A Study of SHY-ONC6, a Novel Proteasome Inhibitor, in Adults With Advanced or Metastatic Solid Tumors

Inclusion Criteria:

* Male or female ≥18 years of age.
* Life expectancy \>3 months.
* ECOG performance status 0-1.
* Histologically/cytologically confirmed advanced or metastatic solid tumors that have progressed on or are intolerant/unsuitable for standard therapies. Eligible tumor types: TNBC, HR+ breast cancer, colon cancer, gastric cancer, HCC, NSCLC (adeno and squamous), mesothelioma, pancreatic cancer, HRPC, soft tissue sarcoma; other tumor types after Medical Monitor discussion. Stable CNS metastases ≥4 weeks post-radiotherapy and off steroids ≥14 days are permitted.
* ≥1 measurable lesion per RECIST v1.1 (prostate cancer with bone-only disease and elevated PSA assessed by PCWG3).
* Accessible tumor for biopsy
* Adequate organ/bone marrow function.
* Willingness and ability to provide informed consent.
* Negative serum pregnancy test and use of effective contraception through 90 days after last dose for women of childbearing potential.
* Male participants must use barrier contraception or abstinence and not donate sperm through 90 days after last dose.

Exclusion Criteria:

* High-risk cardiovascular disease.
* Concurrent anti-cancer treatment.
* Active infection requiring systemic treatment within 2 weeks pre-dose.
* History of another malignancy (with standard exceptions for in situ disease, non-melanoma skin cancers, and remission ≥2 years).
* Active HBV (HBV-DNA \>ULN), HCV (HCV-RNA \>ULN), or HIV (well-controlled HIV with CD4 ≥350 cells/µL and undetectable viral load permitted); AIDS-defining opportunistic infection within 12 months.
* Compromised pulmonary function within 6 months pre-dose .
* Pregnancy or breastfeeding.
* Recent radiotherapy, systemic anti-tumor therapy, other investigational therapy without appropriate washout.
* Major surgery ≤4 weeks pre-dose.
* Unable to swallow tablets or conditions affecting GI absorption.
* Any medical or psychiatric disorders affecting compliance and/or interpretation of study results.
* Persistent toxicities from prior anti-cancer therapy (exceptions apply)
* Clinically significant corneal disease.
* Unable to comply with prohibited concomitant medication restrictions.