Dr Loïc Ysebaert

Targeting the PI3K pathway in lymphoma

Institut Universitaire du Cancer de Toulouse-Oncopôle,

CRCT Inserm UMR1037

Toulouse, France

Outline

• How PI-Kinases get activated in cancer ?

– Biology of PI-3Kinases

– In vitro rationale for PI-Kinase delta isoform targeting in lymphoma

• What are the clinical benefits / most common side effects ?

– Idelalisib in clinical trials

• How do lymphomatous cells evade to PI-3K inhibition ?

– Feedback loops

– Future of PI-3K inhibition strategies

Outline

• How PI-Kinases get activated in cancer ?

– Biology of PI-3Kinases

– In vitro rationale for PI-Kinase delta isoform targeting in lymphoma

• What are the clinical benefits / most common side effects ?

– Idelalisib in clinical trials

• How do lymphomatous cells evade to PI-3K inhibition ?

– Feedback loops

– Future of PI-3K inhibition strategies

p110ɑ

p110β

p110δ

p110g

p85ɑ,β

p55ɑ,γ

p50ɑ

p101

PI3K-C2ɑ

PI3K-C2β

PI3K-C2γ

hVps34p

?

p150

I

II

III PI

B

Class Regulation

Tyr kinase /

associations

Gβγ

?

?

PI / PI4P / PI4,5P2

CPIKRas-B C2

PI / PI4P

Adaptor

subunit

Catalytic

subunit

A

Ras-B: Ras binding domain Adapted from Vanhaesebroeck B, et al. Nat Rev Mol Cell Biol 2012;13:195–203.

The different PI3Ks (8 isoforms in mammals)

CPIKRas-B C2

CPIKRas-BC2 PX C2

CPIKC2

p110b

Only PI-3K class I A/B transform PI-4,5 P2 into PI-3,4,5 P3 = PIP3

Substrate/structure

Courtesy of B.Vanhaesebroeck

PI-3K class IA/B transforms PIP2 into PIP3, which acts as a 2nd messenger for many pathways

cytosol

Tyrosinekinases,GPCRs,small GTPases

proliferation

survival

growth

differentiation

migration

CELLS:

: interacts with lipid-binding domain in:

protein kinasesPDK1, Akt, Btk, Itk, …

adaptor proteinsGab1, Bam32, DAPP1, …

GEFs / GAPs for Rac, Ras, ArfPREX, Vav, ARNO, GAP1m, ARAP3, …

mTORC1 Badp27FOXO

PIP3

PIP2

PTEN: phosphatase and tensin homologue

Dysregulation of PI-3K pathway in cancer, metabolic diseases, …

Inhibitory

Feedback loop

Courtesy of B.Vanhaesebroeck

PI-3K : almost invariably activated in cancers

cytosol

PIP3

PIP2

PI-3Kinase class I isoforms in normal PI-3Kinase i d g b a

mainly mainlyadaptive innate

mainly inleukocytes

mainly inleukocytes

ubiquitous ubiquitous

PI-3kinase class I isoforms in leucocytes

Okkenhaug K, Science 2002, Vanhaesebroeck B, et al. PNAS 1997

p110δ is important in normal B-cell responses:

p110d

BtkSyk

CHEMOKINES[migration]GPCR-linked (d>g)

B-CELL ANTIGEN RECEPTORBAFF-R / CD19 / CYTOKINES …[(co)-stimulation]

ADHESION[retention,homing]

B-cell

mutation CNA

p110a <5% DLBCL MCL: 68.2%

DLBCL: 16.7%

p110b DLBCL:20%

p110g

p110d APDSImmune deficiency

predisposing to lymphoma

PIK3R1

PIK3R2 DLBCL: 20%

PIK3R3

PIK3R5

PTEN loss MCL, FL: 20%

GC-DLBCL: 30%

CLL: 5%

PI-3K is mainly triggered by chronic activation of cellular surface receptor(s)

How PI-3Kinases get activated in lymphoma ?

Gene mutations and chromosome copy number abnormalities (CNA) are rare

Idelalisib: low ORR

BCAP: B-cell adaptor for PI3K; BCR: B-cell receptor; BTK: Bruton's tyrosine kinase; GEF: guanine nucleotide exchange factor; mTOR: mammalian target of rapamycin; PI3K: phosphatidylinositol-3-kinase; PKC: protein kinase C; SFK: Src family kinase; SYK: spleen tyrosine kinase Coutre S, et al. Leuk Lymphoma 2015

Multiple culprits for chronic PI3Kactivation in lymphoma: it is not only the BCR !

