This study is a first-in-human Phase 1, open-label, multicenter, dose escalation study with
      dose expansion to identify the maximum tolerated dose (MTD), the recommended phase 2 doses
      (RP2D) and to evaluate the safety, tolerability, and preliminary anti-tumor activity of
      STRO-001 in adult subjects with B-cell malignancies (MM and NHL) who are refractory to, or
      intolerant of, all established therapy known to provide clinical benefit for their condition
      (i.e., trial subjects must not be candidates for any regimens known to provide clinical
      benefit). The study will consist of two parts: Part 1, dose escalation, and Part 2, dose
      expansion.

      The study uses an accelerated dose titration design for dose escalation. Doses will be
      escalated using an N-of-1 per dosing cohort until the first instance of a treatment-related,
      clinically relevant Grade 2 non-hematologic toxicity or a Grade 3 hematologic toxicity of any
      type is observed during Cycle 1 (first 21 days). Following this a standard 3+3 trial design
      is used for all further escalation cohorts. Dose escalation is conducted independently for
      the two dose escalation tumor cohorts (MM and NHL). A recommended STRO-001 dose for expansion
      will be determined for MM and NHL.

      The dose expansion (Part 2) portion of the study will begin when Part 1 is completed.
      Enrollment in dose expansion will include separate tumor cohorts of MM and NHL.

      In both Part 1 and Part 2 of the study, STRO-001 will be dosed as an intravenous (IV)
      infusion on Day 1 of a 21-day cycle, until disease progression. Labs will be drawn on a
      weekly basis for Cycles 1-4, and every three weeks starting with Cycle 5. Weekly clinical
      evaluations will be conducted during the first 4 cycles; thereafter, clinical evaluations
      will be conducted on infusion days (Day 1 of each cycle). Samples for pharmacokinetics (PK)
      analysis will occur at specific times on Days 1, 2, and 8 of the first two cycles of
      treatment, Day 1 of the third cycle of treatment and at End of Treatment visit. Additional
      clinical evaluations and labs may occur at the discretion of the investigator.

      Subjects who receive any dose of STRO-001 will be included in safety analyses. Disease
      evaluations will include peripheral blood analysis, bone marrow assessments and scans as
      appropriate. Disease status will be evaluated per MM-specific or NHL-specific criteria.
      Samples will be collected to assess the PK and immunogenicity of STRO-001. Biomarkers may be
      assessed from bone marrow, peripheral blood and/or tissue samples. Subjects will continue to
      receive study drug until disease progression, unacceptable toxicity, withdrawal of consent,
      or end of study (study completion).