Study of Oral Ixazomib in Adult Participants With Relapsed or Refractory Light Chain Amyloidosis

Inclusion Criteria:

Male or female participants 18 years or older
Biopsy-proven systemic relapsed or refractory light-chain (AL) amyloidosis, which after at least 1 prior therapy, in the investigator's opinion, requires further treatment
If received stem cell transplant, must be at least 3 months posttransplantation and recovered from side effects
Must have measurable disease defined as serum differential free light chain concentration ≥ 40 mg/L
Must have objective measurable organ (heart or kidney) amyloid involvement
Must have cardiac biomarker risk stage I or II disease
Must have adequate hematologic, hepatic, and renal function
Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2
Female participants who are postmenopausal, surgically sterile, or agree to practice 2 effective methods of contraception or agree to abstain from heterosexual intercourse
Male participants who agree to practice effective barrier contraception or agree to abstain from heterosexual intercourse
Voluntary written consent

Exclusion Criteria

Peripheral neuropathy that is greater or equal to Grade 2
Cardiac status as described in protocol
Severe diarrhea (≥ Grade 3) not controllable with medication or requires administration of total parenteral nutrition
Known gastrointestinal condition or procedure that could interfere with swallowing or the oral absorption of tolerance of MLN9708
Uncontrolled infection requiring systematic antibiotics
Known human immunodeficiency virus (HIV) positive, hepatitis B surface antigen-positive status, or known or suspected active hepatitis C infection
Presence of other active malignancy with the exception of nonmelanoma skin cancer, cervical cancer, treated early-stage prostate cancer provided that prostate-specific antigen is within normal limit, or any completely resected carcinoma in situ
Female participants who are lactating or pregnant
Major surgery within 14 days before the first dose of study drug
Serious medical or psychiatric illness that could, in the investigator's opinion, potentially interfere with the completion of treatment according to the protocol