Eligibility requires: 1) Age ≥18 years with confirmed R/R T-ALL or AML (treatment-refractory to standard therapies); 2) ECOG 0-2; 3) Room air oxygen saturation ≥92%; 4) Protocol compliance commitment; 5) For reproductive-age patients: negative pregnancy test (females) and agreement to use dual contraception methods (both sexes) throughout study participation. Bone marrow confirmation of disease status is mandatory for enrollment.

Key inclusion criteria: 1) Relapsed/refractory multiple myeloma (RRMM) refractory to proteasome inhibitors, immunomodulators, and anti-CD38 therapy; 2) Measurable disease by serum/M-protein, FLC assay, or ≥30% clonal plasma cells; 3) ECOG 0-2; 4) Room air oxygen saturation ≥92%; 5) Protocol compliance commitment; 6) Contraception adherence. All participants must have progressed after multiple prior lines of therapy.

Key inclusion criteria require: 1) Age ≥18 with relapsed/refractory MM after ≥3 prior therapies (including PI, IMiD, and anti-CD38); 2) Measurable disease per IMWG criteria (serum M-protein ≥0.5g/dL, urine M-protein ≥200mg/24h, or abnormal FLC ≥10mg/dL); 3) ECOG 0-2; 4) Protocol compliance; 5) For reproductive-age patients: negative pregnancy test (females) and agreement to use highly effective contraception until 6 months post-treatment.

Pharmacokinetic analysis will quantify plasma concentrations of total anti-CD38 antibody, conjugated toxin (STI 6129), and free toxin (duostatin 5.2) over 2 years. Additional endpoints include: determination of RP2D in phase 1b; progression-free survival (PFS); overall survival (OS); time to first response (TTR); duration of response (DOR); and clinical benefit rate (CBR) - all assessed over the 2-year study duration.

Inclusion Criteria: Confirmed diagnosis of AL amyloidosis by tissue biopsy of an involved organ, or a surrogate site such as abdominal fat demonstrating amyloid deposition by mass spectrometry. The presence of a monoclonal light chain protein in serum. Relapsed or refractory AL amyloidosis is defined as patients who have received ≥ 2 lines of treatment. Patients must have received at least one proteasome inhibitor during their prior therapy. Patients who have received prior daratumumab treatment or prior stem cell transplantation remain eligible. Patients may have relapsed with disease progression or have been refractory to their last prior line of treatment. Progression of disease that develops > 60 days after the last dose of a treatment regimen in a patient who achieved at least a partial response (PR) defines a relapse. Refractory systemic AL amyloidosis is defined as the development of disease progression during therapy with an anti-AL amyloidosis treatment regimen or within 60 days of the last dose of an anti-AL amyloidosis treatment regimen or the achievement of less than a PR after ≥ 2 cycles. Measurable disease defined as the finding by serum-free light chain (FLC) assay that the difference between the involved and uninvolved FLC (dFLC) is ≥ 50 mg/L. Pulse oximetry ≥ 92% on room air. ECOG performance status of 0, 1, or 2. Willing to comply with the study schedule and all other protocol requirements. Females of childbearing potential (FCBP) must have 2 negative pregnancy tests prior to treatment. All heterosexually active FCBP and all heterosexually active male patients must agree to use effective methods of birth control throughout the study.

Overall hematological response rate according to ISA consensus criteria [Time Frame: Every three weeks from day 1 to day 63, and bi-monthly for up to a year.] Complete Response (CR), Very Good Partial Response (VGPR), Partial Response (PR), Stable Disease (SD) and Progressive Disease (PD). Organ response rate according to ISA consensus criteria [Time Frame: Every three weeks from day 1 to day 63, and bi-monthly for up to a year.] Heart (by NT-proBNP or NYHA staging); Kidney (by creatinine and creatinine clearance and 24-hr urine protein), Liver (by serum alkaline phosphatase and liver size) and electromyogram for peripheral nerve system. Correlation of treatment response with disease severity based on the ISA 2012 consensus staging system [Time Frame: Every three weeks from day 1 to day 63, and bi-monthly for up to a year.] Disease staging is by how many hematologic and organ involvement criteria are exceeded. Determine plasma levels of STI-6129, total anti-CD38 antibody and Duostatin 5.2 [Time Frame: Day 1 to day 63] Measurement by ELISA and Mass Spectrophotometry Assays.