Discussion on Abstracts 362, 363, 364, 365, and 366
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Discussion on Abstracts 362, 363, 364, 365, and 366 or…We still have a lot to learn about colorectal cancer. Johanna Bendell, MD Director, GI Oncology Research Associate Director, Drug Development Program Sarah Cannon Research Institute. Disclosures. I have no relevant disclosures.

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Johanna bendell md director gi oncology research associate director drug development program

Discussion on Abstracts 362, 363, 364, 365, and 366or…We still have a lot to learn about colorectal cancer

Johanna Bendell, MD

Director, GI Oncology Research

Associate Director, Drug Development Program

Sarah Cannon Research Institute


Disclosures

Disclosures

  • I have no relevant disclosures


Adjuvant studies

Adjuvant Studies

  • Abstract #362: AVANT, XELOX-bev vs. FOLFOX-bev vs. FOLFOX alone

  • Abstract #363: N0147, FOLFIRI +/- cetuximab

  • Abstract #364: Time to adjuvant chemotherapy


Avant

AVANT

  • Eagerly anticipated given the results of NSABP C-08

  • 3451 patients with high-risk stage II or stage III disease

    • Stage III patient results presented here, 3 year minimum follow up

  • Primary endpoint of DFS

  • Well-designed, well-balanced


Avant results

AVANT Results

  • DFS (3-year minimum follow-up)

    • HR FOLFOX-bev 1.17 (0.98,1.39) (73% 3y DFS)

      • NSABP 74 vs. 72% 3 y DFS for Stage III

    • HR XELOX-bev 1.07 (0.9,1.28) (75% 3y DFS)

    • No difference

    • HR for DFS at year 1, like NSABP C-08, was in favor of bev arms, but disappears after year 1

    • Does the DFS at years 2, 2.5, and 3 suggest rebound effect off bev?

      • Sites of recurrence are similar between arms (no worse in bev arms)

      • What about survival after recurrence???


Avant results1

AVANT Results

  • INTERIM OS

    • HR FOLFOX-bev 1.31 (1.03,1.67)

    • HR XELOX-bev 1.27 (0.99,1.62)

    • Are these results suggestive of rebound effect?

    • Results are not yet mature

    • Time from recurrence to death

      • No significant difference between the arms, but FOLFOX patients seem to do a bit better?

      • BUT – more patients in FOLFOX arm saw bevacizumab after recurrence (35% vs. 16% and 20%) – did this make a difference?


N0147 the folfiri arms

N0147 – The FOLFIRI Arms

  • Irinotecan-based therapy does not improve survival in the adjuvant setting

    • PETACC-3, ACCORD2, CALGB 89803

    • 3 yr DFS around 60%

    • CALGB 89803 analysis with no difference in K-ras WT vs. mut

  • Cetuximab plus FOLFOX does not improve survival in the adjuvant setting

  • Report on 146 stage III patients treated with FOLFIRI (106) or FOLFIRI-cetuximab (40)

  • Primary endpoint DFS

  • Well-balanced

  • Both arms 65% K-ras WT


N0147 results

N0147 - Results

  • DFS

    • Overall (n=146) 3 yr DFS 86.6% vs. 66.7%

      • FOLFOX 72.3% vs. 75.8%

    • K-ras WT (n=95) 3 yr DFS 92.3% vs. 69.8%

      • FOLFOX 72.3% vs. 75.8%

    • K-ras mut (n=46) 3 yr DFS 82.5% vs. 56.3%

      • FOLFOX 64.2% vs. 67.2%

  • OS

    • Overall (n=146) 3 yr OS 91.8% vs. 84.4%

    • K-ras WT (n=95) 3 yr OS 92.0% vs. 85.2%

    • K-ras mut (n=46) 3 yr OS 90.9% vs. 80.6%

  • DFS data in the control arms look in line with previous irinotecan-based data

  • K-ras mut patients benefit too?

    • Small numbers

    • Is micrometastatic disease different?

  • Cetuximab-based treatment arms show very different results from previous studies with irinotecan or cetuximab – why???


Irinotecan and cetuximab a story of synergy

Irinotecan and Cetuximab – A Story of Synergy

  • Preclinical

    • Synergy of EGFR inhibition and DNA damaging agents

      • Cetuximab suppression of repair after DNA damaging agents1,2,3,4,5

      • Cetuximab increases pro-apoptotic molecules and decreases anti-apoptotic molecules, rendering cells more sensitive to cytotoxic chemotherapy6

      • Cellular stress increases EGFR pathway activation5

    • MDR pathways

      • Certain MDR1 polymorphisms in the setting of EGFR inhibition decrease SN38 efflux7

  • Clinical

    • Saltz, et al. and BOND 1

      • Irinotecan-refractory cancers respond to irinotecan plus cetuximab

    • First line irinotecan vs. oxaliplatin cetuximab trials

      • Irinotecan –based therapies seem better

      • We’ll get to this in a moment…

  • Huang SM, Canc Res 1999, 2. Buchsbaum DJ, Int J Rad Oncol Biol Phys 2002, 3. Pery D, Cancer Res 1996

  • 4. Huang SM, Clin Cancer Res 2000, 5. Koizumi F, Int J Cancer 2004, 6. Ellis LM, J Clin Oncol 2004, 7. Paule B, Med Oncol 2010


Time to adjuvant therapy ttac an issue in trial design and overall patient treatment

Time to Adjuvant Therapy (TTAC)– an Issue in Trial Design and Overall Patient Treatment

  • Previous adjuvant trials have allowed for patients to start within either 8 weeks (more recent) or 12 weeks postop

  • Is there a difference in outcomes based on when a patient starts adjuvant therapy?

