Feasibility of targeted therapies in the adjuvant setting of early breast cancer in men: real-world data from a population-based registry

BACKGROUND

Following the positive iDFS and OS results of the phase III clinical trials monarchE, NATALEE and OlympiA, new oral anticancer agents (the CDK4/6 inhibitors abemaciclib, ribociclib as well as the PARP inhibitor olaparib) have recently been introduced into the treatment of high-risk early breast cancer (eBC). However, only few male patients were included in these trials (0.4%, 0.6% and 0.3%, respectively). The objective of this real-world analysis was to determine the proportion of male patients with eBC fulfilling the clinical high-risk criteria of above-mentioned trials.

PATIENTS AND METHODS

We conducted a data inquiry and analysis with the Cancer Registry of Baden-Württemberg of men with breast cancer diagnosed between January 1, 2015 and December 31, 2021. Men with eBC were identified and the number of patients at clinical high-risk according to the inclusion criteria of monarchE, NATALEE and OlympiA was assessed.

RESULTS

Of 397 men with eBC, 354 (89.1%) had a HR + /Her2- and 4 (1.0%) a triple-negative subtype. 84 patients (21.2%) met the clinical high-risk criteria according to the monarchE, 189 (47.6%) those according to the NATALEE and 50 (12.6%) those according to the OlympiA trial.

CONCLUSION

In a large real-world sample, more men with eBC are at clinical high risk according to the inclusion criteria of monarchE, NATALEE and OlympiA than would be expected in women. This is most likely due to more advanced stages at initial diagnosis in men. To evaluate whether CDK4/6 and PARP inhibitors improve prognosis also in men should be the topic of future real- world analyses.

Less necessity of adjuvant S-1 treatment in non-monarchE-eligible patients

BACKGROUND

In monarchE and Postoperative Therapy with Endocrine and TS-1 (POTENT) trials, abemaciclib and S-1 have, respectively, shown to be effective as adjuvant therapies for luminal breast cancer (BC), although whether patients who meet the criteria are at high risk of recurrence compared to non-eligible patients is still unknown. Here, we investigated recurrence risk according to the criteria of each trial in Japanese patients.

METHODS

We reviewed the records of 992 patients who received surgery at Chiba University Hospital for stage I-III BC from January 2017 to May 2022 and selected 553 analytic cohort patients and retrospectively analyzed the relapse-free survival of the patients as the primary endpoint. High-recurrence risk was defined according to monarchE trial and POTENT trial.

RESULTS

The 5-year RFS for monarchE cohort 1 and cohort 2 eligible patients were 77.78% and 89.33%, respectively, which were significantly lower than monarchE non-eligible patients (98.31%; p < 0.0001). However, the 5-year RFS rate for POTENT eligible patients (90.51%) was lower than for POTENT non-eligible patients (98.75%; p = 0.0001); excluding those who met the monarchE criteria, the prognosis of POTENT eligible patients had no significant differences from the prognosis of patients with POTENT non-eligible BC (p = 0.3100).

CONCLUSION

MonarchE criteria accurately identify patients who are prone to relapse. Moreover, although POTENT criteria also suggested a reasonable capacity for recurrence prediction, there was no significant difference in recurrence between POTENT non-eligible patients and the patients who were POTENT but not monarchE eligible. This might offer justification for reconsidering the use of S-1 in monarchE non-eligible patients.

Efficacy and safety results by menopausal status in monarchE: adjuvant abemaciclib combined with endocrine therapy in patients with HR+, HER2-, node-positive, high-risk early breast cancer

Background

Abemaciclib is the first and only cyclin-dependent kinases 4 and 6 inhibitor approved for adjuvant treatment of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), node-positive, and high-risk early breast cancer (EBC), with indications varying by geography. Premenopausal patients with HR+, HER2- tumors may have different tumor biology and treatment response compared to postmenopausal patients.

Objectives

We describe the efficacy and safety of abemaciclib plus endocrine therapy (ET) for the large subgroup of premenopausal patients with HR+, HER2- EBC in monarchE.

Design

Randomized patients (1:1) received adjuvant ET with or without abemaciclib for 2 years plus at least 3 additional years of ET as clinically indicated.

Methods

Patients were stratified by menopausal status (premenopausal versus postmenopausal) at diagnosis. Standard ET (tamoxifen or aromatase inhibitor) with or without gonadotropin-releasing hormone agonist was determined by physician's choice. Invasive disease-free survival (IDFS) and distant relapse-free survival (DRFS) by menopausal status were assessed at data cutoff on 1 April 2021 (median follow-up of 27 months).

