**Author Listing - Lead/ Submitting Author (we will be communicating with this individual): Name, Institution, City and State where the work was done. Co-authors will be added in a separate section.**
Vaishali Sanchorawala,
Amyloidosis Center, Boston University Chobanian and Avedisian School of Medicine and Boston Medical Center, Boston, MA, USA
vaishali.sanchorawala@bmc.org

**Main Body of the Abstract**
Background
There is a high unmet need for new therapies for patients with immunoglobulin light chain (AL) amyloidosis. Therapeutic approaches for AL amyloidosis have long followed multiple myeloma, due to shared pathologic pathways, including expression of membrane-bound B-cell maturation antigen (BCMA) on clonal plasma cells. ABBV-383 is an innovative BCMA x CD3 bispecific antibody that features a unique design with 2 binding domains for high-affinity BCMA targeting, a low-affinity CD3 binding domain to mitigate cytokine release, and a silenced Fc backbone for extended half-life and dosing convenience. Encouraging efficacy and a manageable safety profile were seen in a phase 1 study in patients with relapsed/refractory multiple myeloma. This study will evaluate the safety and efficacy of ABBV-383 in patients with AL amyloidosis.
Methods
This open-label, global phase 1b study (NCT06158854) includes screening and treatment phases (Figure). Patients (≥18 years) with systemic AL amyloidosis who were previously treated with a proteasome inhibitor and anti-CD38 monoclonal antibody are eligible. Patients will receive intravenous ABBV-383 for a fixed duration or until hematologic progression, unacceptable toxicity, or other discontinuation criteria are met. The dose-escalation phase will be guided by Bayesian optimal interval design. After completion of dose escalation, 2 dose levels will be selected for a safety expansion phase (N~40 patients). The primary objectives are to characterize the safety and toxicity profiles and determine the recommended dose of ABBV-383 monotherapy. The secondary objectives include evaluation of the activity, pharmacokinetics, and immunogenicity of ABBV-383.



**Author Listing - Lead/ Submitting Author (we will be communicating with this individual): Name, Institution, City and State where the work was done. Co-authors will be added in a separate section.**
Vaishali Sanchorawala,
Amyloidosis Center, Boston University Chobanian and Avedisian School of Medicine and Boston Medical Center, Boston, MA, USA
vaishali.sanchorawala@bmc.org

**Main Body of the Abstract**
**Background**
There is a high unmet need for new therapies for patients with immunoglobulin light chain (AL) amyloidosis. Therapeutic approaches for AL amyloidosis have long followed multiple myeloma, due to shared pathologic pathways, including expression of membrane-bound B-cell maturation antigen (BCMA) on clonal plasma cells. ABBV-383 is an innovative BCMA x CD3 bispecific antibody that features a unique design with 2 binding domains for high-affinity BCMA targeting, a low-affinity CD3 binding domain to mitigate cytokine release, and a silenced Fc backbone for extended half-life and dosing convenience. Encouraging efficacy and a manageable safety profile were seen in a phase 1 study in patients with relapsed/refractory multiple myeloma. This study will evaluate the safety and efficacy of ABBV-383 in patients with AL amyloidosis.
**Methods**
This open-label, global phase 1b study (NCT06158854) includes screening and treatment phases (**Figure**). Patients (≥18 years) with systemic AL amyloidosis who were previously treated with a proteasome inhibitor and anti-CD38 monoclonal antibody are eligible. Patients will receive intravenous ABBV-383 for a fixed duration or until hematologic progression, unacceptable toxicity, or other discontinuation criteria are met. The dose-escalation phase will be guided by Bayesian optimal interval design. After completion of dose escalation, 2 dose levels will be selected for a safety expansion phase (N~40 patients). The primary objectives are to characterize the safety and toxicity profiles and determine the recommended dose of ABBV-383 monotherapy. The secondary objectives include evaluation of the activity, pharmacokinetics, and immunogenicity of ABBV-383.



Phase 1b study evaluating the safety and efficacy of ABBV-383 monotherapy in patients with light chain amyloidosis PA149 (#178)

We invite you to attend the XIX International Symposium on Amyloidosis to be held in Rochester, MN.

This symposium is organized as a hybrid meeting (with the focus on in-person) held from Sunday, May 26 through Thursday, May 30, 2024.

Together with the ISA Board and members of Mayo Clinic, a very attractive scientific hybrid program is being planned. The program will cover a variety of types of systemic amyloidosis: ATTR (hereditary and wild-type), AL (light-chain), AA and less frequent forms. There will be key lectures, specific symposia including those company sponsored, oral presentations and poster sessions of accepted abstracts.

COURSE DESCRIPTION
This program will provide a comprehensive review of state-of-the-art education in systemic amyloidosis: basic science, pathophysiology, diagnosis, current and emerging treatments. Scientific presentations will include competitive oral and poster abstracts. The rapid evolution of scientific discovery and expanding treatment options has created tremendous interest in the field and this meeting will fill and important gap in educating scientists and clinicians.