Impact of Pertuzumab and Ado-Trastuzumab Emtansine on Cumulative Avoidance of Recurrence Among Women Treated for Locally Advanced, Inflammatory, or Early-Stage Nonmetastatic HER2-Positive Breast Cancer in the United States.

INTRODUCTION: We assessed the impact of HER2-positive early breast cancer (EBC) treatment landscape changes following the introduction of pertuzumab and ado-trastuzumab emtansine (T-DM1) on cumulative population-level recurrences avoided since 2013 (first pertuzumab approval for EBC in the United States; US). METHODS: We constructed a multi-year epidemiologic population treatment-impact model to estimate annual recurrences between 2013 and 2031. Parameters were: BC incidence; stage I-III proportion; HER2-positive disease proportion; treatment proportions for neoadjuvant-only, adjuvant-only, and neoadjuvant-adjuvant continuation; and therapeutic agent proportions within each of those settings (chemotherapy only, trastuzumab ± chemotherapy, pertuzumab with trastuzumab ± chemotherapy, or T-DM1). The primary endpoint was cumulative recurrences, estimated by incorporating extrapolated clinical trial data for each regimen of interest into the model under four scenarios. RESULTS: Approximately 889,057 women were predicted to be diagnosed with stage I-III HER2-positive BC from 2006 to 2031 in the US and potentially indicated for HER2-targeted treatment. In steady-state equilibrium, the model estimated that real-world utilization of pertuzumab and T-DM1 will reduce the population-level number of recurrences by approximately 32%, with 7226 recurrences predicted in 2031 based on current utilization rates. In different modeled scenarios, use of neoadjuvant pertuzumab, continuation of pertuzumab in the adjuvant setting, and T-DM1 in the adjuvant setting in women with residual disease after neoadjuvant treatment were all predicted to reduce the number of recurrences. CONCLUSION: Given the improvement of HER2-targeted treatments, alongside increases in BC disease burden, we expect that the population-level impact of HER2-targeted treatments will accelerate over the next decade. Our results suggest that utilization of HER2-targeted treatments in the US has the potential to change the epidemiology of HER2-positive EBC by preventing a substantial number of women from experiencing disease recurrence. These improvements may help to inform our understanding of the future disease and economic burden of HER2-positive BC in the US.

We predicted whether two treatments for a type of breast cancer called "HER2-positive," that had not yet spread from the breast, could be used to avoid the cancer coming back in women in the United States (US), using computer modeling. The model estimated that approximately 889,057 women were predicted to be diagnosed with this type of breast cancer from 2006 to 2031, and that use of the treatments pertuzumab and ado-trastuzumab emtansine (T-DM1) would reduce the number of breast cancers that came back by around 32%. Treating with pertuzumab before surgery, continuing pertuzumab treatment after surgery, and giving T-DM1 after surgery (in the event that some of the breast cancer remained after being treated before surgery) were all predicted to reduce the number of breast cancers that come back. Overall, we expect use of pertuzumab and T-DM1 to keep lowering the number of breast cancers that come back over the next decade in the US.

Real-World First-Line Use of Pertuzumab With Different Taxanes for Human Epidermal Growth Factor Receptor 2-Positive Metastatic Breast Cancer: A Comparative Effectiveness Study Using US Electronic Health Records.

PURPOSE: On the basis of the results from CLEOPATRA, pertuzumab plus trastuzumab and chemotherapy is the first-line standard of care for human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC). However, discrepancies have been reported between clinical trial and real-world outcomes. We report real-world outcomes for patients with HER2-positive MBC treated with first-line pertuzumab plus trastuzumab and a taxane in routine clinical practice in the United States. METHODS: A retrospective analysis was conducted using electronic health record-derived deidentified data from the Flatiron Health database. Patients were grouped according to the first taxane received (paclitaxel/nab-paclitaxel or docetaxel). Median real-world progression-free survival (rwPFS) and overall survival (rwOS) was estimated using Kaplan-Meier methodology. Subgroup analyses were conducted in patients treated with docetaxel who met CLEOPATRA's key eligibility criteria. RESULTS: We included 1,065 patients; 313 patients received paclitaxel/nab-paclitaxel and 752 received docetaxel. Patients who received paclitaxel/nab-paclitaxel were older, had a worse Eastern Cooperative Oncology Group Performance Status, and had more recurrent metastatic disease compared with the docetaxel group. After adjustment for potential confounders, similar median rwPFS (inverse probability of treatment weighted average treatment effect for the treated [IPTW-ATT] hazard ratio [HR], 1.09; 95% CI, 0.9 to 1.3; P = .365) and rwOS (IPTW-ATT HR, 1.23; 95% CI, 0.96 to 1.58; P = .101) was observed between treatment groups. In the subgroup of CLEOPATRA-eligible patients, median rwPFS and rwOS were 16.9 months and 57.8 months, respectively. CONCLUSION: There was no statistically significant difference in real-world outcomes between patients treated with paclitaxel/nab-paclitaxel and those treated with docetaxel. Selecting patients using key CLEOPATRA eligibility criteria resulted in rwPFS and rwOS similar to those observed in CLEOPATRA, highlighting the importance of ensuring similar patient populations when comparing clinical trial and real-world data.

Event-Free Survival in Patients with Early HER2-Positive Breast Cancer with a Pathological Complete Response after HER2-Targeted Therapy: A Pooled Analysis.

The standard-of-care for patients with pathological complete response (pCR) after neoadjuvant human epidermal growth factor receptor 2 (HER2)-targeted therapy plus chemotherapy is continuation of HER2-targeted therapy in the adjuvant setting. Our objective was to evaluate risk of recurrence or death in these patients and determine if outcomes differed by the HER2-targeted regimen received in each setting. We analyzed patient-level data from five randomized trials evaluating trastuzumab, pertuzumab, or both as part of systemic neoadjuvant and adjuvant therapy for HER2-positive early breast cancer, and assessed event-free survival (EFS) in 1763 patients. Patients with pCR had decreased risk of an EFS event versus those with residual disease (unadjusted hazard ratio [HR] = 0.35; 95% confidence interval [CI]: 0.27-0.46). Regardless of pCR status, after adjusting for baseline factors, reduction in EFS event risk was greater in patients administered pertuzumab/trastuzumab in both settings versus those administered only trastuzumab in both settings (HR = 0.36; 95% CI: 0.26-0.49), or pertuzumab/trastuzumab in the neoadjuvant setting and only trastuzumab in the adjuvant setting (HR = 0.67; 95% CI: 0.47-0.96). Patients with pCR had longer EFS than those with residual disease. Patients treated with pertuzumab/trastuzumab in both the neoadjuvant and adjuvant settings had the lowest risk of breast cancer recurrence.