New data on an experimental drug combination being developed by Vertex Pharmaceuticals of Cambridge, Mass., should give hope to tens of thousands of people suffering from cystic fibrosis, the deadly lung disease that afflicts 70,000 people worldwide and kills most of them in their 20s. If the drug combo proves successful, it could also open up new avenues for genetic research to lead to treatments for terrible diseases, raising the possibility that pairs of drugs developed in tandem could succeed where single pills have failed.