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Resistance to Anti-HER2 Therapy

      George W. Sledge, Jr. MD
         Indiana University
       Simon Cancer Center
What Do We Mean by “Resistance”?
• ChemoRx resistance  Throw away the drug
• Targeted therapy resistance:
  – Is resistance absolute?
  – Should we maintain selective pressure?
Trastuzumab treatment beyond progression sensitises
                tumour cells to chemotherapy
           Initial treatment                  Treatment beyond progression
                                                                    Control
   Tumour volume (mm3)                        Tumour volume (mm3)   lgG 30
                                                                    mg/kg
    1000                                      1000
                                                                    Trastuzumab
                               Control lgG
                               30 mg/kg                             30 mg/kg
                                                                    Paclitaxe
                                                                         l 60
                           *   Herceptin                                 mg/kg
     300                       30 mg/kg         300

                                                                         *

                                                                         Trastuzumab +
     100                                        100
                                                                         paclitaxel




         1    8     15   22                         22 29 36 43 50 57
     Days after treatment start                    Days after treatment start

MDA-MB-361 tumour xenograft; *p<0.05 by U-test
IgG, immunoglobulin; paclitaxelqw iv; Trastuzumab or IgGqwip         Shirane et al 2005
Trastuzumab Benefits Beyond Progression
            GBG 26/BIG 3-05

         (Closed Early With Poor Accrual)


                                    Capecitabine
   Progression on
taxane + trastuzumab
                                     Capecitabine + trastuzumab




                       von Minckwitz G, et al. J Clin Oncol. 2009:27:1999-2006.
Trastuzumab Remains Effective
                                 After Progression
                    100

                     90                                   2-sided P
                                                         OR: P = .011               CB: 75.3%
                     80                                  CB: P = .0068             (95% CI: 64.2-84.4)

                     70

                     60            CB: 54.1%
         % of pts




                                   (95% CI: 42.1-65.7)

                     50

                     40     NC
                          >24wks
                     30

                     20                27.0%                                           48.1%
                           OR                            CR: 2.7%                                        CR: 7.7%
                                   (95% CI: 17.3-38.6)                             (95% CI: 36.5-59.7)
                     10                                  PR: 24.3%                                       PR: 40.3%

                      0
                                           X                                              XH
                                                                     OR = overall response = CR+PR
von Minckwitz G, et al. J Clin Oncol. 2009:27:1999-2006.
                                                                     CB = clinical benefit = CR+PR+NC>24wks
Lapatinib + Trastuzumab Upon
                Progression on Trastuzumab:
                         EGF104900
                                                   Lapatinib 1500 mg PO QD
                                                            (n = 148)
                                                                                               Primary endpoint:
 Heavily pretreated patients                                                                   PFS
                                                               Optional crossover to
with HER2-positive metastatic                                    trastuzumabarm
      breast cancer and                                     if PD after 4 wks (n = 77)         Secondary endpoints:
 progression on trastuzumab                                                                    OS
                                               Lapatinib 1000 mg PO QD +                       ORR
          (N = 296)                            Trastuzumab 4 mg/kg loading                     CBR
                                                dose, then 2 mg/kg IV wkly
                                                         (n = 148)

                  Stratified by visceral disease
                  and hormone receptor status


      PO, orally; QD, once daily.




                                                                     Blackwell K, et al. SABCS 2009. Abstract 61.
Lapatinib + trastuzumab improves OS compared to
lapatinib in patients progressing on or after trastuzumab




                         Blackwell KL, et al. J ClinOncol2010; 28;1124–1130
Conclusion #1:
Trastuzumab resistance is incomplete,
and both switching chemotherapy and
combined HER2 inhibition benefit
patients progressing on trastuzumab.


                            Resistance is
                            Futile!

          Locutis of Borg
But Is Resistance Futile?


                                No: Tumors
                  Trastuzumab   keep finding
                                novel
                                resistance
   HER2+ Cancer
                                mechanisms
What are the mechanisms of
                resistance?
•   Impaired trastuzumab binding
•   Altered downstream signaling
•   Signaling through an alternate receptor
•   Failure to trigger an immune response
•   Pharmacokinetic failures
Mechanisms of resistance (1)




Impaired trastuzumab binding to HER2:
• A constitutively active truncated form of HER2 receptor that
  lacks binding site of trastuzumab (p95 HER2).
• Epitope masking by mucin 4 or CD44/polymeric hyaluronan
  complex.
• Loss of HER2 complex                          Pohlmann PR, et al. Clin Cancer Res 20
Mechanisms of resistance (2)

              • Altered HER2
                downstream
                signaling.


