Irreversible electroporation and Nivolumab combined with intratumoral administration of a toll like receptor ligand as a means of in vivo vaccination for metastatic pancreatic cancer

Pancreatic adenocarcinoma is one of the most aggressive forms of cancer, for
which survival has hardly improved over the past 40 years. It is the 4th
leading cause of cancer-related death in Europe and the United States.
Pancreatic cancer has the highest mortality rate of all major cancers; 94% of
pancreatic cancer patients will die within five years of diagnosis, 74% within
the first year of diagnosis; only 6% will survive for more than five years.
Surgical resection is the only curative option. However, about 50% of patients
present with locally advanced or metastatic pancreatic carcinoma (APC; AJCC
stage III and IV). These patients are no candidates for surgical resection
because these tumors involve major blood vessels such as the superior
mesenteric artery, celiac axis, common hepatic artery and/or portal vein or due
to the metastatic burden. Metastatic pancreatic cancer patients are currently
treated with palliative chemotherapeutic drugs as first line therapy. Since the
introduction of FOLFIRINOX in 2012 median overall survival improved from 3,4 to
is 6,4 months (data IKNL registry). For patients diagnosed with locally
advanced pancreatic cancer (LAPC), a combination of chemotherapy plus local
tumor destruction using irreversible electroporation (IRE), a novel tumor
ablation technique, has recently shown great promise. IRE is based on
permeabilization of the cell membrane through electrical pulses leading to cell
death. Theoretically, IRE only affects viable tumor tissue, leaving surrounding
vital structures relatively intact. It is therefore considered to cause less
morbidity and mortality than thermal ablative strategies. Several studies have
investigated the safety and efficacy of IRE for LAPC. Although the primary aim
of IRE for locally advanced pancreatic tumors is to macroscopically completely
destruct the primary tumor, preliminary data, obtained at the Amsterdam UMC
(VUmc) immuno-oncology research institute, suggests the induction of a T-cell
mediated systemic immune response. Besides the local destructive ability of IRE
the ablation may also generate effective antitumor immunity through the release
of antigens caused by massive cell death in the context of damage-associated
molecular patterns (DAMPs) that can trigger an innate immune response
(immunogenic cell death). Since the blood and lymphatic vessels remain intact,
an efficient immune infiltration and lymph drainage, respectively to and from
the tumor ablation zone, is facilitated. This may allow for the priming in
draining lymph nodes (LN) of effector T cells as well as their subsequent
attraction to the tumor site. This may also translate into a so-called
*abscopal effect*, referring to the phenomenon where localized treatment of the
primary tumor induces a forceful immune response, targeting occult distant
micro-metastases, which could have an additional positive effect on
recurrence-free and overall survival. The observed induced systemic immune
response appeared to be transient and may benefit from combination with immune
modulating drugs. Combining this form of ablative in vivo vaccination with
local and systemic immune potentiation with anti-PD1: Nivolumab and or CpG
oligodeoxynucleotide: IMO-2125 (Tilsotolimod) could hypothetically turn the
immune suppressive pancreatic tumor milieu into an immune permissive
microenvironment. The local generation of effective antitumor immunity may
provide systemic protection against outgrowth and ultimately provoke shrinkage
of distant metastases. In effect, in vivo vaccination would thus have been
achieved.

The main objective of this study is to assess the safety of combining Nivolumab
with IRE alone and of combining Nivolumab with IRE and CpG .The secondary
objectives of this study are : 1) whether the combination of Nivolumab + IRE,
or of CpG + Nivolumab + IRE induces a more potent sustainable loco-regional
and systemic immune response compared to Nivolumab alone and 2) to observe an
induced T cell infiltration in, and possibly an abscopal effect on, untreated
metastatic lesions.

The PANFIRE III-trial is a prospective, two-center randomized controlled
phase-I trial. Primary participating center will be the Amsterdam University
Medical Centers (location VUmc). The study will be conducted following a
step-up design with safety/toxicity interim analysis after inclusion of 6 , 12
and 15 patients. Inclusion will start in arm A and B at the same time.
Inclusion in arm C will start after arm A and B have included the predefined
patients and the interim analysis of these 12 patients proved safe.

