ASCO Review: The GALLIUM Trial

Some more post-game analysis of the ASCO 2020 virtual conference.

There were two presentations on data from the GALLIUM trial. This trial has been really important for Follicular Lymphoma. It was really well designed, and it has looked at a lot of different aspects of FL treatment. On the surface, it's a comparison between Rituxan, the monoclonal antibody that has been around since 1997, and Obinutuzumab, a monoclonal antibody that was created to improve on Rituxan.

What makes it such a great study is that 1) it involves a large number of patients (1202 of them, all getting their first treatment after being diagnoses with FL), and the fact that it is a direct comparison between tow treatments, where half of the participants receive one treatment, and half receive the other. (Some trials give everyone the same treatment, and then compare the results to a study that took place sometime in the past). A large, well-designed study can tell us a lot.

Of course, this is Follicular Lymphoma, the "No Straight Answer Cancer," so even the best studies can be frustrating.

The first presentation from the GALLIUM study was a 5-year follow-up of patients in the study ("Comparison of efficacy and safety with Obinutuzumab plus chemotherapy versus rituximab plus chemotherapy in patients with previously untreated follicular lymphoma: Updated results from the phase III Gallium Study"). Every trial needs to look at efficacy -- how many patients had a good result from the treatment -- and safety -- what kind of side effects they dealt with.

The GALLIUM study compared Rituxan + chemotherapy, followed by Rituxan maintenance, versus Obinutuzumab + chemotherapy, followed by Obinutuzumab maintenance. There were an equal number of patients getting each treatment, and none of them had received any treatment before the trial. (In the ASCO abstract, Obinutuzumab is known as "G," not "O," for its trade name Gazyva.)

It's interesting to look back at a blog post I wrote in 2007 about the trial. The 5 years results from ASCO are pretty much the same story as in 2017. The Obinutuzumab group had a better Progression Free Survival than the Rituxan group: 70.5% of the O patients had their disease remain stable, vs 63.2% for the R group. Also, patients whose disease progressed within 2 years was lower in the O group than the R group (this group is known as POD24, progression of disease within 24 months, and they often have worse prognosis than other FL patients). The percentage of POD24 patients in the O group was 9.2%, versus 16.3% in the R group.

On the other hand, patients in the O group had a higher rate of serious side effects that the R group (19.7% versus 16.8%), mostly related to neutropenia, a low level of neutrophils, a type of white blood cell. This can lead to increased risk of infections.

Also, there was virtually no difference in Overall Survival between the two groups. 90.2% of patients on the O group were alive at the 5 year mark, versus 89.4% of the R group. Both are considered high by the researchers.

So after 5 years, there's not much change than what we saw after 2 years. Better PFS for Obinutuzumab + chemo + O maintenance, but slightly worse side effects, and no difference in OS.

What's the practical outcome of all of this? The researchers say Obinutuzumab should be considered the better choice for first treatments with immunochemotherapy.

Will that actually happen? Hard to say. I've certainly seen more talk online from patients who are getting O as part of their treatment, but there are still plenty getting Rituxan, too. My guess (and this is only a guess) is that some doctors will continue to g with Rituxan out of habit, since there isn't (in their opinion) enough of a difference to make them switch. Speaking from my own experience, when I talked to my oncologist about possible treatments (if and when I need treatment again), he mentioned trying Rituxan again, since it worked well the first time, but didn't bring up Obinutuzumab at all. Maybe that would come up if Rituxan stopped working?

I don't think Rituxan is a bad choice at all, so don't be worried if that's the one you've been going with. They both result in excellent Overall Survival, which is really the important thing.

But if the choice is a possibility, it's worth talking about with your doctor.

I'll get to that other GALLIUM trial presentation next time.