Tyverb gains first approval in US
pharmafile | March 14, 2007 | News story | Sales and Marketing | breast cancer
GlaxoSmithKline's breast cancer drug, Tyverb, has been approved in the US and could help women who have failed to respond to all other treatments.
The drug (known as Tykerb in the US) is the latest targeted drug developed to fight cancer, and may eventually prove a major advance in the therapy area.
The drug works in a similar way to Herceptin, but appears to have a number of advantages over Roche's drugs. Tyverb (lapatinib) could prove to be a major rival for Roche's blockbuster, and analysts predict peak sales in excess of $3 billion.
Like Herceptin, GSK's new drug targets the sub-group of women with breast cancer who have an aggressive form of the disease, known as HER2 or ErbB2 positive.
Herceptin works by blocking the effect of the ErbB2 gene, which is associated with cancer that grows faster and spreads to other organs more quickly. But Tyverb could have significant benefits over Herceptin.
First, the new drug not only targets the ErbB2 receptor, but also the similar ErbB1 receptor, which is also associated with accelerated cancer growth. By blocking the stimulation of both genes, GSK hopes its drug could be even more effective than Herceptin.
Secondly, lapatanib is a small molecule drug taken as a once-a-day pill, making it easier to manufacture and more convenient for patients to take compared with Herceptin, which must be administered via intravenous infusion.
The US regulator has approved the drug to treat advanced breast cancer in women, in combination with capacitabine (Roche's Xeloda) in phase III trials, comparing it with capacitabine alone.
The combination treatment is for women whose condition has progressed despite prior therapy with other cancer drugs, including an anthracycline, a taxane, and Herceptin (trastuzumab).
"Tykerb is a significant breakthrough for women with advanced HER2 (ErbB2) positive breast cancer," said Paolo Paoletti, head of the Oncology Medicine Development Centre at GSK.
"The data clearly show that this small molecule, oral, targeted agent, in combination with capecitabine, is effective for women whose disease has progressed on previous therapies, including anthracyclines, taxanes and trastuzumab. The approval of Tykerb demonstrates our R&D organisation's strong commitment to the discovery and development of novel cancer treatments.
"We are dedicated to the further study and development of Tykerb in a variety of settings, including adjuvant breast cancer as well as in other solid tumor types."
Results from trials in 2006 were so positive that an independent monitoring committee halted the trial in order to allow all women on the trial the choice of receiving the dual therapy.
Advanced breast cancer
By the time women are first diagnosed with breast cancer, between 10-20% are already in the advanced stages of the disease, with either locally advanced tumours or a metastatic tumour spreading the cancer to other organs.
Currently, the median survival time for these women is just two years, and GSK hopes Tyverb will prove to be an advance in treating these women.
GSK has not released extensive details of the trial results for Tyverb but has confirmed that the drug significantly exceeded its primary endpoint of a 50% increase in the time to disease progression (TTP).
GSK says it is using advanced technologies, including pharmacogenetics to determine which patients will respond the most to the new drug.
The most commonly reported side effects related to Tyverb include diarrhoea, nausea, vomiting and rash. 'Hand-foot syndrome' was also observed in some patients – a side-effect seen in some chemo regimes, which can include numbness, tingling, swelling and discomfort of hands and feet.
A significant downside to Herceptin treatment is the significantly increased risk of cardiotoxicity when combined with other treatments, which leads to congestive heart failure in some cases.
If large-scale trials of Tyverb could show an absence of these side-effects, it would prove to be a major advantage over Herceptin.
So far, Tyverb trials have shown "generally reversible" decreases in heart function in a small number of patients, but its full safety profile will only emerge after launch.
The drug was filed with the European regulator in October last year, and its decision is likely to be announced in next few months.
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