This oral presentation made during ESMO 2016 highlight novel targets and drugs developed for patients with advanced neuroendocrine tumors. This includes targeted agents aiming probing cell signaling in tumor microenvironment and immune responses. Genetic alterations on major anti-oncogenes are reported in the perspective of pathway activations. Combinations using VEGFR, mTOR, Somatostatin receptors inhibitors with novel strategies and immunotherapy are also suggested. This presentation focuses mainly on gastrointestinal neuroendocrine tumors but may also be of interest for those involved in the care of patients with thoracic neuroendocrine tumors.

1. esmo.org
PRECISION MEDICINE IN NET
Targeted drugs: Where are we heading to?
Prof Eric Raymond, MD, PhD
GH PARIS SAINT JOSEPH – France
eraymond@hpsj.fr
185 rue Raymond Losserand – 75014 Paris

2. DISCLOSURE SLIDE
Honoraria and Research Grants:
Pfizer
Ipsen
Novartis
Eli Lilly

3. u Neuroendocrine tumors are characterized by specific genetic (mutations &
epigenetic changes) alterations that primarily concern anti-oncogene
u Mutation-driving activations of the mTOR pathway is thought to be responsible
of changes in metabolic fate and proliferation of neuroendocrine tumor cells
u Pancreatic neuroendocrine tumors are also characterized by a strong activation
of VEGF/VEGFR-dependent angiogenesis either induced by VHL mutations or
a hypoxic microenvironment induced by tumor growth
u Other targets and the immune microenvironment are poorly known but may
represent exciting potentials for novel therapeutic approaches
Biological patterns in neuroendocrine tumors

4. MS Lawrence et al. Nature 000, 1-5 (2013) doi:10.1038/nature12213
Somatic mutation frequencies observed in exomes from 3,083 tumor–normal pairs

5. Neuroendocrine tumors are diseases characterized by
loss of tumor suppressor genes
> 50%
unknown somatic
mutations or other
abnormalities

6. TGF-β R1 & R2
SMAD7
AKT1
TGF-α
EGFR
RAS/RAF
MEK/ERK
PI3K
AKT
MEN1
Protein interactome involved in
neuroendocrine neoplasm proliferation

7. Endothelial cell
Tumor
cell
PDGF
VEGF
Apoptosis
PDGF
VEGF
IGF
IGF1-R
P
HIF-1 HIF-2
Survival
Proliferation
P
Ras
PAKT
P
Nucleus
Mitochondria
Mitochondria
P
Nucleus
Angiogenesis:
Differentiation
Proliferation
Migration
Tubule formationApoptosis
PDGF-BB
PI3k
x
P P P
VEGF-A
VEGF-C
Paracrine
stimulation
PI3k
S6K1
PmTOR
PAKT
VEGFR-2 VEGFR-3PDGFR-b
Hypoxia
PDGF-BB
PDGFR-b
NucleusP
PI3k
S6K1
PmTOR
PAKT
mTOR
SSR
Somatostatin
Hypoxia
Pericytes
Neuroendocrine
Tumors
Tumor vessel
permeability
Autocrine
& paracrine
stimulation
Faivre S, et al. Endocrinol Metab Clin N Am 2010;39:811–826

8. Cellular consequences of genetic and epigenetic changes observed in NETs
Activation of proliferation and
loss of cell cycle control
Loss of apoptosis
Increased invasiveness &
metastases
Changes in metabolism
(Kreb’s cycle)
Hypoxia and pseudo hypoxia
Epigenetic oncogene activation
related to losses in anti-oncogene
control and chromatin remodeling
Adapted from Joakim Crona and Britt Skogseid; European Journal of Endocrinology (2016) 174, R275–R290

9. Losses of genetic, proteomic, and epigenetic controls of NET cells yield novel
paradigms for clinical interventions
Capdevila J et al. Oncogene advance online publication, 2016

10. Pharmacological attempts to control tumor growth on major reactivation pathways are
likely to be associated with adaptive resistance mechanisms
Adaptive
resistance
mechanisms
Cellular
differentiation
Somatostatin analogues
PRRT
SSR
Metabolic pathway
activation
EverolimusmTOR
Hypoxia & pseudo
hypoxia
SunitinibVEGFR
Genetic and
epigenetic
oncogene
reactivation
Immunotherapy
?
Novel antigens
Other microenvironment
changes

11. u Resistance to VEGF/VEGFR and mTOR inhibitors have been evaluated in
some preclinical models leading so far to limited clinical applications
u Preclinical data suggest peculiar patterns:
u Unlike resistance to chemotherapy, mechanisms leading to lost of sensitivity to
targeted therapy could be at least in part reversible
u Resistance to VEGFR inhibitors does not affect sensitivity to mTOR inhibitors
u This offers the opportunity of using sequential therapy with VEGFR and mTOR
inhibitors
Resistance to VEGFR and mTOR inhibitors
1. Sui X et al. Cell Death Dis. 2013;4:e838. doi:10.1038/cddis.2013.350. 2. Zahreddine H et al. Front Pharmacol. 2013;4:28. doi:10.3389/fphar.2013.00028.
3. Buczek M et al. Biochem Biophys Acta. 2014;1845:31-41. 4. Bergers G et al. Nat Rev Cancer .2008;8(8):592-603. 5. Izar B et al. Pharmacol Rev .2013; 65:1351-1395.11

12. What do we know about resistance to mTOR Inhibitors?
Acquired resistance
- Activation of alternative pathways
- Mutations in mTORC1/FKPB12
- Loss of PP2A function
- Stimulation of autophagy (competes with
apoptosis)
12Reprinted with permission from: Tijeras-Raballand et al. Targ Oncol .2012; 7:173-181.

