The present invention relates generally to the fields of chemotherapeutic treatments. More particularly, it concerns the use of ibuprofen, a non-steroid anti-inflammatory drug, in the treatments of disease. More particularly, it has been discovered that the R-enantiomer of ibuprofen, previously thought to be inactive, may be used as an antineoplastic agent and also in the prophylactic and therapeutic treatment of Alzheimer's and Alzheimer's related diseases.