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

The study is a dose escalation study. The protocol specifies rules for dose-limiting toxicity
and a maximum tolerated dose (MTD). To gain further experience with the MTD, and/or at some
lower optimal biologic dose level, an expansion cohort (Part B) will be enrolled in patients
with metastatic urothelial carcinoma with fibroblast growth factor receptor (FGFR) 1, 2, 3 or
4 genetic alterations.

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).