Erin Roesch, MD
The predilection for brain metastases in human epidermal growth factor receptor 2 (HER2)-positive breast cancer has historically presented a therapeutic challenge, and agents with enhanced central nervous system (CNS) penetrance are certainly desired. Pyrotinib is a small molecule irreversible tyrosine kinase inhibitor against epidermal growth factor receptor (EGFR), HER2, and HER4. Yan et al investigated the activity and safety of pyrotinib + capecitabine in the single-arm, two-cohort, phase 2 PERMEATE study among 78 patients with HER2-positive metastatic breast cancer (MBC) with brain metastases. The intracranial objective response rate was 74.6% in radiotherapy-naive patients and 42.1% in those progressing after prior radiotherapy. The combination showed good tolerability with the most common grade 3 treatment-related adverse events of diarrhea and neutropenia. Additional studies have shown impressive CNS activity with other HER2-targeted therapies including tucatinib + capecitabine + trastuzumab combination, as well as trastuzumab deruxtecan (HER2CLIMB and DESTINY-Breast03 trials, respectively). The evolution of these agents in both the metastatic and early settings will continue to transform the treatment algorithm for HER2-positive breast cancer. A particularly interesting concept is whether earlier use of drugs with better CNS efficacy can reduce risk or prevent development of brain metastases.
Endocrine therapy in early-stage hormone receptor-positive (HR+) breast cancer leads to significant reductions in recurrence and breast cancer mortality. A meta-analysis was performed by Early Breast Cancer Trialists' Collaborative Group including four trials (ABCSG XII, SOFT, TEXT and HOBOE), 7030 premenopausal patients with early-stage ER+ breast cancer, who received an aromatase inhibitor or tamoxifen for 3-5 years with ovarian suppression. Rates of breast cancer recurrence were lower with an aromatase inhibitor vs tamoxifen, with the main benefit seen during years 0-4 (relative risk [RR] 0.68, P < .0001) and an absolute reduction in 5-year recurrence risk of 3.2% (6.9% vs 10.1%). Aromatase inhibitor use was associated with decreased distant recurrence risk (RR 0.83), but there was no significant difference for breast cancer or all-cause mortality. The favored endocrine therapy approach for an individual patient is often complex and based on overall risk, comorbidities and toxicity concerns, as well as patient preference. Longer follow-up of trials with endocrine therapy and ovarian suppression will provide further insight on mortality impact.
Aromatase inhibitor (AI)-associated musculoskeletal symptoms are not infrequent and can contribute to treatment discontinuation. Current management practices include use of non-steroidal anti-inflammatory drugs (NSAID), weight loss and exercise, trial of alternative AI or tamoxifen, use of serotonin and norepinephrine reuptake inhibitors (SNRI) (duloxetine) and acupuncture. Martinez et al reported on outcomes of the non-selective NSAID, sulindac (150mg twice daily for 12 months), in a phase 2 study among postmenopausal women with early HR+ breast cancer who were stable on AI therapy for at least 3 months. At 12 months, patients receiving sulindac (n = 43) reported improvements (decreases) in Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index (-5.85, P = .003), pain (-5.40, P = .043), stiffness (-9.53, P < .001) and physical function (-5.61, P = .006); those in the observation group (n = 40) did not experience improvements in these variables. The most significant improvement with sulindac was seen in those with a higher degree of baseline symptoms and in overweight/obese patients. These findings support further investigation into abbreviated NSAID use and strategies focused on exercise and healthy body weight maintenance for breast cancer patients.
The treatment landscape for early-stage triple-negative breast cancer (TNBC) continues to evolve with integration of new drugs into our armamentarium, and use of pathologic complete response (pCR) as a surrogate for outcome and for tailoring adjuvant therapy. Geyer et al reported on event-free survival outcomes with a 4.5 year follow-up of the phase 3 BrighTNess trial, which included 634 patients with stage II-III TNBC. Significant improvement in event-free survival (EFS) was seen in the carboplatin + veliparib + paclitaxel arm vs. paclitaxel alone (HR 0.63, P = .02), but no difference in EFS in carboplatin + veliparib + paclitaxel vs. carboplatin + paclitaxel (HR 1.12, P = .62). The EFS rates at 4 years were 78% (carboplatin + veliparib + paclitaxel), 79% (carboplatin + paclitaxel) and 69% (paclitaxel alone). The phase 3 KEYNOTE-522 trial demonstrated improvement in EFS with the addition of neoadjuvant pembrolizumab to chemotherapy (carboplatin/paclitaxel followed by AC) followed by adjuvant pembrolizumab compared to chemotherapy alone in patients with stage II-III TNBC. The emergence of new therapies for early TNBC, including immunotherapy and poly (ADP-ribose) polymerase (PARP) inhibitors (the latter for patients with germline BRCA mutations), has created more treatment options for patients along with questions regarding combinations and sequencing.
Recommended Additional Reading:
Lin N et al. Updated results of tucatinib vs placebo added to trastuzumab and capecitabine for patients with previously treated HER2+ metastatic breast cancer with brain metastases (HER2CLIMB). Presented at: 2021 San Antonio Breast Cancer Symposium; December 7-10, 2021;Spotlight Poster Session, PD4-04 Abstract 858. https://www.abstractsonline.com/pp8/#!/10462/presentation/482
Hurvitz S et al. Trastuzumab deruxtecan (T-DXd) versus trastuzumab emtansine (T-DM1) in patients with HER2+ metastatic breast cancer: subgroup analyses from the randomized phase 3 study DESTINY-Breast03. Presented at: 2021 San Antonio Breast Cancer Symposium; December 7-10, 2021;General Session, GS3-01. https://www.abstractsonline.com/pp8/#!/10462/presentation/649
Rosati MS, Di Seri M, Baciarello G, et al. Etoricoxib and anastrozole in adjuvant early breast cancer: ETAN trial (phase III). J Clin Oncol. 2011;29:suppl.533. https://ascopubs.org/doi/10.1200/jco.2011.29.15_suppl.533
Schmid P et al for the KEYNOTE-522 Investigators. Event-free survival with pembrolizumab in early triple-negative breast cancer. N Engl J Med. 2022;386(6):556-567. https://www.nejm.org/doi/full/10.1056/NEJMoa2112651