DNA ploidy and P-glycoprotein expression as predictive factors of response to neoadjuvant chemotherapy for invasive bladder cancer.

Objective: To identify a factor or factors that could predict response of muscle invasive transitional cell carcinoma of the bladder to neoadjuvant cisplatin, methotrexate, and vinblastine chemotherapy.

Methods: DNA ploidy analysis and immunohistochemical staining for p-glycoprotein (the product of the multidrug resistance gene, MDR-1) were performed on bladder biopsies obtained prior to chemotherapy. Radical cystectomy specimens were utilized for complete pathologic staging.

Results: Tissue was available for DNA ploidy analysis in 25 patients. Ten patients had complete responses to neoadjuvant chemotherapy and 15 patients did not respond. Nineteen patients had aneuploid tumors, of which 7 (37%) were complete responders. Six patients had diploid tumors, of which 3 (50%) were complete responders. This difference was not statistically significant. Tissue was available for immunostaining in 15 patients. Seven of 9 patients (78%) who did not respond to chemotherapy stained positively for p-glycoprotein, whereas 5 of 6 patients (83%) who had complete responses stained positively. This difference was not statistically significant.

Conclusions: Neither DNA ploidy nor p-glycoprotein expression appears to predict successfully those patients likely to respond to neoadjuvant cisplatin, methotrexate, and vinblastine chemotherapy in the treatment of invasive bladder cancer.