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Background: Monocytes comprise subsets of classical, intermediate and non-classical monocytes with distinct anti- or pro-tumor effects in breast cancer (BC). They are modulated by estrogen, and can contribute to BC control by endocrine therapy in preclinical models. Methods: To elucidate whether changes in monocyte subsets are associated with treatment and response, we investigated peripheral blood samples of 73 postmenopausal women with estrogen receptor (ER) positive BC, who received aromatase inhibitor therapy with or without the mucin-1 vaccine tecemotide in the ABCSG34 trial. Blood was retrieved at baseline, midterm and end of therapy, and was analyzed for the distribution and ER expression of monocyte subsets by flow cytometry. Results: When 40 healthy, age-matched women were compared with BC patients before treatment start, ER levels of monocytes did not differ, yet patients presented with a higher frequency of classical and fewer non-classical monocytes. Endocrine therapy triggered a significant increase in ER levels in all monocyte subsets, without affecting subset distribution. Vaccination had no overall impact on subset frequency and ER expression. Yet, a shift from intermediate to classical monocytes during therapy correlated with changes in plasma cytokines and chemokines and was significantly associated with low residual cancer burden in vaccinated patients. Without tecemotide, baseline ER levels in classical monocytes were significantly higher in women with good response to endocrine therapy. Conclusions: This study identified classical monocytes to be associated with ER positive BC and with patient response to neoadjuvant endocrine treatment and cancer vaccination. [ABSTRACT FROM AUTHOR]

Introduction: Adjuvant treatment with aromatase inhibitors (AI) in oestrogen receptor-positive and/or progesterone receptor-positive breast cancer (BC) has been shown to increase overall survival. However, arthralgias and myalgias are common adverse effects in patients treated with AI. Objective: To evaluate the frequency and characteristics of arthralgias and myalgias in patients with early BC-treated adjuvantly with AI in the Mastology Unit of the Oncology Service of the Hospital de Clínicas and the Departmental Hospital of Soriano. Materials and methods: A prospective, cross-sectional and descriptive study was performed. A questionnaire was administered to patients to assess the presence and characteristics of arthralgias and myalgias associated with AI. Statistical analysis: 'Age' was described with measures of central tendency and dispersion. Qualitative variables were presented in absolute and relative frequencies. Logistic models were used to evaluate the association between patient characteristics, tumour characteristics, treatment characteristics and the presence of pain. Results were presented by odds ratio and p-value, using R software (version 4.1.2) with a significance threshold of 5%. Results: 83 patients were included, with a median age of 69 years. 75.9% presented arthralgias and/or myalgias related to treatment, with an average intensity of 5-7. 80.9% received non-steroidal anti-inflammatory drugs (NSAIDs), achieving satisfactory analgesia. The presence of arthralgias and myalgias was significantly associated with age and time since the last menstrual period (LMP), being more frequent in patients older than 50 years and those with more than 5 years since the LMP. Conclusion: Approximately 70% of the patients presented arthralgias or myalgias. These findings suggest a possible role of oestrogen withdrawal in its mechanism of development. Multidisciplinary and translational research is crucial to evaluate the ethology and therapeutic options for patients with AI-related arthralgia. [ABSTRACT FROM AUTHOR]

Toremifene, a selective estrogen receptor modulator, is commonly used in China for premenopausal breast cancer patients. This real‐world study aimed to compare patient‐reported outcome (PRO) and survival between toremifene and aromatase inhibitor (AI) plus ovarian function suppression (OFS) in patients with moderate‐/high‐risk premenopausal hormone receptor (HR)‐positive breast cancer. The primary endpoint was PROs, assessed using SF‐36 and EQ‐5D‐5L questionnaires between January and March 2023. A total of 392 patients were included, with 171 receiving toremifene and 221 receiving AI. The toremifene group showed significantly higher scores in the role physical (p = 0.034) and mental health (p = 0.009) dimensions of SF‐36 and lower anxiety/depression (AD) scores (p = 0.038) in EQ‐5D‐5L compared to AI group. The estimated 5‐ and 8‐year disease‐free survival (DFS) rates were similar in toremifene and AI groups: 96.5% versus 91.9%, and 87.4% versus 87.8% (p = 0.39), respectively. Adverse event rates were similar in two groups, except for a greater risk of endometrial thickening (p < 0.001) and a lower occurrence of morning stiffness (p < 0.001) in the toremifene compared to the AI group. Premenopausal HR‐positive breast cancer patients receiving toremifene plus OFS had better role physical and mental health outcomes and lower AD dimensions than those receiving AI plus OFS. Both treatments had comparable DFS and favorable tolerability profiles. [ABSTRACT FROM AUTHOR]

