The purpose of the study is to determine the safety of MLN9708 as maintenance therapy following allogeneic stem cell transplant in patients with multiple myeloma.

Although multiple myeloma is considered fatal, survival has dramatically improved over the last two decades with the introduction of more effective treatment options. Proteasome inhibitors have an anti-myeloma effect and are often used as either initial treatment or at relapse in patients with multiple myeloma. MLN9708 is an orally bioavailable, potent, reversible inhibitor of the 20S proteasome. Phase I studies have shown MLN9708 to be very well tolerated with minimal peripheral neuropathy. It has also shown impressive anti-myeloma activity in both the relapsed/refractory setting and the upfront setting (Kumar et al. 2011, Berdeja et al. 2011, Richardson et al. 2011). These characteristics make MLN9708 an ideal proteasome inhibitor to use after allogeneic stem cell transplant. In this Phase II, open-label, multicenter, non-randomized study the investigators will investigate the role of MLN9708 as maintenance after allogeneic stem cell transplant in patients with high-risk multiple myeloma, and in patients with multiple myeloma who have relapsed after an autologous stem cell transplant.

Inclusion Criteria:

KEY POINTS:

1. Symptomatic multiple myeloma or asymptomatic myeloma with myeloma-related organ damage diagnosed according to standard criteria in patients who received allogeneic transplant due to high-risk prognostic features, such as, but not limited to:

   • Chromosome 17p, partial deletion [del(17p)], t(4;14), t(14;16), t(14;20)
   • Plasma cell leukemia
   • PFS of less than 2 years after autologous stem cell transplant

2. Evidence of engraftment of neutrophils (absolute neutrophil count [ANC] >1000 cells/mm3) and platelets (platelets >60,000 cells/mm3) [dose escalation phase] and >50,000 cells/mm3 [dose expansion phase]).

3. Achievement of at least a PR prior to allogeneic stem cell transplant

4. Adequate liver and kidney function

5. Ability to swallow oral medication

6. Absence of gastrointestinal symptoms that precludes oral intake and absorption of MLN9708

7. Off antibiotics and amphotericin B formulations, voriconazole or other anti-fungal therapy for the treatment of proven, probable or possible infections

8. ECOG of ≤ 2

9. Life expectancy ≥3 months

10. Ability to understand the nature of this study and give written informed consent

Exclusion Criteria:

1. Patients with progressive disease when compared to pre-transplant staging as defined by IMWG Uniform Response criteria for Multiple Myeloma.
2. Umbilical cord blood transplant
3. Patients with > Grade 2 peripheral neuropathy with pain, or ≥ Grade 3 peripheral neuropathy per NCI CTCAE Version 4.0
4. Patients with uncontrolled bacterial, viral, or fungal infections
5. New York Heart Association (NYHA) Class III or IV heart failure uncontrolled angina, severe uncontrolled ventricular arrhythmias, or electrocardiographic evidence of acute ischemia or active conduction system abnormalities.
6. Patients who are pregnant or breastfeeding
7. Most recent chemotherapy ≤21 days and ≤ Grade 1 chemotherapy-related side effects, with the exception of alopecia
8. Use of a study drug ≤21 days or 5 half-lives (whichever is shorter) prior to the first dose of MLN9708. For study drugs for which 5 half-lives is ≤21 days, a minimum of 10 days between termination of the study drug and administration of MLN9708 is required.
9. Wide field radiotherapy (including therapeutic radioisotopes such as strontium 89) administered ≤14 days or limited field radiation for palliation ≤7 days prior to starting study drug or has not recovered from side effects of such therapy
10. Major surgical procedures ≤14 days of beginning study drug, or minor surgical procedures ≤7 days. No waiting is required following port-a-cath placement.
11. Ongoing or active systemic infection. Known diagnosis of human immunodeficiency virus, hepatitis B, or hepatitis C
12. Central Nervous System involvement
13. Known allergy to any of the study medications, their analogues, or excipients in the various formulations of any agent.
14. Systemic treatment with moderate and strong inhibitors of cytochrome P450 (CYP) 1A2, CYP3A, or clinically significant CYP3A inducers, or use of Ginkgo biloba or St. John's wort within 14 days before study drug administration in the study.
15. Presence of other active cancers, or history of treatment for invasive cancer ≤5 years. Patients with Stage I cancer who have received definitive local treatment and are considered unlikely to recur are eligible. All patients with previously treated in situ carcinoma (i.e., non-invasive) are eligible, as are patients with history of non-melanoma skin cancer.
16. Graft versus host disease > Grade 2; or GVHD grade 1 or Grade 2 which requires > 0.5 mg/kg methylprednisolone, or equivalent.

There are additional Inclusion/Exclusion criteria. The Study Center will determine if you meet all criteria and will answer any questions you may have about the trial.

All patients who received at least one dose of MLN9708.

Adverse event data was collected from the start of study treatment, until 30 calendar days after discontinuation or completion of study treatment. All AEs resulting in discontinuation from the study treatment were followed until resolution or stabilization. After 30 days of completion of protocol-specific treatment or discontinuation, only AEs, SAEs, or deaths assessed by the Investigator as treatment related were reported.

Any untoward medical occurrence in a participant regardless of the relationship with the study drug per the Investigator's assessment. Adverse events were evaluated using the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) v4.0. All-Cause Mortality was assessed in all randomized participants, while Serious and Other (Not Including Serious) Adverse Events was only assessed in participants who received at least one dose of study treatment.