Daniele SantiniUniversity Campus Bio-Medico

Rome, Italy

Anti EGFR therapy and colorectal cancer

Adapted from Ciardiello F. and Tortora G. NEJM 2008;358:1160-74

Cetuximab or Panitumumab

Responders (15-20%) Non-Responders

Who will benefit from treatment with antibodies targeting EGFR in mCRCs ?

Bardelli and Siena, J Clin Oncol 2010

Targeted therapies: primary resistance

PTEN

SOS

K-Ras

B-Raf

MEK

MAPK

EGFR

ShcGrb2

S6K

AKT

PDK

PI3K

GSK

DUSPs

Genetic alterations of the EGFR signalling pathway predict response to cetuximab

Sartore-Bianchi A et al., Cancer Res 2009

Siena,Di Nicolantonio and Bardelli JNCI 2009

Benvenuti et al., Cancer Research. 2007

Di Nicolantonio et al., J Clin Oncol. 2008

Moroni et al., Lancet Oncology 2005

Bardelli and Siena J Clin Oncol 2010

De Roock, Martini et al Lancet Oncology 2010

Di Nicolantonio, Arena et al., JCI 2011

De Roock, Di Nicolantonio et al, JAMA 2011

Bertotti et al., Cancer Discovery 2011

HER2

Prahallad et al., Nature 2012

Misale et al., Nature 2012

A new type of primary resistance: KRAS amplification

Valtorta E et al. IJC, Feb. 2013

Targeted therapies: primary resistance

Three small “Caveat”

KRAS p.G13D Mutation and OS With Cetuximab in mCRC

De Roock W, et al. JAMA. 2010;304:1812-1820.

Per

cent

age

Aliv

e

100806040200

Months Since Randomizationor Start of Cetuximab

0 5 10 15 20 25

p.G13D Mutation

Any cetuximab therapyNo cetuximab therapy*Log-rank P < .001

Months Since Randomizationor Start of Cetuximab

Other KRAS Mutation

Log-rank P = .49

0 5 10 15 20 25Months Since Randomization

or Start of Cetuximab

KRAS WT

Log-rank P < .001

0 5 10 15 20 25

Per

cent

age

Aliv

e

100806040200

Months Since Randomizationor Start of Cetuximab

0 2 4 6

Cetuximab monotherapyNo cetuximab therapy

Log-rank P = .02

Months Since Randomizationor Start of Cetuximab

0 2 4 10 12 14

Log-rank P > .99

Months Since Randomizationor Start of Cetuximab

0

Log-rank P < .001

6 8 2 4 10 12 146 8

*The no-cetuximab group for all patients from the pooled data set is the best supportive care group from the CO.17 trial. Horizontal axis in blue indicates range of time since randomization from 0 though 6 mos.

CRYSTAL: OS by BRAF Mutation Status

• “There was no evidence of an independent treatment by tumor BRAF mutation status interaction. Thus, with the current data set, BRAF mutation status cannot be shown to be predictive of treatment effects of cetuximab plus FOLFIRI.”

Van Cutsem E, et al. J Clin Oncol. 2011;29:2011-2019.

Ove

rall

Sur

viva

l (pr

opor

tion)

1.0

0.8

0.6

0.4

0.2

00 6 12 18 24 30 36 42 48 54 60

Time (months)

FOLFIRI BRAF MT (n = 33)Cetuximab + FOLFIRIBRAF MT (n = 26)FOLFIRI BRAF WT (n = 289)Cetuximab + FOLFIRIBRAF WT (n = 277)

Events33

22229

207

Median(months)

10.3

14.121.6

25.1

95% CI8.4 to 14.9

8.5 to 18.520.0 to 24.9

22.5 to 28.7

Cetuximab e Pyrosequencing

Direct sequencing analysis and Real-time PCR are commonly used. The detection limit of these two methods is around 20% of the mutation rate

Pyrosequencing has recently emerged as a new powerful sequencing methodology for SNP/mutation analysis. The detection limit is less than 20% of the analysed sample.

Risk to overscore KRAS mutated patients?

• Formalin-fixed paraffin-embedded tumor samples from 29 patients with primary CRC k-ras wild type for codon 12/13 were identified. Other main selection criteria were: tumour tissue availability, clinical response (partial or complete response) following cetuximab + irinotecan after progression on prior irinotecan-based therapy

• Of 29 patients, 3 (10.3%) were identify as K-ras mutant in codon 12 G for 12D mutation by pyrosequencing whereas all of them were reconfirmed k-ras wild type by Real time-PCR.

