Paclitaxel and concurrent radiation therapy for locally advanced adenocarcinomas of the pancreas, stomach, and gastroesophageal junction.

ABSTRACT

An effective locoregional therapy is needed for adenocarcinomas of the pancreas, stomach, and gastroesophageal junction. Paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) may enhance the effect of radiation therapy (RT). Paclitaxel synchronizes cells at G2/M, a relatively radiosensitive phase of the cell cycle. We have shown that response to paclitaxel and concurrent RT (paclitaxel/RT) was not affected by p53 mutations in non-small cell lung cancer. This finding suggested that paclitaxel/RT was a rational treatment approach for other malignancies that frequently harbor p53 mutations, such as upper gastrointestinal malignancies. We completed a phase I study of paclitaxel/RT for locally advanced pancreatic and gastric cancer. The maximum tolerated dose of paclitaxel was 50 mg/m2/wk for 6 weeks with abdominal RT. The dose-limiting toxicities were abdominal pain within the radiation field, nausea, and anorexia. Phase II studies are now under way. Twenty-five patients with locally advanced pancreatic cancer have been entered at the phase II dose level of paclitaxel 50 mg/m2/wk with concurrent RT (total dose, 50 Gy). Thus far, the only grade 3/4 toxicities have been hypersensitivity reactions (n = 2), asymptomatic grade 4 neutropenia (n = 3), and nonneutropenic biliary sepsis (n = 1). Of the first 18 assessable patients with pancreatic cancer treated on the phase II study, six obtained a partial response, for a preliminary response rate of 33%. In the phase II study for locally advanced gastric cancer, 20 patients have been enrolled. Of the first 19 patients who have completed treatment, nine (47%) had grade 3/4 toxicities, including nausea, anorexia, esophagitis, and gastritis. Of the first 16 patients with gastric cancer, complete and partial responses have been observed in one and eight patients, respectively, for a preliminary response rate of 56%. We have also completed treatment on 24 patients with potentially resectable adenocarcinomas of the gastroesophageal junction with neoadjuvant paclitaxel 60 mg/m2 and cisplatin 25 mg/m2, weekly for 4 weeks, with concurrent RT (total dose, 40 Gy) followed by surgical resection. Ten patients (41%) had grade 3/4 toxicities, including neutropenia, nausea, and dehydration. Of 24 patients, four complete responses (17%) and 14 partial responses (58%) were observed, for an overall response rate of 75%. Severe esophagitis was uncommon, making this a well-tolerated outpatient regimen for adenocarcinomas of the distal esophagus. These findings demonstrate that paclitaxel-based chemoradiation for locally advanced upper gastrointestinal malignancies is well-tolerated with substantial activity.