Is pathologic complete response a valid surrogate parameter of treatment efficacy in HER2 positive breast cancer patients undergoing primary chemotherapy plus trastuzamab? [13]

TO THE EDITOR: Data from multiple clinical trials have indicated that pathologic complete response (pCR) after primary chemotherapy in patients with breast cancer (BC) (ie, no residual cancer in the breast or lymph nodes) is associated with an excellent long-term prognosis.1 These results have suggested that pCR can be used as a surrogate marker of efficacy. Many primary chemotherapy trials have been designed with this as the primary end point. It should be noted however, that while this data has demonstrated pCR as a strong prognostic parameter, this does not necessarily imply that it is also a valid surrogate end point of efficacy. pCR, in fact, may have selected a subgroup of patients already destined to a better outcome even without treatment. Prentice provided a definition and a set of criteria to be used to identify a surrogate end point of treatment efficacy.2 Accordingly, to prove that pCR is a surrogate parameter of efficacy of primary chemotherapy, it is not sufficient to demonstrate that it occurs with treatment and correlates with overall outcome. We should also demonstrate that any difference in survival disappears once we adjust for pCR. In other words, prognosis, once the surrogate is known, should be independent of treatment, and responders to more and less active treatment should have the same survival

Presurgical systemic treatment of nonmetastatic breast cancer: Facts and open questions

7noThere are several advantages of administering primary systemic therapy (PST) instead of adjuvant therapy in the management of early breast cancer patients: (a) PST allows for a quantifiable evaluation of the sensitivity or resistance of any treated case and (b) the response assessment offers the opportunity to "cross over" to a different regimen for an individual patient, leading to more flexible, "tailored" therapies. Indeed, these advantages are tenable if one assumes that the primary tumor response serves as a surrogate marker of the efficacy of PST in terms of survival. Unfortunately, this has not yet been validated. The data that are actually available show that both clinical complete response (cCR) and pathological (p)CR have prognostic significance. pCR after chemotherapy has a greater prognostic impact than cCR; however, it is frequently observed in a subset of tumors-such as those that are estrogen receptor negative, are human epidermal growth factor receptor positive, and have elevated proliferative activity-but occurs rarely in their human epidermal growth factor receptor-2/neu counterparts. cCR is more sensitive than pCR, but its assessment presents many hindrances. cCR after chemotherapy can predict early on which tumors are destined to undergo pCR, suggesting a role for this endpoint guiding further treatment decisions early on. The pCR rate in small randomized PST studies comparing chemotherapy with chemotherapy plus trastuzumab was able to predict the difference in survival observed in large, randomized adjuvant trials with a similar study design. Conversely pCR cannot predict the outcome benefit of patients undergoing different hormonal therapies. In conclusion, pCR may be a reliable surrogate endpoint for PST efficacy in a subset of patients undergoing chemotherapynonemixedBerruti, Alfredo; Brizzi, Maria Pia; Generali, Daniele; Ardine, Mara; Dogliotti, Luigi; Bruzzi, Paolo; Bottini, AlbertoBerruti, Alfredo; Brizzi, Maria Pia; Generali, Daniele; Ardine, Mara; Dogliotti, Luigi; Bruzzi, Paolo; Bottini, Albert

Neoadjuvant treatment approach: The rosetta stone for breast cancer?