Context Insufficient efficacy and safety data for off-label use of aromatase inhibitors to augment height in boys with short stature. Objective To compare anastrozole and letrozole in treatment of idiopathic short stature in pubertal boys. Design Open-label trial with 2 treatment arms. Setting Pediatric Endocrine Clinic at Stanford. Participants A total of 79 pubertal males ≥10 years with bone age (BA) ≤ 14 years, predicted adult height (PAH) < 5th percentile or >10 cm below mid-parental height. Intervention Anastrozole 1.0 mg or letrozole 2.5 mg daily for up to 3 years. Main Outcome Measures Annual hormone levels and growth parameters during treatment and a year posttherapy; annual BA and PAH (primary outcome measure); spine x-rays and dual energy X-ray absorptiometry at baseline and 2 years. Results Compared with anastrozole (n = 35), letrozole (n = 30) resulted in higher testosterone levels, lower estradiol and IGF-1 levels, and slower growth velocity and BA advance. The PAH increase observed at year 1 in both groups did not persist at years 2 and 3. Change in PAH from baseline was not different between treatment groups. In groups combined, PAH gain over 3 years vs baseline was +1.3 cm (P =.043) in linear mixed models. Conclusion Letrozole caused greater deviations than anastrozole in hormone levels, growth velocity, and BA advancement, but no group differences in PAH or side effects were found. Change in PAH after 2 to 3 years of treatment was minimal. The efficacy of AI as monotherapy for height augmentation in pubertal boys with idiopathic short stature may be limited, and safety remains an issue. [ABSTRACT FROM AUTHOR]

Aromatase inhibitors are effective in treating hormone receptor‐positive breast cancer, particularly in postmenopausal women. However, the challenges of inconsistent dissolution, variable absorption and side effects with oral administration persist. To address these issues, transdermal delivery has emerged as a viable alternative. In our study, we have developed nanoemulsion‐based transdermal creams containing third‐generation aromatase inhibitors Exemestane (EXE) or Letrozole (LE) and evaluated their toxicity, anti‐tumour effects and androgenic potency using preclinical models including Bama minipigs, DMBA‐induced breast cancer rats and orchidectomized male rats. The results of our study are significant, suggesting that both creams effectively penetrated the skin, demonstrating an impressive anti‐breast cancer effect. Importantly, EXE cream had no organ toxicity at the tested dose, providing a reassuring safety profile for its use. In contrast, LE cream displayed reversible toxicity from drug molecule itself in animals at the given dose, dissipating after 3 weeks of withdrawal and recovery. This study establishes a solid foundation for the safe clinical use of third‐generation aromatase inhibitors. It highlights transdermal creams as a promising drug delivery carrier for administering them. [ABSTRACT FROM AUTHOR]

A 33-year-old young woman with a rare female appendage tumor of suspected Wolffian origin was initially diagnosed with a benign lesion after the resection of a tubal lesion due to the benign cytomorphology of the tumor tissue. However, 1 year after surgery, she was diagnosed with stage IV fallopian tube cancer due to a recurrence, which presented with substantial ascites and invasion of multiple organs, including the bilateral ovaries, intestines, pelvic peritoneum, greater omentum, and appendix. After tumor cytoreduction, the patient responded well to treatment, which included a regimen of platinum-based drugs combined with docetaxel, aromatase inhibitors such as letrozole, antihormonal therapy, and targeted therapy with bevacizumab. [ABSTRACT FROM AUTHOR]

