²¹¹At-OKT10-B10 and Fludarabine Alone or in Combination With Cyclophosphamide and Low-Dose TBI Before Donor Stem Cell Transplant for the Treatment of Newly Diagnosed, Recurrent, or Refractory High-Risk Multiple Myeloma

Patients with newly diagnosed or relapsed/refractory multiple myeloma

Patients with multiple myeloma must have at least one of the following high-risk features:

* t(4;14), t(14;16), t(14;20) or deletion 17p, gain in chromosome 1q (\> 3 copies of CKS1b) by fluorescence in situ hybridization (FISH); hypodiploidy; complex karyotype

* Revised International Staging System III

* Plasmablastic morphology

* History of primary or secondary plasma cell leukemia

Patients must start ²¹¹At-OKT10-B10 within 40-180 days of autologous stem cell transplant (either as part of their induction, or as salvage)

Patients must have an estimated creatinine clearance greater than 50/ml per minute measured by 24-hour urine collection

Total bilirubin \< 2 times the upper limit of normal

Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) \< 2 times the upper limit of normal)

Patients must have an Eastern Cooperative Oncology Group (ECOG) =\< 2 or Karnofsky \>= 70

Patients must have CD38+ myeloma cells as demonstrated by either flow cytometry or immunohistochemistry in most recent bone marrow that had evidence of clonal plasma cells

For patients of childbearing potential, must have a negative urinary pregnancy test on the day of and prior to infusion of ²¹¹At-OKT10-B10

Ability to provide informed consent

Patients must have an HLA-matched related donor or an HLA-matched unrelated donor who meets standard Fred Hutchinson Cancer Center and/or National Marrow Donor Program (NMDP) or other donor center criteria for peripheral blood stem cell (PBSC) or bone marrow donation, as follows:

* Related donor: related to the patient and genotypically or phenotypically identical for HLA-A, B, C, DRB1 and DQB1. Phenotypic identity must be confirmed by high-resolution typing

* Unrelated donor:

* Matched for HLA-A, B, C, DRB1 and DQB1 by high resolution typing; OR

* Mismatched for a single allele without antigen mismatching at HLA-A, B, or C as defined by high resolution typing but otherwise matched for HLA-A, B, C, DRB1 and DQB1 by high resolution typing

* Donors are excluded when preexisting immunoreactivity is identified that would jeopardize donor hematopoietic cell engraftment. The recommended procedure for patients with 10 of 10 HLA allele level (phenotypic) match is to obtain panel reactive antibody (PRA) screens to class I and class II antigens for all patients before HCT. If the PRA shows \> 10% activity, then flow cytometric or B and T cell cytotoxic cross matches should be obtained. The donor should be excluded if any of the cytotoxic cross match assays are positive. For those patients with an HLA class I allele mismatch, flow cytometric or B and T cell cytotoxic cross matches should be obtained regardless of the PRA results. A positive anti-donor cytotoxic crossmatch is an absolute donor exclusion

* Patient and donor pairs homozygous at a mismatched allele in the graft rejection vector are considered a two-allele mismatch, i.e., the patient is A\*0101 and the donor is A\*0102, and this type of mismatch is not allowed

Patients without an HLA-matched related or unrelated donor available must have a related donor who is identical for one HLA haplotype and mismatched at the HLA-A, -B or DRB1 loci of the unshared haplotype with the exception of single HLA-A, -B or DRB1 mismatches

What this study is about