Adoptive therapy with TCR gene-engineered T cells to treat patients with MAGE-C2-positive melanoma and head and neck cancer.

• In patients with advanced melanoma and other tumor types, prior clinical
studies have shown efficacy of T lymphocytes directed towards tumor antigens.
To this end, tumor reactivity can be imposed by the transfer of T cell receptor
(TCR) genes into previously non-reactive T cells.
• MAGE-C2 (MC2) is a Cancer Germline Antigen (CGA) that is highly expressed in
melanoma and head and neck squamous cell carcinoma (HNSCC), but not in normal
mature tissues. MC2 can evoke clinically effective T cell responses, as
demonstrated in previous vaccination studies.
• In this phase I/IIa study, we will investigate the safety of adoptive T cell
therapy (AT) with T cells gene-engineered to express MC2-specific TCRs in
patients with advanced melanoma or HNSCC.

This study has been transitioned to CTIS with ID 2024-516922-70-00 check the CTIS register for the current data.

Phase I
• Primary objectives:
o To study the safety and feasibility of AT with autologous MC2 TCR T cells,
combined with epigenetic drug treatment, in patients with advanced melanoma or
HNSCC. Adverse events (AEs) will be documented according to CTCAE v5.0.
o To define the maximum tolerated dose (MTD) of MC2 TCR T cells in the
combination treatment.
• Secondary and exploratory objectives:
o To study presence and function of MC2 TCR T cells in peripheral blood samples
after treatment.
o To study the systemic release of inflammatory cytokines after administration
of autologous MC2 TCR T cells.
o To study immune parameters, in particular T cell parameters, in blood and
tumor tissues (when available) prior to and during treatment.
o To document the induction of global DNA hypomethylation and histone
acetylation in peripheral blood mononuclear cells (PBMC) by epigenetic drug
treatment.

Phase II
• Primary objectives:
o To assess the efficacy of AT with autologous MC2 TCR T cells at MTD, combined
with epigenetic drug treatment, in patients with advanced melanoma or HNSCC.
Tumor response will be evaluated using RECIST v1.1.
• Secondary objectives:
o To determine the following outcomes in patients treated with MC2 TCR T cells
at MTD:
- Progression free survival
- Duration of response
- Overall survival
• Exploratory objectives:
o To study presence and function of MC2 TCR T cells in peripheral blood samples
after treatment.
o To study the systemic release of inflammatory cytokines after administration
of autologous MC2 TCR T cells.
o To study immune parameters, in particular T cell parameters, in blood and
tumor tissues (when available) prior to and during treatment.
o To document the induction of global DNA hypomethylation and histone
acetylation in PBMCs by epigenetic drug treatment.

Study design
• This is a single institution phase I/IIa trial consisting of an accelerated
titration phase I design and a subsequent single arm (2-stage) phase IIa study.
In the phase I part, the recommended T cell number for phase IIa will be
determined.
• Eighteen patients with advanced melanoma or HNSCC, a HLA-A2 genotype and
MC2-positive tumors will be included in the study.
• Screening will consist of genotyping for HLA-A2 and MC2 immunohistochemistry
on tumor tissue.
• Prior to T cell transfer (day 0), patients will be treated with the
epigenetic drugs valproic acid (VP, dose 50 mg/kg/d, 7d; days -9 to day -2) and
5-azacitidine (AZA, dose 75mg/m2/d, 7d; days -9 to day -2).
• Phase I: patients will be treated with one single intravenous administration
of TCR T cells at 5 different escalated doses of 5x10e7, 5x10e8, 5x10e9,
1x10e10, and the total number of cultured TCR T cells (i.e. usually 1 - 5
x10e10 TCR T cells).
• In case of any grade 3 AE in the accelerated titration phase, the phase I
part will continue in a classical 3x3 phase I design with semi-logaritmic dose
escalation.
• In case 1 (or 3) patient(s) has(ve) been treated in a particular dose level,
but not before 3 weeks after treatment of the (3rd) patient, AEs will be
evaluated and the project team (PI, co-investigator, project leaders) together
IDMC will decide whether the trial will continue to the next dose level.
• If dose limiting toxicities (DLT) are observed in 2 out of 6 patients (3x3
extended cohort), the previous dose level will be the maximum tolerated dose
(MTD) (see section 4.4).
• Phase IIa: Simon 2-stage design starts with 6 patients at MTD and at 1
clinical response will be extended with 6 additional patients.
• Clinical response evaluation according RECIST v1.1 will be performed at 8 and
12 weeks after T cell infusion and every 3 months thereafter.
• In both bhase I and IIa, peripheral persistence, differentiation state and
tumor recognition of peripheral and intra-tumoral TCR T cells will be
evaluated, as well as additional immune and T cell parameters in blood and
tumor tissue.

Autologous T cells, obtained by leukapheresis, will be transduced with a
retroviral vector encoding the MC2 TCR. Subsequently, these TCR T cells will be
expanded ex vivo in the presence of defined cytokines. Following pre-treatment
with epigenetic drugs, TCR T cells will administered intravenously. For safety
measures, AEs will be documented according to CTCAE 5.0. Tumor response will be
evaluated using RECIST v1.1. Tumor biopsies will be taken before treatment (to
assess MC2 expression) at 4 weeks after MC2 TCR T cell infusion and at
progressive disease to evaluate therapy induced changes of the tumor
microenvironment. An optional tumor biopsy may be taken after epigenetic
pre-treatment and prior to MC2 TCR T cell infusion to document the in vivo
upregulation of the MC2 expression.

For patients included in this phase I/IIa trial, no standard therapies are
available in the Netherlands.
Previous trials have shown efficacy of AT in several patient populations.
In patients with metastatic melanoma or synovial carcinoma, AT with a CGA
NY-ESO TCR T cells has shown very limited AEs and significant objective
clinical responses of 55 and 61%, respectively.[1, 2] In patients with multiple
myeloma, infusion of NY-ESO TCR T cells 2 days after an autologous stem cell
transplant (preceded by Melphalan) resulted in a clinical response of 80%,
thereby inducing various serious AEs (SAEs), which were reversible. In patients
with melanoma, AT using autologous TCR T cells with affinity enhanced TCRs for
MAGE-A3 has shown clinical responses, but also fatal on- and off target
toxicities as a result of either targeting a common epitope of the MAGE-A
antigen superfamily or a TCR with a non-restricted binding motif. In the
current study, these (S)AEs are not expected as the MC2-specific TCR has a
restricted binding motif without enhanced affinity.
Here we have chosen to target MAGE-C2 treat is expessed in melanoma and HNSCC,
but not in healthy tissues, therfore the risk of 'on target' toxicity is
expected to be low. The MAGE-C2-specific TCR (TCR16) has a stringent bindings
motief, and is noy affinity enhanced, therefor the risk of off target toxicity
is expected to be low. Nevertheless, in case patients may experience a cytokine
release syndrome (CRS) with severe symptoms in the current study, patients will
be treated with high dose corticosteroids, the anti-IL6R antibody tocilizumab
[6], and the anti-CD52 antibody alemtuzumab, depending on the severity of the
symptoms.
In addition, the doses of the administered epigenetic drugs are well tolerated
and are only associated with mild transient leucopenia and neutropenic fever.
In this patient population, the potential burden and AEs are justified by the
substantial chance of (durable) tumor responses as a result of the proposed
treatment.