RYZ401-101: A Phase 1 First-in-Human (FIH), Dose Escalation and Dose Expansion Study of RYZ401, a Novel Radiopharmaceutical Therapy Labeled with Actinium-225 (225Ac), in Subjects with Neuroendocrine Tumors (NETs) and Other Selected Solid Tumors Express…

Inclusion Criteria:
*  At least 18 years old at the time of signing the main study informed consent form (ICF).
*  Histologically confirmed: Dose Escalation (all cohorts): Grades 1-3 WD, metastatic or locally advanced and unresectable NET at any primary site, including, but not limited to, GI, pancreatic, lung, thyroid, breast, urogenital, and adrenal tumors.
*  Dose Expansion Cohort A: Grades 1-3 WD, metastatic or locally advanced and unresectable GEP-NETs
*  Dose Expansion Cohort B: metastatic or locally advanced and unresectable tumors known to frequently express SSTR, limited to the following indications:
*  WD NETs (Grades 1-3) from primary sites other than gastrointestinal and pancreatic (including, but not limited to, lung, thyroid, breast, urogenital, and adrenal tumors) Meningioma (Grades 1-3)
*  SSTR-positive disease, as assessed by SSTR-PET imaging
*  Adequate renal, hematologic and hepatic function

Exclusion Criteria:
*  Prior RPT, including Lu-177.
*  Prior solid organ or bone marrow transplantation.
*  Use of chronic systemic steroid therapy.
*  Significant cardiovascular disease
*  Resistant hypertension
*  Uncontrolled diabetes
*  Prior history of liver cirrhosis
*  HIV, hepatitis B infection or known active hepatitis C virus infection. Note: Additional criteria may apply and will be assessed by the study site