Abstract P4-14-12: Evaluation of the effect of pasireotide LAR administration in the lymphocele prevention after mastectomy with axillary lymph node dissection for breast cancer: results of a phase 2 randomized study.

Background: Lymphocele is the principal post-operative morbidity following axillary node dissection. According to the literature, the incidence can vary from 4% to 89%. Encouraging results in terms of reducing postoperative lymphoceles as well as the volume and duration of drainage using octreotide LAR has been recently reported. Pasireotide LAR, a long acting drug designed to target multiple somatostatin receptors, was evaluated in this trial. Trial design: A phase II, two centers, randomized, double-blind, non-comparative pilot study was carried out in order to evaluate efficacy and safety of a single injection of pasireotide LAR 60 mg administered 7–10 days before scheduled mastectomy with axillary dissection surgery. This study included a parallel placebo arm to assess the natural course of the disease. Eligibility criteria: Adult female breast cancer patients planned to undergo a mastectomy (without reconstruction at the same time) and axillary node dissection. Specific aims: To assess the efficacy and safety of a single injection of pasireotide LAR 60 mg or placebo prior to mastectomy with axillary lymph node dissection surgery in reducing symptomatic lymphocele development. Symptomatic lymphocele was evaluated and was defined as: 1. total lymphocele drainage/aspiration volume (unique or iterative) >60 cc inclusive within the 28 days after surgery (excluding post-surgery drain) or; 2. a systematic aspiration volume at day 28 > 120 cc. Statistical methods: The statistical analysis was carried out sequentially after observing the absence of symptomatic lymphocele for each patient. It involves estimating the probability of a response in each group using a Bayesian design based on a beta-binomial model. The probability of response was considered random and its prior distribution was centered on 80% in the pasireotide group and 60% in the placebo group according to the investigators initial guesses. The distribution of the probability of response was updated after the observation of the patients included in the trial. Results: A total of 90 patients were included over 18 months: 42 in the treatment group and 48 in the placebo group. In the treatment group, the posterior mean estimation of the response rate (i.e. patients who did not experience a symptomatic lymphocele) was 62.4% (95% CI: 48.6%–75.3%) and 50.2% in the placebo group (95% CI: 37.6%–62.8%%). In the treatment group, one serious adverse event occurred in a patient with known insulin dependent diabetes requiring hospitalization for hyperglycaemia. Conclusion: A one time injection of pasireotide LAR to prevent symptomatic lymphocele development in women undergoing mastectomy with axillary dissection is promising. Further clinical studies are warranted. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-14-12.