Japanese subgroup analysis of the phase 3 MONARCH 3 study of abemaciclib as initial therapy for patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer

Association of Neutrophil-to-Lymphocyte Ratio and Absolute Lymphocyte Count With Clinical Outcomes in Advanced Breast Cancer in the MONARCH 2 Trial

BACKGROUND

Established prognostic factors for treatment response to cyclin-dependent kinases 4 and 6 inhibitors are currently lacking. We aimed to investigate the relationship of pretreatment neutrophil-to-lymphocyte ratio (NLR) and absolute lymphocyte count (ALC) to abemaciclib outcomes.

PATIENTS AND METHODS

This was a post hoc analysis of data from MONARCH 2, a phase III study of abemaciclib or placebo plus fulvestrant in hormone-receptor positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer that progressed on endocrine therapy. Patients were divided into high and low categories based on baseline NLR (cutoff: 2.5) and ALC (cutoff: 1.5 × 109/L). The association of baseline NLR and ALC with progression-free survival (PFS) and overall survival (OS) was explored using Cox models and Kaplan-Meier estimates. Tumor response and safety were also examined.

RESULTS

NLR and ALC data were available for 645 patients (abemaciclib: N = 426; placebo: N = 219). Low-baseline NLR or high-baseline ALC was consistently associated with positive PFS and OS trends; low-baseline NLR subgroups also showed trends for better response. The abemaciclib treatment effect against placebo was observed regardless of baseline NLR or ALC. Univariate analyses showed baseline NLR and ALC were prognostic of PFS and OS. Baseline NLR remained significant in the multivariate model (P < .0001). No unexpected differences in safety were observed by baseline NLR or ALC.

CONCLUSION

Baseline NLR was independently prognostic of PFS and OS. Low-baseline NLR was associated with numerically better efficacy outcomes, but the benefit of adding abemaciclib to fulvestrant was similar irrespective of baseline NLR status.

Reporting of older subgroups in registration breast cancer trials 2012-2021

INTRODUCTION

Adequate reporting of data specific to older populations enrolled to breast cancer trials is critical, given the high incidence of the disease among this demographic. This study aimed to examine the completeness of reporting of older subgroups among patients recruited to registration clinical trials investigating systemic treatments for breast cancer.

METHODS

Clinical trials leading to a US food and drug administration (FDA) approval in breast cancer between 2012 and 2021 were included. Primary study reports and and all available secondary publications were systematically and objectively assessed with regard to the availability of data regarding efficacy, baseline characteristics, safety, and health-related quality of life (HRQOL) outcomes among older subgroups.

RESULTS

27 trials and 216 publications were assessed. 20.3% of patients were aged ≥65. 70.0% of patients had an eastern cooperative oncology group (ECOG) performance status of 0. Although complete reporting of primary endpoints was adequate (72.7%), most protocol-defined primary endpoints were surrogate endpoints (84.8%). Overall survival data among older populations was unavailable in 50.0% of studies. Reporting was poor for secondary efficacy endpoints (81.8% unreported), baseline characteristics (70.4% unreported), toxicity (55.6% unreported), and health-related quality of life outcomes (87.5% unreported).

CONCLUSION

The findings underline significant deficits in the reporting of age-specific data in breast cancer registration trials. The underreporting of key efficacy, safety, and HRQOL outcomes highlights the need for mandatory reporting standards and a dedicated emphasis on older populations' priorities and needs in the reporting of registration clinical trials.

Detection of high-risk patients resistant to CDK4/6 inhibitors with hormone receptor-positive HER2-negative advanced and metastatic breast cancer in Japan (KBCSG-TR-1316)

BACKGROUND

Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) improve the prognosis of hormone receptor-positive HER2-negative advanced/metastatic breast cancer (HR+/HER2- mBC). However, some cancers show resistance to CDK4/6i and have a poor prognosis. The non-luminal disease score (NOLUS) was developed to predict non-luminal disease using immunohistochemical analysis.

METHODS

The association between the efficacy of CDK4/6i and NOLUS was investigated by evaluating pathological and clinical data, including real-world progression-free survival (rw-PFS) and overall survival (OS). Real-world data of patients with HR+/HER2- mBC who received CDK4/6i therapy [palbociclib or abemaciclib] as first- or second-line endocrine treatments was obtained. NOLUS was calculated using the formula: NOLUS (0-100) = - 0.45 × estrogen receptor (ER) (%) - 0.28 × progesterone receptor (PR) (%) + 0.27 × Ki67(%) + 73, and the patients were divided into two groups: NOLUS-positive (≥ 51.38) and NOLUS-negative (< 51.38).

