Vertex Pharmaceuticals (NASDAQ: VRTX) has made a fortune developing medicines for cystic fibrosis (CF), a rare disease that causes damage to the lungs. The company is awaiting approval for exa-cel -- a therapy for the blood disorder sickle cell disease -- which it developed in combination with CRISPR Therapeutics. Recently, these two longtime partners announced a new deal to target another disease, type 1 diabetes (T1D).