Phase II Trial Using a Combination of Oxaliplatin, Capecitabine, and Celecoxib with Concurrent Radiation for Newly Diagnosed Resectable Rectal Cancer

LESSONS LEARNED

Colorectal cancers exhibit a high level of cyclooxygenase-2 (COX-2) expression with strong preclinical rationale for improved clinical outcomes with COX-2 inhibition. Celecoxib is a COX-2 inhibitor and we have shown that it can be safely combined with capecitabine and oxaliplatin as part of neoadjuvant treatment with radiation therapy (RT) in rectal cancer.There was a significant improvement in skin toxicity with this combination as compared with historical data. Considering the field has moved on to single-agent capecitabine, we believe future trials with capecitabine and celecoxib hold potential.

BACKGROUND

Improved survival is seen among patients with rectal cancer who achieve pathologic complete response (pCR) after neoadjuvant therapy. Cyclooxygenase-2 (COX-2) expression is increased in gastrointestinal malignancies and it may serve as a target to enhance pathologic response. A trial combining chemoradiation and COX-2 inhibition was conducted to evaluate the pCR rate, surgical outcomes, survival, and treatment toxicity.

METHODS

Patients with resectable (T3-4, N1-2) rectal cancer within 12 cm of the anal verge were included in this phase II clinical trial. The neoadjuvant treatment consisted of capecitabine 850 mg/m² b.i.d. Monday through Friday for 5 weeks, weekly oxaliplatin 50 mg/m² intravenous (IV), celecoxib 200 mg b.i.d. daily, along with concurrent 45 gray radiation therapy in 25 fractions.

RESULTS

Thirty-two patients were included in the final analysis. The primary endpoint was pCR: 31% (95% confidence interval [CI]: 16%-50%). Secondary endpoints were surgical downstaging (SD): 75% (95% CI: 57%-89%) and sphincter-sparing surgery (SSS): 56% (95% CI: 38%-74%). Common grade >3 toxicities were diarrhea and abnormal liver function tests (9% each). Grade 0 and 1 toxicities included radiation dermatitis (59% and 34%, respectively) and proctitis (63% and 28%, respectively). At 3 years, disease-free survival and overall survival (OS) were 84% (95% CI: 65%-93%) and 94% (95% CI: 77%-98%), respectively.

CONCLUSION

Chemoradiation with celecoxib in rectal cancer was well tolerated and demonstrated high rates of pCR, SD, and SSS. Improvement in skin toxicity (34% grade 1 and no grade 3/4) as compared with historical results (43%-78% grade 3/4) seems to be a significant improvement with addition of celecoxib to neoadjuvant chemotherapy.

Sensitization and individual differences to IP amphetamine, cocaine, or caffeine following repeated intracranial amphetamine infusions

Rats that have a high locomotor response to novelty (HR) sensitize more readily to IP-administered amphetamine than rats with a low locomotor response (LR) to novelty. This experiment compared sensitization in HR and LR rats following amphetamine (3.0 micrograms/side for 5 days) infused bilaterally into either the nucleus accumbens (NACC), ventral tegmental area (VTA), or the medial frontal cortex (MFC). The subsequent locomotor response to IP-administered d-amphetamine sulfate (1 mg/kg), cocaine HCl (15 mg/kg), and caffeine benzoate (20 mg/kg) was also examined. No differences were observed between HR and LR rats following amphetamine infusion into either the MFC, NACC, or VTA. However, HR rats showed greater locomotor activity compared to LR rats following either IP amphetamine, cocaine, or caffeine for subjects cannulated in the NACC, MFC, or the VTA. Repeated infusions of amphetamine into the VTA increased the locomotor response to both IP amphetamine and cocaine, but not to IP caffeine, while repeated infusions of amphetamine into the NACC or MFC had no effect on locomotor response to any drug subsequently administered IP. The results support previous findings that changes induced by intra-VTA infusions, but not intra-NACC or MFC infusions, of amphetamine induce sensitization to IP-administered amphetamine and cocaine. Findings from the present experiment indicate the ability of the dopamine cell body region, but not the dopamine terminal fields, to produce locomotor sensitization to amphetamine and cocaine. The results from the present experiment also indicate the lack of localization to one of studied regions of individual differences.(ABSTRACT TRUNCATED AT 250 WORDS)

Anomalous effect of mazindol on dopamine uptake as measured by in vivo voltammetry and microdialysis

The effect of mazindol on the dopamine (DA) uptake system in the rat striatum was studied by in vivo voltammetry and microdialysis. An increase in the maximal uptake rate was observed by voltammetry 30 min after i.p. administration of 1, 5, 10, 15, and 20 mg/kg doses but not after a dose of 25 mg/kg, while stimulated release was enhanced at all doses. The increased maximal uptake is in contrast to increased levels of extracellular DA observed with microdialysis following mazindol administration. This divergence of action is anomalous in the context of current understanding of the DA uptake system.