              Increased ligand
              production (ADAM17)



              • Signaling through an
                alternate receptor
                pathway

                            Pohlmann PR, et al. Clin Cancer Res 2009
Mechanisms of resistance (3)




• Failure to trigger immune-mediated mechanisms to destroy tumor cells
FcγRIII F158 polymorphism interfere with antibody-dependent cellular
   cytotoxicityfunction

                                                    Pohlmann PR, et al. Clin Cancer Res 2009
Trastuzumab Resistance:
              The List Grows
• HER2 protein expression
• Sprouty 2 expression (via PTEN & ERK)
• Cyclin E amplification/overexpression; loss of
  p27Kip1 (downstream HER2 effectors)
• Calpain inactivation (via pHER2 cleavage)
• miR21 upregulation (via PTEN)
• Loss of HER2 amplification (post-adjuvant Trast)
• Notch-1 overexpression
Pharmacokinetic Resistance: Inability to Penetrate the CNS

Lapatinibas 1st-Line Treatment in HER-2+ Advanced Breast
                          Cancer
            Gomez HL et al, ASCO 2005, abstract #3046
         Patient D: Brain Lesion Baseline and 12 Weeks
Lapatinib/RTK Resistance
• Many trastuzumab resistance mechanism do
  not apply: (IGF-1, p95, PTEN, HER3, PI3K/AKT)
• Increased pSRC kinase (via PTEN/PI3K/AKT)
• Altered antiapoptotic proteins (MCL-1 and
  survivin)
• Activated FOXO3a and increased expression of
  estrogen receptor
• Quasi-resistance: lack of immune reponse
Conclusion #2:

There are many mechanisms of
resistance; most affect common
pathways.

Resistance mechanisms are complex
but not infinite.
Which mechanisms are
 proven in the clinic?
PTEN Impact on Sensitivity or
           Resistance to Trastuzumab
• Preclinical data suggest PTEN loss associated with
  trastuzumab resistance
   – O’Brien NA, 2010; Stemke-Hale K, 2008; Saal LH, 2005; Nagata Y,
     2004
• Clinical data available to date: limited and conflicting
   – PTEN loss associated with trastuzumab resistance
      • Dave, 2011; Esteva, 2010,
      Faratian, 2009                                              N = 122
   – PTEN loss NOT associated with
       trastuzumab resistance
      • Fabi, 2010; Gori, 2009;
      Yonemori, 2009



                                        Faratian et al Cancer Res 69(16):6713–20
DFS by Treatment Arm for Pts with
                                   PTEN Negative Tumors: N9831

                 100

                  90                                                                       AC →T+H → H
                                                                                               AC → T → H
                  80
                           Arm    N         Events   HR      95% CI      p      5yr
Event free (%)




                  70                                                            DFS                     AC → T
                           A      176        53                                 72.3
                           B      146        38      0.85   0.55-1.30   0.44    77.8
                  60
                           A      176        53                                 72.3
                           C      138        19      0.47   0.28-0.79   0.005   86.7
                  50       B      146        38                                 77.8
                           C      138        19      0.56   0.32-0.97   0.04    86.7
                 40
                       0                1             2             3                  4            5
                                                     Years from randomization


                                                                                           Perez EA, et al. ASCO 2011; Abst 79057
Multifactorial Resistance: Clinical Data
   Mechanism/Reference            Outcome (all significant p values)

• p95HER2/CCR 16:4226, 2010       • PFS HR = 1.9, OS HR = 2.2
• PTEN/Cancer Res 69:6713,2009    • OS HR = 3.0
• HER2 prot exp/Ann Oncol 22:     • TTP HR = 3.7, OS HR = 2.0
  2014,2011
• Sprouty 2/PLOS One 6:           • OS HR = 2.28
  e23772, 2011
• Cyclin E/PNAS 108: 3761, 2011   • Lower RR and PFS
• FcR Polymorphisms/JCO 26:       • PFS HR = 5.3
  1789, 2008
REMARK Criteria for Biomarker Reporting
Conclusion #3:
Laboratory mechanisms of resistance have
not been confirmed in any meaningful
sense in the clinic:
  1. We lack large data sets
  2. Most studies are small, lack
     confirmatory studies, level 4 evidence
  3. Adjuvant studies can reject
     metastatic hypotheses
  4. Assays not validated and variable
  5. Multifactorial resistance mechanisms
      not examined
What are the Therapeutic Implications
    of Resistance Mechanisms?
• Since different resistance mechanisms
  affect different drugs, combined HER2
  pathway blockade should be superior.
• Multifactorial nature of resistance
  suggests that no single therapeutic
  approach will overcome resistance.
What are the Therapeutic Implications
    of Resistance Mechanisms?
• Since many resistance mechanisms have
  common downstream effectors (e.g.,
  mTOR), downstream inhibition may
  prove useful.
• Improved measurement of resistance
  mechanisms might improve targeting.
Thank You
HER family




