1. Circulating Tumor Cells: Emerging Biology and Practical Application Massimo Cristofanilli, MD Minetta C. Liu, MD Jeffrey B. Smerage, MD, PhD

2. Prognostic Significance and Predictive Value of Circulating Tumor Cells (CTCs) in Metastatic Breast Cancer Massimo Cristofanilli, MD Associate Professor, Breast Medical Oncology The University of Texas MD Anderson Cancer Center Houston, Texas

3. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application CTCs in Breast Cancer: Introduction  Definition  Detection Methods  Microscopic Disease in Breast Cancer  CTCs in Metastatic Breast Cancer –Prognostic and Predictive Value –Comparison With Serum Markers  Future Directions

4. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Definition  Circulating tumor cells –Peripheral blood epithelial cells shed from tumor surface of cancer patients –Defined by phenotypic characteristics –Expression of cytokeratin or mucin markers such as CK18, CK19, and MUC-1  Phenotypically similar to primary and/or metastatic tumor cells Fehm T, et al. Clin Cancer Res. 2002;8:2073-2084.

5. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Detection Methods  Direct methods (enrichment/detection) –Immunomagnetic –Immunohistochemistry (IHC) –PCR analysis –Automated fluorescent methods  Indirect methods –PCR analysis

6. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application CellSearch System

7. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Microscopic Disease in Breast Cancer  Current detection methods –Indirect assessment –Pathological features –Tumor size –Nuclear grade (low, medium, high) –Molecular biomarkers (eg, uPA/PAI, cyclin E) –Direct assessment –Sentinel node (IHC, RT-PCR) –Bone marrow (IHC) uPA/PAI, urokinase-type plasminogen activator/plasminogen activator inhibitor; RT-PCR, real-time PCR.

8. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Bone Marrow Assessment at Baseline: Prognostic Value Braun S, et al. N Engl J Med. 2005;353:793-802.  Micrometastasis in bone marrow at time of breast cancer diagnosis associated with poor prognosis Outcome, Micrometastasis Positive vs Negative Multivariate HR for 5-yr Follow-up (95% CI) (n = 3974) P Value Death, any cause1.81 (1.51-2.16)<.001 Death, breast cancer1.93 (1.58-2.36)<.001 Disease recurrence1.85 (1.59-2.14)<.001 Distant metastasis2.03 (1.72-2.39)<.001 *Risk estimate not available. Variables dropped from final model according to selection process.

9. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Follow-up Microscopic Assessment of Bone Marrow: Prognostic Value Wiedswang G, et al. Clin Cancer Res. 2004;10:5342-5348. B A  Isolated tumor cells (ITCs) in bone marrow at 3-year follow-up associated with unfavorable outcome  Distant metastasis rate significantly higher in patients ITC+ at both diagnosis and follow-up (P <.001) –29% for ITC+/ITC+ patients vs ≤ 6% in 3 other patient groups –ITC+ at diagnosis only (ITC+/ITC-) –ITC+ at follow-up only (ITC-/ITC+) –No detected ITCs at either time point (ITC-/ITC-)  Distant disease–free and breast cancer–specific survival worse for ITC+/ITC+ patients (P <.001)

10. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Metastatic Breast Cancer  MBC is a heterogeneous condition  Treatment is palliative  Current clinical, laboratory, and radiological methods inadequate for –Assessment of prognosis –Definition of biology –Measurement of efficacy/treatment benefit

11. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Prognostic and Predictive Value of CTCs in MBC Hypothesis  Measurement of CTCs in MBC may: –Identify aggressive disease (prognostic value) –Provide early determination of treatment efficacy/benefit (predictive value)

12. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application CTC Significance in MBC: Prognostic and Predictive Values  Prognosis — strongest independent factor –In newly diagnosed disease (first-line treatment) –Over the course of the disease (second-, third-, or higher- line treatment)  Prediction — predict treatment efficacy at 3-4 weeks  May represent a new standard of care

13. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Progression-Free Survival Probability of Progression-Free Survival Time From Baseline (Months) 0 2 4 6 8 1012 14161822242628 30 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 20 Log rank P =.0001 7.0 months 2.7 months ≥ 5 CTCs/7.5 mL n = 87 (49%) < 5 CTCs/7.5 mL n = 90 (51%) Cristofanilli M, et al. N Engl J Med. 2004;351:781-791. Prognostic Value of Baseline CTC Counts

14. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Overall Survival Time From Baseline (Months) 0 2 46 8 1012 14161822242628 30 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 20 Log rank P <.0001 21.9 months 10.9 months ≥ 5 CTCs/7.5 mL n = 87 (49%) < 5 CTCs/7.5 mL n = 90 (51%) Cristofanilli M, et al. N Engl J Med. 2004;351:781-791. Prognostic Value of Baseline CTC Counts (continued) Probability of Progression-Free Survival

15. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application 64% 43% < 5 CTCs n = 90 (51%) Cristofanilli M, et al. ASCO 2005. Abstract 524. Probability of Death and Baseline CTC Counts Time From Baseline (Months) 0 2 4 6 8 1012 14161822242628 30 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 20 29% ≥ 5 CTCs n = 87 (49%) 53% 12% 19% Probability of Death

16. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Time From Baseline (Months) 02 4 6 8 1012 14161822242628 30 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 20 Log rank: P =.0021 Cox hazard ratio (HR): 2.7 HR, 95% CI: 1.4-5.4 Chi-square: 9.60 P =.0019 > 25 Months 16.2 Months 25.0 (21.9 - > 25.0) ≥ 5 CTC: 48 (51%) Median OS: 16.2 (9.2-24.9) Fisher's exact P value:.040.019 N = 94 Newly Diagnosed MBC Baseline CTC Counts Predict OS Cristofanilli M, et al. ASCO 2005. Abstract 524. Overall Survival

17. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Change in CTC Count During Therapy Predicts Overall Survival Cristofanilli M, et al. ASCO 2005. Abstract 524. 4 1vs4P <.0001 4> 5 CTCs at all time points 39 (22%) 2 1vs2P =.3188 2vs4 P <.0001 2> 5 at baseline and < 5 CTC at last draw38 (21%) 3 1vs3P =.0014 3vs4P =.0051 2vs3P =.0397 3 5 CTC at last draw 17 (10%) Time From Baseline (Months) 0 2 4 6 8 1012 14161822242628 30 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 20 1 1<5 CTCs at all time points 83 (47%) Probability of Survival

18. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Prognostic and Predictive Value of CTCs in MBC  Prognostic –May measure tumor burden –May represent new potential tumor markers (eg, MUC-1, CK18) –May reflect disease biology and host–tumor interaction  Predictive –May be early indicator of clinical response –May be ‘biological sensor’ of treatment’s long-term effects

19. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application CTCs and Serum Tumor Markers in Breast Cancer  MUC-1 glycoproteins (eg, CA15-3, CA27-29) –Most widely used serum tumor markers –Serum marker levels correlate with tumor burden –30%-50% in primary breast cancer –50%-70% in MBC  Correlation with disease-free and overall survival questionable Gonzalez Buitrago JM, et al. Tumor Biol. 1991;12:24-27. Molina R, et al. Breast Cancer Res Treat. 1995;36:41-48.

20. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application CTCs and Serum Markers Prediction of Survival: First Follow-up Time From Baseline (Months) 0246810121416182224262830 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 20 Log rank P =.21 19.5 months 14.2 months Change in MUC-1 # Dead Within Median OS from BL to 1st FU N (%) 6 Months 12 Months Mos (95% CI) ≤ 25% Increase 46 (71%) 5 (11%) 12 (26%) 19.5 (14.2 to > 25) > 25% Increase 19 (29%) 6 (32%) 8 (42%) 14.2 (4.6 to > 25) Fisher's Exact P-value.067.244 Cox hazard ratio: 1.55 Std error:.54 95% CI: 0.77 to 3.10 Chi-square: 1.45 (P =.22) ≥ 5 CTC 24 (37%) 8 (33%) 13 (54%) 10.9 (4.8 to 18.1) CTCs/7.5 mL # Dead Within Median OS at 1st Follow-up N (%) 6 Months 12 Months Mos (95% CI) 25) Fisher's Exact P-value.014 0.005 Time From Baseline (Months) 0 2 4 6 8 1012 14161822242628 30 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 20 26.9 months 10.9 months Cox hazard ratio: 2.54 Std error: 0.85 95% CI: 1.31 to 4.90 Chi-square = 7.44 (P =.0064) Log rank P =.0041 Stopeck A, et al. ASCO 2005. Abstract 9516. Probability of Survival

21. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application CTCs and Serum Markers Prediction of Survival: First Imaging Evaluation Time From Baseline (Months) 0246810121416182224262830 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 20 Log rank P =.3374 20.8 Months 16.2 Months Change in MUC-1 # Dead Within Median OS from BL to Visit 1 N (%) 6 Months 12 Months Mos (95% CI) ≤ 25% Increase 36 (67%) 2 ( 6%) 8 (22%) 20.8 (12.9 to >25) > 25% Increase 18 (33%) 5 (28%) 7 (39%) 16.2 ( 4.8 to >25) Fisher's Exact P-value.034.216 Cox hazard ratio: 1.44 Std error: 0.55 95% CI: 0.67 to 3.07 Chi-square: 0.88 (P =.34) Time From Baseline (Months) 0 2 4 6 8 1012 14161822242628 30 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 20 Log rank P =.0096 20.8 Months 10.9 Months Cox hazard ratio: 2.36 Std error: 0.81 95% CI: 1.2080 to 4.62 Chi-square: 5.99 (P =.0144) CTCs/7.5 mL at # Dead Within Median OS 1st Imaging Visit N (%) 6 Months 12 Months Mos (95% CI) 25) ≥ 5 CTC 20 (31%) 6 (30%) 11 (55%) 10.9 (3.9 to 24.9) Fisher's Exact P-value.061.007 Probability of Survival

22. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Future Directions  Prognostic utility of CTCs in MBC –Validation trial in MBC: International Stage IV Stratification Study (ISSS)  Predictive utility of CTCs in MBC –Southwest Oncology Group (SWOG) S0500

23. International Stage IV Stratification Study

24. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Hypothesis I. Two distinct subgroups of MBC –Indolent (OS: > 25 months) –Aggressive disease (OS: < 16 months) II. Subgroups can be identified by CTC counts at diagnosis –< 5 CTCs = indolent disease –≥ 5 CTCs = aggressive disease

25. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Patients with newly diagnosed MBC Treatment selected by physician Staging/diagnostic procedures per institutional guidelines (N = 660) 012345678910111213141516171836 Months Clinical follow-up Baseline blood collection for CTC detection (No interim assessments of CTC) International Stage IV Stratification Study

26. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application ~ 660 newly diagnosed MBC patients 20-40 patients/month ~ 660 newly diagnosed MBC patients 20-40 patients/month Treatment plan / Registration / Blood draw Hormonal treatment Statistical analysis or report Trial Flowchart Chemotherapy Clinical follow-up or death

27. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Standard Treatments Time From Baseline (months) 0246810121416182224262830 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 20 Stage IVB Stage IVA 16.2 months Investigational agents New Recurrence Staging for MBC Probability of Survival

28. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application  Randomized phase III trial (N = 120)  MBC patients with elevated CTC counts at first follow-up assessment  Evaluate strategy of changing therapy vs maintaining therapy  Primary endpoint: OS SWOG S0500

29. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Blood drawn at baseline prior to first-line chemotherapy Arm B Maintain first-line chemotherapy until progression Arm C1 Maintain first-line chemotherapy until progression Arm C2 Switch to alternate chemotherapy Arm A Monitor for PFS and OS Eligible for other first- line chemotherapy trials R CTC ≥ 5 Blood drawn 3 weeks after first chemotherapy dose CTC ≥ 5 SWOG S0500

30. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application  CTCs –Valid surrogate marker for assessment of treatment benefit –Should be used for risk stratification  Presence of CTCs in patients with MBC –Independent prognostic factor –More valuable than standard measures of tumor burden  Future studies –Further characterize CTC phenotype –Assess utility of CTCs for predicting primary disease (neoadjuvant model) Conclusions

31. Massimo Cristofanilli, MD Minetta C. Liu, MD Jeffrey B. Smerage, MD, PhD Circulating Tumor Cells: Emerging Biology and Practical Application

32. Interactive Case Studies

33. Case 1

34. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application History  55-year-old postmenopausal woman  Diagnosis 2 years prior –Stage IIIA invasive breast cancer –ER+, HER2-  Treatment –4 cycles adjuvant dose-dense doxorubicin and cyclophosphamide (AC) –4 cycles dose-dense paclitaxel  Taking adjuvant tamoxifen

35. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Current Presentation  New and vague abdominal discomfort (persistent 1 month)  Normal physical exam and serum chemistries  CT scan demonstrates 2-cm hepatic lesion  CT-guided biopsy –ER-positive carcinoma –Consistent with recurrence of primary breast cancer  Otherwise negative findings in chest and abdominal CT scan as well as bone scan  No detectable CTCs  HER2 testing results negative

