Resistance to chemotherapy induced by plasma from healthy volunteers after fish oil consumption

In previous preclinical studies from our lab, mesenchymal stem cells have been
shown to be involved in chemoresistance by secreting two specific fatty acids
KHT and 16:4(n-3). These fatty acids are present in human plasma and increase
after chemotherapy exposure. In a preliminary analysis this increase has been
shown to correlate with therapy response. Moreover, patient plasma containing
elevated levels of 16:4(n-3) can induce resistance to chemotherapy in an in
vitro tumor cell line.

Mass spectrometry analysis has shown that these two fatty acids are abundantly
present in fish oil, which is often used by cancer patients due to its presumed
beneficial effect. We found that fish oil can induce chemoresistance in
preclinical mouse studies.

Very recently we have also found that certain species of fish contain hight
levels of these 'bad fatty acids', specifically herring and mackerel. In this
study, we would therefore like to study the effect of fish consumption on
plasma levels of these fatty acids.

We hypothesize that consumption of fish oil or fish can induce resistance to
chemotherapy by upregulating plasma levels of KHT and 16:4(n-3). The next step
to test this hypothesis in a human situation is by performing a study in
healthy volunteers.

The objective of this study is to determine whether oral intake of commercially
available fish oil or fish induces a rise in plasma levels of KHT and
16:4(n-3), and whether this plasma can thereby induce chemoresistance in an in
vitro tumor cell culture and in in vivo mouse models.

Healthy volunteers who are willing to participate and who signed informed
consent will receive 5x the advised daily dose of fish oil for oral intake. An
infuse will be placed and blood will be withdrawn from the infuse 7 times. The
infuse will be removed at the end of the day. The next day, the volunteer will
come back to the hospital for a venapuncture 24 hours after fish intake. In
total, a volume of 47.5 ml blood will be collected.
Analysis of 16:4(n-3) levels will be performed by mass spectrometry, and plasma
will be added to in vitro immortalized tumor cell cultures and in vivo in mouse
models, together with chemotherapy, to determine the degree of resistance by
counting the number of tumor cells after 24 hours of treatment.

Intake fish oil after t=0 blood sampling
t=0 2 CPT 8 ml 16:4(n-3) levels, KHT levels, resistance in in vitro tumor cel
cultures and in vivo mouse models
t=0.5 uur 1 citrate 4.5 ml 16:4(n-3) levels, KHT levels, resistance in in
vitro tumor cel cultures and in vivo mouse models
t=1 uur 1 citrate 4.5 ml 16:4(n-3) levels, KHT levels, resistance in in vitro
tumor cel cultures and in vivo mouse models
t=2 uur 1 citrate 4.5 ml 16:4(n-3) levels, KHT levels, resistance in in vitro
tumor cel cultures and in vivo mouse models
t=4 uur 1 citrate 4.5 ml 16:4(n-3) levels, KHT levels, resistance in in vitro
tumor cel cultures and in vivo mouse models
t=6 uur 1 citrate 4.5 ml 16:4(n-3) levels, KHT levels, resistance in in vitro
tumor cel cultures and in vivo mouse models
t=8 uur 1 citrate 4.5 ml 16:4(n-3) levels, KHT levels, resistance in in vitro
tumor cel cultures and in vivo mouse models
t=24 uur 1 citrate 4.5 ml 16:4(n-3) levels, KHT levels, resistance in in vitro
tumor cel cultures and in vivo mouse models

Total
8 9 47.5 ml

When we find differences in FFA levels, or resistance either in vitro or in
vivo in an internal interim analysis, there will be a follow-up with the
recommended daily amount of fish oil. In addition, fish intake will be tested.
This will be doen in the different volunteers with intervals of at least two
weeks.

The intervention is this study is intake of fish or fish oil at T0.
Volunteers will be randomly assigned to one of three fish oil brands, or to
each of the fish species.

The burden for the volunteers is that blood withdrawal will take place in the
hospital. This means that the volunteers will have to spend 8.5 hours in the
hospital, in which 7 blood withdrawals will be performed via an infuse needle.
In case of fish intake, the volunteer will come to the hospital the next day as
well for a venipuncture 24 hours after fish intake. This will take
approximately 15 minutes.

During the day, the volunteer is not expected to stay in the same location,
only at times of blood withdrawal will he/she be expected to be present.

Placing of an infuse needle and venapunction can result in an haematoma.
Further risks are minimal.
Fish oil and fish consumption is not expected to lead to any side effects.