Safety and Preliminary Efficacy Study of the Antibody PAT-SM6 in Patients With Relapsed or Refractory Multiple Myeloma

Inclusion Criteria:

* Male or female subjects ≥ 18 years of age
* Relapsed or refractory multiple myeloma defined as: Failure of at least 2 previous therapies including an immunomodulatory agent (thalidomide or lenalidomide) and a proteasome inhibitor (unless the subjects were not eligible or refused to receive those treatments), and with progressive disease, defined by an increase of serological or urine myeloma parameters by 25% to the last value
* Presence of serum M-protein ≥ 1 g per 100 mL (≥ 10 g/L) and/or urine M-protein ≥ 200 mg per 24-hour period and/or serum FLCs ≥ 10 mg per 100 mL (≥ 100 mg/L) combined with an abnormal ratio of lambda and kappa chains
* Life expectancy of \> 6 months
* Karnofsky performance status ≥ 60%, Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2.
* Absolute neutrophil count (ANC) ≥ 1.0 (1,000/mm3) and platelets ≥ 30 × 109/L without previous transfusion within the last 2 weeks before first study drug administration
* Creatinine clearance ≥ 30 mL/min (calculated using the Cockcroft-Gault equation)
* Total bilirubin ≤ 2 × upper normal limit (UNL)
* Alanine transaminase (ALT) and aspartate aminotransferase (AST) ≤ 2.5 × UNL
* Haemoglobin ≥ 8 g/dL
* If a female of childbearing potential, confirmation of a negative pregnancy test before enrolment and use of double-barrier contraception, oral contraceptive plus barrier contraceptive, or confirmation of having undergone clinically documented total hysterectomy and/or oophorectomy, tubal ligation
* If a male, use of an effective barrier method of contraception during the study and for 3 months after the last dose if sexually active with a female of childbearing potential
* Ability to comply with all study-related procedures, medication use, and evaluations
* Ability to understand and give written informed consent, and comply with the protocol

Exclusion Criteria:

* Primary refractory multiple myeloma
* Previous treatment with cytotoxic chemotherapy or large-field radiotherapy or other myeloma-specific therapy within 28 days prior to the screening visit (radiation to a single site as concurrent therapy is allowed)
* Treatment with a systemic investigational agent within 28 days prior to the screening visit
* Hypercalcemia (\> 2.7 mmol/L)
* Extramedullary plasmocytoma not originating from bone or plasma cell leukaemia
* Previous allogenic stem cell transplantation
* Known or suspected hypersensitivity to the excipients contained in the study drug formulation
* Significant uncontrolled cardiovascular disease or cardiac insufficiency (New York Heart Association (NYHA) classes III-IV)
* Prior therapy with other monoclonal antibodies
* Clinical or laboratory evidence of active hepatitis B (positive HBsAg with negative HBsAb) or hepatitis C (positive hepatitis c virus antibody and detectable hepatitis C virus RNA with ALT above the normal range)
* Positive HIV test result (ELISA or Western blot)
* History of ischemic colitis, stroke or myocardial infarction within the last 6 months
* Presence of diarrhoea of grade 2 or higher
* Any active uncontrolled systemic infection
* Any antibiotic therapy due to infections 2 weeks prior to first study drug administration
* Regular dose of corticosteroids during the 2 weeks prior to study entry or anticipated need of corticosteroids exceeding prednisone 20 mg/day or equivalent, or any other immunosuppressive therapy within 2 weeks prior to study entry.
* Major surgery ≤ 4 weeks prior to first study drug administration or ongoing side effects of such surgery
* Systemic diseases (cardiovascular, renal, hepatic, etc) that would prevent study treatment
* Multiple myeloma with central nervous system involvement.
* Second active malignant disease, currently requiring treatment (with the exception of basal cell carcinoma of the skin or curative surgery treated tumours).
* Pregnancy or breastfeeding in women and women of childbearing potential not using an acceptable method of birth control
* others