Description

Tesofensine was originally investigated for the treatment of Alzheimer’s disease and Parkinson’s disease,^[4] and was subsequently dropped from development for these applications after early trial results showed limited efficacy for treatment of these diseases.^[5][6] However, weight loss was consistently reported as an adverse event in the original studies, especially in overweight or obese patients.^[7] Therefore, it was decided to pursue development of tesofensine for the treatment of obesity.

Tesofensine primarily acts as an appetite suppressant, but possibly also acts by increasing resting energy expenditure.^[8] Phase II clinical trials for the treatment of obesity have been successfully completed.

Phase IIB trial (TIPO-1) results reported in The Lancet^[18] showed levels of weight loss over a 6-month period that were significantly greater than those achieved with any currently available drugs. Patients lost an average of 12.8 kg on the 1 mg dose, 11.3 kg on the 0.5 mg dose and 6.7 kg on the 0.25 mg dose, compared with a 2.2 kg loss in the placebo group.

All participants were instructed to follow a diet with a 300 kcal deficit and to increase their physical activity gradually to 30–60 minutes of exercise per day. The placebo-subtracted mean weight losses were 4.5%, 9.2% and 10.6% in the 0.25 mg, 0.5 mg and 1 mg dose groups, respectively. This is approximately twice the weight loss produced by medications currently approved by the US Food and Drug Administration (FDA) for the treatment of obesity.

NeuroSearch has also reported interim results^[8] from a 48-week, open-label, extension trial (TIPO-4) in which 140 patients who completed the 24-week phase IIB trial (TIPO-1) were re-enrolled after an average of 3 months’ wash-out. All were initially treated with 0.5 mg tesofensine once daily but up-titration to 1.0 mg once daily was allowed in the first 24 weeks of the extension study. At this time point, all subjects were continued on the 0.5 mg dose for an additional 24 weeks. The 24-week interim results for those who were previously treated with tesofensine 0.5 mg in TIPO-1 showed a total mean weight loss of between 13 kg and 14 kg over 48 weeks of treatment. Furthermore, TIPO-4 confirmed the TIPO-1 results since those patients who were previously treated with placebo lost approximately 9 kg in the first 24 weeks of the TIPO-4 study.