             Hudis CA, NEJM 2007
Figure 1 Proposed mechanisms of trastuzumab resistance




Nahta R et al. (2006) Mechanisms of Disease: understanding resistance to HER2-targeted therapy in human breast cancer
                              Nat Clin Pract Oncol 3: 269–280 doi:10.1038/ncponc0509
Figure 1 Molecular targets and therapeutic approaches in trastuzumab and lapatinib
                                    resistance




       Esteva, F. J.et al.(2009)Molecular predictors of response to trastuzumab and lapatinib in breast cancer
                                 Nat. Rev. Clin. Oncol. doi:10.1038/nrclinonc.2009.216
Clin Cancer Res. 2009 Dec
Clin Cancer Res. 2009 Dec
Clin Cancer Res. 2009 Dec
Clin Cancer Res. 2009 Dec
Clin Cancer Res. 2009 Dec
Trastuzumab-DM1 (T-DM1), is
designed to combine the anti-
tumor activity of trastuzumab
with a means of delivering highly
potent chemotherapy directly
into HER2-expressing cells.

DM-1 (also known as
maytansine) is an inhibitor of
tubulin polymerization, binding
tubulin competitively with vinca
alkaloids.
Background



Classic PTEN Pathway




              Planchon SM, et al. J Cell Sci 2008;121: 249-253
Analysis 1

                                 DFS by Treatment Arm for Pts with
                                       PTEN Positive Tumors

                 100

                  90                                                                       AC →T+H → H
                  80
                                                                                               AC → T → H
                           Arm    N         Events   HR      95% CI      p      5yr
Event free (%)




                  70                                                            DFS                     AC → T
                           A      425        120                                73.9
                           B      504        106     0.70   0.54-0.92   0.009   81.0
                  60
                           A      425        120                                73.9
                           C      413        77      0.65   0.48-0.86   0.003   85.1
                  50       B      504        106                                81.0
                           C      413        77      0.90   0.67-1.21   0.49    85.1
                 40
                       0                1              2             3                 4            5
                                                      Years from randomization


                                                                                           Perez EA, et al. ASCO 2011; Abst 79057
Analysis 1

Impact of PTEN on DFS Based for Different Treatment
        Arm Comparisons: N9831 Adjuvant

   • Arm C vs Arm A
     – PTEN+ HR: 0.65 (p=0.003)
                                   Interaction p=0.16
     – PTEN- HR: 0.47 (p=0.005)
   • Arm B vs Arm A
     – PTEN+ HR: 0.70 (p=0.009)
     – PTEN- HR: 0.85 (p=0.44)     Interaction p=0.47

   • Arm C vs Arm B
     – PTEN+ HR: 0.90 (p=0.49)
     – PTEN- HR: 0.56 (p=0.04)     Interaction p=0.08

                                   Perez EA, et al. ASCO 2011; Abst 79057
The mammalian target of rapamycin (mTOR) signaling network.




            Meric-Bernstam F , Gonzalez-Angulo A M JCO
            2009;27:2278-2287


©2009 by American Society of Clinical Oncology
Table 1 Characteristics and mechanisms of action of trastuzumab and lapatinib




    Esteva, F. J.et al.(2009)Molecular predictors of response to trastuzumab and lapatinib in breast cancer
                              Nat. Rev. Clin. Oncol. doi:10.1038/nrclinonc.2009.216
Table 3 Efficacy of HER2-directed therapy in trastuzumab-resistant metastatic breast
                                       cancer




       Esteva, F. J.et al.(2009)Molecular predictors of response to trastuzumab and lapatinib in breast cancer
                                 Nat. Rev. Clin. Oncol. doi:10.1038/nrclinonc.2009.216
Table 2 Treatment of HER2 breast cancer: trastuzumab-based combinations beyond
                            trastuzumab progression