RESULTS

Of the 300 patients, 28 (9.3%) were NOLUS-positive, and 272 (90.7%) were NOLUS-negative. The expression rates (%) of ER and PgR in NOLUS-positive patients were lower than those in NOLUS-negative patients (p < 0.001). Ki67 expression was higher in NOLUS-positive patients. There were statistically significant differences in prognosis (rw-PFS and OS) between the two groups. Moreover, NOLUS-negative patients showed statistically better rw-PFS with first-line therapy than second-line therapy. However, NOLUS-positive patients showed poor prognoses with both the first and second therapeutic lines, suggesting CDK4/6i inefficacy for NOLUS-positive patients.

CONCLUSIONS

The efficacy and prognosis of CDK4/6i significantly differed between the NOLUS-positive and NOLUS-negative patients. This feasible method can predict patients with HR+/HER2- mBC resistant to CDK4/6i and help select a better therapeutic approach to overcome resistance.

Efficacy of probiotics and trimebutine maleate for abemaciclib-induced diarrhea: A randomized, open-label phase II trial (MERMAID, WJOG11318B)

BACKGROUND

Abemaciclib-induced diarrhea (AID) impairs quality of life (QOL) and treatment adherence in patients with breast cancer. Supportive treatment with loperamide is associated with constipation. We hypothesized that probiotics and trimebutine maleate (TM) would decrease the frequency of AID without causing constipation.

METHODS

Hormone receptor-positive, human epidermal growth factor 2-negative advanced breast cancer patients were randomized into the probiotic Bifidobacterium (A) or probiotic Bifidobacterium and TM (B) groups. Endocrine therapy, Abemaciclib and probiotic Bifidobacterium three times a day for 28 days, was administered to both arms. Arm B was treated with TM upon the onset of diarrhea. The primary endpoint was the percentage of patients who experienced grade ≥2 diarrhea. The secondary endpoints were safety, frequency, and duration of all-grade diarrhea; frequency of emesis and constipation; usage of loperamide; and health-related QOL/patient-reported outcome during the study. We evaluated whether the primary endpoint of each arm exceeded the predetermined threshold.

RESULTS

Fifty-one patients completed treatment. Grade 2 diarrhea occurred in 52% and 50% of patients in Arm A and Arm B, respectively. One patient experienced grade 3 diarrhea in each arm. The median duration of grade2 diarrhea was 2 and 2.5day, and only one patient required dose reduction. Grade ≥2 constipation was observed in 4% of Arm A and 3.6% of Arm B.

CONCLUSIONS

Probiotic Bifidobacterium or the combination of probiotic Bifidobacterium with TM did not decrease the incidence of grade 2 or greater diarrhea compared with historical control, although the grade 3 or greater diarrhea was reduced.

CLINICAL TRIAL REGISTRATION

jRCT (Japan registry of clinical trials). jRCTs031190154.

Clinical Management of Potential Toxicity of Abemaciclib and Approaches to Ensure Treatment Continuation

INTRODUCTION

The association between abemaciclib dose reduction and treatment adherence is not clear. In this study, we examined real-world data of Japanese patients with advanced breast cancer (ABC) to determine how abemaciclib dose reduction is related to treatment continuation.

METHODS

This retrospective observational study involved 120 consecutive patients with ABC who received abemaciclib from December 2018 to March 2021. The time to treatment failure (TTF) was estimated using the Kaplan-Meier method. Univariate and multivariate analyses were performed to identify factors associated with a TTF of >365 days (TTF365).

RESULTS

According to the dose reduction during treatment, the patients were classified into 100, 200, and 300 mg/day abemaciclib groups. The 300 mg/day group had a TTF of 7.4 months, whereas the 100 and 200 mg/day groups had significantly longer TTFs (17.9 and 17.3 months, respectively; P = 0.0002). In this study, relative to the 300 mg/day arm, TTF was improved in 200mg/day arm and 100 mg/day arm (hazard ratio [HR], 0.55; 95% confidence interval [CI], 0.33-0.93) and [HR], 0.37; 95% CI, 0.19-0.74). For patients who received 300mg/day of abemaciclib dose arm, 200mg/day, and 100mg/day, the median TTF was 7.4 ,17.9 and 17.3 months. The frequently reported adverse effects (AEs) were anemia, increased blood creatinine levels, diarrhea, and neutropenia (90%, 83%, 83%, and 75% of the patients, respectively). Neutropenia, fatigue, and diarrhea were the top AEs causing dose reduction. A multivariate analysis that examined factors associated with achieving TTF 365 confirmed that dose down was an important factor (odds ratio: 3.95, 95% confidence interval: 1.68-9.36, P = 0.002).

CONCLUSIONS

In this study, the 100 and 200 mg/day groups had a longer TTF than the 300 mg/day group, and dose reduction was identified as an important factor in achieving longer TTF.