36. Audience Vote

37. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application What would be appropriate management for this patient? A.Combination taxane-based chemotherapy B.Antiestrogen therapy C.Watchful waiting D.Single-agent chemotherapy

38. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Decision  Patient treated with endocrine therapy –Good radiographic response observed

39. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Survival in Women With MBC and No Detectable CTCs  Favorable prognosis in women with undetectable (0) CTCs per 7.5 mL of blood  Median OS, women beginning new hormonal therapy –No CTCs: not reached –CTCs detected: ~ 24 months  Median OS, women beginning chemotherapy –No CTCs: ~ 18 months –CTCs detected: 6-9 months Ellis MJ, et al. SABCS 2005. Abstract 6.

40. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Outcome  After disease progression, patient started on fulvestrant  Clinical response of short duration (~ 5 months)  Imaging studies demonstrate progressive disease  CT demonstrates multiple, widespread, hepatic lesions  Liver function studies normal  New lesions on bone scan consistent with skeletal metastasis  Treating physician believes chemotherapy is next step  CTC assay results: 50 CTCs/7.5 mL blood

41. Audience Vote

42. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Which treatment option would be an appropriate next step for this patient? A.Antiestrogen therapy B.Combination taxane-based chemotherapy C.Single-agent chemotherapy (taxane) D.Refer to hospice care

43. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Decision  Patient receives combination chemotherapy due to poor prognosis –Liver metastases –≥ 5 CTCs/7.5 mL before first-line therapy 1 1. Cristofanilli M, et al. J Clin Oncol. 2005;23:1420-1430.

44. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application CTC Levels and Prognosis in Women With MBC  CTC levels before treatment predict outcome in women with metastatic breast cancer  ≥ 5 CTCs/7.5 mL vs < 5 CTCs/ 7.5 mL –Median progression-free survival –2.7 mo vs 7.0 mo (P =.001) –Median overall survival –10.1 mo vs > 18.0 mo (P =.001) Cristofanilli M, et al. N Engl J Med. 2004;351:781-791. 2.7 7.0 10.1 18+ 0 2 4 6 8 10 12 14 16 18 Median PFSMedian OS ≥ 5 CTCs/7.5 mL < 5 CTCs/7.5 mL Months

45. Case 2

46. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application History  65-year-old woman presents with bone pain –Bone scan reveals widespread metastases –Slightly elevated calcium and alkaline phosphatase –Initially treated with tamoxifen –Resolution of pain (discontinuation of pain medication)  New presentation: pain in right hip 6 months after tx starts –Plain films showed new lytic lesion in right femoral neck –Radiotherapy provides pain relief

47. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Current Presentation  Patient returns to medical oncologist  CTC assay ordered –Results: 200 CTCs/7.5 mL blood

48. Audience Vote

49. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Which treatment option would you recommend for this patient? A.Antiestrogen therapy B.Single-agent chemotherapy C.Single-agent taxane D.Refer to hospice care

50. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Decision  Patient treated with chemotherapy due to poor prognosis –Short duration of response on tamoxifen –≥ 5 CTCs/7.5 mL

51. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application CTCs and Prognostic Risk in Nonmeasurable MBC  For patients with ≥ 5 CTCs/7.5 mL at baseline: –PFS: 4.4 mos vs 9.5 mos for patients with < 5 CTCs/7.5 mL (P =.4412) –Overall survival not significantly different vs patients with < 5 CTCs (P =.2602)  For patients with ≥ 5 CTCs/7.5 mL at 1st follow-up: –PFS: 3.5 mos vs 14.4 mos for pts with < 5 CTCs/7.5 mL (P =.0318) –Overall survival: 65% vs 96% for pts with < 5 CTCs/7.5 mL (P =.02) Budd GT, et al. ASCO 2005. Abstract 503. 3.5 14.4 0 2 4 6 8 10 12 14 16 PFS by CTCs at 1 st follow-up ≥ 5 CTCs/7.5 mL < 5 CTCs/7.5 mL P =.0318 Months

52. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Outcome  Patient continued chemotherapy for ~ 4 months  Follow-up evaluation –Calcium and alkaline phosphatase normalized –Repeat bone scan showed no new lesion

