The present invention describes biomarkers that have been discovered to correlate with varied individual responses (e.g., efficacy, adverse effect, and other end points) to enzastaurin, in treating diseases such as, DLBCL, GBM, and other cancer types. The newly discovered biomarkers and others in linkage disequilibrium with them can be used in companion diagnostic tests which can help to predict drug responses and apply drugs only to those who will be benefited, or exclude those who might not be beneficial, by the treatment.