Download HIF-α

Basi molecolari delle
terapie mirate nel
carcinoma del rene
metastatico
Nicola Tinari
Oncologia Medica
Università G. D’Annunzio
Chieti
Targeted therapies as a paradigm shift in the
treatment of metastatic kidney cancer
• Historically considered as an “orphan” disease for its limited response to
conventional chemotherapeutics agents (ORR 2.4%)
• “First generation” immunotherapy (IFN, high dose IL-2) associated with an
ORR of 12.4% and a median OS of 1 yr
• The development of targeted agents has completely changed the therapeutic
landscape of mRCC
• Starting with sorafenib in 2005, seven different agents have been sequentially
approved targeting VEGF/VEGFR or mTOR
Rini. JCO 2009; 27:3225-3234
Coppin et al. Cochrane Database Syst Rev 2005; CD001425
Molecularly Targeted agents currently approved
by EMA in mRCC
TYROSINE KINASE INHIBITORS
• SUNITINIB
inhibits VEGFR, PDGFR, FLT-3 and c-Kit
• PAZOPANIB
inhibits VEGFR, PDGFR, c-Kit
• SORAFENIB
Inhibits VEGFR, PDGFR, FLT-3 and Raf
• AXITINIB
Inhibits VEGFR, PDGF, c-Kit
MONOCLONAL ANTIBODIES
• BEVACIZUMAB
Anti-VEGF antibody
SERINE-THREONINE KINASE INHIBITORS
• TEMSIROLIMUS
Inhibits mTOR
• EVEROLIMUS
Inhibits mTOR
The story behind the use of targeted
therapies in mRCC
History of research on the von Hippel-Lindau disease
• CNS Hemangioblastomas, pheochromocytoma, papillary cystoadenomas,
endocrine pancreatic tumors and clear-cell carcinoma of the kidney
• Germline heterozygous inactivation of the tumor-suppressor gene VHL (3p25),
followed by somatic inactivation or loss of the second wild-type allele
• VHL encodes for pVHL
Latif et al. Science 1993; 260:1317-1320
Gossage et al. Nature Rev Cancer 2015; 15:55-64
Somatic biallelic inactivation of VHL gene
in sporadic mRCC
• It is the main pathogenetic event
• Consistent with the Knudson “two-hits” model of tumorigenesis
• Prevalence in sporadic RCC: 50% to 90% of cases
• VHL inactivation may occur through:
- mutations
- promoter hypermethylation
- chromosomal loss
• Restoration of pVHL function suppresses tumor formation in vivo and
restores the ability to enter G0 in low serum
Iliopoulos et al. Nat Med 1995; 1: 822-826
Pause et al. PNAS 1998; 95: 993-998
Zimmer et al. Mol Cancer Res 2004; 2: 89-95
Kondo et al. Genes Chromosomes Cancer 2002; 34: 58-68
Nickerson et al. Clin Cancer Res 2008; 14: 4726-4734, 2008
pVHL is a component of
a E3-ubiquitin ligase
Rbx-1
Elongin C
Elongin B
Cullin-2
E2
HIF-a
α-domain
VHL:
the substrate-recognition
component (the “receptor”)
Elongin B/C:
the connection between
VHL and Cul2
Rbx-1:
E2 enzyme recruiter
Cullin-2:
the rigid scaffold
E2:
ubiquitinase
β-domain
VHL
The specific substrate of the VBC-CR complex is HIF-α
Stebbins et al. Science 1999; 284: 455-461
Lonergan et al. Mol Cell Biol 1998; 18: 732-741
Kamura et al. Science 1999; 284: 657-661
Iwai et al. PNAS 1999; 96:12436–12441
Maxwell et al. Nature 1999; 399: 271-275
HIF (hypoxia-inducible factor)
• Belongs to the PAS (Per-arylhydrocarbon receptor nuclear
translocator, ARNT) family of basic helix-loop-helix transcription
factors
•
Three isoforms: HIF1, HIF2 and HIF3
• Binds hypoxia-response elements (HRE) on DNA as a heterodimer:
α
α-subunit (oxygen-sensitive, interacts with pVHL)
β
β-subunit (constitutively expressed,)
• More than 800 genes controlled by HIF
• Among them: VEGF, PDGF, TGF-α, EPO, Glut-1
• HIF2-α is the key driver of RCC
Semenza. Trends Pharmacol Sci 2012; 33: 207-214
Keith et al. Nature Rev Cancer 2012; 12: 9-22
Gordan et al. Cancer Cell 2009; 14: 435-446
CANCER CELL
(VHL defective)
NORMAL CELL
HYPOXIA
NORMOXIA
Pro402 & 564
Hydroxilation (PHD)
NO hydroxilation
HIF-α
HIF-α
OH-
VHL OH
OH-
HIF-α