Arm A (control arm): 3x i.v. infusion of 240 mg Nivolumab every 2 weeks,
starting at T=0 , followed by 480 mg Nivolumab every 4 weeks
Arm B: Percutaneous computed tomography (CT)-guided IRE of the primary
pancreatic tumor followed by 2x i.v. infusion of 240 mg Nivolumab every 2
weeks, starting 2 weeks after T=0 ( IRE ablation), followed by 480 mg Nivolumab
every 4 weeks
Arm C: Single intratumoral CpG injection (8mg) 1 week prior to percutaneous
CT-guided partial IRE of the pancreas followed by 2x i.v. infusion of 240 mg
Nivolumab every 2 weeks, starting 3 weeks after T=0 (CpG injection) followed by
480 mg Nivolumab every 4 weeks

Several studies have investigated the safety and efficacy of open and
percutaneous IRE for locally advanced disease, with an overall complication
rate of 10-37% and an overall survival time from IRE ranging from 16.0 to 24.9
months.[1] One trial compared the results to a matched group of patients
treated with chemoradiation alone, which showed a potential survival benefit of
9 months in favor of the IRE group. For complete pancreatic IRE procedures
clinically relevant complications are expected in up to 17% of procedures with
a 1-2% mortality rate. In this study incomplete IRE will be performed with the
aim to kill enough tumor cells for sufficient antigen release to induce a
durable T-cell response. Since complete tumor destruction is not required to
achieve this goal the ablation will be less destructive, with larger margins
and on the safe side of what is necessary, consequently we expect complication
and mortality rates to be lower than described in previous studies.

The risks associated with treatment with Nivolumab and/or CpG consist of
immune related side effects. This is due to an increase of T cell activity,
inflammatory cytokines and pre-existent autoantibodies. The most common adverse
events (AEs) related to CpG are injection site reactions (ISR) and flu-like
symptoms. In general, these reactions occur early and resolve within 48 hrs
with non-specific measures. The most common adverse events related to
checkpoint inhibition with Nivolumab are tiredness, transient fever, mucositis,
or colitis and are mostly easily managable. Potential benefits of Nivolumab
alone or combined with IRE and CpG treatment in this trial may include
primary pancreatic tumor clearance, metastatic tumor clearance and a longer
progression-free and overall survival. Possible side effects will be treated
following the international guidelines on managing toxicities of immune
checkpoint blockade.

The burden associated with participation comprises of percutaneous CT-guided
incomplete IRE treatment for 12 patients, percutaneous CT-/ ultrasound guided
intratumoral CpG injection for 6 patients (6 patients receive both) and all
patients receive i.v. Nivolumab treatment every 2 weeks up to progression.
There will be 4 time points for data collection: 1) baseline: prior to any
treatment, 2) 3 weeks after first treatment, 3) 6 weeks after first treatment,
4) 3 months after first treatment (only PET CT-scan). Biopsies will be taken of
the primary and a metastatic tumor site at T=0, T=2 weeks, and T=6 weeks (arm
A, B) or T=0, T=1week, T=3weeks and T=6weeks (arm C), and 50 ml heparinized
blood will be drawn from each patient at these 3 (or 4 in arm C) different time
points. To warrant safe administration of Nivolumab blood will be drawn at
baseline and prior to administration of every cycle of Nivolumab for
determination of electrolytes (Na, Ka), kidney function (kreatinine), liver
enzymes and bilirubin, C- reactive protein, full blood with leukocyte
differentiation and TSH and T4.

2 PET CT-scans (18F-FDG and 18F-BMS-986192 tracers) will be performed pre-
treatment, at 5-6 weeks (arm A and B) or 6-7 weeks (arm C), after start of
treatment. 3 months after treatment another 18F-FDG PET CT scan will be
performed. The number of hospital visits will be kept to a minimum of 4 (arm A
and B) or 5 (arm C) times depending on the study arm. For IRE treatment
patients will be admitted to the hospital for at least 3 days and all different
tests will be performed during this admission periods. Furthermore,
questionnaires concerning pain scores and quality of life will be sent to the
patient every 3 months during the first year, and every half year hereafter.