Figure 2.

Tumor growth rates following chemotherapy vs vaccine therapy [adapted from data in references (86–88)]. A) Average tumor growth rates and time to death in patients with metastatic prostate cancer, from five clinical trials [four with chemotherapy and one with PROSTVAC vaccine (also known as PSA-TRICOM)]. Growth rate of tumor if no therapy is initiated (line a). With the use of chemotherapy, there was an initial tumor reduction, but the growth rate of tumors at relapse was similar to the initial tumor growth rate before therapy (line b). With PROSTVAC, there was a reduction in tumor growth rate following vaccine therapy (line c). Thus, for patients who received vaccine therapy with little if any tumor reduction (among whom there was virtually no increase in time to progression), an increase in overall survival was observed. Dagger denotes time to death. B) This phenomenon could potentially be enhanced if vaccine therapy is initiated earlier in disease progression or in patients with low tumor burden metastatic disease (line d) but would have minimal effect in patients with large tumor burden (line e). C) Predictions of enhanced overall survival if patients are treated with both vaccination and chemotherapy.