VHL
Rbx-1
Cullin-2
Elongin C
Elongin B
Rbx-1
E2
Poly-Ub
E2
HIF-α
HIF-β
E2
VHL
OH-
OH-
HIF-α
PROTEASOME
HIF-α
Cullin-2
Elongin C
Elongin B
Rbx-1
Cullin-2
Elongin C
Elongin B
OH-
NORMOXIA/HYPOXIA
Pro402 & 564
Hydroxilation (PHD)
nucleus
VEGF
PDGF
TGF-α
Epo
nucleus
VEGF
PDGF
TGF-α
Epo
HIF-α
HIF-β
mTOR signaling
• Activated by growth factors (via
Pi3K or MAPK pathways),
nutrients, stress
• Often induced by mutations of
PTEN or TSC1/TSC2
• Temsirolimus and Everolimus
mainly inhibit mTORC1
• The mTORC1 activate a negative
feedback loop on mTORC2
• HIF1-α is induced by mTORC1
• HIF2-α is induced by mTORC2
Cellular pathways implicated in clear cell RCC
Shuch et al. Eur Urol 2015; 67: 85–97
Chromatin remodelling genes as potential
therapeutic targets in ccRCC
Cancer Genome Atlas Research Network. Nature 2013; 499: 43-49
Renal cancers were not created equal…
Renal cell tumors listed in the International Society of Urological Pathology
Vancouver Modification
Srigley et al. Mod Pathol 2009;22(Suppl 2):S2–3.
Papillary renal-cell carcinoma
• Second most common subtype of RCC, occurring in approximately
10-15% of cases
• Two microscopic pattern designated papillary type 1 and 2, sporadic
or hereditary, with different molecular profile
• Hereditary papillary renal cancer syndrome (HPRC):
- risk of bilateral, multifocal pRCC type 1
- activating mutations of MET (more often chromosome 7 polysomy in
the sporadic form)
• Hereditary leiomyomatosis RCC (HLRCC)
- cutaneous and uterine leyomiomatosis, pRCC type 2
- inactivating mutations of FH (fumarate hydratase)
MET signaling pathway
Cabozantinib
Foretinib
Pathways activated by loss of fumarate hydratase
(FH) in the familiar form of pRCC type II
Srinivasan et al. Clin Cancer Res 2015;21:10-17
Chromophobe renal cell carcinoma
• Third most common subtype of RCC accounting for 5-7% of case
• Prognosis is generally excellent exept when sarcomatoid
transformation is present
• Sporadic and hereditary forms
• Limited genomic characterization is currently available
• Birt-Hogg-Dubé syndrome: benign cutaneous tumors, pulmunary
cysts and chromophobe RCC
• Mutations of FLCN gene, encoding for Fulliculin, in 90% of the
affected families.
Fulliculin pathway
Bukowski, Figlin, Motzer (Eds). Renal cell carcinoma. Molecular targets and clinical applications. 3 Ed. Springer
Science+Business Media New York (2015)
All roads lead to HIF!!
Linehan et al. Nature Rev Urol 2010; 7: 277-285
Remarks
• Alterated signaling converge on HIF, regardless of the
underlying molecular defect
• Targets of TKIs are only a small portion of the downstream
genes regulated by HIF
• mTOR inhibitors only marginally affect HIF2-α which is
induced by mTORC2
• Inhibition of HIF2-α may represent a more potent
therapeutic strategy
• More targets to be exploited
Remarks
• Alterated signaling converge on HIF, regardless of the
underlying molecular defect
• Targets of TKIs are only a small portion of the downstream
genes regulated by HIF
• mTOR inhibitors only marginally affect HIF2-α which is
induced by mTORC2
• Inhibition of HIF2-α may represent a more potent
therapeutic strategy
• A number of HIF2-α inhibitors are being tested, but clinical
grade agents have yet to be developed
• More targets to be exploited
Impact on survival of targeted therapies
• Targeted therapies clinical trials showed ORR of 30% and median
OS exceeding 2 years
• Patient risk and agents account for variations among studies
• Impromements might be less pronounced in the heterogeneous,
“real world” population of mRCC
Coppin et al. Cochrane Database Syst 2005; CD001425
Albiges et al. Eur Urol 2015; 67: 100-110
MacLeod et al. Urology 2015; 86: 262-268