The main purpose of this study is to find out whether the study drug, LY4050784, is safe, tolerable and effective in participants alone or in combination with other anticancer agents. In addition, with locally advanced or metastatic solid tumors with a BRG1 (Brahma-related gene 1, also known as SMARCA4) alteration who have previously received, do not qualify for, or are refusing standard of care treatments, or there is no standard therapy available for the disease. The study is conducted in two parts - phase Ia (dose-escalation) and phase Ib (dose-optimization, dose-expansion). The study will last up to approximately 4 years.

The main purpose of this study is to learn more about the safety, side effects, and effectiveness of LOXO-435 by itself or when it is combined with other standard medicines that treat cancer. LOXO-435 may be used to treat cancer of the cells that line the urinary system and other solid tumor cancers that have a change in a particular gene (known as the FGFR3 gene). Participation could last up to 30 months (2.5 years) and possibly longer if the disease does not get worse.