• These observations would advice oncologists in considering critically pyrosequencing as routine diagnostic test to mandatory discriminate patients eligible to receive anti-egfr therapy in clinical practice.

Santini D et al. J Clin Oncol, 2011

Responder (15%)

PIK3CA mutated and/or PTEN loss (15-20%)

BRAF mutated (8%)

KRAS/PIK3CA mutated

BRAF/PIK3CA mutatedKRAS-NRAS mutated (35-45%)

20-25% ? (quadruple negative)

Martini et al., Nat Rev Clin Oncology, 2011

Targeted therapies: secondary resistance

Responders (15-20%)

Non-Responders

Secondary resistance to EGFR targeted therapies

Responders (15-20%)

Non-Responders

Secondary resistance to EGFRtargeted therapies

6-12 months later

Emergence of KRAS mutations and acquired resistance to anti EGFR therapy in colorectal cancer

R1

R2

+ cetuximab

DiFi: 350 nM

Lim1215: 1400 nM

+ cetuximab

DiFi: 3.5 nM

Lim1215: 350 nM

+ cetuximab

DiFi: 35 nM

Lim1215: 700 nM

+ cetuximab

DiFi: 350 nM

Lim1215: 1400 nM

+ cetuximab

DiFi: 350 nM

Lim1215: 1400 nM

+ cetuximab

DiFi: 350 nM

Lim1215: 1400 nM

R1: Constant dosage

R2: Incremental dosage

Sandra Misale, Sebastijan Hobor

Misale et al., Nature 2012

DiFi DiFi R

EGFR

KRAS

DiFi

DiFi R

Misale et al., Nature 2012

De novo acquisition of KRAS mutations during cetuximab treatment

DiFi DiFi R2

KRAS Mutations Lim Lim R1 Lim R2

G12R 0% 20% 0%

G13D 0.22% 0% 47%

Marcello Gambacorta & Salvatore Siena

De novo acquisition of KRAS mutations during cetuximab treatment

How about patients ?

KRAS mutations and acquired resistance to anti EGFR targeted therapies in CRC patients

With David Solit MSKCC

KRAS mutations and acquired resistance to anti EGFR targeted therapies in CRC patients

Misale S et al, Nature, 2012

# Total Patients

# Patients who develop KRAS mutations/amplification at resistance %

Misale et al., 2012 11 7 63.6%

Diaz et al., 2012 28 13 46%

KRAS‐mediated acquired resistance to anti‐EGFR therapy

KRAS gene alterations mediates acquired resistance to anti-EGFR therapy in CRC patients

Eduardo Vilar & Josep Tabernero

Editorial; Nature 2012

How to measure acquired resistance ?The potential role of KRAS-mutant ctDNA

Diaz & Vogelstein, Nature 2012

The potential role of KRAS-mutant ctDNA

Misale S et al, Nature, 2012

A new type of secondary resistance

Acquired EGFR ectodomain mutation (S492R) that prevents cetuximab binding and confers resistance to cetuximab

A subject with cetuximab resistance harboring the S492R mutation responded to treatment with panitumumab.

Montagut C, Nature Med, 2012

How to overcome secondary resistance?

Cetuximab treatment and rechallenge in irinotecan‐refractory mCRC

Erbitux* + irinotecan-based CT**

Erbitux* + irinotecan-based CT**

Treat until

PD or tox

Phase II, multicenter, prospective study Eligibility: patients with KRAS wt irinotecan-refractory mCRC

PDPDErbitux* + irinotecan-based CT**

Erbitux* + irinotecan-based CT**

SD (≥6 m) or PR/CR, then PD

SD: n=4PR: n=29CR: n=6

CT***

Median no. of therapy lines before Erbitux rechallenge: 4 (range 3–7)*Erbitux: Loading dose 400 mg/m2 followed by weekly infusions of 250 mg/m2

**Irinotecan-based CT: irinotecan monotherapy or FOLFIRI; during Erbitux treatment irinotecan was administered at 180 mg/m2 as a 90-minute infusion ***CT: 5-Fluorouracil- or oxaliplatin- or irinotecan-based CT +/− bevacizumab