   Di Cosimo, S. & Baselga, J.(2010)Management of breast cancer with targeted agents: importance of heterogenicity
                                  Nat. Rev. Clin. Oncol. doi:10.1038/nrclinonc.2009.234
Figure 1 Overall response rates in HER2-positive and hormone
             receptor-positive metastatic breast cancer




Cortés, J. et al.(2010)HER2 and hormone receptor-positive breast cancer—blocking the right target
                        Nat. Rev. Clin. Oncol. doi:10.1038/nrclinonc.2010.185
Figure 2 Receptor cross-talk and response to therapy




Cortés, J. et al.(2010)HER2 and hormone receptor-positive breast cancer—blocking the right target
                        Nat. Rev. Clin. Oncol. doi:10.1038/nrclinonc.2010.185
Novel HER2 Agents
HER1/2 TKI                     Lapatinib, HKI-272, BIBW 2992, PKI-166, EKB-569
Pan HER TKI                    Canertinib, BMS-599626
HER1/2/VEGFR TKI               XL647, AEE788
HER2 dimerization inhibitor    Pertuzumab
Bispecific antibody            Ertumaxomab
Conjugated antibodies          Trastuzumab-MCC-DM1, trastuzumab-A-Z-CINN
                               310-paclitaxel
HSP90 inhibitors               Tanespimycin, alvespimycin, CNF2024, IPI-504, AUY922,
                               SNX5422
IGF-1R inhibitors (mAb, TKI)   CP-751871, EM164, IMC-A12, NVP-ADW742, INSM-18
HDAC inhibitors                Vorinostat, LBH589, PXD101, NVP-LAQ824, depsipeptide,
                               CI-994, MS-275
PI3K inhibitors                SF1126, BEZ235, XL147, XL765
Akt inhibitors                 Perifosine, XL418
mTOR inhibitors                Rapamycin (sirolimus), temsirolimus, everolimus,
                               deforolimus
HER2 vaccines

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ABC1 - G.W. Sledge - Resistance to anti-HER2 therapies

