Lin found the paper discussing results from the phase 2 study of lampalizumab. It is a little dense but I will try to pre-digest it a bit for you. [Lin/Linda: we’ve been calling it ‘lamp stuff’.]
The study design itself was somewhat basic. There were two independent variables and two controls or shams. Independent variables are the things the researchers are manipulating. In this case it was two dosage schedules. Shots of the drug were given every month and every other month.
Controls, or sham treatment groups, were given shots on the same schedules. However, their shots did not contain lampalizumab. They just thought they did.
Overall, when the every month dosage of lampalizumab people were compared to the every month fake treatment people (sham condition), their rate of degeneration was slowed by a fifth. That is where the 20% number comes from.
However, when the researchers looked at their raw scores, they made a discovery. Some of the subjects absolutely rocked it! They were showing decreases of 44% in rate of deterioration. Others did not differ at all from the controls. Their eyes just continued to get worse at the usual rate. What the hey?
Thinking the difference might be genetic, the researchers thought about which genes to consider. They ended up with the complement factor I at-risk allele as a possible suspect.
An allele is half a gene pair. Genes come in pairs; remember? One from Mom and one from Dad. Alleles can be matched or mismatched. Terms are homozygotes and heterozygotes, but that’s not important in this case. It wasn’t important to the researchers either. They decided to look at people with one and two ‘bad’ alleles of complement factor I.
When they put everyone with good CFI alleles in one pile and everyone with at least one bad one in another pile, they made another discovery. It was the people with the bad CFI alleles who had responded to the lampalizumab. There appeared to be something about that gene that interacted with the lampalizumab in a way that slowed things down.
Looking back at their numbers, the researchers decided all of the ‘work’ done in the initial, whole group was done by the bad CFI allele people. There was an overall difference of 20%; right? But remember we are talking arithmetic averages here. If half of your group ‘improves’ by 40% but the rest of the group improves by 0% when you add them together and divide by 2, you get 20%. 20% is sort of misleading. No research subject showed a 20% rate decrease. They were either at somewhere around 44% or somewhere around 0%.
There are some things that need to be further studied. The number of subjects was not large and they need to replicate things with lots more people, for example. However, for right now the takeaway message for us is this: as suspected, AMD is looking like not one disease but a family of diseases. It is created by several different genetic flaws. The lampalizumab phase 2 study results suggest this drug will only be good for the AMD ‘family member’ that is caused by complement factor I at-risk allele. Those of us – like me – who do not have bad CFI alleles will have to wait for another breakthrough.
Those of you with CFI at-risk allele can rejoice! It looks as if they have found the first real TREATMENT and it is for you! Congratulations! We are all happy for you and want to follow you very soon.
If you really want to look at the scientific paper from the study, click here.
written July 24th, 2017
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