Venetoclax, MLN9708 (Ixazomib Citrate) and Dexamethasone for the Treatment of Relapsed or Refractory Light Chain Amyloidosis

Inclusion Criteria: * Histologically-proven systemic anti-light chain amyloidosis (AL) confirmed by positive Congo red staining with green birefringence on polarized light microscopy and evidence of a measurable clonal disease that requires active treatment. An underlying plasma cell disorder can be identified by one of the following: clonal plasma cells in the bone marrow (BM), monoclonal protein in the serum or urine, or abnormal free light chain ratio. For patients who are African-American or males \>= 70 years with isolated cardiac involvement, mass spectrometry must be performed to confirm subtyping * Presence of t(11;14) by fluorescence in situ hybridization (FISH) on bone marrow biopsy, either confirmed at screening or documented with a prior biopsy * Patient requires therapy, as determined by the treating physician, following at least one line of treatment (No limit on the number of prior treatments) * Age \>= 18 years. Because no dosing or adverse event data are currently available on the use of venetoclax in combination with MLN9708 (ixazomib citrate) and dexamethasone in patients \< 18 years of age, children are excluded from this study * Eastern Cooperative Oncology Group (ECOG) performance status =\< 2 (Karnofsky \>= 60%) * Leukocytes \>= 3,000/mcL * Absolute neutrophil count \>= 1,000/mcL. Screening absolute neutrophil count (ANC) should be independent of granulocyte- and granulocyte/macrophage colony stimulating factor (G-CSF and GM-CSF) support for at least 1…