  • 1. Resistance to Anti-HER2 Therapy George W. Sledge, Jr. MD Indiana University Simon Cancer Center
  • 2. What Do We Mean by “Resistance”? • ChemoRx resistance  Throw away the drug • Targeted therapy resistance: – Is resistance absolute? – Should we maintain selective pressure?
  • 3. Trastuzumab treatment beyond progression sensitises tumour cells to chemotherapy Initial treatment Treatment beyond progression Control Tumour volume (mm3) Tumour volume (mm3) lgG 30 mg/kg 1000 1000 Trastuzumab Control lgG 30 mg/kg 30 mg/kg Paclitaxe l 60 * Herceptin mg/kg 300 30 mg/kg 300 * Trastuzumab + 100 100 paclitaxel 1 8 15 22 22 29 36 43 50 57 Days after treatment start Days after treatment start MDA-MB-361 tumour xenograft; *p<0.05 by U-test IgG, immunoglobulin; paclitaxelqw iv; Trastuzumab or IgGqwip Shirane et al 2005
  • 4. Trastuzumab Benefits Beyond Progression GBG 26/BIG 3-05 (Closed Early With Poor Accrual) Capecitabine Progression on taxane + trastuzumab Capecitabine + trastuzumab von Minckwitz G, et al. J Clin Oncol. 2009:27:1999-2006.
  • 5. Trastuzumab Remains Effective After Progression 100 90 2-sided P OR: P = .011 CB: 75.3% 80 CB: P = .0068 (95% CI: 64.2-84.4) 70 60 CB: 54.1% % of pts (95% CI: 42.1-65.7) 50 40 NC >24wks 30 20 27.0% 48.1% OR CR: 2.7% CR: 7.7% (95% CI: 17.3-38.6) (95% CI: 36.5-59.7) 10 PR: 24.3% PR: 40.3% 0 X XH OR = overall response = CR+PR von Minckwitz G, et al. J Clin Oncol. 2009:27:1999-2006. CB = clinical benefit = CR+PR+NC>24wks
  • 6. Lapatinib + Trastuzumab Upon Progression on Trastuzumab: EGF104900 Lapatinib 1500 mg PO QD (n = 148) Primary endpoint: Heavily pretreated patients PFS Optional crossover to with HER2-positive metastatic trastuzumabarm breast cancer and if PD after 4 wks (n = 77) Secondary endpoints: progression on trastuzumab OS Lapatinib 1000 mg PO QD + ORR (N = 296) Trastuzumab 4 mg/kg loading CBR dose, then 2 mg/kg IV wkly (n = 148) Stratified by visceral disease and hormone receptor status PO, orally; QD, once daily. Blackwell K, et al. SABCS 2009. Abstract 61.
  • 7. Lapatinib + trastuzumab improves OS compared to lapatinib in patients progressing on or after trastuzumab Blackwell KL, et al. J ClinOncol2010; 28;1124–1130
  • 8. Conclusion #1: Trastuzumab resistance is incomplete, and both switching chemotherapy and combined HER2 inhibition benefit patients progressing on trastuzumab. Resistance is Futile! Locutis of Borg
  • 9. But Is Resistance Futile? No: Tumors Trastuzumab keep finding novel resistance HER2+ Cancer mechanisms
  • 10. What are the mechanisms of resistance? • Impaired trastuzumab binding • Altered downstream signaling • Signaling through an alternate receptor • Failure to trigger an immune response • Pharmacokinetic failures
  • 11. Mechanisms of resistance (1) Impaired trastuzumab binding to HER2: • A constitutively active truncated form of HER2 receptor that lacks binding site of trastuzumab (p95 HER2). • Epitope masking by mucin 4 or CD44/polymeric hyaluronan complex. • Loss of HER2 complex Pohlmann PR, et al. Clin Cancer Res 20
  • 12. Mechanisms of resistance (2) • Altered HER2 downstream signaling. Increased ligand production (ADAM17) • Signaling through an alternate receptor pathway Pohlmann PR, et al. Clin Cancer Res 2009
  • 13. Mechanisms of resistance (3) • Failure to trigger immune-mediated mechanisms to destroy tumor cells FcγRIII F158 polymorphism interfere with antibody-dependent cellular cytotoxicityfunction Pohlmann PR, et al. Clin Cancer Res 2009
