The US Food and Drug Administration (FDA) has approved Orexigen’s Contrave (naltrexone + bupropion) for the treatment of obesity, while panelists on an FDA advisory committee voted in favor of recommending the approval of Saxenda (liraglutide; Novo Nordisk).
Between 8 and 14 September 2014, two investigational weight loss drugs were under scrutiny ahead of their prospective entries into the US obesity market. On 9 September 2014, Contrave, Orexigen’s fixed-dose combination of bupropion and naltrexone, finally received FDA approval, over four years after its first application was submitted to the agency. It is indicated for the chronic weight management of obese patients (those with a body mass index [BMI] of ≥30), and overweight patients (those with a BMI of ≥27) with at least one weight-related co-morbidity. Moreover, on 11 September 2014, the Endocrinologic and Metabolic Drugs Advisory Committee voted 14-1 in favor of recommending the approval of Saxenda, a higher-dose formulation of the popular antidiabetic drug Victoza. While the 16-member panel was unable to conclude unanimously that Saxenda’s risk-benefit profile supports its approval, and the FDA is not bound to the committee’s decision, the overall endorsement is highly suggestive of final regulatory approval in October.
Contrave’s approval followed the completion of four pivotal trials evaluating the drug in 4,536 patients, as well as the ongoing LIGHT study, the largest clinical trial to date assessing Contrave’s cardiovascular safety in approximately 8,900 obese and overweight individuals. Patients receiving Contrave experienced a mean placebo-subtracted weight loss of 2.0–4.1%, with 36–57% of patients achieving ≥5% weight loss. These numbers place Contrave’s weight loss efficacy broadly in line with the long-standing obesity drug Xenical (orlistat; Roche) and Eisai’s recent market entrant Belviq (lorcaserin), although considerably behind the best-in-class Qsymia (phentermine/topiramate; Vivus).
Orexigen and its commercialization partner Takeda will face several challenges in launching Contrave. The long wait for FDA approval has allowed Belviq and Qsymia to launch well in advance of Contrave, and in the absence of compelling data suggesting that Contrave has superior efficacy and tolerability, Datamonitor Healthcare predicts that physicians will be reluctant to prescribe it ahead of these other diet pills. Furthermore, Contrave itself carries black box warnings owing to the class-wide risk of antidepressants increasing the risk of suicidal thoughts and behaviors in adolescents, as well as bupropion’s association with serious neuropsychiatric events when used for smoking cessation.
Saxenda represents a break from tradition in the treatment of obesity. The active ingredient, liraglutide, is more commonly known as the antidiabetic Victoza, acting as a glucagon-like peptide receptor 1 agonist. It has a known weight loss effect in patients with type 2 diabetes, which led Novo Nordisk to investigate the drug in obese patients, increasing the daily dose from 1.8mg to 3.0mg. In its obesity clinical program, Saxenda was able to match Qsymia in the proportion of patients achieving ≥5% weight loss (64%) at 56 weeks, with 33% of patients reaching ≥10% weight loss.
Novo Nordisk’s decision to rebrand its higher-dose formulation as Saxenda can be seen as a move to distinguish the diabetes market from that for weight loss drugs, despite the large amount of overlap. It will also allow the company to separate its Victoza and Saxenda pricing structures, with reports suggesting that Novo Nordisk intends to price Saxenda at $9,000/year, which is approximately three times higher than what Victoza formulations would cost for 3mg daily dosing. This move is likely to be met with opposition from payers, especially given that Saxenda would also cost considerably more than existing oral drugs. Targeting such a high price point may also indicate that Novo Nordisk intends for Saxenda to be a niche product, which is perhaps reflective of its subcutaneous mode of administration, rather than a mass-market weight loss pill.
The drug market for obesity is failing to meet its considerable commercial potential, considering the enormous patient population. Datamonitor Healthcare’s Epidemiology: Obesity review found there to be 175 million obese and 198 million overweight patients in the US, Japan, and five major EU markets (France, Germany, Italy, Spain, and the UK) in 2013. Given the clinical inadequacies of current drug therapies, with key opinion leaders citing short- and long-term efficacy as the most important drivers of treatment choice, it is unlikely that either Contrave or Saxenda will prove to be revolutionary. Nevertheless, Saxenda appears to be the product most likely to grow the obesity market, owing to its peripheral mechanism and lack of psychiatric effects, the longstanding physician familiarity with liraglutide, and considerable overlap between the type 2 diabetes and obesity populations.
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