Pfizer has given oncologists a first view of data from its Phase III trial of Sutent (sunitinib malate; formerly SU11248) showing that it doubled survival compared to placebo in patients with a rare form of stomach cancer.

The data, presented at the American Society of Clinical Oncology meeting, show that Sutent extended survival to nearly 20 months in patients with gastrointestinal stromal tumours (GIST) that had not responded to Novartis’ similar offering Glivec/Gleevec (imatinib mesylate), the first drug to be approved for this indication.

Glivec has been a real money-spinner for Novartis, initially launched as a treatment for chronic myelogenous leukaemia but latterly approved for GIST, which helped drive sales of the drug to just shy of $500 million dollars in the first quarter of this year [[21/04/05b]]. GIST patients who do not respond to Glivec currently have no further treatment options, although Novartis itself is developing a follow-up to Glivec – code-named AMN107 – to address this unmet medical need.

Pfizer announced in February that it was terminating the trial several months earlier than planned because of the robust response seen in Sutent-treated patients compared to those on placebo [[09/02/05c]].

Sutent, which works by simultaneously stopping the blood supply and directly attacking tumour cells, is also being investigated as a potential treatment for kidney cancer. At ASCO, Pfizer reported data from two Phase II trials that showed around 40% of patients with metastatic renal cell carcinoma responded to treatment with a reduction in tumour volume, with a further 23%-28% experiencing stabilisation of their disease. The drug will shortly enter a Phase III trial in this indication, said Pfizer.

Meanwhile, Sutent is also in development as a treatment for breast cancer, and yesterday ASCO saw data from another Phase II study indicating that the drug shrank breast tumours by more than 50% in seven out of 51 patients (15%).

The drug is given daily by mouth for four weeks, after which patients are given a two-week break from treatment in order to recover from side effects, which include fatigue, immune system suppression and anaemia.

At ASCO, Pfizer also reported positive new results for its breast cancer drug Aromasin (exemestane), suggesting that it has only modest effects on the skeleton when used to treat postmenopausal women with early breast cancer. The data could help Aromasin compete better with other members of the aromatase inhibitor class, including AstraZeneca’s Arimidex (anastrazole) and Novartis’ Femara (letrozole), as bone loss is a recognised side effect with these drugs.

Pfizer is spending 12% of its $8 billion dollar cancer budget in oncology, according to a Forbes report.