A Study of Mirdametinib on Its Own or in Combination With Fulvestrant in People With Solid Tumor Cancer

Dose Level -2INT: 2mg PO BID, 3 weeks on/1 week off Dose Level -2: 2mg PO BID given continuously Dose Level -1INT: 3mg PO BID, 3 weeks on/1 week off Dose Level -1: 3mg PO BID given continuously Dose Level 1: 4mg PO BID given continuously Dose Level 2: 6mg PO BID given continuously Dose Level 3: 8mg PO BID given continuously

"The starting dose of mirdametinib in combination with fulvestrant in each Dose Level will be as follows:~* Dose Level 1: mirdametinib 4 mg BID PO + fulvestrant~* (Only to be triggered pending DLTs on higher Dose Levels as described below)~ * Dose Level -2: mirdametinib 2 mg BID PO continuous + fulvestrant, and Dose Level -2INT: mirdametinib 2 mg BID PO on 3 weeks on, 1 week off + fulvestrant"