Is bortezomib, a proteasome inhibitor, effective in treating cancer-associated weight loss? Preliminary results from the North Central Cancer Treatment Group

Background: Weight loss predicts a poor prognosis for cancer patients, and previous studies have implicated the ubiquitin-proteasome pathway as a major mediator of cancer-associated weight loss. The recent emergence of bortezomib, a proteasome inhibitor, now allows testing on whether proteasome inhibition is effective therapy for cancer-associated weight loss. Methods: This study represents a subanalysis from two prior antineoplastic trials in patients with adenocarcinoma of the pancreas. The first included 46 patients with metastatic pancreatic cancer who were treated with single-agent bortezomib (intravenous doses of 1.5 or 1.3 mg/m² on days 1, 4, 8, and 11 of a 21-day cycle). The second included 42 patients with pancreatic cancer treated with single-agent octreotide (200 or 500 μg subcutaneously three times a day). The FACT-C questionnaire provided appetite and related data for bortezomib-treated patients. Serial weight data were available from both trials. Such data from the octreotide trial were utilized for comparative purposes because the latter holds no track record in treating cancer-associated weight loss. Results: Bortezomib- and octreotide-treated patients were roughly comparable at baseline, and neither agent demonstrated notable antineoplastic effects. FACT-C data suggested stable appetite, but high patient dropout rates invite caution in interpretation. For example, in response to "I have a good appetite," mean scores for bortezomib-treated patients were 45 at baseline (n=42), 45 at the end of cycle 1 (n=26), and 44 at the end of cycle 2 (n=9). In contrast, weight data appeared more straightforward to interpret: direct comparisons of mean change in weight from baseline between bortezomib- and octreotide-treated patients showed no significant differences between groups. Conclusions: These preliminary results suggest that bortezomib shows negligible favorable effects on cancer-associated weight loss in patients with metastatic pancreatic cancer. We conclude that further study of bortezomib specifically in this setting and for this indication is not warranted.