Registering the immune response to an influenza vaccination challenge in PTEN Hamartoma Tumour Syndrome

PTEN hamartoma tumour syndrome(PHTS) is a hereditary tumour syndrome caused
by a heterozygous mutation in the PTEN gene. It is a rare disease affecting 1
in 200000 individuals, it is theorised to be more prevalent than that ,
however. Many features of PHTS also exist in the general population, making
detection complicated. Patients with PHTS are at high risk of developing
cancer, especially breast, thyroid, endometrial and colon cancer. In recent
years, PHTS has been reported in multiple case reports and case series to
feature immune dysregulation. Hypogammaglobulinemia and decreased response to
Haemophilus influenzae vaccine has been reported. In one case report, an
increase in transitional B cells in peripheral blood was reported in a patient
with hypogammaglobulinemia. One small case series could not replicate this
finding, but did note that in PHTS, immunoglobulin levels were in the lower
normal range.
Recently, it has been suggested that immune dysregulation in PHTS should be
considered as a contributor to increased cancer risk in this syndrome. Immune
dysregulation has not yet been thoroughly studied in PHTS individuals, as the
impact of losing PTEN expression has primarily been investigated in murine
lineage specific PTEN knockout models. In regards to the humoral immune system,
class switch recombination has been shown in B cell specific PTEN -/- mouse
models, with lowered IgG and IgA, but increased IgM. Translation of these
findings to PHTS individuals is difficult and investigating immune
dysregulation in patients circumvents this hindrance.
Identifying the link between immune dysregulation and increased cancer
risk in PHTS requires further elucidation of immune impairments in PHTS
individuals. One of such impairments that is measurable and therefore
objectifiable, is the humoral and cellular immune response to vaccination. The
proven safety of the seasonal flu vaccination and the widespread availability
of the vaccine, make it a logical and practical choice to use for this
investigation. The profile in antibody response or T cell activation and
proliferation after vaccination could expose immune deficiency.
Elucidation of immune impairments in PHTS may eventually lead to the
finding of interesting molecular or immunological *signatures* of PHTS. These
PHTS associated phenotypes could be instrumental in the detection of new PHTS
diagnoses, allowing proper cancer surveillance in individuals that would
otherwise be at risk and overlooked.
As PHTS is a rare syndrome, it is a challenge to include enough
individuals for a study in PHTS individuals. At the moment, the Radboudumc has
more than 60 PHTS patients of 18 years and older and is a centre for expertise
on the subject, providing the unique opportunity to investigate this patient
group and reveal the problems and the opportunities that the PHTS immune system
harbours.

Primary Objective: The primary objective is to analyse the humoral and cellular
immune response to influenza vaccination in PHTS individuals.
• Is the immune response to seasonal influenza vaccinations impaired in PHTS?
• Do characteristics in humoral and cellular immune response to vaccinations
point to specific dysregulation in the immune system?

The design used will be a prospective, non-randomised clinical trial with
comparison group. There will be two groups that will both receive intervention
at the start of study. The study will take place over a period of two months,
half October through half December. This coincides with the start of the
national flu vaccination campaign and includes time required for follow up. The
setting of the study is in an academic medical center, Radboudumc. The
Radboudumc has a large group of PHTS patients.

The study will consist of two groups of 15 individuals, one PHTS group and one
group of unaffected individuals, it is the aim of the study to recruit
unaffected individuals out of the partners of patients. It is our expectation
that this will make the two groups more similar in terms of age, socio-economic
status and environment.

At T=0, influenza vaccination will be administered, samples will be drawn for
baseline T cell proliferation assay and baseline measurement of cytokines. A
baseline hemagglutination assay will be performed.
At T=14 hemagglutination assay will be repeated, as well as the proliferation
assay and cytokine measurements.

Influenza vaccinations will be administered at the outpatient clinic of the
Radboudumc by a research nurse, after which blood sample collection will be
performed by blood testing employees working at the polyclinic blood sample
collection unit. After the blood samples for that day have been collected,
they will be taken by the researcher to the tumour Immunology lab for analysis.
At day 15, blood samples will be collected at the blood collection unit, and
will be transported to the tumour immunology lab by the researcher. Test
results will be reported blindly for the code the subject received.
Subsequently, data will be entered into Castor fully anonymized . The key file
containing subject identity and subject identification number will be guarded
by a password only known to the researcher. Data will be analysed using SPSS.

All subjects will be administered a registered flu vaccination (Influvac Tetra)
at T=0.

The use of a seasonal flu vaccine as intervention medication is safe and
effective. All medication has some adverse side effects, but flu vaccination is
very safe and adverse effects are extremely rare. Flu vaccination programmes
have been used for some time by the Dutch government for protecting vulnerable
populations to influenza infection. Exposing this population to the risks of
the seasonal flu vaccine will be likely to incur less damage than protection
against influenza infection. It is our belief that this makes the study
ethically sound and sensible with only minor physical burden to future subjects.

This study will provide insight into immune dysregulation in PHTS using a
reliable and tested method that confers little risk. By garnering new data on
the dysfunction of the immune system, new venues for treatment and recognition
of PHTS may emerge. Additionally, increasing knowledge on the immune system in
PHTS will improve recognition and awareness of immunological symptoms in known
PHTS individuals.