The following criteria is provided for health care professionals.

Inclusion Criteria:

• Documented diagnosis of relapsed/refractory multiple myeloma (MM) with measurable disease (serum, urine, or free light chain [FLC]) per International Myeloma Working Group (IMWG) criteria
• At least 3 prior lines of MM therapy, including a proteasome inhibitor, immunomodulatory agent, and anti-CD38 antibody (unless contraindicated), and refractory to the last treatment line.
• Eastern Cooperative Oncology Group (ECOG) 0 or 1
• Absence of donor (product)-specific anti-HLA antibodies
• Adequate hematologic, renal, hepatic, pulmonary, and cardiac function

Exclusion Criteria:

• Current or history of Central Nervous System (CNS) involvement of myeloma or plasma cell leukemia
• Clinically significant CNS disorder
• Current or history of thyroid disorder
• Autologous stem cell transplant within the last 6 weeks, or any allogeneic stem cell transplant
• Prior treatment with anti-BCMA therapy, any gene therapy, any genetically modified cell therapy, or adoptive T cell therapy
• History of HIV infection or acute or chronic active hepatitis B or C infection
• Patients unwilling to participate in an extended safety monitoring period

Additional Exclusion Criteria for Nirogacestat plus ALLO-715 Cohorts

• Inability to swallow tablets
• Subject has known malabsorption syndrome or preexisting gastrointestinal conditions that may impair absorption of nirogacestat
• Use of strong/moderate CYP3A4 inhibitors, and strong CYP3A4 inducers within 14 days before starting nirogacestat.
• Use of concomitant medications that are known to prolong the QT/QTcF interval