  • 14. Trastuzumab Resistance: The List Grows • HER2 protein expression • Sprouty 2 expression (via PTEN & ERK) • Cyclin E amplification/overexpression; loss of p27Kip1 (downstream HER2 effectors) • Calpain inactivation (via pHER2 cleavage) • miR21 upregulation (via PTEN) • Loss of HER2 amplification (post-adjuvant Trast) • Notch-1 overexpression
  • 15. Pharmacokinetic Resistance: Inability to Penetrate the CNS Lapatinibas 1st-Line Treatment in HER-2+ Advanced Breast Cancer Gomez HL et al, ASCO 2005, abstract #3046 Patient D: Brain Lesion Baseline and 12 Weeks
  • 16. Lapatinib/RTK Resistance • Many trastuzumab resistance mechanism do not apply: (IGF-1, p95, PTEN, HER3, PI3K/AKT) • Increased pSRC kinase (via PTEN/PI3K/AKT) • Altered antiapoptotic proteins (MCL-1 and survivin) • Activated FOXO3a and increased expression of estrogen receptor • Quasi-resistance: lack of immune reponse
  • 17. Conclusion #2: There are many mechanisms of resistance; most affect common pathways. Resistance mechanisms are complex but not infinite.
  • 18. Which mechanisms are proven in the clinic?
  • 19. PTEN Impact on Sensitivity or Resistance to Trastuzumab • Preclinical data suggest PTEN loss associated with trastuzumab resistance – O’Brien NA, 2010; Stemke-Hale K, 2008; Saal LH, 2005; Nagata Y, 2004 • Clinical data available to date: limited and conflicting – PTEN loss associated with trastuzumab resistance • Dave, 2011; Esteva, 2010, Faratian, 2009 N = 122 – PTEN loss NOT associated with trastuzumab resistance • Fabi, 2010; Gori, 2009; Yonemori, 2009 Faratian et al Cancer Res 69(16):6713–20
  • 20. DFS by Treatment Arm for Pts with PTEN Negative Tumors: N9831 100 90 AC →T+H → H AC → T → H 80 Arm N Events HR 95% CI p 5yr Event free (%) 70 DFS AC → T A 176 53 72.3 B 146 38 0.85 0.55-1.30 0.44 77.8 60 A 176 53 72.3 C 138 19 0.47 0.28-0.79 0.005 86.7 50 B 146 38 77.8 C 138 19 0.56 0.32-0.97 0.04 86.7 40 0 1 2 3 4 5 Years from randomization Perez EA, et al. ASCO 2011; Abst 79057
  • 21. Multifactorial Resistance: Clinical Data Mechanism/Reference Outcome (all significant p values) • p95HER2/CCR 16:4226, 2010 • PFS HR = 1.9, OS HR = 2.2 • PTEN/Cancer Res 69:6713,2009 • OS HR = 3.0 • HER2 prot exp/Ann Oncol 22: • TTP HR = 3.7, OS HR = 2.0 2014,2011 • Sprouty 2/PLOS One 6: • OS HR = 2.28 e23772, 2011 • Cyclin E/PNAS 108: 3761, 2011 • Lower RR and PFS • FcR Polymorphisms/JCO 26: • PFS HR = 5.3 1789, 2008
  • 22.
  • 23. REMARK Criteria for Biomarker Reporting
  • 24. Conclusion #3: Laboratory mechanisms of resistance have not been confirmed in any meaningful sense in the clinic: 1. We lack large data sets 2. Most studies are small, lack confirmatory studies, level 4 evidence 3. Adjuvant studies can reject metastatic hypotheses 4. Assays not validated and variable 5. Multifactorial resistance mechanisms not examined
  • 25. What are the Therapeutic Implications of Resistance Mechanisms? • Since different resistance mechanisms affect different drugs, combined HER2 pathway blockade should be superior. • Multifactorial nature of resistance suggests that no single therapeutic approach will overcome resistance.
  • 26. What are the Therapeutic Implications of Resistance Mechanisms? • Since many resistance mechanisms have common downstream effectors (e.g., mTOR), downstream inhibition may prove useful. • Improved measurement of resistance mechanisms might improve targeting.
  • 28.
  • 29. HER family Hudis CA, NEJM 2007
  • 30. Figure 1 Proposed mechanisms of trastuzumab resistance Nahta R et al. (2006) Mechanisms of Disease: understanding resistance to HER2-targeted therapy in human breast cancer Nat Clin Pract Oncol 3: 269–280 doi:10.1038/ncponc0509
  • 31. Figure 1 Molecular targets and therapeutic approaches in trastuzumab and lapatinib resistance Esteva, F. J.et al.(2009)Molecular predictors of response to trastuzumab and lapatinib in breast cancer Nat. Rev. Clin. Oncol. doi:10.1038/nrclinonc.2009.216
