An effective local-regional therapy is needed for adenocarcinomas of the pancreas. Paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton NJ) may enhance the effect of radiation therapy. Paclitaxel synchronizes cells at G2/M, a relatively radiosensitive phase of the cell cycle. We have shown that response to paclitaxel and concurrent radiation (paclitaxel/RT) was not affected by p53 mutations in non-small cell lung cancer (NSCLC). This suggested that paclitaxel/RT was a rationale treatment approach for other malignancies which frequently harbor p53 mutations such as upper gastrointestinal malignancies. We have completed a phase I study of paclitaxel/RT for locally advanced pancreatic and gastric cancers. The maximum tolerated dose (MTD) of paclitaxel was 50 mg/m²/week for 6 weeks with abdominal radiation. The dose limiting toxicities were abdominal pain within the radiation field, nausea and anorexia. Twenty-five patients with locally advanced pancreatic cancer have now completed treatment at the phase II dose level of paclitaxel 50 mg/m²/week with 50 Gy concurrent RT. Thus far, the only grade 3/4 toxicities have been hypersensitivity reactions in 2 patients, asymptomatic grade 4 neutropenia in 3 patients, and non-neutropenic biliary sepsis in 1 patient. Of the first 22 assessable patients treated at the phase II study, 8 obtained a partial response (PR) for a preliminary response rate of 36%. These findings demonstrate that paclitaxel/RT is well tolerated with substantial activity for locally advanced pancreatic cancer.