Phase 1b/2 Study Testing Radium-223 Dichloride/Bortezomib/Dexamethasone Combination in Relapsed Multiple Myeloma

This study will be conducted in 2 parts. The phase 1b part will be an international, phase 1b, open-label, dose-escalation assessment of radium-223 dichloride administered with bortezomib and dexamethasone in subjects with relapsed multiple myeloma. The primary endpoint of the phase 1b part is to determine the optimal dose of radium-223 dichloride in combination with bortezomib/dexamethasone for the Phase 2 portion of the study.

The phase 2 part will be an international, phase 2, double-blind, randomized, placebo-controlled assessment of radium-223 dichloride versus placebo administered with bortezomib and dexamethasone, in subjects with relapsed multiple myeloma. Randomization (1:1) in the phase 2 part will be stratified by:

* Prior bortezomib treatment (yes, no)
* Prior treatment (1 prior line of treatment, \>1 prior line of treatment) Approximately 30 subjects (10 subjects per cohort) will be enrolled in the phase 1b part of the study and approximately 196 subjects will be enrolled in the phase 2 part of the study.


Eligibility Criteria:
Inclusion Criteria:

* Cytologically or histologically confirmed diagnosis of multiple myeloma
* Subjects must have received at least 1 and not more than 3 previous lines of treatment and have had a response to treatment (i.e., achieved a minimal response \[MR\] or better) according to the International Myeloma Working Group (IMWG) uniform response criteria
* Subjects must have had progressive disease according to the IMWG uniform response criteria following the last multiple myeloma treatment
* Subjects must have measurable disease defined as at least 1 of the following (according to central laboratory results):

  * Serum M-protein ≥1 g/dL
  * Urine M-protein ≥200 mg/24 hours
  * Serum free light chain (FLC) ≥10 mg/dL with abnormal ratio
* ≥1 bone lesion identifiable by radiograph, computed tomography, magnetic resonance imaging, or bone scintigraphy
* Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0-2
* Subjects must be nonrefractory to bortezomib and had no progression during or within 60 days after completion of bortezomib
* Absolute neutrophil count (ANC) ≥1.5 × 10e9/L, hemoglobin (Hb) ≥9.0 g/dL, and platelet count ≥75.0 × 10e9/L independent of transfusion of red blood cells (RBC) or platelet concentrates and independent of granulocyte colony stimulating factor (G-CSF) or granulocyte macrophage colony stimulating factor (GM-CSF)

Exclusion Criteria:

* Systemic glucocorticoid therapy (prednisone \>10 mg/day orally or equivalent) within the last 4 weeks prior to first dose, unless tapered and on a stable dose ≤10 mg/day for at least 1 week
* Subjects with known POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes) or light chain (AL) amyloidosis
* Plasma cell leukemia
* Systemic anti-cancer therapy within 4 weeks prior to first dose
* Radiation therapy in the previous 4 weeks prior to first dose except if given for pain management and involves less than 10% of the bone marrow
* Prior treatment with radium-223 dichloride or any experimental radiopharmaceutical
* Congestive heart failure (New York Heart Association \[NYHA\] class III to IV), symptomatic cardiac ischemia, cardiomyopathy, clinically relevant ventricular arrhythmia, pericardial disease, unstable angina or myocardial infarct in the previous 6 months prior to first dose, left ventricular ejection fraction \<40%
* Neuropathy ≥ Grade 2 or Grade 1 with pain