Chemotherapy for Patients With Gastroesophageal Cancers Who Have Progressed After One Prior Chemo Regimen

Gastric cancer is the second most frequent cancer-related cause of death after lung cancer worldwide with approximately 900,000 cases per year. The incidence of gastric cancer is highest in East Asia, China and Japan. In the last two decades there has been a dramatic increase in North America and Europe of adenocarcinoma of the distal esophagus and GE junction which are indistinguishable from proximal gastric cancer.

Cabazitaxel (XRP6258) is a semi-synthetic novel taxoid. Like traditional taxane drugs, it binds to and stabilizes tubilin structures resulting in inhibition of cold-induced microtubule depolymerization and cell division with subsequent inhibition of tumor cell proliferation. This novel agent, however, has poor affinity for P-glycoprotein--the protein product of multidrug resistance gene ABCB1. P-glycoprotein is a membrane-associated drug efflux pump and is thought to be a potential cause of taxane resistance in tumors. Also unlike traditional taxanes, Cabazitaxel has exhibited penetration through the blood-brain barrier (BBB.) Preclinical studies have demonstrated that Cabazitaxel was cytotoxic for cell lines with acquired resistance to doxorubicin, vincristine, vinblastine, paclitaxel or docetaxel.

Taxanes have demonstrated statistically significant antitumor activity as both monotherapy and as part of combination triplet regimens in gastroesophageal carcinoma.Cabazitaxel has emerged as a novel investigational semi-synthetic taxoid that has established activity in cell lines refractory to traditional taxanes in preclinical studies and now in a phase III study in patients with metastatic prostate cancer. Cabazitaxel, with its low affinity for the P-glycoprotein drug efflux pump, may demonstrate superior response rates to docetaxel. Furthermore, as demonstrated in prostate cancer, cabazitaxel appears to have substantial activity in patients who have previously been treated with docetaxel.

Phase I and II trials have been conducted demonstrating safety and efficacy of Cabazitaxel (XRP6258) in metastatic breast and prostate cancer. Neutropenia was the primary dose-limiting toxicity with the recommended dose established at 20 and 25mg/m2. The latter dose was used in the TROPIC trial, the pivotal phase III trial demonstrating improved overall survival and median progression free survival in patients with hormone resistant prostate cancer refractory to docetaxel who had received Cabazitaxel plus prednisone versus those who received mitaxantrone plus prednisone. Cabazitaxel given at IV doses of 25mg/m2 has demonstrated both safety and anti-tumor efficacy in phase I, II and now phase III trials

The primary goal is to evaluate the activity of Cabazitaxel for the treatment of advanced gastroesophageal cancer that has progressed after at least one line of treatment for metastatic disease. Activity will be defined as a complete or partial response. The investigators will differentiate between a 10% level of activity and a 30% level of activity.