This is a Phase 1a/1b Clinical Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Preliminary Efficacy of SG301 in Patients with Relapsed or Refractory Multiple Myeloma and Other Hematological Malignancies

After a screening period of up to 28 days for each study phase, qualified patients will be enrolled to receive their assigned dose of SG301, administered weekly for the first 2 cycles and every 2 weeks thereafter, until disease progression or intolerable toxicity, starting of a new anticancer treatment, withdrawal of consent, lost to follow up, death, or end of the study, whichever occurs first.

The study consists of a dose escalation phase (Phase 1a) and a dose expansion phase (Phase 1b) in subjects with relapsed or refractory multiple myeloma and other hematological malignancies.

Inclusion Criteria:

1. Understand and voluntarily sign the informed consent form (ICF).

2. Age ≥18 years.

3. Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0, 1 or 2.

4. Expected survival time of ≥3 months.

5. Patients with histologically or cytologically confirmed hematological malignancies who are relapsed or refractory to or intolerant of standard therapies.

   For patients with multiple myeloma: should be relapsed or refractory multiple myeloma with measurable disease

6. Adequate organ function

7. Toxicity caused by prior anti-tumor therapy recovered to Grade 0 to 1 (CTCAE 5.0), except for alopecia, controlled Grade ≤2 sensory neuropathy, lymphocytopenia, and endocrine disorders.

8. Female patients of childbearing potential and male patients whose female partners are of childbearing potential need to use at least one approved contraceptive (e.g., intrauterine device, pill, or condom) during study treatment and for at least 6 months (180 days) after the last dose; female patients of childbearing potential must have a negative blood human chorionic gonadotropin (HCG) test during screening period and must not be lactating.

Exclusion Criteria:

Patient Exclusion Criteria:

1. Presence of central nervous system metastatic lesions.
2. uncontrolled cardiac disease requiring treatment, congestive heart failure NYHA III or IV, unstable angina pectoris even if medically controlled, history of myocardial infarction during the last 6 months.
3. Active infection requiring antimicrobial therapy within 2 weeks prior to study drug administration.
4. Patients with active viral hepatitis (any etiology) are excluded.
5. Anticancer therapy within 5 half-lives or 2 weeks (whichever is longer)
6. Primary refractory to previous anti-CD38 therapy.
7. Major surgery within 4 weeks prior to study entry.
8. Prior or concurrent malignancy within 2 years prior to entry, other than adequately controlled skin basal cell carcinoma, cervical carcinoma in situ, breast carcinoma in situ, skin squamous cell carcinoma.
9. Any other condition that, in the opinion of the Investigator, may lead to inappropriate participation in this study.