The present study details the design, synthesis, and bio-evaluation of indoles 3-16 as dual inhibitors of aromatase and inducible nitric oxide synthase (iNOS) with antiproliferative activity. The study evaluates the antiproliferative efficacy of 3-16 against various cancer cell lines, highlighting hybrids 12 and 16 for their exceptional activity with GI50 values of 25 nM and 28 nM, respectively. The inhibitory effects of the most active hybrids 5, 7,12, and 16, on both aromatase and iNOS were evaluated. Compounds 12 and 16 were investigated for their apoptotic potential activity, and the results showed that the studied compounds enhance apoptosis by activating caspase-3, 8, and Bax and down-regulating the anti-apoptotic Bcl-2. Molecular docking studies are intricately discussed to confirm most active hybrids' 12and 16-binding interactions with the aromatase active site. Additionally, our novel study discussed the ADME characteristics of derivatives 8-16, highlighting their potential as therapeutic agents with reduced toxicity. [ABSTRACT FROM AUTHOR]

Simple Summary: Neoadjuvant chemotherapy is the standard of care for locally advanced breast cancer; however, it is less effective in hormone receptor (HR)-positive tumors. Therefore, we aimed to evaluate the safety and efficacy of adding an aromatase inhibitor to standard neoadjuvant chemotherapy in patients with stage II or stage III HR-positive, HER2-negative breast cancer. Adding letrozole to standard neoadjuvant chemotherapy did not significantly increase the pathologic complete response (pCR) rate; however, it enhanced the overall response rate with acceptable safety. Further research is necessary to determine the optimal neoadjuvant therapy for HR-positive, HER2-negative breast cancer to address the ongoing unmet need compared with recent advances in clinical outcomes observed in HER2-positive and triple-negative subtypes. The role of combining neoadjuvant endocrine therapy with conventional chemotherapy remains unclear; therefore, we conducted an open-label, single-center, nonrandomized phase II trial to assess the effect of this combination. Patients with previously untreated stage II or III HR-positive, HER2-negative breast cancer received concurrent letrozole 2.5 mg with standard neoadjuvant chemotherapy. The primary endpoint was pathologic complete response (pCR) at the time of surgery. We used Simon's minimax two-stage design; a pCR rate > 6% was necessary at the first stage to continue. Between November 2017 and November 2020, 53 women were enrolled in the first stage of the trial. Their median age was 49 years (range, 33–63), and 60% of them were premenopausal. Subsequently, 66% and 34% of patients with clinical stages II and III, respectively, were included; 93% had clinically node-positive disease. Two patients (4%) achieved pCR after neoadjuvant chemo–endocrine treatment, which did not satisfy the criteria for continuing to the second stage. The overall response rate was 83%. During the median follow-up of 53.7 months, the 3-year disease-free survival and overall survival rates were 87% and 98%, respectively. Neutropenia was the most common grade 3/4 adverse event (40%), but rarely led to febrile neutropenic episodes (4%). Myalgia (32%), nausea (19%), constipation (17%), heartburn (11%), oral mucositis (9%), and sensory neuropathy (9%) were frequently observed, but classified as grade 1 or 2. No deaths occurred during preoperative treatment. The addition of letrozole to standard neoadjuvant chemotherapy was safe and beneficial in terms of overall response rate, but did not provide a higher pCR rate in locally advanced HR-positive, HER2-negative breast cancer. Further research is needed to enhance neoadjuvant treatment strategies for this cancer subtype. [ABSTRACT FROM AUTHOR]

Background: Aromatase inhibitors improve male fertility by modifying the hormonal control of spermatogenesis. The present study aimed to investigate the effects of oral administration of letrozole on testosterone and estradiol concentrations and their ratios in blood serum, seminal plasma, prostatic fluid, sperm quality in fresh semen, and prostate gland dimensions. Seven adult male intact mixed-breed dogs were selected. The animals received letrozole (72 µg/kg, PO) daily for four weeks. Blood samplings and semen collections were carried out on days 0 (control), 14 (treatment), 28 (treatment), and 42 (post-treatment). Results: Our results showed that letrozole administration resulted in a 4.3 fold significant increase in serum, seminal plasma, and prostatic fluid testosterone levels after 14 days. This remained high until the end of the study. Serum and prostatic fluid estradiol levels did not change significantly over the study period. However, the seminal plasma estradiol level showed a significant increase on day 14. The estradiol: testosterone ratio was significantly reduced on day 14 in serum, seminal plasma, and prostatic fluid samples. Letrozole significantly improved the ejaculated spermatozoa viability and concentration after 28 days of oral administration. However, the sperm plasma membrane functional integrity and kinematic parameters were not significantly affected by the treatment. Transabdominal ultrasound examination revealed a significant increase in the height, width, and volume of the prostate gland after 28 days of treatment. Conclusions: According to the present research, oral administration of letrozole for 28 days affects local and systemic sex hormone balance leading to an improvement of the ejaculated canine spermatozoa viability and concentration concurrent with an increase in the prostate gland dimensions. [ABSTRACT FROM AUTHOR]

