Advances in the understanding of glioblastoma at a molecular level along with
technological progress have led to the identification of key genetic alterations, not
only in scientific projects but also in every-day clinical practice. These alterations
increasingly refine the sub-classification of glioblastoma and the introduction of
molecular markers in this classification, which ultimately may allow defining subset
specific treatments.
The present umbrella concept for multiple biomarker-driven subtrials anchors at the
Heidelberg-based INFORM registry trial in recurrent pediatric malignancies, where in
analogy to NCT Neuro Master Match (N²M²) whole-exome, low-coverage whole-genome and
transcriptome sequencing is used to identify targeted agents, single or in combinations
according to a dedicated algorithm. It also shares conceptual similarities with
international projects currently developed for lung and breast cancer. Finally,
approaches to use molecular information in glioblastoma for the definition of a therapy
at progression are also planned by the "Defeat Glioma" Consortium in the US and a group
of excellence centers also in the US.
The N²M² concept excels the aforementioned initiatives in the strict focus on newly
diagnosed patients, the option to cross-validate molecular biomarkers in an already
analyzed contemporary cohort of glioblastoma patients analyzed in the German Consortium
for Translational Cancer Research (DKTK) and the use of a parallel group treated with
standard-of-care (SOC). Further restriction is made by the inclusion of patients only
with a low likelihood to benefit from the SOC, temozolomide (TMZ) chemotherapy on the
basis of O6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation, allowing to
replace TMZ with a molecularly targeted agent in combination with radiotherapy (RT) in
each of the experimental subtrials. Replacing TMZ by an experimental agent in the primary
chemo-radiotherapy has been done in at least four completed trials, albeit without
pre-selection of a targeted therapy but the more opportunistic use of an available drug
with no known MGMT interaction. Focusing on newly diagnosed patients not only harbors the
greater likelihood of impact on the disease, but also allows addressing questions on
acquired resistance in the more likely obtained tumor tissue at recurrence.
N²M² is formally divided into a DISCOVERY and a TREATMENT aspect. DISCOVERY starts with
an (epigenomewide) Illumina methylation array and a panel sequencing followed by an
appropriate and accepted standard method (Sanger Sequencing or Immunohistochemistry)
within the scope of these methods for target validation prior to any suggestion for
patient allocation into one of the subtrials. Suggestions for patients' allocation to one
of the subtrials will be based on results of accepted standard methods. These data will
be generated from formaline-fixed paraffine embedded (FFPE) tissue within in 2-3 weeks
after surgery. The Heidelberg site has already established the next generation gene panel
sequencing (used for target discovery in case of N²M²) and genome wide DNA methylation
analyses for aiding daily routine. To meet the criteria for a safe use of these data for
decision-making the orthogonal, standard methods performed in the Institute of Pathology
are supplemented.
DISCOVERY also includes the use of whole exome, low-coverage whole-genome, and
transcriptome sequencing, the methylome analysis, and gene expression arrays to find new,
unexpected targets and get a more comprehensive view on affected pathways. Discovery is
also the driving force behind the work on resistant tumors. The latter may result in
individual treatment decisions at recurrence, knowing there are no relevantly active
treatments in this setting.
TREATMENT is driven by a match/no match decision rendered in an algorithm that will be
subject to refinement in the process of the project, both by data generated in N²M², but
also external evidence; i.e. there may be some linear relations between an alteration,
e.g. BRAF V600E mutation and a distinct treatment or some others, but it is expected that
these linear relations will be replaced in a learning system by relations that take
upstream and downstream target alterations and also parallel signaling pathways into
account and may therefore already predict a certain likelihood of resistance development.
In detail, FFPE tissue (and blood) from patients diagnosed with a glioblastoma harboring
an unmethylated MGMT promoter after informed consent will be subjected to a
(epigenomewide) methylation array and panel sequencing as well as the appropriate methods
to validate any of the trial immanent targets, if they are present, with results
available within a maximum of 3 weeks postoperatively. This allows for a timely decision
at the molecular Neurooncology Tumor Board and a timely initiation (within 4 to 6 weeks)
of the postoperative treatment. Further examinations on fresh tumor tissue (and blood)
such as whole exome, low-coverage whole genome and transcriptome sequencing as well as
expression arrays will be done to enhance the scientific background on the tumor tissue.
These data will not be used for decision-making, Runs already done within the INFORM
project with glioblastoma samples and also dry runs (n=43) for the N²M² project support
the feasibility of the timelines and principal options for discovery.
Matching will be defined as a molecular situation, which makes treatment with RT and a
matching targeted drug from a prespecified warehouse separated in subtrials meaningful.
Patients will be informed about the identified treatment option within the "matching"
open-label, parallel group Phase I/IIa trial. As for 2 of the experimental compounds
(APG101 and Atezolizumab) no specific biomarker is validated at the moment, the
nonmatching patients will be equally allocated to receive either APG101, Atezolizumab or
the current SOC (radiochemotherapy with TMZ, TMZ-group). Patients allocated to the
TMZ-group will serve as a meaningful control group with basic efficacy parameters
documented, if consent has been obtained.
The objective of N²M² is the improvement of overall survival of patients with
glioblastoma with an unmethylated MGMT promoter based on molecular characterization and
use of targeted compounds in a modern trial design. The progression-free survival rate at
six months (PFS-6) will be used to make decisions.
Parallel and ongoing translational projects within the DKTK will examine prognostic
properties of the biomarkers identified to drive therapy decisions in this trial. Trial
accrual will be asymmetric into the different subtrials. It is expected that 75-100
patients will be accrued into this trial per year at about 14 sites in Germany (mainly
Deutsches Konsortium für Translationale Krebsforschung, DKTK and Neuroonkologische
Arbeitsgemeinschaft, NOA). Importantly, the parallel SPECTAbrain initiative of the
European Organization for the Research and Treatment of Cancer (EORTC) is synergistic and
not competitive to our study proposal since it is focused on the treatment at recurrence,
using paraffin-embedded tissues, panels/arrays only and it would be desirable that data
from these initiatives are looked at in a joined manner.
