Drug development expenses have been going up while FDA approvals of new drug treatments have been going down. We know more about biology now than in the past so this increased understanding should make us more efficient and effective at finding new and improved treatments. This could be a low hanging fruit problem where we found the easier treatments and new treatment are getting harder to find. One of the main problems stopping new drug treatment approvals is side effects.
To develop new drugs we identify a gene->protein target in a disease pathway, develop an assay that measures the activity of the gene->protein and test chemicals that down regulate or up regulate the gene target that affect other genes->proteins as little as possible. Finding a chemical compound that only affects the target and nothing else is quite difficult.
A non-repetitive sequence of 20-25 nucleic acid base pairs is unique in the human genome. This means a biologic drug like an siRNA, anti-sense RNA or gene therapeutic is our best method to uniquely target a single gene and best chance to reduce side effects of new treatments.