  • 32. Clin Cancer Res. 2009 Dec
  • 33. Clin Cancer Res. 2009 Dec
  • 34. Clin Cancer Res. 2009 Dec
  • 35. Clin Cancer Res. 2009 Dec
  • 36. Clin Cancer Res. 2009 Dec
  • 37. Trastuzumab-DM1 (T-DM1), is designed to combine the anti- tumor activity of trastuzumab with a means of delivering highly potent chemotherapy directly into HER2-expressing cells. DM-1 (also known as maytansine) is an inhibitor of tubulin polymerization, binding tubulin competitively with vinca alkaloids.
  • 38. Background Classic PTEN Pathway Planchon SM, et al. J Cell Sci 2008;121: 249-253
  • 39. Analysis 1 DFS by Treatment Arm for Pts with PTEN Positive Tumors 100 90 AC →T+H → H 80 AC → T → H Arm N Events HR 95% CI p 5yr Event free (%) 70 DFS AC → T A 425 120 73.9 B 504 106 0.70 0.54-0.92 0.009 81.0 60 A 425 120 73.9 C 413 77 0.65 0.48-0.86 0.003 85.1 50 B 504 106 81.0 C 413 77 0.90 0.67-1.21 0.49 85.1 40 0 1 2 3 4 5 Years from randomization Perez EA, et al. ASCO 2011; Abst 79057
  • 40. Analysis 1 Impact of PTEN on DFS Based for Different Treatment Arm Comparisons: N9831 Adjuvant • Arm C vs Arm A – PTEN+ HR: 0.65 (p=0.003) Interaction p=0.16 – PTEN- HR: 0.47 (p=0.005) • Arm B vs Arm A – PTEN+ HR: 0.70 (p=0.009) – PTEN- HR: 0.85 (p=0.44) Interaction p=0.47 • Arm C vs Arm B – PTEN+ HR: 0.90 (p=0.49) – PTEN- HR: 0.56 (p=0.04) Interaction p=0.08 Perez EA, et al. ASCO 2011; Abst 79057
  • 41. The mammalian target of rapamycin (mTOR) signaling network. Meric-Bernstam F , Gonzalez-Angulo A M JCO 2009;27:2278-2287 ©2009 by American Society of Clinical Oncology
  • 42. Table 1 Characteristics and mechanisms of action of trastuzumab and lapatinib Esteva, F. J.et al.(2009)Molecular predictors of response to trastuzumab and lapatinib in breast cancer Nat. Rev. Clin. Oncol. doi:10.1038/nrclinonc.2009.216
  • 43. Table 3 Efficacy of HER2-directed therapy in trastuzumab-resistant metastatic breast cancer Esteva, F. J.et al.(2009)Molecular predictors of response to trastuzumab and lapatinib in breast cancer Nat. Rev. Clin. Oncol. doi:10.1038/nrclinonc.2009.216
  • 44. Table 2 Treatment of HER2 breast cancer: trastuzumab-based combinations beyond trastuzumab progression Di Cosimo, S. & Baselga, J.(2010)Management of breast cancer with targeted agents: importance of heterogenicity Nat. Rev. Clin. Oncol. doi:10.1038/nrclinonc.2009.234
  • 45. Figure 1 Overall response rates in HER2-positive and hormone receptor-positive metastatic breast cancer Cortés, J. et al.(2010)HER2 and hormone receptor-positive breast cancer—blocking the right target Nat. Rev. Clin. Oncol. doi:10.1038/nrclinonc.2010.185
  • 46. Figure 2 Receptor cross-talk and response to therapy Cortés, J. et al.(2010)HER2 and hormone receptor-positive breast cancer—blocking the right target Nat. Rev. Clin. Oncol. doi:10.1038/nrclinonc.2010.185
  • 47.
  • 48. Novel HER2 Agents HER1/2 TKI Lapatinib, HKI-272, BIBW 2992, PKI-166, EKB-569 Pan HER TKI Canertinib, BMS-599626 HER1/2/VEGFR TKI XL647, AEE788 HER2 dimerization inhibitor Pertuzumab Bispecific antibody Ertumaxomab Conjugated antibodies Trastuzumab-MCC-DM1, trastuzumab-A-Z-CINN 310-paclitaxel HSP90 inhibitors Tanespimycin, alvespimycin, CNF2024, IPI-504, AUY922, SNX5422 IGF-1R inhibitors (mAb, TKI) CP-751871, EM164, IMC-A12, NVP-ADW742, INSM-18 HDAC inhibitors Vorinostat, LBH589, PXD101, NVP-LAQ824, depsipeptide, CI-994, MS-275 PI3K inhibitors SF1126, BEZ235, XL147, XL765 Akt inhibitors Perifosine, XL418 mTOR inhibitors Rapamycin (sirolimus), temsirolimus, everolimus, deforolimus HER2 vaccines

