herceptin and the brain

[gdpawel]

A study from Dana Farber Cancer Institute identified (as many as 34%) central nervous system metastases (brain mets) in women who receive Herceptin therapy for metastatic breast carcinoma. Patients receiving Herceptin as first-line therapy may develop brain metastases while responding to or stable on Herceptin.

The research doesn't necessarily suggest that Herceptin causes breast cancer spread to the CNS, but instead that CNS mets are common to Her2-positive patients and that more than likely, because Herceptin doesn't cross the blood-brain barrier (BBB), the drug while effective outside the CNS cannot treat cancer inside the CNS, or stop it from spreading there.

Monoclonal antibodies like Herceptin are enormous. Very large molecules don't have a convenient way of getting access to the large majority of cells. Plus, there is multicellular resistance, the drug affecting only the cells on the outside may not kill these cells if they are in contact with cells on the inside, which are protected from the drug. The cells may pass small molecules back and forth (in the same way that neighbors can share food).

Exciting results have come from studies of multitargeted tyrosine kinase inhibitors, small molecules that act on multiple receptors in the cancerous cells, like Tykerb and Sutent. Maybe Tykerb or Sutent may be better than Herceptin.