Results

Among randomized patients, 2451 (43.5%) were premenopausal and 3181 (56.4%) were postmenopausal. The choice of ET for premenopausal patients varied considerably between countries. Treatment benefit was consistent across menopausal status, with a numerically greater effect size in premenopausal patients. For premenopausal patients, abemaciclib with ET resulted in a 42.2% and 40.3% reduction in the risk of developing IDFS and DRFS events, respectively. Absolute improvement at 3 years was 5.7% for IDFS and 4.4% for DRFS rates. Safety profile for premenopausal patients was consistent with the overall safety population.

Conclusion

Abemaciclib with ET demonstrated clinically meaningful treatment benefit for IDFS and DRFS versus ET alone regardless of menopausal status and first ET, with a numerically greater benefit in the premenopausal compared to the postmenopausal population. Safety data in premenopausal patients are consistent with the overall safety profile of abemaciclib.

The Evolution of Ki-67 and Breast Carcinoma: Past Observations, Present Directions, and Future Considerations

The 1983 discovery of a mouse monoclonal antibody-the Ki-67 antibody-that recognized a nuclear antigen present only in proliferating cells represented a seminal discovery for the pathologic assessment of cellular proliferation in breast cancer and other solid tumors. Cellular proliferation is a central determinant of prognosis and response to cytotoxic chemotherapy in patients with breast cancer, and since the discovery of the Ki-67 antibody, Ki-67 has evolved as an important biomarker with both prognostic and predictive potential in breast cancer. Although there is universal recognition among the international guideline recommendations of the value of Ki-67 in breast cancer, recommendations for the actual use of Ki-67 assays in the prognostic and predictive evaluation of breast cancer remain mixed, primarily due to the lack of assay standardization and inconsistent inter-observer and inter-laboratory reproducibility. The treatment of high-risk ER-positive/human epidermal growth factor receptor-2 (HER2) negative breast cancer with the recently FDA-approved drug abemaciclib relies on a quantitative assessment of Ki-67 expression in the treatment decision algorithm. This further reinforces the urgent need for standardization of Ki-67 antibody selection and staining interpretation, which will hopefully lead to multidisciplinary consensus on the use of Ki-67 as a prognostic and predictive marker in breast cancer. The goals of this review are to highlight the historical evolution of Ki-67 in breast cancer, summarize the present literature on Ki-67 in breast cancer, and discuss the evolving literature on the use of Ki-67 as a companion diagnostic biomarker in breast cancer, with consideration for the necessary changes required across pathology practices to help increase the reliability and widespread adoption of Ki-67 as a prognostic and predictive marker for breast cancer in clinical practice.

Adjuvant Abemaciclib Combined with Endocrine Therapy for High Risk Early Breast Cancer: Safety and Patient-Reported Outcomes From the monarchE Study

BACKGROUND

In monarchE, abemaciclib plus endocrine therapy (ET) as adjuvant treatment of hormone receptor-positive, human epidermal growth factor 2-negative, high risk, early breast cancer demonstrated a clinically meaningful improvement in invasive disease-free survival versus ET alone. Detailed safety analyses conducted at a median follow-up of 27 months and key patient-reported outcomes (PRO) are presented.

PATIENTS AND METHODS

The safety population included all patients who received at least one dose of study treatment (n=5591). Safety analyses included incidence, management, and outcomes of common and clinically relevant adverse events (AEs). Patient-reported health-related quality-of-life, ET symptoms, fatigue, and side effect burden were assessed.

RESULTS

The addition of abemaciclib to ET resulted in higher incidence of Grade≥3 AEs (49.7% vs 16.3% with ET alone), predominantly laboratory cytopenias (e.g., neutropenia [19.6%]) without clinical complications. Abemaciclib-treated patients experienced more serious adverse events (SAEs; 13.3% vs 7.8%). Discontinuation of abemaciclib and/or ET due to AEs occurred in 18.5% of patients, mainly due to Grade1/2 AEs (66.8%). AEs were managed with comedications (e.g., antidiarrheals), abemaciclib dose holds (61.7%), and/or dose reductions (43.4%). Diarrhea was generally low grade (Grade1/2: 77%); Grade2/3 events were highest in the first month (20.5%), most short-lived (≤7 days) and did not recur. Venous thromboembolic events (VTE) were higher with abemaciclib+ET (2.5%) vs ET (0.6%); in the abemaciclib arm, increased VTE risk was observed with tamoxifen vs AIs (4.3% vs 1.8%). PROs were similar between arms, including being 'bothered by side effects of treatment', except for diarrhea. At ≥3 months, most patients reporting diarrhea reported "a little bit" or "somewhat".

CONCLUSION

In patients with high risk EBC, adjuvant abemaciclib+ET has an acceptable safety profile and tolerability is supported by PRO findings. Most AEs were reversible and manageable with comedications and/or dose modifications, consistent with the known abemaciclib toxicity profile.