This study evaluates MBC-11 (a conjugate of a bone-targeting vehicle (etidronate) and a cytostatic agent [ara-C] in patients with malignant tumors with CIBD. This is a first use in human.

A standard "3+3" dose escalation design to determine Maximum Tolerated Dose with consecutive different dose level cohort recruitment.

The following dose levels to be investigated: 0.5 mg/kg, 1.0 mg/kg, 2.5 mg/kg, 5.0 mg/kg, 10 mg/kgm 20 mg/kg. The study for each patient consists of 14-days screening period, single dose administration of MBC-11 followed by 7-day safety monitoring and then 2 cycles of multiple use of MBC-11 (28 days each cycle, study drug is administered at Days1-5). In case of partial metabolic reaction/stable metabolic reaction therapy maybe prolonged up to 4 cycles (at investigator and sponsor consideration)

Inclusion Criteria:

• Histologically confirmed malignant tumor (breast cancer, prostate cancer etc)
• Bone metastases, documented by radiographs, bone scan
• No available standard chemotherapy or no indication for chemotherapy at the time of screening
• Eastern Cooperative Oncology Group [ECOG] status 0-2
• Adequate bone marrow function (hemoglobin ≥ 9 g/dL with or without transfusion requirement, absolute neutrophil count ≥ 1500/mm3, and platelets ≥ 75,000/mm3)
• Adequate liver function (bilirubin ≤ 2 x Upper Limit of Normal [ULN], Alanine aminotransferase [ALT] ≤ 2.5 x ULN).
• Adequate renal function (creatinine ≤ 1.5 x ULN) and creatinine clearance ≥ 50 mL/min [measured or calculated by nomogram]).

Exclusion Criteria:

• Systemic chemotherapy and/or investigational therapy within the previous 4 weeks
• Fracture ≤ 6 month prior the inclusion in the study
• Brain metastasis
• Serum calcium levels < 8.5 mg/dL (< 2.2 mmol/L)