Notas del editor

  1. Fig. 4 A-B
  2. General mechanisms ofresistance to trastuzumab: obstacles fortrastuzumab binding to HER2. A, aconstitutively active truncated form ofHER2 receptor that has kinase activitybut lacks the extracellular domain andthe binding site of trastuzumab isoriginated from metalloproteasedependentcleavage of the full-lengthHER2 receptor (p185; refs. 45, 130).Trastuzumab does not bind to p95HER2and therefore has no effect against it.The remaining intracellular domain ofp95HER2 has operational kinasedomains and can be targeted by the TKinhibitor lapatinib (63)
  3. B, epitopemasking by MUC4 or CD44/polymerichyaluronan complex. MUC4 is a largemembrane-associated mucin producedby epithelia as part of the epithelialprotective mechanisms. MUC4 hasmultiple repeat regions containingserine and threonine. Glycosylation ofthese repeats forces them into a highlyextended, rigid conformation andmakes them hydrophilic (69). MUC4 isnormally present on the apical surfacesof epithelial cells, but overexpressed inseveral carcinomas. MUC4 has closeassociation with HER2 and may masktrastuzumab cognate epitope,interfering with antibody binding andactivity. CD44/hyaluronan polymercomplex activates RAS and PI3Kpathways, but it is not clear if theseeffects depend on HER2. Inhibition ofhyaluronan synthesis in vitro reduceshyaluronan polymer binding to CD44,and increases trastuzumab binding toHER2.
  4. Fig. 4. General mechanisms of resistance to trastuzumab: presence of upregulation of HER2 downstream signaling pathways. PTEN is a tumor suppressor.Trastuzumab binding stabilizes and activates PTEN and consequently down-regulates the PI3K/Akt signaling pathway (39). When PTEN function is lost,PI3K remains constitutively active regardless of binding of trastuzumab to HER2. PTEN loss correlates with clinical unresponsiveness to trastuzumabtreatment. Genomic aberrations in the PI3K pathway are a common event in a variety of cancer types (127). Multiple components of this pathway are affectedby germline or somatic mutation, amplification, rearrangement, methylation, overexpression, and aberrant splicing, but only in a few instances PIK3CAand PTEN mutations are seen simultaneously (86). Genomic aberrations in the PI3K pathway produce constitutive activation of the pathway, which will signaldownstream to the nucleus regardless of trastuzumab binding to HER2. This is the case with activating mutations of PIK3R1 and PIK3CA, encoding genesfor PI3K p85α and p110α, respectively. Increased Akt kinase activity and PDPK1 overexpression have also been implicated with trastuzumab resistance.
  5. Fig. 5. General mechanisms of resistance to trastuzumab: presence of signaling through an alternate receptor and/or pathway. Signaling may continueregardless of trastuzumab binding to HER2 when other receptors remain active on the tumor cell. The activity of certain receptors may also increase as aresult of trastuzumab blockage of HER2, as a cell survival mechanism (see text for details). Trastuzumab-induced growth inhibition in HER2-overexpressingcells can be compensated for by increased IGF-IR signaling, resulting in resistance to trastuzumab. In preclinical models in which HER2-overexpressingtumor cells are cultured in the presence of ligand, resembling what is likely to happen in vivo, trastuzumab does not interfere with HER2/HER3heterodimerization and therefore does not block signaling from these heterodimers (42). c-Met is frequently co-expressed with HER2 in cell lines andcontributes to trastuzumab resistance through sustained Akt activation.
  6. Fig. 6. General mechanisms of resistance to trastuzumab: failure to trigger immune-mediated mechanisms to destroy tumor cells. ADCC is a process inwhich the Fab region of an antibody binds to its cognate antigen present on a target cell (for instance cancer cell), whereas its Fc region engages with the Fcreceptor present on an effector cell from immune system. This process triggers degranulation of cytotoxic granules from effector cell toward the target celland culminates with target cell apoptosis (131). In humans, the Fc receptor family comprises FcγRI (CD64); FcγRII (CD32), with three isoforms FcγRIIa, FcγRIIb(inhibitory), and FcγRIIc; and FcγRIII (CD16), including two isoforms FcγRIIIa and FcγRIIIb (132). There is a correlation between the clinical efficacy oftherapeutic antibodies in humans and their allotype of high-affinity (V158) or low-affinity (F158) polymorphic forms of FcγRIIIa. Epitope masking previouslydiscussed in the obstacles for trastuzumab binding to HER2 section would also play a role by preventing antibody-based cell destruction
  7. The investigational agent, trastuzumab-DM1 (T-DM1), is designed to combine the anti-tumor activity of trastuzumab with a means of delivering highly potent chemotherapy directly into HER2-expressing cells. DM-1 (also known as maytansine) is an inhibitor of tubulin polymerization, binding tubulin competitively with vinca alkaloids. Compared with drugs like vincristine, however, it is 20 to 100 times more potent, said principal investigator Murali Beeram, MD, of the Institute for Drug Development, San Antonio. &quot;DM-1 was developed in 1975 but was found to be too toxic for standard chemotherapy,&quot; Dr. Beeram said. &quot;We tagged it in a very small amount to the trastuzumab molecule with a linker. The linker provides a stable bond between the two agents that is designed to prolong exposure and reduce the toxicity of T-DM1. We are, in essence, sending a chemotherapy payload into the cell via the antibody. We get a twofold effect—an increase in the efficacy of trastuzumab and direct delivery of the cytotoxic agent, which reduces treatment toxicity.&quot; The compound was well tolerated. The only grade 3-4 toxicity was a rapidly reversible grade 4 thrombocytopenia at the highest dose in one patientA phase II trial of the immunoconjugate is being initiated in HER2-positive metastatic breast cancer patients. Genentech, which is developing the new agent, has enlisted ImmunoGen, Inc. to develop a commercial-scale process for making T-DM1, using ImmunoGen&apos;s tumor-activated prodrug (TAP) technology.