The goal of this clinical trial is to learn if teclistamab in combination with daratumumab (Tec-Dara) works to treat newly diagnosed multiple myeloma with concurrent light chain amyloidosis (MM+AL). It will also learn about the safety of this combination. The main questions it aims to answer are:

Does Tec-Dara improve the 1-year progression-free survival rate compared to historical data (50% to 75%) in MM+AL patients? What are the rates of hematologic response (ORR, VGPR, CR, MRD negativity) and organ response in MM+AL patients treated with Tec-Dara? What medical problems do participants have when taking Tec-Dara?

Participants will:

Receive teclistamab subcutaneous injection with step-up dosing (0.06, 0.3, 1.5 mg/kg), followed by 1.5 mg/kg weekly in Cycle 1, 3.0 mg/kg every 2 weeks in Cycles 2-3, and 3.0 mg/kg every 4 weeks in Cycles 4-24 Receive daratumumab subcutaneous injection 1800 mg weekly in Cycles 1-2, every 2 weeks in Cycles 3-6, and every 4 weeks in Cycles 7-24 Continue treatment until disease progression, unacceptable toxicity, or a maximum of 24 cycles Undergo disease assessments every 28 days (±7 days) including laboratory tests for hematologic and organ response evaluation Provide bone marrow samples for MRD and RNA sequencing analysis

Inclusion Criteria:

1. Age ≥18 years, any sex/gender

2. Diagnosis of multiple myeloma according to IMWG criteria

3. Histopathologic diagnosis of AL amyloidosis confirmed by:

   • Green birefringence under polarized light microscopy with Congo red staining; AND at least one of the following:

     1. Immunohistochemistry and/or immunofluorescence
     2. Mass spectrometry
     3. Electron microscopy/immunoelectron microscopy

4. Measurable disease at screening

5. Newly diagnosed, no prior anti-plasma cell therapy

6. Adequate laboratory values:

   • Hemoglobin ≥7.5 g/dL
   • Absolute neutrophil count ≥1.0×10⁹/L
   • Platelet count ≥70×10⁹/L (platelet transfusion acceptable; >50×10⁹/L if ≥50% bone marrow nucleated cells are plasma cells)
   • ALT ≤2.5× upper limit of normal (ULN)
   • AST ≤2.5× ULN
   • Total bilirubin ≤2.0× ULN
   • Creatinine clearance ≥30 mL/min
   • Corrected serum calcium ≤14 mg/dL

7. Male and female participants of childbearing potential must use at least 2 effective contraceptive methods during the study

8. Voluntarily signed informed consent form (ICF)

Exclusion Criteria:

1. Prior anti-myeloma therapy or stem cell transplantation
2. Diagnosis of monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma, primary AL amyloidosis without concurrent MM, Waldenström macroglobulinemia, plasma cell leukemia, POEMS syndrome, or other malignancies within 3 years prior to enrollment
3. Active infection or autoimmune disease
4. Uncontrolled diabetes, hypertension, or other comorbidities
5. Pregnant or lactating female
6. Currently participating in another interventional study
7. Any other condition that the investigator considers unsuitable for study participation

All IPD that underlie results in a publication

starting 6 months after publication

IPD could be requested by contacting the corresponding author via email after publication.