PDPD

Santini D, et al. Ann Oncol 2012;Mar 5 [Epub ahead of print]

Irinotecan-based CT**

n=39 n=39

Median interval between first Erbitux treatment and rechallenge: 6 months (range 2–12 months)

Tumor response after Erbitux treatment and rechallenge: Outcomes

Clinical outcomes after Erbitux treatment and rechallenge (n=39)% Patients (95% CI)

ORR 53.8 (39.1–63.7)PR  48.7CR  5.1SD 35.9 (24.7–51.6)

DCR  89.8PD  10.2

• Median PFS after first Erbitux therapy: 10 months (range 3–30 months)

• Median PFS after Erbitux rechallenge: 6.6 months (95% CI: 4.1–9.1)

Santini D, et al. Ann Oncol 2012;Mar 5 [Epub ahead of print]

Median interval between first Erbitux treatment and rechallenge: 6 months (range 2–12 months)

Erbitux treatment and rechallenge: Potential benefit for some patients

Clinical response after first and second Erbitux‐based therapy (n=39)Best response:First Erbitux

Best response:Erbitux 

rechallenge

No. of patients  Total no. of patients (%)

PRCR

12 (5)

CR 1SD

PR1

19 (49)PR 14CR 4SD

SD3

14 (36)PR 10CR 1PR PD 4 4 (10)

Santini D, et al. Ann Oncol 2012;Mar 5 [Epub ahead of print]

Santini D, et al. Ann Oncol 2012;Mar 5 [Epub ahead of print]

Erbitux-resistant cloneErbitux-sensitive clone

1st line CT + Erbitux

2nd line CT - Erbitux

3rd line CT + Erbitux

PD PD

KRAS and cetuximab-driven selection in CRC cells

Tumor response after cetuximab treatment and panitumumab rechallenge: the PANERB STUDY

Porneuf m. et al, ESMO, 2012

Among the patients who had an OR with cetuximab, 31% also had an OR with panitumumab and 16% were stabilized with panitumumab (clinical benefit 47%).

In case of cetuximab resistance, only 14% of the patients had a clinical benefit with panitumumab.

The median OS for the patients who achieved a response with both targeted therapies was 25.4 months IC 95% [22.4-42.6] vs 15.0 months IC 95% [12.9-18.3] for the patients who did not (p < 0.0001).

The “Rechallenge” TrialPhase II, multicenter, prospective, proof of concept study Eligibility: patients with KRAS wt mCRC

• Primary objective: to evaluate the activity in terms of response rate according to RECIST 1.1• Secondary objectives: Progression-free survival; Disease control rate; Safety profile;Traslational studies (KRAS mutated ctDNA, tissue samples at different time points)

*CT: 5-Fluorouracil- and oxaliplatin or CPT-11- CT +/− bevacizumab (window therapy)

Cetuximab based CT

(oxaliplatin or CPT-11 or both)

Cetuximab based CT

(oxaliplatin or CPT-11 or both)

Treat until

PD or tox

PDPD cetuximab + CPT-11

cetuximab + CPT-11

SD (≥6 m) or PR/CR, then PD

WindowCT *PDPD

PDPD Study exit

Inclusion in the study

1 line 2 line rechallenge

Cetuximab beyond progressionThe “CAPRI” Trial

• Primary objectives: • Of 1st line treatment: PFS time when treated with Erbitux + FOLFIRI• Of 2nd line treatment: PFS when treated with Erbitux + FOLFOX after progression of

1st line treatment with Erbitux + FOLFIRI• Screen ~600 for KRAS, enroll at least 320 for 1st line, randomize 240 to 2nd line

• Enrollment for 1st line completed in July 2012; 80 patients in 2nd line.

Erbitux + FOLFIRIErbitux + FOLFIRI

Treat until PD or tox

Treat until PD or tox

2nd line1st line mFOLFOX4 +

ErbituxmFOLFOX4 +

Erbitux

mFOLFOX

Treat until PD or tox

Treat until PD or tox

Phase II, multicenterEligibility: Patients with KRAS wt mCRC

Which are the “best” patients for rechallenge?

Only clinical predictive factors

• KRAS wild‐type and…• First‐line cetuximab‐containing therapy achieving response or stable disease ≥6 months and ….

• Progression after a second “window” therapy line

Thank you very much for your attention