A patient with progressive multiple myeloma treated successfully with arsenic trioxide after allogeneic bone marrow transplantation

Neuroblastoma cell death is induced by inorganic arsenic trioxide (As(2)O(3)) and inhibited by a normal human bone marrow cell-derived factor

Three phenotypically distinct cell types are present in human neuroblastomas (NB) and NB cell lines: I-type stem cells, N-type neuroblastic precursors, and S-type Schwannian/melanoblastic precursors. The stimulation of human N-type neuroblastoma cell proliferation by normal human bone marrow monocytic cell conditioned medium (BMCM) has been demonstrated in vitro, a finding consistent with the high frequency of bone marrow (BM) metastases in patients with advanced NB. Inorganic arsenic trioxide (As₂O₃), already clinically approved for the treatment of several hematological malignancies, is currently under investigation for NB. Recent studies show that As₂O₃ induces apoptosis in NB cells. We examined the impact of BMCM on growth and survival of As₂O₃-treated NB cell lines, to evaluate the response of cultured NB cell variants to regulatory agents. We studied the effect of BMCM on survival and clonogenic growth of eleven As₂O₃-treated NB cell lines grown in sparsely seeded, non-adherent, semi-solid cultures. As₂O₃ had a strong inhibitory effect on survival of all tested NB cell lines. BMCM augmented cell growth and survival and reversed the inhibitory action of As₂O₃ in all tested cell lines, but most strongly in N-type cells_. While As₂O₃ effectively reduced survival of all tested NB cell lines, BMCM effectively impacted its inhibitory action. Better understanding of micro-environmental regulators affecting human NB tumor cell growth and survival may be seminal to the development of therapeutic strategies and clinically effective agents for this condition.

Arsenical-based cancer drugs

Arsenic is a semi-metal or metalloid with two biologically important oxidation states, As(III) and As(V). As(III), in particular, reacts with closely spaced protein thiols, forming stable cyclic dithioarsinite complexes in which both sulfur atoms are bound to arsenic. It is this reaction that is mostly responsible for arsenics cytotoxicity. Arsenic compounds have been used as medicinal agents for many centuries for the treatment of diseases such as psoriasis, syphilis, and rheumatosis. From the 1700's until the introduction of and use of modern chemotherapy and radiation therapy in the mid 1900's, arsenic was a mainstay in the treatment of leukemia. Concerns about the toxicity of arsenical compounds led eventually to their abandonment for the treatment of cancer. The discovery in the 1980's that arsenic trioxide induces complete remission in a high percentage of patients with acute promyelocytic leukemia has awakened interest in this metalloid for the treatment of human disease. In particular, a new class or organoarsenicals are being trialed for the treatment of hematological malignancies and solid tumors. In this review, we discuss the arsenical-based compounds used in the past and present for the treatment of various forms of cancer. Mechanisms of action and selectivity and acute and chronic toxicities are discussed along with the prospects of this class of molecule.