In each of the two Phase 3 trials, patients were randomized to one of three treatment groups: there was a 10mg/kg group, a 1 mg/kg group and a placebo group. Patients received an intravenous dose on days 0, 14 and 28, then every 28 days thereafter for the duration of the study. All patients receive standard of care therapy in addition to the study medication.
Primary end point results from BLISS-76 (at 52 weeks)
The 10 mg Benlysta dose resulted in statistically significant improvement in patient response rate as measured by the SLE Responder Index at Week 52 when compared with placebo.Adverse events (serious side effects) were similar between Benlysta and placebo.
43.2% of those receiving the 10 mg dose were improved at week 52.
40.6% of those receiving the 1 mg dose were improved at week 52.
33.8% of those receiving a placebo were improved at week 52.
Number Needed To Treat (NNT)
The number needed to treat (NNT) is simply the number of patients who must be treated in order to achieve one ‘good’ outcome. It is simply 1 divided by (active – placebo)
In this case: 1/(.432 – .338) = 10.7
Since the NNT is always rounded up to the nearest whole number, the NNT in this case would be 11.
In common sense terms, if 11 are treated, 5 will improve, but 4 would have improved even without treatment. That is one of the problems when using a relatively modest improvement as your primary end point – you get a large placebo response.
NNT is one of the most useful ways of looking at clinical trial results, since it gives you a good sense of how likely you are to benefit from the drug and, as a simple number, allows for easy and direct comparisons between treatment options.
NNT is of particular value when a drug is associated with significant side effects – which appears not to be the case with Benlysta. Since it might help a patient, or physician, more readily assess risk vs. reward – the chance of serious side effects vs. the likelihood of improvement.
Secondary end point results from BLISS-76 (at 52 weeks)
The percent of patients with a a reduction in SELENA SLEDAI score of at least 4 points by Week 52:
10 mg dose: 46.9%
1 mg dose: 42.8%