data is available from Phase IIb and pending further discussions with the US Food and Drug Administration.

Another study, called ACTIVATE, of 21 newly-diagnosed GBM patients who had had surgical tumour removal and radiation therapy before starting the vaccine lived an average of 26 months compared with 15.2 months in patients on standard therapy alone. No significant adverse events were reported and the two studies led to a 28.3% rise in Avant shares to $17.98.

Aside from CDX-110, Pfizer said it expects to start seven Phase III studies of its cancer drugs this year, two of which open and enrolling, while five are planned to begin by the end of the year.

The trials involve three different compounds, notably the kidney cancer drug Sutent (sunitinib), which will be tested as a first-line hepatocellular cancer treatment and in second-line metastatic hormone refractory prostate cancer. Axitinib is going to be in Phase III trials for renal cell carcinoma and non-small cvell lung cancer, while CP-751,871 is being investigated for NSCLCin combination with gemcitabine and cisplatin

Since 2003, Pfizer has increased its number of oncology R&D projects by 400% and now dedicates 22% of its overall budget to the sector. The company has 22 cancer compounds in a total of 232 ongoing or planned, sponsored, oncology clinical studies and noted that Pfizer’s presence at ASCO has expanded 10-fold since 2006, with 299 presentations on new agents this year, compared with only 26 two years ago.

“We are seeing our sustained efforts in oncology mature as our development programs continue to advance into late-stage clinical trials,” said Charles Baum, vice president of Pfizer Global R&D.