  • Review of 9 adjuvant studies that data on waiting time

    • 8 retrospective, 1 RCT

    • All 5-FU based chemotherapy only

  • Each 4 week delay from start of therapy results in a 12% increase in mortality

  • Implications:

    • Needs to be controlled in clinical trials

    • Needs to be encouraged in health systems – importance of coordinated care


Where are we with adjuvant therapy

Where are we with adjuvant therapy?

  • Adjuvant bevacizumab: No improvement in DFS or OS

    • Prolonging bevacizumab therapy might hold down disease for some period of time, but at what cost?

  • Adjuvant FOLFIRI plus cetuximab may work

  • Treat patients as quickly as possible after surgery

    • Should be controlled in clinical trials

  • Common paradigms do not hold

    • What works in the metastatic setting does not hold true for the adjuvant setting

    • Is this a difference in tumor biology?

  • Where should we go from here?

    • Adjuvant bevacizumab development should stop for now

      • Metastatic adjuvant setting? Proof of concept as single agent maintenance rx?

    • FOLFIRI-cetuximab vs. FOLFOX?

    • We need new agents

    • We need biomarkers


Metastatic studies

Metastatic Studies

  • Abstract #365: NORDIC VII Study

  • Abstract #366: AMG 102 or AMG 479 with panitumumab


Nordic vii

NORDIC VII

  • FLOX vs. FLOX-cetuximab vs. Intermittent FLOX with continuous cetuximab

  • First-line therapy

  • Primary endpoint PFS

  • Arms were well-balanced

  • Previous data of EGFR inhibitors with oxaliplatin-based regimens

    • In K-ras WT patients, only 2 studies have shown an improvement in PFS (OPUS and PRIME)

    • In K-ras mut patients, there are trends towards decreased survivals treating patients with anti-EGFR and oxaliplatin-based regimens

    • Irinotecan-based regimens show stronger data (CRYSTAL)


Egfr inhibitors in first line therapy kras wt patients

EGFR Inhibitors in First-Line Therapy - Kras WT patients


Nordic vii1

NORDIC VII

  • This trial shows no improvement in outcomes for patients with cetuximab plus oxaliplatin-based therapy

    • Is this an issue with the chemotherapy or an interaction with oxaliplatin and cetuximab?

  • Trend towards worse outcomes for cetuximab-treated patients, but numbers are small


One possible reason for oxaliplatin and anti egfr negative outcomes

One possible reason for oxaliplatin and anti-EGFR negative outcomes

Oxaliplatin

R

R

Src

activity

Src

Y

Y

Signal Transduction

EGFR can be activated by Src in the absence of ligand binding

EGFR resistance in vitro is mediated by Src

Src is acutely and chronically activated by oxaliplatin

Combination therapy is synergistic in vitro, in vivo

Kopetz GI ESMO 2010

Kopetz, et al Cancer Res 2009, Liu et al Cancer Res 2007


New agents for colorectal cancer patients

New agents for colorectal cancer patients

  • Combination therapies

    • Panitumumab plus AMG 479 (IGF-1R antibody)

    • Panitumumab plus AMG 102 (HGF antibody)

    • K-ras WT patients

    • Refractory to at least one previous chemotherapy and no prior anti-EGFR

    • Primary endpoint RR

      • RR better for AMG 102 plus pmab (31% vs. 21%)

      • IGF-1R plus EGFR inhibitor combinations show no clear signals

    • Median f/u 6.9 months (still early)


C met hepatocyte growth factor pathway

C-met/Hepatocyte Growth Factor Pathway

Abouander R, 2004


C met proof of concept in nsclc pfs and os met high population

c-met proof of concept in NSCLC - PFS and OS: Met High Population

OS, HR=0.55

PFS, HR=0.56

  • MetMAb+Erlotinib improves both PFS and OS in

  • Met High NSCLC patients

Spigel, SCRI, ESMO 2010


C met proof of concept in nsclc pfs and os met low population

c-met proof of concept in NSCLC - PFS and OS: Met Low Population

PFS, HR=2.01

OS, HR=3.02

  • Met Low NSCLC Patients Do Worse with

  • MetMAb+Erlotinib

Spigel, SCRI, ESMO 2010


We have movement forward

We have movement forward…

  • Targeting of the c-met/HGF pathway in combination with anti-EGFR therapy looks promising for colorectal cancer as well as NSCLC

  • We await further PFS data

    • Early look shows 5.2 mo vs. 3.7 mo

  • Other c-met inhibitors are currently in trial in colorectal cancer patients

  • Biomarker data will be important in assessing to see if c-met expression in colorectal cancers has same effect on outcomes as NSCLC


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