Does progressive MS respond the same to available disease modifying treatments?

In some cases. The most robust benefit of currently available treatment appears to be in the earlier phases of relapsing forms of ms. As times goes on, and with the development of progressive disability, there is a less obvious physical or cognitive benefit from such agents. While inflammation never ceases, loss of pathways in the central nervous system drives progressive loss of function.
Area of challenge. First, the disease modifying therapies on the market currently highly vary in terms of efficacy, and there is no current approved drug for primary progressive ms, and only mitoxantrone for secondary progressive, which i will not use due to high risks and modest efficacy. A non-approved drug, rituxamab, holds some promise for spms, and Gilenya (fingolimod) is being studied for ppms. One study maybe betaseron.
Multiple sclerosis. With the exception of novantrone, the available disease modifying therapies are only effective on relapsing remitting multiple sclerosis.