Combo therapy could tackle drug-resistant cancer

Using two drugs instead of just one could help cancer patients whose tumours do not respond to standard treatment, researchers said on Wednesday.

When they tested the combination therapy in mice with a type of lymphoma that is resistant to standard therapy, it caused complete remission in all the animals.

If tests in humans show it is safe and effective, scientists at the Cold Spring Harbor Laboratory in New York believe it could provide a new strategy for overcoming drug resistance in many forms of cancer.

"Our results provide in vivo (living) validation for a strategy to reverse drug resistance in human cancers," Scott Lowe, the head of the research team, said in a report in the science journal Nature.

Chemotherapy drugs work by triggering a self-destruct programme in cancerous cells, but some do not respond to the toxic treatments and continue to replicate and form tumours.

Lowe and his team decided to use two drugs to deliver a "one two punch" as in boxing to knock out the drug-resistant cells. They found than rapamycin combined with the chemotherapy drug doxorubicin resulted in massive death of lymphoma cells in mice.

The tumours disappeared quickly and the mice tolerated the combination therapy well.

Mice treated with the therapy had lymphomas containing a protein called Akt that inactivates the cell death mechanism in cancerous cells, which make them resistant to the chemotherapy drugs.

The researchers found that rapamycin blocked the action of Akt and restored the cell death mechanism, which the second drug triggered to deliver the knock-out punch.

Lymphoma includes a variety of cancers of the lymphatic system. The two main types of lymphoma are Hodgkin's disease and non-Hodgkin's lymphoma.

The disease can be treated with surgery, radiotherapy, chemotherapy and immunotherapy or a combination of treatments.

SOURCE: Nature, March 18, 2004.