Background: Premenopausal, high-risk, hormone receptor-positive breast cancer patients are often treated with ovarian suppression in combination with aromatase inhibitors (AI). This combination has important adverse effects, particularly in sexual function, such as vaginal dryness and loss of libido. There is no effective therapy for reduced sexual function in this setting. Our study aimed to determine the efficacy and safety, particularly regarding sexual function, of a low-dose, topical testosterone gel administration. Methods: This is a pilot, single-center study, designed to evaluate the efficacy of topical testosterone gel (3 mg/day) in improving sexual function in 29 premenopausal patients on ovarian suppression in combination with an AI. The primary safety endpoint was to assess serum estradiol elevation. The primary efficacy endpoint was sexual function improvement, assessed by the Female Sexual Function Index questionnaire. Results: We report the results on 29 patients. Twenty-two patients (75%) completed the 3-month treatment, and seven discontinued treatment before completion, mostly due to logistical difficulties related to the COVID-19 pandemic. All patients maintained the value of baseline mass spectrometry assay for estradiol of less than 2.7 pg/mL during the undertaken measurements. We observed a significant improvement in Female Sexual Function Index measures over the visits, with an increase from a mean of 11.7 at baseline to 19.1 in the third month (p < 0.001), with the greatest improvement observed between the second and third months. Conclusions: Our findings suggest that topical testosterone seems to be safe and may be effective in improving sexual function in patients on ovarian suppression and AI. Trial registration: The project was submitted and approved through the hospital's SGPP platform in 11/26/2019 (Project No. SGPP 393819) and CAAE (Research Ethics Committee) (CAAE No 25609719.5.0000.007). [ABSTRACT FROM AUTHOR]

Primary endometrial squamous cell carcinoma (PESCC) is a rare malignant tumor. To investigate the clinical and pathological features of PESCC, two cases of PESCC in Fujian Maternal and Child Health Hospital were retrospectively studied and the literatures were reviewed. Both of the two cases were menopausal women aged 57-62 years, clinically presenting with "vaginal discharge". Case 1 was a non-keratinising squamous cell carcinoma with high-risk HPV infection. Tumor infiltrated in deep myometrium with multifocal intravascular thrombus and macro metastases to one pelvic lymph node (1/15) and abdominal aortic lymph node (1/1). Lung metastasis occurred 36 months after the surgery. After surgical resection and without postoperative supplemental therapy, the patient remained tumor-free for 110 months to date. Case 2 had a history of breast cancer for 5 years and long-term intake of aromatase inhibitor drugs without HPV infection. It was a keratinized squamous cell carcinoma. Tumor also infiltrated in deep myometrium with multifocal intravascular thrombus and one pelvic lymph node metastasis (1/18), However, no metastasis was seen elsewhere. To date, the patient survived for 16 months without tumor after surgery. Both of the two cases expressed squamous epithelial markers P40, P63, and CK5/6, but neither expressed PAX8 or PR. Case 1 had diffuse expression of P16, wild-type P53, and ER-negative. Case 2 had negative P16, mutant P53, and focal positive ER. PESCC is often associated with HPV infection and low estrogen levels. However, studies in the literatures have found that P16 expression is not always consistent with HPV infection, indicating that PESCC cannot be easily classified as HPV-associated or non-dependent like cervical cancer. There are two main patterns of P16 and P53 expression, P16- positive/P53 wild-type and P16-negative/P53-mutant, but no positive expression of both has been seen so far. It is worth noting that we reported the second case of PESCC with a history of breast cancer, where the patient had been taking the oral aromatase inhibitor drug (exemestane) for a long period of time to reduce the estrogen level, indicating the low estrogen level may be also a key factor in the pathogenesis of PESCC. [ABSTRACT FROM AUTHOR]

