UBX-303061 in Subjects With Relapsed/Refractory B-Cell Malignancies

Key Inclusion Criteria

* Capable of giving signed informed consent
* Age ≥18 years
* ECOG performance status ≤2.
* Phase Ia (dose-escalation part only): Subjects with relapsed and/or refractory B-cell malignancies (CLL/SLL, DLBCL, FL, MCL, WM or MZL) who have received at least 2 prior therapies and for subjects with no available treatment options as per the Investigator's discretion.
* Phase Ib (dose-expansion only): Subjects with relapsed and/or refractory B-cell malignancies who have received at least 2 prior therapies and for subjects with no available treatment options as per the Investigator's discretion, and fit into one of the following groups: CLL/SLL or DLBCL or MCL or FL, WM, MZL
* All subjects must have evaluable or measurable disease based on the appropriate tumor type criteria
* Adequate organ and bone marrow function

Key Exclusion Criteria

* For subjects with lymphoma:

  * Systemic antineoplastic therapy or any experimental therapy within 3 weeks or 5 half-lives, whichever is shorter, before the first dose of study treatment.
  * Therapy with tyrosine kinase inhibitor within 5 half-lives before the first dose of study treatment.
  * Unconjugated monoclonal antibody therapies \<6 weeks before the first dose of study treatment.
  * Subjects that have undergone autologous stem cell rescue within 100 days prior to the first dose of study treatment.
  * Subjects that have undergone allogeneic stem cell transplant within 6 months prior to the first dose of study treatment.
  * Subjects with active graft-versus-host disease (GVHD) or on anti-GVHD treatment or prophylaxis.
  * History of chimeric antigen receptor T cell (CAR-T) therapy within 100 days prior to start of study drug.
  * Any immunotherapy within 4 weeks of first dose of study drug.
  * The time from the last dose of the most recent chemotherapy or experimental therapy to the first dose of study drug is \<5 times the t1/2 of the previously administered agent(s).
* Previously exposed to BTK degradation therapy
* Malignant disease, other than that being treated in this study.
* Radiotherapy within 2 weeks of the first dose of study treatment
* Known hypersensitivity to BTK degraders or any of the ingredients.
* Impaired cardiac function or clinically significant cardiac disease
* Subjects with history of severe bleeding disorders and known/suspected other autoimmune disease
* Major surgery within 4 weeks of the first dose of study treatment