Breast cancer represents a heterogeneous group of diseases with varied biological features, behavior, and response to therapy; thus, management of breast cancer relies on the availability of robust predictive and prognostic factors to support therapy decision-making. Traditionally, neoadjuvant treatment for breast cancer was preserved for locally advanced, converting an inoperable to a surgical resectable cancer. Neoadjuvant trials, additionally, offer: 1) the opportunity to evaluate new treatment options in a faster way and with fewer patients than large adjuvant trials; 2) to identify and validate the prognostic and predictive value of a marker with its association with clinical outcome in relation to the administered treatment. In this setting, thanks to new, affordable technologies which help to detail the molecular profiles of tumors, new trial designs based on new target therapies, like window-of-opportunity, are also suggested, as they represent the chance to identify tumor sensitivity or to overcome tumor resistance to the treatment used, based on its interaction with tumor biology in early tumor stages. However, clinicians and researchers should pay particular attention: In this setting, the safety of patients is paramount, given the exposure of potentially curable patients to investigational agents with limited safety experience, the definition of the study population and the study design, such as adaptive strategies, should limit patient exposure to ineffective agents, and intensify safety monitoring in the course of the treatment. Here, issues related to outcome determination in breast cancer, including some critical points of view, are presented

Neoadjuvant treatment approach: The rosetta stone for breast cancer?

Breast cancer represents a heterogeneous group of diseases with varied biological features, behavior, and response to therapy; thus, management of breast cancer relies on the availability of robust predictive and prognostic factors to support therapy decision-making. Traditionally, neoadjuvant treatment for breast cancer was preserved for locally advanced, converting an inoperable to a surgical resectable cancer. Neoadjuvant trials, additionally, offer: 1) the opportunity to evaluate new treatment options in a faster way and with fewer patients than large adjuvant trials; 2) to identify and validate the prognostic and predictive value of a marker with its association with clinical outcome in relation to the administered treatment. In this setting, thanks to new, affordable technologies which help to detail the molecular profiles of tumors, new trial designs based on new target therapies, like window-of-opportunity, are also suggested, as they represent the chance to identify tumor sensitivity or to overcome tumor resistance to the treatment used, based on its interaction with tumor biology in early tumor stages. However, clinicians and researchers should pay particular attention: In this setting, the safety of patients is paramount, given the exposure of potentially curable patients to investigational agents with limited safety experience, the definition of the study population and the study design, such as adaptive strategies, should limit patient exposure to ineffective agents, and intensify safety monitoring in the course of the treatment. Here, issues related to outcome determination in breast cancer, including some critical points of view, are presented

Effect of primary letrozole treatment on tumor expression of mTOR and HIF-1α and relation to clinical response

INTRODUCTION: Recently the combination of the mammalian target of rapamycin (mTOR) inhibitor everolimus and the aromatase inhibitor exemestane has been shown to double the progression-free survival rate in advanced breast cancer. However, the effect of the interrelated pathways of hypoxia-inducible factor-1α (HIF-1α) and mTOR signaling, both of which are associated with a more aggressive breast cancer phenotype and endocrine resistance, on response in the neoadjuvant setting is unknown. We, therefore, have investigated the influence of these pathways with the aim of better defining those patients most likely to benefit from an endocrine-based therapy associated with/without mTOR inhibitors. PATIENTS AND METHODS: A total of 107 women with T2-4 N0-1 and estrogen receptor-positive breast cancer were randomly assigned to 6 months of primary letrozole (2.5 mg/daily) (LET) or LET plus oral "metronomic" cyclophosphamide (50mg/daily) (LET-CYC). Phospo-mTOR and HIF-1α were evaluated in tumor specimens collected before and after treatment using a tissue microarray format. RESULTS: LET-based therapy induced a downregulation of phospho-mTOR and HIF-1α expression (P = .0001 and P < .004, respectively). The reduction of HIF-1α expression observed was positively correlated with phospho-mTOR reduction (P < .03); however, no treatment interaction between the two proteins was detected. HIF-1α expression was significantly modulated by the treatment (P < .004) with a reduction both in the LET arm (45%, n = 36/80) (P = .05) and LET-CYC arm (55%, n = 44/80) (P = .04). HIF-1α reduction showed a relationship with clinical response confined in LET arm only (P < .03). CONCLUSIONS: In this neoadjuvant population, LET was able to modulate the phospho-mTOR and HIF-1α pathways and may define a subpopulation of nonresponders who may be most likely to benefit from mTOR inhibitors