Can you help me with the gene therapy?

!) Step, in this sentence, means progression. It means that there has been really good progress in the experiments done in this subject.

2) This expression means that science has done a good job at creating medicine that is still not available at this time, but hopefully will be in the future.

For 1, step means advance or the latest and, for 2, it means the most futuristic or progressive. An alternative for 2 might be tomorrow's medicine.

Idiomatic or metaphorical idea of "step", as in an advancement along a path, just like taking a step on a path toward your house when walking home.  The medicine of the future is, literally, the medicine which will exist in the future.  The general idea is usually that the future thing already exists in a beginning form at this moment.  Kind of like a two-year old boy is the man of the future.  It exists in a form now, but not its final form yet. 

What will be comes from what is now, but is not the same as what is now.  It changes while becoming what will be.