Rituxan

Just when you thought we knew everything there was to know about Rituxan....

A new study from Austria found that among Follicular NHL patients, women respond much better to Rituxan than men do. Also, the "volume of lymphoma cells" plays a role. Combine the two and, according to the head of the study, "This means that men with a large tumour or bone marrow infiltration respond poorest to antibody therapy, while women without bone marrow involvement and a small tumour respond best."

Here's where, in my opinion, it gets fascinating: Why?

Is there something in the genetic make up of women's lymphoma cells that makes them take to Rituxan more readily?

Or is it something simpler -- women generally have smaller bodies, and so the dosage is enough for them, but not enough for (generally) larger-framed men?

We need to find out. And that's where it gets interesting. There hasn't been a ton of research on Rituxan lately, other than two-armed trials that test newer monoclonal antibodies against Rituxan, to see if the new one is an improvement on the old standard.

I've read a little bit about how the standard dosage of Rituxan came about -- pretty much randomly. The standard dosage for NHL,  no matter the type, is the same. But Rheumatoid Arthritis patients (they also benefit from Rituxan) get a dose almost 3 times as large. So it's not like the body can't handle more. The initial dosing was chosen, well, not exactly randomly, but it was chosen for a reason, and it worked, and it's never really been messed with.

But, if we look at this new study and decide that, well, maybe it is a question of body mass, then we might be looking at some dosing trials to see if different levels produce different results. As the linked article notes, "The study has shown that blood concentrations (serum concentrations) in women are around 20 per cent higher than in men over the period of treatment with Rituximab. Women achieve saturation of the blood concentration with the antibody during the fourth cycle of therapy, significantly earlier than male patients." So maybe we need to front-load the Rituxan for men, giving much higher dosesin the earlier rounds, to achieve the same kind of sayuration that women get?

It's going to be interesting. It will be a few years before anything comes of this, but it might also mean re-figuring dosages for all those other monoclonal antibodies that do a great job, but not a hugely better job than Rituxan.

I don't think we'll see an explosion of new Rituxan studies, but maybe what we will see is a redosing of Rituxan or other MABs in combination studies. Maybe when rituxan is combined with one of those funky 3rd generation protease inhibitors, the dosage will go up from 375 to 500 mg/m2.

Total guess, but it's always fun to look back later and see just how right I was.....