ASH 2015

Quality assessment looking at rivaroxaban for cancer-related thrombosis

Dr Gerald Soff - Memorial Sloan Kettering Cancer Center, New York, USA

You’re looking at the use of a novel oral anti-coagulant in cancer-associated thrombosis, why?

Well there has been a knowledge gap. Rivaroxaban, since late 2012, has been FDA approved to treat thrombosis, DVT and pulmonary embolism in the general population including cancer patients, there’s no exclusion. But the studies that led to the Food and Drug Administration approval did not focus specifically on the cancer niche. So there has been a question of whether safety and efficacy would be adequate in the cancer population to go ahead and use these drugs.

So what have you been doing?

We went to our institution, we said we’re going to do a quality assessment initiative. We’re going to use the drug on label for its FDA approved indication to treat DVT and PE but we’re going to track our cancer patients. I’m at Sloan Kettering, everybody’s got cancer. We’re going to track our patients looking for bleeding, looking for recurrent thrombosis and making sure that the safety and efficacy are good. We set out to do a 200 patient cohort with active cancer, cancer-associated thrombosis including pulmonary emboli or proximal symptomatic deep vein thrombosis, whose full course of anti-coagulation was with rivaroxaban. Our data just came out, they’re being presented Monday morning here. It’s very exciting for us because our major bleeding rate is very low at 1.6%; our recurrent thrombosis rate is also low at 4.4%; our mortality rate, we’re not saying it’s saving lives but clearly we’re not seeing any loss in efficacy, safety or mortality compared to the older generation of injectable anti-coagulants like enoxaparin. Plus rivaroxaban compared to enoxaparin, it’s a pill instead of a shot so patient satisfaction is dramatically better and it’s also about 10% of the cost, which is also a big advantage.

Does this open the door for things like warfarin as well, though?

Warfarin works in a totally different mechanism and there have been a number of studies suggesting that warfarin, at least in the general cancer patient population, is not a good choice. So what we’ve been having to deal with is not rivaroxaban versus warfarin but rivaroxaban versus low molecular weight heparin.

What about the other NOACs?

We have not tested those.

But in principle they might also be suitable?

In principle they may. They would have to be independently validated.

So how is this looking for cancer doctors right now in deciding whether to use rivaroxaban and how sure they can be about whether it’s doing the job in thrombosis associated with cancer?

Our data certainly provide reassurance, nothing is definitive but it certainly provides reassurance. There has been some subgroup analysis from the earlier clinical trials, the EINSTEIN clinical trials, also suggesting that in the cancer patients rivaroxaban does provide safety and efficacy in the general cancer population. But that was a subgroup analysis, our programme was the first specifically looking only and specifically at cancer patients.

So what’s the take-home message for doctors now?

The take-home message is that for appropriately chosen patients who do not have a relative contra-indication to the drug, that they can be treating their patients with rivaroxaban with reasonable reassurance of safety and efficacy. Like all anti-coagulants it requires understanding the drug, how it works, how it’s cleared, when to use it, when not to use it, but there is no evidence right now that there’s a problem using it in the cancer niche and, if anything, we seem to see favourable safety and efficacy compared to the standard of care.