A Phase Ia/Ib Study of HW221043 in Participants With Advanced Solid Tumors

Inclusion Criteria:

* Men or women ≥18 years old.
* Histologically and/or cytologically confirmed recurrent or metastatic advanced solid tumors.
* Absence of available standard therapy, failure of standard therapy, or ineligibility for standard therapy.
* Survival expectation is ≥12 weeks.
* Adequate major organ function at screening; no blood transfusion or hematopoietic growth factor administration within 14 days prior to screening; and no significant abnormalities in hematology, coagulation profiles, or blood chemistry.
* Eastern Cooperative Oncology Group (ECOG) performance status 0 to 1.
* Presence of at least one measurable target lesion as defined by RECIST 1.1
* Participants are willing to provide tumor tissue samples.
* Participants of childbearing potential must be non-pregnant at screening. Male and female of childbearing potential must agree to use effective methods of contraception throughout the study.
* Participants must have demonstrated a full understanding of the study, voluntarily signed the informed consent form (ICF), and be willing and able to comply with all study procedures and required follow-up visits.

Exclusion Criteria:

* Allergic to HW221043 Tablet or its components.
* Has a treatment history of KIF18A inhibitor.
* Known presence of a recognizable hypermutated phenotype.
* Prior receipt of any unapproved investigational drug or therapy within 28 days before first dose.
* Inadequate washout from prior antitumor therapy.
* Use of any medication that may interfere with the safety conduct of the study within 14 days prior to the first dose (or within at least 5 half-lives of the agent, whichever is longer), or planned use of such medications during the study period.
* Continuous use of systemic corticosteroids within 4 weeks prior to the first dose.
* Live vaccination within 28 days prior to first dose or anticipated during the study.
* Major surgery within 28 days prior to the first dose of the investigational product.
* Major surgical procedure within 28 days prior to first dose.
* History of another active malignancy within 3 years prior to initiation of the investigational product.
* ≥ Grade 2 prior antitumor therapy-related toxicity per CTCAE v6.0 (except abnormalities deemed clinically insignificant).
* Tumor invasion into adjacent vital organs, major vessels, or central nervous system (CNS), or evidence of progressive brain metastases.
* Presence of severe underlying pulmonary disease, severe cardiac/cerebrovascular disease, or clinically significant QTc prolongation.
* Presence of an active infectious disease.
* Diagnosis of an autoimmune disease or presence of an immunodeficient state.
* Inability to swallow oral medications, or uncontrolled nausea, vomiting, diarrhea, or other gastrointestinal dysfunction likely to affect drug absorption.
* History of alcohol abuse or substance abuse.
* Women who are pregnant, breastfeeding, or planning to become pregnant/ breastfeeding during the study.
* Any condition that, in the judgment of the Investigator, would make the participant unsuitable for enrollment.