Health: other; individualized investigational treatment for certain patients suffering from a life-threatening or severely debilitating illness; provide for. Amends title & secs. 1, 2, 3, 4, 5, 6 & 7 of 2014 PA 345 (MCL 333.26451 et seq.) & adds sec. 2a.

HB 4789 expands Michigan's "Right to Try Act" to specifically cover personalized experimental treatments based on a patient's genetic data (like gene therapies or custom vaccines). It allows eligible patients with advanced, life-threatening, or severely debilitating illnesses - who have exhausted all FDA-approved treatments - to access these individualized treatments after obtaining written consent from their physician and providing detailed risk disclosures. The bill clarifies that manufacturers aren't required to provide such treatments but may charge for production costs, and it prohibits health insurers from denying coverage solely for recommending these treatments. This affects patients with serious conditions who qualify under the new definition of "individualized investigational treatment" and their healthcare providers.