Survival

Survival

Proliferation

Chemokine secretion

Motility

Homing

Retention

Adhesion

chronic BCR signaling

1. Herman SE, et al. Blood 2010;116:2078‒882. Yahiaoui OI, et al. BMC Cancer 2014; 14:565

3. Leseux L, et al. Blood 2006;108:4156–4162

Chronic BCR signaling leads to constitutive PI3Kd activity

• PI3K pathway may be constitutively activated in some patients with

follicular2,3, marginal zone, or lymphoplasmacytic lymphomas

CLL cells have a significantly higher intrinsic PI3K activity

than normal B cells (p=0.006)1P

I3K

acti

vit

y p

er

µg

of

pro

tein

1.75

1.00

0.75

0.50

0.25

0

1.25

1.50

CLL cellsNormal B cells

Hoellenriegel J, Blood 2011.

Idelalisib directly inhibits PI3Kactivation via the BCR and chemokine receptors…

Co

ntr

ol

BC

R

stim

ula

tion

Ide

lalis

ib

Idela

lisib

+ B

CR

stim

ula

tio

nP-Akt

Akt

ERK1/2

β-actin

P-ERK1/2

Idelalisib inhibited BCR-induced AKT

activation in CLL cells

Idelalisib antagonized activation of CXCR4

and CXCR5 in CLL cells

P-Akt

Akt

ERK1/2

β-actin

P-ERK1/2

Co

ntr

ol

BC

R s

tim

ula

tio

n

Ide

la+

BC

R

stim

ula

tio

n

CX

CL

12

Ide

la

Ide

la+

CX

CL

12

CX

CL

13

Ide

la+

CX

CL

13

Furman RR, New Engl J Med 2014

…leading to abrogation of adhesion/retention within lymphoma niches

Rituximab allows rapid resolution of this MOA based hyperlymphocytosis

Transient hyperlymphocytosis due to lymph nodes/spleen shrinkage

Outline

• How PI-Kinases get activated in cancer ?

– Biology of PI-3Kinases

– In vitro rationale for PI-Kinase delta isoform targeting in lymphoma

• What are the clinical benefits / most common side effects ?

– Idelalisib in clinical trials

• How do lymphomatous cells evade to PI-3K inhibition ?

– Feedback loops

– Future of PI-3K inhibition strategies

Phase I idelalisib alone in R/R CLL

No Dose Limiting Toxicity

Recommended phase II dose: 150mg x21,2

At this threshold: Csteadystate > 10 fold EC501

t½ = 8h1 Twice a day (BID)

Nodal response at low doses2

1.Webb HK, et al. Blood (ASH Annual Meeting Abstracts) 2010 116: Abstract 1774

2.Brown JR, Blood 2014;123:3390-7

Best nodal response rates at various

idelalisib dosages (N = 50)

Efficacy data in monotherapy

ZYDELIG®

(n = 54)

ORR 72% (39/54)

Partial response (PR) 39% (21/54)

>50% nodal reduction 81,5% (44/54)

Duration of Response (DoR) 16,2 mo

Progression-free survival (PFS) 15,8 mo

Overall survival Not reached

Phase III idelalisib/placebo + RTX in R/R CLL

Furman RR, New Engl J Med 2014

Efficacy

ZYDELIG®+ R

(n=110)

R

(n = 110)OR / HR p

ORR 81% 13% OR = 29,92 <0,0001

Nodal response 93% 4% OR = 264 <0,0001

OS NA NAHR = 0,28

[IC95% : 0,09;0,86]0,02

p< 0,001p= 0,02

R-Idela= approval for R/R CLL

Phase II idelalisib alone in R/R indolent NHL

-100

-75

-25

0

-50a

+25

+50

Individual Patients (N=125)

SP

D o

f M

easu

red

Lym

ph

No

des

,B

est

% C

han

ge

fro

m B

asel

ine

•90% had improvement in lymphadenopathy

•57% had ≥50% decrease from baseline

Gopal A, New Engl J med 2014

Idela = approval for double-refractory FL

median PFS 11 mo

Phase II idelalisib + RTX in CLL (>65y)

O’Brien SM, Blood 2015;126:2686-94

Efficacy

ZYDELIG®+ R

(n=64)

Del17p and/or mutation TP53

(n=9)

ORR97%

Incl. 19 % CR and 78 % PR

100%

Incl. 33 % CR and 67 % PR

PFS 83% at 3y Not reached

3 year OS 90% NC

Problem: toxicity (main cause for drug

discontinuation the 1st year):

1/ late onset diarrhea/colitis: 68%

2/ very early onset transaminitis (23%

grade 3-4)

More SAE in 1L than R/R patients,

effect of « spared » immune system

R-Idela = approval for 1L del17p CLL

Summary of most common AEs

Compilation of trials: phase III (0116) and 7 phase I-II trials, idelalisib alone or with RTX (N=600)

