The primary objectives are to determine the recommended Phase 2 dose (RP2D) and optimal treatment regimen, characterize safety and tolerability, and evaluate preliminary efficacy of RYZ401 in subjects with NETs and other selected solid tumors expressing SSTRs.

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