GlaxoSmithKline and Merck & Co have been extolling the virtues of their respective cervical cancer vaccines as the battle for market share starts to heat up.

GSK has presented new data at the Society of Gynaecologic annual meeting in Tampa, Florida, which shows that the firm’s Cervarix provides significant protection for women against the four most common cancer-causing human papillomavirus types for nearly six and a half years, “the longest duration of protection reported to date”. Over this time, the jab showed 100% efficacy in preventing precancerous lesions due to virus types 16 and 18 and “substantial protection” against infection caused by virus types 31 (60%) and 45 (78%).

James Tursi, director of medical affairs for GSK in North America, said the study results are important “because women remain at risk for infection with cancer-causing virus types throughout their lives, and long-term protection will be an essential component of a successful vaccination strategy". The firm will be hoping that the data will convince the US Food and Drug Administration to give its approval to Cervarix so that it can soon start making inroads into the market there that is currently a monopoly operated by Merck & Co with Gardasil.

Cervarix got the green light in Europe last October but two months later, the FDA said it wanted more information before it will approve the jab. The problem is not thought to be one of safety or efficacy and GSK hopes that approval for Cervarix will happen around the middle of this year.

Drop in abnormal Pap tests with Gardasil
Back to the Tampa meeting and a researcher at the University of Alabama at Birmingham presented data which showed that a significant drop in abnormal Pap (smear) test results happened after girls and women were given Gardasil. This suggests that the Merck jab appears to prevent the development of cell changes that lead to cervical disease.

The results, which are a compilation of three separate trials involving more than 18,000 women aged 16 to 26, in the USA, Europe and Asia, showed that Gardasil reduced abnormal Pap test results by 43% compared to women not given the vaccine. The reduction was for tests that found pre-cancerous changes called high-grade squamous intraepithelial lesions more than three years after women were given the vaccine. Gardasil reduced other abnormal Pap results, including milder pre-malignant cell changes, by 16%-35%.

Presenting the data, Warner Huh said that while the findings are not definitive that Gardasil prevents cancer, they do signal the vaccine will spare thousands of women a diagnosis of cell abnormality or malignant changes that may lead to more tests and possibly surgery.

“Clearly the vaccine’s benefits include something that can be appreciated by women and daughters fairly quickly,” Prof Huh said. “This is a positive first sign, and it will take many more years to know definitively if the vaccine prevents cancer.”