ASCO - Roche's Herceptin receives useful endorsement in gastric cancer

The power of predictive biomarkers was amply illustrated by a study of Roche’s Herceptin in gastric cancer at Asco, a study that is almost certain to immediately change clinical practice and have big implications for HER2 positive patients.

The addition of Herceptin to chemotherapy significantly extended the survival of patients with HER2 positive advanced gastric cancer, and is the first targeted agent to establish efficacy in this setting. As the high cost of biologics becomes increasingly hard to justify even in the big spending US market, this sort of study, identifying the patients who will benefit from treatment, is to be welcomed.

Patients with advanced gastric cancer already have a limited life expectancy; for this study almost 4,000 were screened, with around 22% testing positive for HER2. The study, called ToGA, looked at 584 patients with HER2 positive gastric cancer, who were given either chemotherapy and herceptin, or chemotherapy alone.

Patients in the active arm had a 26% lower risk of death, whilst median survival was prolonged by nearly three months, to 13.8 months, compared with 11.1 months in the chemotherapy arm. A subset of patients had even longer survival, of up to 17 months.

“This is a practise changing study, and exciting for a group of patients with poor prognosis,” said Dr Sonali Smith, Associate Professor of Medicine at the University of Chicago Medical Center.

Common cause of death

Gastric cancer is the second most common cause of cancer-related death worldwide, and the fourth most diagnosed, with around a million cases a year. Of those cases around 20% are likely to carry the HER2 positive gene. It is relatively rare in the US and Europe; 56% of new cases derive in East Asia, particularly in China and Japan.

Five year survival ranges from 20%-50%, as by the time many patients are diagnosed the disease has already advanced locally or metastised more widely.

HER2, or the human epidermal growth factor, promotes cell growth and HER2-positive cells can contain many more receptors, promoting a particularly aggressive tumour. Therefore, like breast cancer HER2 positive is likely to be predictive of a poor prognosis in gastric cancer, although this has not been established in trials.

Matter of course

Prior to this study there had be no reason to test patients for HER2 in gastric cancer, Dr Eric Van Cutsem, who ran the trial said, but now this should be offered as a matter of course.

For the Swiss pharma giant the impact of this study will not be huge. Many analysts were anticipating success and had already included sales in the indication in forecasts; the market opportunity is seen at around $450m.

Sales of Herceptin reached $4.71bn last year and are forecast to reach $5.80bn by 2014, according to consensus data from EvaluatePharma. Although the drug’s period of rapid growth is over, the antibody still ranks as Roche’s third biggest product, now and in 2014.

Those forecasts give Herceptin an NPV of $27.32bn, making it Roche’s second most valuable drug, behind Avastin. Therefore even if not providing a huge uplift, this study certain helps bolster one of Roche’s most important franchises.

Share This Article