A Dose Escalation Study in Solid Tumors and a Dose Expansion Study of PRN1371 in Adult Patients With Metastatic Urothelial Carcinoma

Inclusion Criteria:

* Age ≥ 18 years
* Histological or cytological documentation of an advanced solid tumor
* Subject must have metastatic or recurrent disease and have failed first-line systemic treatment, and if indicated, failed approved second-line therapy, and for whom no standard therapy options are anticipated to result in a durable remission
* Subject must have evaluable, progressive, and measurable disease per the Response Evaluation Criteria in Solid Tumors (RECIST) guidelines, Version 1.1
* Adequate bone marrow, liver, and renal function
* Patient has an Eastern Cooperative Oncology Group (ECOG) performance status ≤ 1

For Part B (expansion) in subjects metastatic urothelial carcinoma:

* The patient's tumor has been evaluated and prospectively identified as having FGFR 1, 2, 3, or 4 genetic alterations.

Exclusion Criteria:

* Patients who have received adequate prior treatment with a highly selective FGFR inhibitor
* Patients with other major uncontrolled medical conditions, e.g., recent myocardial infarction, stroke, diabetes, active hepatitis
* Patients who have received prior systemic anticancer therapy ≤ 3 weeks prior to study start (6 weeks for nitrosourea, antibodies, or mitomycin-C)
* Patients diagnosed with another primary malignancy within 3 years prior to study start, with the exception of adequately treated basal cell carcinoma, squamous cell carcinoma, or other non-melanomatous skin cancer, or carcinoma in situ of the uterine cervix
* Patients with glioblastoma multiforme
* Patient has a primary neoplasm of the brain or known uncontrolled metastases to the central nervous system (CNS).