Allergy/auto-immunity

On-target Top 5 to know

FrequencyReversible at short Tx

interruptionTime of onset % Grade ≥3

Infections Yes No specific pattern ≥10%

Neutropenia Yes (+G-CSF if >grade 3) 1-6mo≥10%

2nd most frequent (40%)

Increased transaminase

levelsYes 1-3 mo ≥10%

Diarrhoea/colitis

NO, but YES at prolonged

interruption 4 wks

(+budesonide if grade 3-4)

6-24mo

DELAYED

≥10%

Most frequent (40-60%)

Rash Yes 0-1 mo 1 to <10%

Increased triglyceride

levelsYes 0-1 mo 1 to <10%

Pyrexia no Tx interruption needed 0-1 mo 1 to <10%

Pneumonitis/pneumonitis NO 3-6mo 1 to <10%

Adapted from: Zydelig SmPC (May 2015; available at www.ema.europa.eu)

Auto-immunity with idelalisib ?

Coutre S, Leuk Lymphoma 2015

Nature 2014:509:407

PI-3Kd inhibition blocks Treg differentiation favoring CTL expansion

This immunomodulatory effect is INdependent from PI-3Kd activity within tumor cells

Outline

• How PI-Kinases get activated in cancer ?

– Biology of PI-3Kinases

– In vitro rationale for PI-Kinase delta isoform targeting in lymphoma

• What are the clinical benefits / most common side effects ?

– Idelalisib in clinical trials

• How do lymphomatous cells evade to PI-3K inhibition ?

– Feedback loops

– Future of PI-3K inhibition strategies

Foucas L, PNAS 2010

Inhibitors of lipid kinases (-isibs) in aggressive NHL: maybe the wrong way…

cells

x 1

0-6

/ml

time (h)

0.5

1.0

1.5

2.0

24 48 720

proliferation

p110a null

p110d null

p110a/d null

WT

0

20

40

60

80

100

120

PI3K activity

IL3-dependent leukocytes

PI3

K a

ctiv

ity

Mouse origin of cell lines:

excellent PI-3K inhibition…

…yet sustained proliferation

= PI-3K inhibitors are cytostatic

not cytotoxic (no TLS in CLL !)

Westin JR. Clin Lymph Myel Leuk 2014

Multiple PI3K inhibition: the future ?

Ysebaert L, Correspondances en Onco-Hématologie 2016

PI3K inhibition: obstacles in the way

Signal: receptors coupled to PI-3K

Adaptor: PI3Kd

Effector: Akt/mTOR

Cellular response

Feedback loops

if only Akt or mTOR is blocked

dual PI-3K/mTORinhibitors

Activating mutation PIK3CA (isoform p110a)

bi- ou pan-PI-3K inhibitors

PTEN loss

hyperactivation PI-3K

bi- ou pan-PI-3K inhibitors

Adaptor: RAS/MEK

Effector: ERK

PI3K/MEKK dual inhibitors

Receptor(s) uncoupled to PI-3K

Effector: MAPK, STAT5

PI3K/MEKK dual inhibitors

Resistance to dual PI3K/mTOR or pan-PI3K

PAK1 (p21 activated kinase)

SAFETY

SAFETY

Will M, Cancer Discov 2014

PI3K inhibition: use alternative conceptsModel: breast cancer Her2 activated, PIK3CA mutated

Apoptosis = PI3K/ERK rather than PI3K/Akt, avoid mTOR inhibition

Low dose range and pulsatile inhibition of PI-3K = combination of AKT+MEK

BUT much less toxicity and no feedback loop reactivating PI3K !

PD901: ERKi (5d/wk)

MK2206: AKTi (5d/wk)

PD+MK

BAY80-6946: PI3Ka/d i

(3d/wk)

Summary : build multi-scales strategies with PI-3Kinase inhibitors = find smart genotype dependent PI-3Ki-based combinations

SUCCESS

TUMOR

SYNERGYSTROMA

Synthetic lethality (ABT-199, Benda, MoAb)

Multi-hit the same BCR pathway (SYKi,BTKi)

Sensitize cells to other drugs (p110a+TMX)

Context-specific choice of PI-3K (p110a or b if PTEN null/PIK3CA)

Multi-hit the same PI-3K pathway (dual PI-3K/mTORi)

p110 inhibitors anti-stroma: vessels, myloid cells (p110ab or g)

Unleash immune responses (Treg depletion: vaccines, checkpoint therapy)

Summary : build multi-scales strategies with PI-3Kinase inhibitors: beware the AEs !

Transaminitis Interstitial pneumopathyDiarrhea/colitis Neutropenia