Primary predictors of survival outcomes for HER2-positive advanced breast cancer patients initiating ado-trastuzumab emtansine

Physical Activity, Weight, and Outcomes in Patients Receiving Chemotherapy for Metastatic Breast Cancer (C40502/Alliance)

Background

Obesity and inactivity are associated with increased risk of cancer-related and overall mortality in breast cancer, but there are few data in metastatic disease.

Methods

Cancer and Leukemia Group B 40502 was a randomized trial of first-line taxane-based chemotherapy for patients with metastatic breast cancer. Height and weight were collected at enrollment. After 299 patients enrolled, the study was amended to assess recreational physical activity (PA) at enrollment using the Nurses' Health Study Exercise Questionnaire. Associations with progression-free survival (PFS) and overall survival (OS) were evaluated using stratified Cox modeling (strata included hormone receptor status, prior taxane, bevacizumab use, and treatment arm). All statistical tests were 2-sided.

Results

A total of 799 patients were enrolled, and at the time of data lock, median follow-up was 60 months. At enrollment, median age was 56.7 years, 73.1% of participants had hormone receptor-positive cancers, 42.6% had obesity, and 47.6% engaged in less than 3 metabolic equivalents of task (MET) hours of PA per week (<1 hour of moderate PA). Neither baseline body mass index nor PA was statistically significantly associated with PFS or OS, although there was a marginally statistically significant increase in PFS (hazard ratio = 0.83, 95% confidence interval = 0.79 to 1.02; P = .08) and OS (hazard ratio = 0.81, 95% confidence interval = 0.65 to 1.02; P = .07) in patients who reported PA greater than 9 MET hours per week vs 0-9 MET hours per week.

Conclusions

In a trial of first-line chemotherapy for metastatic breast cancer, rates of obesity and inactivity were high. There was no statistically significant relationship between body mass index and outcomes. More information is needed regarding the relationship between PA and outcomes.

Patient-Reported Outcomes Predict Progression-Free Survival of Patients with Advanced Breast Cancer Treated with Abemaciclib

BACKGROUND

Abemaciclib is a CDK4/6 inhibitor used to treat hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer. The prognostic value of patient-reported outcomes (PROs) has been minimally explored for treatment outcomes with CDK4/6 inhibitors. The performance of PROs compared with Eastern Cooperative Oncology Group performance status (ECOG-PS) is unknown.

MATERIALS AND METHODS

This study pooled data from single-arm trial, MONARCH 1, and randomized trials, MONARCH 2 and 3. In total, 900 patients initiated abemaciclib and 384 comparator therapy. Pretreatment PRO association with progression-free survival (PFS) was modeled using Cox proportional hazards regression. Prediction performance was assessed via the C-statistic (c). PROs were recorded via the European Organisation for Research and Treatment of Cancer QLQ-C30.

RESULTS

Patient-reported physical function, pain, role function, fatigue, and appetite loss were associated with PFS on univariable and adjusted analysis (p < .05). Physical function (c = 0.55) was most predictive, superior to ECOG-PS (c = 0.54), with multivariable analysis indicating both provide independent information (p < .02). In the pooled randomized arms of MONARCH 2 and 3, the PFS treatment benefit (hazard ratio [95% confidence interval]) of abemaciclib (vs. comparators) was 0.75 (0.57-1.0) for low physical function, compared with 0.48 (0.40-0.59) for intermediate/high (p[interaction] = .01).

CONCLUSION

PROs were identified as prognostic factors for PFS in patients initiating abemaciclib, with patient-reported physical function containing independent predictive information beyond ECOG-PS. Low physical function was associated with a decrease in the magnitude of PFS benefit from abemaciclib. PROs should be explored as prognostic, predictive, and stratification factors for clinical use and research trials of CDK4/6 inhibitors.

IMPLICATIONS FOR PRACTICE

For the first time, pretreatment patient-reported outcomes have been shown to be independent prognostic markers for progression-free survival (PFS) in patients diagnosed with hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer treated with abemaciclib. Importantly, patients with low physical function had a smaller PFS benefit from abemaciclib (vs. comparator) than patients with intermediate/high physical function. The present study demonstrates patient-reported outcomes as a simple, effective, inexpensive, and independent prognostic marker for patients with HR+/HER2- advanced breast cancer treated with abemaciclib.