53. Case 3

54. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Current Presentation  45-year-old woman with newly diagnosed MBC  Multiple pulmonary and hepatic metastases  Biopsy demonstrates ER/PR-, HER2- infiltrating ductal carcinoma  Mild elevations in transaminases but bilirubin normal  CA 15-3 level elevated at 45 U/mL (normal < 30 U/mL)  CTC level: 20 CTCs/7.5 mL

55. Audience Vote

56. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application What would be an appropriate treatment choice for this patient? A.Antiestrogen therapy B.Taxane-based combination chemotherapy C.Single-agent chemotherapy D.Refer to hospice care

57. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Decision  Combination chemotherapy with docetaxel and capecitabine initiated –Poor prognosis –Extensive visceral disease –≥ 5 CTCs/7.5 mL Cristofanilli M, et al. N Engl J Med. 2004;351:781-791.

58. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application MBC With ≥ 5 CTCs/7.5 mL and Other High-Risk Factors  Patients with MBC and ≥ 5 CTCs/7.5 mL at baseline –Median PFS ~ 3 months 1  Combination therapy may be more appropriate 1. Cristofanilli M, et al. N Engl J Med. 2004;351:781-791.

59. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application CTC Detection Prior to First-Line Therapy for MBC  Patients with newly diagnosed MBC ready to begin first-line therapy (N = 83), including 43 (52%) with ≥ 5 CTCs/7.5 mL at baseline  ≥ 5 CTCs/7.5 mL at baseline predictive of PFS and OS –Worse prognosis vs patients with < 5 CTCs/7.5 mL –Median PFS: 4.9 vs 9.5 months, respectively (P =.0014) –Median OS: 14.2 vs > 18 months, respectively (P =.0048)  CTC enumeration may aid in patient stratification and design of tailored therapy Cristofanilli M, et al. J Clin Oncol. 2005;23:1420-1430.

60. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Outcome  Combination chemotherapy initiated  3-week follow-up –Patient clinically unchanged –CA15-3 increased further to 70 U/mL –CTC assay declined to 2 CTCs/7.5 mL

61. Audience Vote

62. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application What would be an appropriate next step in the treatment of this patient? A.Continue current treatment (combination chemotherapy) B.Switch to a new taxane-based combination regimen C.Switch to new single-agent chemotherapy D.Refer to hospice care due to primary refractory disease

63. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Conflicting Results From CA 15-3 and CTC Assays in MBC  CA 15-3 useful for monitoring in breast cancer 1,2 –Known “spike” phenomenon in ~ 30% of patients –Confounding early increase during response to therapy  CTC results suggest patient probably responding to therapy –Conversion from high to low CTCs after 1 cycle: similar prognosis as patients with low CTCs at baseline 3  Unknown if switching therapy early (before progression) improves outcome in patients with persistent ≥ 5 CTCs/7.5 mL –Concept being tested in prospective, randomized phase III trial –Southwest Oncology Group (SWOG S0500) 1. Hayes DF, et al. J Clin Oncol. 1986;4:1542-1550. 2. Hayes DF. Diseases of the breast. Lippincott Williams and Wilkins; 2000. p 723. 3. Cristofanilli M, et al. J Clin Oncol. 2005;23:1420-1430.

64. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Conclusions  CTCs ≥ 5/7.5 mL suggest poor prognosis  Change in CTCs after treatment correlates with change in prognosis  CTCs and MUC1 tumor marker assays –May return conflicting results after chemotherapy is started –MUC1 elevation may be due to “spike” phenomenon  Prognosis particularly favorable in hormone receptor– positive patients with 0 CTCs  Preliminary data suggest CTCs may be prognostic in bone-only disease (not just measurable disease)

65. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application Unanswered Questions  Will switching therapy early due to high CTCs at first follow-up change outcome? –SWOG S0500 will address this question  Will previously untreated patients with increased CTCs benefit from upfront chemotherapy vs upfront hormonal therapy? –In studies, tx choice made before CTC levels known  CTCs better (or earlier) predictor of PFS and OS vs response? –CTCs at first follow-up imaging may be better predictor of PFS and OS than radiographic response 1 1. Budd GT, et al. SABCS 2004. Abstract 6018.

66. clinicaloptions.com/oncology Circulating Tumor Cells: Emerging Biology and Practical Application For more information on this topic, visit: http://clinicaloptions.com/ctc  Live presentation of these slides by –Massimo Cristofanilli, MD –Minetta C. Liu, MD  Audience voting on Interactive Cases: Compare your responses with those of your colleagues  Free, online CME credit available