A Phase 1 First-in-Human Study with ABBV-155 Alone and in Combination with Taxane Therapy in Adults with Relapsed and/or Refractory Tumors

Has a histologic or cytologic diagnosis of a malignant solid tumor.
• Subjects enrolled in Part 2a (monotherapy, dose expansion) must have SCLC
diagnosis.
• Subjects enrolled to Part 2b (combination therapy, dose expansion) must have
either NSCLC or HR-positive/HER2-negative breast cancer. For Part 2, sponsor
may elect (at its discretion) to prospectively screen for subjects whose tumor
express B7H3 based on central IHC assessment of fresh or archival tumor tissue.
• Measurable disease defined by Response Evaluation Criteria in Solid Tumors
(RECIST) criteria.
• An Eastern Cooperative Oncology Group (ECOG)performance status less than or
equal to 2.
• Failure of at least 1 prior systemic chemotherapy including all available
standard therapies for subjects in the dose-escalation phase (Parts 1a and 1b).
• All subjects with breast cancer for subjects in the dose expansion phase
(Part 2b only) must have the following:
- locally advanced or metastatic HR-positive/HER2-negative breast cancer
after failing cyclindependent kinase (CDK)4/6 inhibitor-based therapy.
- HR-positivity and HER-2-negativity should be confirmed based on
American Society of Clinical Oncology (ASCO)/College of American Pathologists
(CAP) criteria.
• All subjects with non-small cell lung cancer (NSCLC) for subjects in the
dose-expansion phase (Part 2b only) must have R/R NSCLC after at least 1 line
of therapy.
• All subjects with SCLC in the dose-expansion phase (Part 2a only) must have
R/R SCLC from at least 1 line of therapy which includes a platinum-based
therapy with or without an anti-PD-L1/PD-1 therapy.
• All subjects with either breast cancer or NSCLC must have the following if
exposed to prior taxane-based therapy:
-no history of taxane allergy (Parts 1b and 2b only)
-disease that has relapsed or progressed at least 2 months after initiation
of the most recent taxane-based therapy.
• Available tumor tissue suitable for immunohistochemistry testing.
• Adequate kidney, liver, and hematologic laboratory values as described in the
protocol.

• No untreated brain or meningeal metastases (i.e., subjects with history of
metastases are eligible provided they do not require ongoing steroid treatment
and have shown clinical and radiographic stability for at least 28 days after
definitive therapy.
• Grade 2 or higher peripheral neuropathy (only applies to subjects who would
receive taxane therapy).
• Unresolved Grade 2 or higher toxicities related to previous anticancer
therapy except alopecia.
• Known active infection of hepatitis B, hepatitis C, or human immunodeficiency
virus with exceptions as described in the protocol.
• Recent history (within 6 months) of congestive heart failure (defined in the
protocol), ischemic cardiovascular event, cardiac arrhythmia requiring
pharmacological or surgical intervention, pericardial effusion, or pericarditis.
• Any history of hypersensitivity to any ingredients of ABBV-155 will be
excluded. For combination therapy only (Parts 1b and 2b), history of serious
allergic reaction to any taxane or any ingredients used in taxane formulation.