Results from a phase II clinical trial for Ofatumumab were published in the British Journal of Haematology. They look good, but not as good as some had hoped for.
The article is called "Phase 2 Multicentre Study of Single‐Agent Ofatumumab in Previously Untreated Follicular Lymphoma: CALGB 50901 (Alliance)."
First, a little bit about Ofatumumab.
It's a monoclonal antibody that targets CD20, much like Rituxan and Obinutuzumab. (And if you're like me, you might keep getting Ofatumumaband Obinutuzumab mixed up when you read about them, because they both start with O and end with mab and you read too fast and your eyes are going because you're getting old. So slow down and read carefully.)
Ofatumumab is like Rituxan, but it's a little different. For one thing, it is humanized. That is, it's made from human cells, unlike Rituxan, which is made from mouse cells. It is also works a little differently than Rituxan. I'm not going to try to explain what the difference is, because, honestly, I'm not sure I could. It involves things like lipid rafts and Fc Gamma Receptors. If you want to learn about all of that, read this article. But we can probably get away with just knowing that Ofatumumab works differently from Rituxan, and in some ways works better, because it grabs onto cancer cells more tightly.
Ofatumumab has been approved by the FDA for people with CLL, another slow-growing blood cancer, who have tried a particular treatment. So it's been around for a little while.
The clinical trial that is described in the article involved 51 FL patients. None of them had been treated before. they were divided into two groups. A smaller group had four weekly dosesof 500 mg of Ofatumumab, and a larger group of 36 had four weekly doses of 1000mg. After that, they all got four more doses, one every 8 weeks.
Results were good. The patients in the 1000mg group had an Overall Response rate of 84% (9% Complete Response, 75% Partial Respose, with another 9% having stable disease). In the 500mg group, there was a 60% ORR, with a 7% CR and 53% PR, and 33% stable).
After a median follow-up of about 30 months, the median Progression free Survival for both groups was a little under 2 years. The 500mg group had a longer median duration of response (just under 2 years, as opposed to 16.5 months for the 1000mg group).
Side effects were similar to those of other monoclonal antibodies: infections, low blood counts, allergic reactions. All were manageable, and none were life threatening.
In the end, the researchers say "Activity appears similar to that reported with single‐agent rituximab." So while it does a good job on its own, it doesn't do a better job than Rituximab or Obinutuzumab.
And that's key. If the goal is to replace Rituxan, it needs to be more effective or more safe, and it doesn't seem to be either.
Which doesn't mean it's bad, just not better.
It might still work in combination with other agents. (Unfortunately, last May, a research report showed it hadn't worked as well as hoped in combination with Bendamustine for FL and other slow-growing blood cancers.)
I'm not sure there's much of a future for Ofatumumab and FL, given the results of trials. There are still a few trials out there that need to report results, but none that are openly recruiting.
So while this has been a good treatment for CLL, my guess is that it won't be another arrow for our quiver. And that's OK. We have lots of other treatment possibilities to look forward to.
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