Real-world treatment patterns and outcomes of abemaciclib for the treatment of HR + , HER2- metastatic breast cancer patients in Japan

INTRODUCTION

This study described, in routine clinical practice in Japan, the patient characteristics, treatment patterns, and outcomes of female patients with HR + /HER2- metastatic breast cancer (MBC) who started abemaciclib treatment.

METHODS

Clinical charts were reviewed for patients starting abemaciclib in 12/2018-08/2021 with a minimum of 3 months follow-up data post-abemaciclib initiation regardless of abemaciclib discontinuation. Patient characteristics, treatment patterns, and tumor response were descriptively summarized. Kaplan-Meier curves estimated progression-free survival (PFS).

RESULTS

200 patients from 14 institutions were included. At abemaciclib initiation, median age was 59 years, and the Eastern Cooperative Oncology Group performance status score was 0/1/2 for 102/68/5 patients (58.3/38.9/2.9%), respectively. Most had an abemaciclib starting dose of 150 mg (92.5%). The percentage of patients receiving abemaciclib as 1st, 2nd, or 3rd line treatment was 31.5%, 25.8%, and 25.2%, respectively. The most frequent endocrine therapy drugs used with abemaciclib were fulvestrant (59%) and aromatase inhibitors (40%). Evaluation of tumor response was available for 171 patients, 30.4% of whom had complete/partial response. Median PFS was 13.0 months (95% CI 10.1-15.8 months).

CONCLUSIONS

In a routine clinical practice setting in Japan, patients with HR + , HER2- MBC appear to benefit from abemaciclib treatment in terms of treatment response and median PFS, with the results broadly reflecting the evidence demonstrated in clinical trials.

An experimental study: the effect of S. boulardii on abemaciclibinduced diarrhea

BACKGROUND

In our study, we aimed to investigate the protective effects of Saccharomyces boulardii on abemaciclib-induced diarrhea model, which is a commonly used drug in breast cancer.

METHODS

Thirty rats were divided into 3 groups as control (Group 1), abemaciclib (Group 2), and abemaciclib + Saccharomyces boulardii (Group 3) groups. The clinical status, body weight, and defecation status were monitored daily. At the end of the 15-day experiment period, the rats were killed with high-dose anesthesia and the resected small intestine segments were evaluated histopathologically. Lesions were classified according to thickening of the villus, inflammation and edema of mucosa and intraepithelial leukocyte accumulation. Then, mean values of both crypt depths and villi thicknesses were calculated for each rat. Normal distribution assumption was controlled with the Shapiro-Wilk test. One-way analysis of variance for normally distributed variables in the comparisons of more than two independent groups and Kruskal-Wallis test for nonnormally distributed variables were used. The significance value was accepted as 0.05.

RESULTS

: There was one death in Group 3, but none in the others. There were no findings of mucositis in Group I. There was mild diarrhea and weight loss in only one rat in Group 1. For the comparison of the severity of diarrhea (72.5%/39%) and weight loss (72.5%/45%), a decrease was found in Group 3 according to Group 2 (p < 0.01). Histopathological findings such as edema, inflammation, and intraepithelial leukocyte accumulation also showed a decrease in Group 3 compared to Group 2 (p < 0.01).

DISCUSSION

Saccharomyces boulardii should be considered as a treatment option in abaemaciclib (chemotherapy)-induced diarrhea. Further comparative studies and in vivo human randomized controlled studies can be conducted in the future.

Patient characteristics, treatment patterns, and outcomes of hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer patients prescribed cyclin-dependent kinase 4 and 6 inhibitors: large-scale data analysis using a Japanese claims database

PURPOSE

The aim was to understand real-world cyclin-dependent kinase (CDK) 4 and 6 inhibitor use in Japan.

METHODS

This retrospective observational study used a Japanese administrative claims database and included patients with presumptive hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer (ABC) prescribed CDK4 and 6 inhibitor therapy between December 2017 and March 2021. Patient characteristics, treatment patterns, and selected clinical and safety outcomes were descriptively summarized. Time to discontinuation (TTD) and chemotherapy-free survival (CFS) were examined using Kaplan-Meier estimates.

RESULTS

The study cohort (N = 6442) was predominantly female (99.4%; median [range] age 64 [26-99] years) with records of metastases (79.6%) within 1 year prior to initiating CDK4 and 6 inhibitor therapy. In total, 4463 (69.3%) and 1979 (30.7%) were prescribed palbociclib and abemaciclib, respectively, as their first CDK4 and 6 inhibitor, most commonly in combination with fulvestrant (n = 3801; 59.0%). Overall, 3756 patients initiated a subsequent anticancer treatment, of whom 748 (19.9%) initiated a different CDK4 and 6 inhibitor in combination with the same or different endocrine therapy. Median TTD (95% confidence interval) was 9.7 (9.3, 10.1) months for the first CDK4 and 6 inhibitor therapy. Median CFS was 26.1 (24.6, 27.8) months. Incidence of clinically relevant diarrhea was higher after abemaciclib initiation (9.8%) than after palbociclib initiation (1.5%). More patients experienced dose reduction with palbociclib (69.3%) than with abemaciclib (53.0%).

