The sodium salt of a phosphorothioate antisense oligonucleotide targeted to the initiation codon region of mRNA for the anti-apoptotic gene Bcl-2. Oblimersen inhibits Bcl-2 mRNA translation, which may result in decreased expression of the Bcl-2 protein and tumor cell apoptosis. This agent may enhance the efficacy of standard cytotoxic chemotherapy. The anti-apoptotic bcl-2 protein is an integral outer mitochondrial membrane protein (OMMP) that is overexpressed in some cancer cell types and is linked to tumor drug resistance. or A type of study in which individuals are observed or certain outcomes are measured. No attempt is made to affect the outcome (for example, no treatment is given).