1. Nuovi pathways nuovi farmaci: quali prospettive?
Angelo Di Leo
“Sandro Pitigliani”
Medical Oncology Department
Hospital of Prato
Istituto Toscano Tumori,
Prato, Italy

2. Conflict of Interest Disclosure
Applicability
Company
(1) Advisory role
Yes
AstraZeneca, Bayer, Celgene, Lilly, Novartis, Pfizer, Roche 　
(2) Stock ownership/profit　
None
(3) Patent royalties/licensing fees　
(4) Lecture fees
AstraZeneca, Eisai, Genomic Health, Novartis, Pfizer, Pierre Fabre, Roche
(5) Manuscript fees
(6) Scholarship fund
(7) Other remuneration

3. Focus on ER+ / HER-2 negative breast cancer CDK 4-6 inhibitors
PI3K inhibitors

4. Cooperation between ER and Cyclic D1 pathways enhances proliferation in luminal breast cancer
Cyclin D1 ER
Inhibitory control
Inhibitory control
p Rb
CDK4-6
Cell Cycle:
G S
Inhibitors:
Palbociclib
Abemaciclib
Ribociclib
proliferation

5. Considerations on CDK4/6 inhibitor activity
PD has shown activity preferentially on ER+, luminal breast cancer cell lines with or without HER2 amplification.
IC50 nM
Subtype
Luminal
Non -
luminal/post EMT
HER2 Amplified
luminal
Immortalized
RB1, cyclin D1, and CDKN2A (p16) were differentially expressed - with higher levels of RB1 and cyclin D1, and lower levels of p16, in the sensitive group.
Resistance to PD in many of the nonluminal breast cancer cell lines may be explained by the absence of pRb. Recent publications highlighted the lack of pRb in basal-like breast cancer tissue and observed that pRb depletion can result in the characteristic epithelial-to-mesenchymal transition changes
The lack of activity of a CDK4/6 inhibitor in cell lines and tumors that lack pRb can be explained by the fact that cyclin D1 does not offer G1 control in the absence of pRb.
Finn et al, BCR 2011 5

6. We have results from two Phase III trials testing CDK 4-6 inhibitors in the first-line treatment of HR+/HER-2 advanced breast cancer patients:
- PALOMA 2
- MONA LEESA 2

11. MONA LEESA 2: Study design
Postmenopausal
Ribociclib + Letrozole
ER+/HER-2 neg ABC
First-line
AI – resistant excluded
Placebo + Letrozole 1
Hortobagyi GN et al, New Engl J Med, 2016 (published online on October 8)

12. PFS (investigator-assessed) – ITT population
Hortobagyi GN et al, New Engl J Med, 2016 (published online on October 8)

13. MONA LEESA 2: Adverse events
Hortobagyi GN et al, New Engl J Med, 2016 (published online on October 8)

14. Do we have strong evidence that the
combination CDK 4-6 inh. + endocrine
therapy should be the upfront option??

15. (In my opinion) not yet …
Cross-over would have been important to address this question
CDK 4-6 inh + endocrine therapy
endocrine therapy CDK 4-6 inh + endocrine therapy
In addition, the clinical activity of endocrine therapy after PD to CDK 4-6 inhibitors is not clear

16. First-line therapy for HR+/HER-2 negative advanced breast cancer: Back-home message (my personal view)
Life-threatening disease: chemotherapy
Visceral involvement and/or symptomatic disease:
CDK 4-6 inhibitor + endocrine therapy (HT)
Non visceral involvement and non symptomatic disease (previously treated or untreated with HT):
Fulvestrant CDK 4-6 inhibitor + aromatase inhibitor

17. breast cancers in the TCGA Differential gene expression analysis
Perspectives: Identifying patients with primary resistance to CDK 4-6 inhibitors. The Rb Sig
E2F1 and E2F2 high vs low
breast cancers in the TCGA
Expression data
Differential gene expression analysis
Functional RBsig
Correlation with palbociclib activity (in-vitro)
Prognostic value (in-silico analysis)
Malorni L et al, Oncotarget, 13: , 2016

18. Functional RBsig discriminates sensitive vs resistant BC cell lines
AUC = 0.93
Malorni L et al, Oncotarget, 13: , 2016

19. RBsig is prognostic in patients with ER+ tumors
Untreated
ER+
Luminal A
Luminal B
Endocrine treated only
Malorni L et al, Oncotarget, 13: , 2016

20. New agents currently tested in Phase III trials

22. PI3K Pathway Inhibitors in Clinical Development in Breast Cancer
Drug
Source
Target(s)
GDC-0032
Genentech
PI3Kα
MLN-1117
Millenium
BYL719
Novartis
GS-1101
Gilead
PI3Kd
XL-147/SA245408
Exelixis/Sanofi
Pan-PI3K
BKM120
GDC-0941
PF /PKI-587
Pfizer
XL-765/SAR245409
PI3K/mTOR
BEZ235
GDC-0980
MLN-128/MLN0128
TORC1/2
OSI-027
OSI Pharma
AZD2014
AstraZeneca
AZD5363
AKT (catalytic)
MK2206
Merck
AKT (allosteric)
GDC-0068
ClinicalTrials.gov. From: Accessed August 2013. 22

23. Baselga J et al, proc. SABCS, 2015

24. Baselga J et al, proc. SABCS, 2015

25. Baselga J et al, proc. SABCS, 2015

26. Pre-clinical rationale for a PI3K inhibitor after progression to mTORC1 inhibitors
mTORC1 inhibition elicits AKT phosphorylation (feedback activation)
mTORC2
PI3K
IGFR1
IRS1
AKT
mTORC1 S6
inhibition
Short loop
Long loop
Phospho
PI3K inhibitors abrogate or attenuate AKT phosphorylation elicited by mTORC1 inhibition
Any role for PI3K inhibitors after progression to Everolimus?
Sun SY et al, Cancer Res 2005; O’Reilly KE et al, Cancer Res 2006; Breuleux M et al, Mol Canc Ther 2009; O’Brien NA et al, Clin Cancer Res 2014; Wander SA et al, J Clin Invest 2011; Mayer IA et al, Annu Rev Med 2016

27. BELLE-3 trial design and Endpoints
Post menopausal women with HR+, HER2-, locally advanced or metastatic breast cancer, who received Everolimus + AIs as last line of therapy, N= 432
Primary Endpoint
PFS in the full population
Key secondary Endpoint
OS in the full population
Other Secondary Endpoints
PFS by PIK3CA status based on ctDNA
OS by PIK3CA status based on ctDNA
ORR and CBR in the full population and by PIK3CA status based on ctDNA
Safety, Pharmacokinetics, Quality of Life
Randomization (2:1)
Stratification by visceral disease status
Buparlisib (100 mg/day) +
Fulvestrant (500 mg)
n=289
Placebo +
fulvestrant (500 mg)
n=143
90% power to detect a 33% reduction in the risk of progression (α one-sided= 0.025)
(313 events required)

28. Primary tumor vs. Circulating Tumor Cells (CTC)
vs. circulating tumor DNA (ct DNA)
Analysis of single CTCs, ct DNA and primary tumor tissue from pt 11, pt 12, and pt 18
Pt18
Pt11
ct DNA
ct DNA
Primary
Primary
Pt12
ct DNA
Primary
De Luca F et al, Oncotarget, 2016; 7: 28

29. Acknowledgments