Introduction: The aromatase enzyme plays an important role in the progress of hormonedependent breast cancer, especially in estrogen receptor-positive (ER+) breast cancers. In case of postmenopausal women, the aromatization of androstenedione to estrone in adipose tissue is the most important source of estrogen. Generally 60%-75% of pre- and post-menopausal women suffer from estrogendependent breast cancer, and thus suppressing estrogen has been recognized to be a successful therapy. Hence, to limit the stimulation of estrogen, aromatase inhibitors (AIs) are used in the second-line treatment of breast cancer. Methods: The present computational study employed an in silico approach in the identification of natural actives targeting the aromatase enzyme from a structurally diverse set of natural products. Molecular docking, QSAR studies and pharmacophore modeling were carried out using the VLife Molecular Design Suite (version 4.6). The stability of the compounds was confirmed by molecular dynamics. Results: From molecular docking and analysis of interactions with the amino acid residues of the binding cavity, it was found that the amino acid residues interacting with the non-steroidal inhibitors exhibited p-stacking interactions with PHE134, PHE 221, and TRP 224, while the steroidal drug exemestane lacked p-stacking interactions. QSAR studies were performed using the flavonoid compounds, in order to identify the structural functionalities needed to improve the anti-breast cancer activity. Molecular dynamics of the screened hits confirmed the stability of compounds with the target in the binding cavity. Moreover, pharmacophore modelling presented the pharmacophoric features of the selected scaffolds for aromatase inhibitory activity. Conclusion: The results presented 23 hit compounds that can be developed as anti-breast cancer modulating agents in the near future. Additionally, anthraquinone compounds with minor structural modification can also serve to be potential aromatase inhibitors. The in silico protocol utilised can be useful in the drug discovery process for development of new leads from structurally diverse set of natural products that are comparable to the drugs used clinically in breast cancer therapy. [ABSTRACT FROM AUTHOR]

Background Patients with hormone receptor-positive (HR+), human epidermal growth factor receptor-2 negative (HER2−) early breast cancer (EBC) with high-risk clinicopathological features face an increased risk of recurrence. This study explored the evolving treatment landscape and clinical outcomes in patients with EBC using a nationwide database. Patients and Methods The study cohort comprised HR+/HER2−, stages 1-3, patients with EBC who underwent surgery and received adjuvant endocrine therapy (AET) from January 2013 to March 2021. High-risk patients were defined by ≥4 positive axillary lymph nodes, or 1-3 positive lymph node(s) with at least one high-risk feature (histologic grade 3, tumor size ≥5 cm, or Ki-67 ≥20%). A low-risk cohort included patients not meeting the criteria. Survival analysis was conducted with a cutoff of September 2021. Results The study included 4088 eligible patients (1310 high-risk patients and 2778 low-risk patients). High-risk patients were more likely to receive adjuvant chemotherapy and radiotherapy compared to low-risk patients. From 2013 to 2021, an increasing proportion of patients received aromatase inhibitors and ovarian function suppression as part of their AET. The 2-, 5-, and 7-year invasive disease-free survival for high-risk cohort were 90.67%, 75.26%, and 57.10%, respectively, these rates were notably higher for low-risk cohort at 97.14%, 89.85%, and 84.83%. High-risk patients demonstrated a higher risk of recurrence or death compared with low-risk patients (hazard ratio, 2.38; 95% CI, 1.82-3.12). Conclusion In the setting of standard or even intensive AET, patients with EBC with high-risk features still present high recurrence risk, highlighting the urgent need for innovative adjuvant treatment strategies. [ABSTRACT FROM AUTHOR]