13. Mechanisms for Overcoming Resistance to mTOR Inhibitors
mTOR, mammalian target of rapamycin; mTORC mammalian target of rapamycin complex; IGFR, insulinlike growth
factor receptor; MOA, mechanism of action.
1. Tijeras-Raballand A et al. Target Oncol. 2012;7(3):173-181. 2. Izar B et al. Pharmacol Rev. 2013; 65:1351-1395. 13
Potential strategies to overcome resistance1,2
• Novel inhibitors that block both mTORC1 and mTORC2
• Combination therapies with mTOR inhibitor and a second agent that blocks
upstream kinases (AKT or PI3K) or receptors (IGFR)
• mTOR/EGFR dual inhibition (eg, rapamycin/erlotinib)
• Sequential treatment with agents having different MOAs

14. u mTORC1 blockade induces AKT activation by feedback loop, which can be attenuated by
IGR blockade induced by SSAs2
u SSAs decrease secretion of IGF-1 ligand, thereby diminishing paracrine/autocrine
activation of IGF-1R and its downstream effects (ie, on AKT)3
u Everolimus and SSA might act synergistically to inhibit protein synthesis and decrease
angiogenesis4
u However, the addition of pasireotide to everolimus did not improve PFS in pts with
progressive pNETs - COOPERATE-2 study [NCT01374451]5
Combinations of mTOR Inhibitors and SSAs1
1. Salazar R et al. Drugs. 2011;71(7):841-852. 2. O’Reilly KE et al. Cancer Res. 2006;66(3):1500-1508.
3. Susini C et al. Ann Oncol. 2006;17:1733-1742. 4. Bousquet C.
J Clin Endocrinol Metab. 2012;97:727-737. 5. Kulke et al. ENETS Congress 2015 (oral presentation)
14

15. Resistance to anti-angiognic agents:
Intrinsic (Primary) vs Adaptive (Secondary)
Reprinted with permission from: Bergers G, et al. Nat Rev Cancer. 2008;8:592-603. 15

16. STRATEGIES TO REVERT RESISTANCE
TO ANTIANGIOGENESIS APPROACH
Moserle L, et al. Cancer Discovery 2014

17. Sequential administration of sunitinib and everolimus may delay substantially
progression in well differentiated PNET
Sunitinib
37.5 mg/day
re-challenge
Sunitinib
25 mg/day
Sunitinib
37.5 mg/day
Chemotherapy
Everolimus
Time from diagnosis of advanced
pNET ~7 years, 3 months
63 66 69 72 7548 51 54 57 6033 36 39 42 4518 21 24 27 303 6 9 12 15 84 87 9078 810
15
20
25
30
35
40
45
Sizeoflongestdiameters(mm)
Evaluations (months)
*
*Performed at 2 months

18. Senino B, et al. Cancer Discovery 2012;
Faris JE, et al. ASCO 2014
NCT01466036
Cabozantinib pNET & Carcinoids
Dual VEGFR/C-MET inhibitors may counteract EMT activation
developed under anti-VEGF/VEGFR inhibitors

19. Native & treatment-induced antigen releases in neuroendocrine
tumors offer the potential for immunotherapy
Adapted from Pietro Ameri, Diego Ferone, Neuroendocrinology 2011
CD73
Vaccination
Checkpoint
inhibitors

20. Reversing resistance: Future of targeted therapies in neuroendocrine tumors
mTOR inhibition
Everolimus
VEGFR/PDGFR inhibition
Sunitinib
Somatostatin analogues
Octreotide
Lanreotide
PRRT
Primary targets
mTOR inhibition
Others
VEGFR/PDGFR inhibition
Others
Somatostatin analogues
Others
Analog targets
TT with checkpoint inhibitors
TT with chemotherapy
TT with PRRT
TT with nanoparticles
Combinations
TGF-beta R1/2 inhibitors
CXCR4 inhibitors
EGFR inhibitors
PI3K/MEK/ERK inhibitors
NOTCH inhibitors
Novel targets
MET inhibitors

21. u Resistance to targeted agents in pNET remains poorly understood
u Based on clinical observations, sequential administrations of targeted
therapies seem to be able delaying progression
u Understanding mechanisms of NET carcinogenesis may help identifying
targets and drugs that can counteract primary and acquired resistance to
targeted therapies
Conclusion
21