Safety and Tolerability of BION-1301 in Adults With Relapsed or Refractory Multiple Myeloma (MM)

An open-label, multi-center, dose-selection Phase 1/2 study (also referred to as ADU-CL-16)
evaluating BION-1301, a humanized monoclonal antibody directed against APRIL for the
treatment of relapsed or refractory MM. This first-in-human study is designed to evaluate the
safety, tolerability, pharmacokinetics, pharmacodynamics and initial clinical activity of
BION-1301 administered as a single agent.

The study will be conducted in 2 parts. Phase 1 is dose escalation and seeks to determine the
recommended phase 2 dose (RP2D). Once an RP2D is identified, Phase 2 of the study will open
and continue to evaluate the safety and preliminary efficacy of BION-1301 administered at
selected dose level(s).

The population for this study will consist of adults with relapsed or refractory MM whose
disease has progressed after at least 3 prior systemic therapies. BION-1301 will be
administered in 28-day cycles; the dosing interval will be once every two weeks (Q2W).

Key Inclusion Criteria:

Individuals eligible to participate in this study must meet the following key criteria and
additional criteria as specified in the protocol:

1. Male or female, aged ≥ 18 years

2. Confirmed diagnosis of MM per IMWG criteria

3. Measurable disease as defined by one or more of the following:

- Serum M-protein ≥ 0.5 g/dL

- Urine M-protein ≥ 200 mg/24 hours

- Serum Free Light Chain (FLC) assay: involved FLC level ≥ 10 mg/dL provided serum
FLC ratio is abnormal

- In cases where SPEP is unreliable, serum quantitative immunoglobulin (qIgA) ≥ 750
mg/dL (0.75 g/dL) is acceptable

4. Relapsed or refractory (Rajkumar, 2011) to 3 or more different prior lines of therapy
for MM, including immunomodulatory drugs (IMiDs), proteasome inhibitors (PIs),
chemotherapies, or monoclonal antibodies, and not a candidate for, or intolerant to
established therapy known to provide clinical benefit.

5. Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 - 1

6. Adequate organ and marrow function at Screening, as defined by the study protocol.

Key Exclusion Criteria:

1. Monoclonal gammopathy of undetermined significance (MGUS), smoldering myeloma,
Waldenstrom's macroglobulinemia, or IgM myeloma

2. Active plasma cell leukemia (˃ 2.0 × 109/L circulating plasma cells by standard
differential)

3. POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and
skin changes)

4. Prior treatment directed to B-cell Activating Factor (BAFF; BLyS), B-cell Maturation
Antigen (BCMA;TNFSF17) or Transmembrane Activator and CAML interactor (TACI;
TNFSF13B), including antibodies or BCMA- or TACI-directed Chimeric Antigen Receptor
(CAR)-T cell therapy