CONCLUSION

The data provide insights into current clinical practices for CDK4 and 6 inhibitor use in Japan that could help establish future treatment strategies for ABC.

Health-related quality of life in breast cancer patients treated with CDK4/6 inhibitors: a systematic review

BACKGROUND

Evaluation of health-related quality of life (HR-QoL) among cancer patients has gained an increasing importance and is now a key determinant of anticancer treatments' value. HR-QoL has been assessed in trials testing cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) in breast cancer (BC), using various questionnaires at different timepoints. HR-QoL reports from BC patients treated with CDK4/6i in the real-world setting are also available.

METHODS

We systematically reviewed the literature, searching for full-length articles, and selected conference abstracts reporting data on HR-QoL in BC patients at any stage and of any molecular subtype treated with abemaciclib, palbociclib or ribociclib.

RESULTS

A total of 533 full-length articles and 143 abstracts were retrieved. After screening for eligibility, 38 records were included (31 clinical trials; 7 real-world reports). Assessment methods were heterogeneous across studies in terms of questionnaires, evaluation timepoints and endpoints. Overall, adding CDK4/6i to endocrine therapy did not worsen patients' HR-QoL, with a positive trend towards pain improvement. Gastrointestinal scores (diarrhea, nausea and appetite loss) statistically favored the control arm among metastatic BC patients receiving abemaciclib, whereas they were superimposable in the early setting. The combination of palbociclib and endocrine therapy showed similar HR-QoL outcomes compared with endocrine therapy alone, but determined better scores compared with chemotherapy. HR-QoL was specifically assessed in premenopausal patients treated with ribociclib, showing similar scores compared with postmenopausal patients.

CONCLUSIONS

Despite methodological heterogeneity does not allow a proper comparison, HR-QoL was generally maintained with CDK4/6i. However, differences between abemaciclib, palbociclib and ribociclib exist and mainly rely on the distinct safety profiles of the compounds. These differences should be acknowledged and taken into account in the clinical practice.

Safety in Japanese Advanced Breast Cancer Patients Who Received Abemaciclib in MONARCH 2 and MONARCH 3: Assessment of Treatment-Emergent Neutropenia, Diarrhea, and Increased Alanine Aminotransferase and Aspartate Aminotransferase Levels

Purpose

Our objective was to gain a better understanding of the safety of abemaciclib in Japanese patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer.

Patients and Methods

Treatment-emergent adverse events (TEAEs) were assessed in pooled Japanese subpopulation data from two phase 3 studies assessing abemaciclib/placebo in combination with fulvestrant (MONARCH 2; M2) or non-steroidal aromatase inhibitors (MONARCH 3; M3). For common, clinically relevant TEAEs, event characteristics and management were summarized by study.

Results

In the Japanese safety subpopulation (abemaciclib: N=101; placebo: N=46), all patients experienced ≥1 TEAE (Grade ≥ 3: abemaciclib, 71.3%; placebo, 23.9%; no Grade 5). Clinically relevant TEAEs that were more frequent in abemaciclib-treated Japanese patients compared to the overall safety populations included diarrhea (any grade, 95.0%; Grade ≥ 3, 12.9%), neutropenia (any grade, 75.2%; Grade 3–4, 35.6%), increased alanine aminotransferase (ALT; any grade, 39.6%; Grade 3–4, 14.9%), and increased aspartate aminotransferase (AST; any grade, 37.6%; Grade 3–4, 8.9%). Diarrhea was Grade ≤3 and successfully managed with medications (≥87%) and dose reductions (≤25%) and/or omissions (≤23.3%). Most Grade ≥2 diarrhea occurred in the first treatment cycle, declining thereafter. Neutropenia, the most common Grade ≥3 TEAE in abemaciclib-treated Japanese patients, was generally manageable with dose omissions (M2: 42.0%; M3: 23.1%) and/or reductions (M2: 16%; M3: 15.4%). Neutrophil counts plateaued after Cycle 2, recovering to pretreatment levels after discontinuation of abemaciclib. Hepatic events were managed with medication (≤21%) and dose adjustments (≤33.3%), with most Grade ≥2 events occurring in early treatment cycles. Discontinuation of any study treatment in Japanese patients occurred more frequently due to increased ALT/AST (M2: 9.1%/10.5%; M3: 16.7%/10.5%) compared with diarrhea (M2: 0%; M3: 2.8%) or neutropenia (M2: 0%; M3: 3.8%).

Conclusion

Abemaciclib was well tolerated in Japanese patients in MONARCH 2 and MONARCH 3, with common, clinically relevant TEAEs manageable with appropriate interventions.