Prolonged Responses With Trastuzumab Emtasine Treatment of Human Epidermal Growth Factor Receptor 2-positive Metastatic Breast Cancer Refractory to Trastuzumab and Pertuzumab: Systematic Review of Evidence

Amplification of human epidermal growth factor receptor 2 (HER2) occurs in around 25% of breast cancers and has been associated with aggressive disease. Here, we summarize published evidence on efficacy and prolonged responses with trastuzumab emtansine (T-DM1) after first-line trastuzumab plus pertuzumab and provide possible factors related to prolonged responses to T-DM1. We conducted a literature search using PubMed, and articles that were published in English between July 1, 2012 and December 31, 2019 were included. A review of the bibliography included in the articles found was made. Nine articles were eligible; 2 were case reports, and the remaining 7 were nonexperimental studies, all retrospective. Five were multi-center works. The total number of patients was 796 (276 received pertuzumab). The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was used for this systematic review. The population included was heterogeneous among studies according to hormone receptor status, de novo metastatic disease, number of metastatic sites, visceral involvement, brain metastasis, previous neoadjuvant or adjuvant trastuzumab, and line of therapy in which T-DM1 was administered. Less efficacy in terms of responses (overall response rate, 18%-33%) and progression-free survival (4-6 months) with second-line T-DM1, in patients pretreated with pertuzumab, was shown (if compared with the EMILIA trial). The results are more similar to those of the TH3RESA trial (very pretreated population). Prolonged treatments (6 months or more) were observed in at least 17% of cases. The efficacy of T-DM1 after a previous pertuzumab treatment is lower than if pertuzumab is not given, although prolonged responses are observed in this setting.

A literature review of treatment-specific clinical prediction models in patients with breast cancer

Despite advances in the breast cancer treatment, significant variability in patient outcomes remain. This results in significant stress to patients and clinicians. Treatment-specific clinical prediction models allow patients to be matched against historical outcomes of patients with similar characteristics; thereby reducing uncertainty by providing personalised estimates of benefits, harms, and prognosis. To achieve this objective, models need to be clinical-grade with evidence of accuracy, reproducibility, generalizability, and be user-friendly. A structured search was undertaken to identify treatment-specific clinical prediction models for therapeutic or adverse outcomes in breast cancer using clinicopathological data. Significant gaps in the presence of validated models for available treatments was identified, along with gaps in prediction of therapeutic and adverse outcomes. Most models did not have user-friendly tools available. With the aim being to facilitate the selection of the best medicine for a specific patient and shared-decision making, future research will need to address these gaps.

Real-world data on T-DM1 efficacy - results of a single-center retrospective study of HER2-positive breast cancer patients

T-DM1 is an antibody drug conjugate that combines trastuzumab with emtansine via a stable thioether linker. In two phase III clinical trials, EMILIA and TH3RESA, T-DM1 was shown to be effective in HER2-positive metastatic breast cancer patients who had progressed to taxanes and trastuzumab. We have performed a real-world study to complement the findings of the clinical trials. From 2012 to 2016, 15 patients with HER2-positive breast cancer who had progressed to prior treatment received T-DM1 at our center. We have retrospectively analyzed outcomes in these patients and compared our findings with those of the two clinical trials. Progression-free survival (PFS) was 10 months compared with the 9.6 months of the EMILIA trial and the 6.2 months of the TH3RESA trial, overall survival was 34 months compared with the 29.9 months of the EMILIA trial and the 22.7 months of the TH3RESA trial. PFS was ≥12 months in five patients, three of whom attained a PFS of ≥23 months. Among five patients with metastases of the central nervous system, PFS was six months, OS was not reached, and the objective response rate was 80%. Our findings are in line with those of the EMILIA study and slightly superior to those of the TH3RESA study. In our series of patients, T-DM1 has demonstrated efficacy in the treatment of HER2-positive metastatic breast cancer. Our real-world data thus confirm and support the findings of the two major phase III trials and indicate the usefulness of T-DM1 in routine clinical practice.