CaPPtain's Blog: John Burn, February 2024
posted on Thursday, 15th February 2024
Not tagged.
The end is in sight.
Fewer than 25 of our 1879 CaPP3 recruits are now awaiting their
final 60 month follow up visit. We need to have all of
the 60-month visits completed with the data added to MACRO by
30th June 2024. This includes those participants
who withdrew but agreed to follow up and bloods, so that we can
begin the study analysis. Needless to say, the results are
eagerly awaited and will be pivotal in our efforts in the UK to
complete the repurposing of aspirin as a cancer preventive in Lynch
syndrome.
The first two years of the intervention were blinded to capture
a reliable record of adverse events in the three dosage
groups. These data are with Tim Bishop and Faye Elliott, the
study statisticians, for processing and we hope to have this
analysis ready for the summer.
We have been working for five years with colleagues in London,
Boston and Italy as part of the AsCaP programme funded by Cancer
Research UK to explore the way aspirin works. An exciting
piece of research has recently been published by our Italian
partners. They have bred a mouse which has a gene change
making it prone to bowel polyps and has the gene for COX1 out of
action. Aspirin blocks COX1 in platelets, the tiny blood
cells which block small leaks. It also blocks COX2 which is
active in inflammation. For a long time, we have assumed the
main anti-cancer effect is based on blocking COX2. In the
mouse model, stopping COX1 from working suppressed polyp
formation. This supports the idea that activated platelets
expressing COX1 might then trigger the COX2 effect. This is
important because platelets are blocked by small doses of aspirin,
and it would explain why studies involving very low dose aspirin
still show a reduced rate of cancer. If this is the main
effect of aspirin, then we would expect the similar levels of
protection against cancer in all three groups taking part in
CaPP3. On the other hand, if a direct effect on inflammation
is important, then there should be more protection with the bigger
doses.
We are now planning more research into these questions while we
await the final data from CaPP3.
In June I will attend the inaugural Cancer Prevention Conference
in Boston sponsored by Cancer Research UK, the American Cancer
Society and the US National Cancer Institute. I am a co-chair
of the conference alongside Tim Rebbeck from Harvard and Thea Tlsty
from University of California. The plan is that the three-day
conference will bring together the research community around cancer
prevention and stimulate new ideas and studies. It will be in
the UK in 2025 and continue to alternate thereafter. Needless
to say, we will be keen to talk about the CaPP3 results next
year!
John Burn
February 2024