Background/Aim: Endocrine therapy is the standard treatment for hormone receptor-positive (HR+) breast cancer (BC). Yet, it is accompanied by treatment-related toxicities, leading to poor treatment adherence, high relapse, and low rates of survival. While pharmacogenomic variants have the potential to guide personalized treatment, their predictive value is inconsistent across published studies. Materials and Methods: To systematically assess the literature's current landscape of pharmacogenomics of endocrine therapy-related adverse drug effects, systematic searches in MEDLINE, Embase, Cochrane CENTRAL, Google Scholar and PharmGKB databases were conducted. Results: We identified 87 articles. Substantial heterogeneity and variability in pharmacogenomic effects were evident across studies, with many using data from the same cohorts and predominantly focusing on the Caucasian population and postmenopausal women. Meta-analyses revealed Factor V Leiden mutation as a predictor of thromboembolic events in tamoxifen-treated women (p<0.0001). Meta-analyses also found that rs7984870 and rs2234693 were associated with musculoskeletal toxicities in postmenopausal women receiving aromatase inhibitors (p<0.0001 and p<0.0001, respectively). Conclusion: Overall, the current body of evidence regarding the potential role of pharmacogenomics in endocrine therapy-related toxicity in BC remains largely inconclusive. Key concerns include the heterogeneity in toxicity definitions, lack of consideration for genotype-treatment interactions, and the failure to account for multiple testing. The review underscores the necessity for larger and well-designed studies, particularly with the inclusion of premenopausal women and non-Caucasian populations. [ABSTRACT FROM AUTHOR]

Abstract Background Aromatase inhibitors improve male fertility by modifying the hormonal control of spermatogenesis. The present study aimed to investigate the effects of oral administration of letrozole on testosterone and estradiol concentrations and their ratios in blood serum, seminal plasma, prostatic fluid, sperm quality in fresh semen, and prostate gland dimensions. Seven adult male intact mixed-breed dogs were selected. The animals received letrozole (72 µg/kg, PO) daily for four weeks. Blood samplings and semen collections were carried out on days 0 (control), 14 (treatment), 28 (treatment), and 42 (post-treatment). Results Our results showed that letrozole administration resulted in a 4.3 fold significant increase in serum, seminal plasma, and prostatic fluid testosterone levels after 14 days. This remained high until the end of the study. Serum and prostatic fluid estradiol levels did not change significantly over the study period. However, the seminal plasma estradiol level showed a significant increase on day 14. The estradiol: testosterone ratio was significantly reduced on day 14 in serum, seminal plasma, and prostatic fluid samples. Letrozole significantly improved the ejaculated spermatozoa viability and concentration after 28 days of oral administration. However, the sperm plasma membrane functional integrity and kinematic parameters were not significantly affected by the treatment. Transabdominal ultrasound examination revealed a significant increase in the height, width, and volume of the prostate gland after 28 days of treatment. Conclusions According to the present research, oral administration of letrozole for 28 days affects local and systemic sex hormone balance leading to an improvement of the ejaculated canine spermatozoa viability and concentration concurrent with an increase in the prostate gland dimensions.

Abstract Background Premenopausal, high-risk, hormone receptor-positive breast cancer patients are often treated with ovarian suppression in combination with aromatase inhibitors (AI). This combination has important adverse effects, particularly in sexual function, such as vaginal dryness and loss of libido. There is no effective therapy for reduced sexual function in this setting. Our study aimed to determine the efficacy and safety, particularly regarding sexual function, of a low-dose, topical testosterone gel administration. Methods This is a pilot, single-center study, designed to evaluate the efficacy of topical testosterone gel (3 mg/day) in improving sexual function in 29 premenopausal patients on ovarian suppression in combination with an AI. The primary safety endpoint was to assess serum estradiol elevation. The primary efficacy endpoint was sexual function improvement, assessed by the Female Sexual Function Index questionnaire. Results We report the results on 29 patients. Twenty-two patients (75%) completed the 3-month treatment, and seven discontinued treatment before completion, mostly due to logistical difficulties related to the COVID-19 pandemic. All patients maintained the value of baseline mass spectrometry assay for estradiol of less than 2.7 pg/mL during the undertaken measurements. We observed a significant improvement in Female Sexual Function Index measures over the visits, with an increase from a mean of 11.7 at baseline to 19.1 in the third month (p

Hikmat Abdel-Razeq,1,2 Baha Sharaf,1 Suhaib Khater,1 Huda Jafar Baidoun,2 Hira Bani Hani,1 Ayat Taqash,3 Osama El Khatib,1 Sarah Edaily,1 Mahmoud Abunasser,1 Faris Tamimi,1 Yosra Nabeel Al-Masri,1 Tamer Moh’d Waleed Al-Batsh,1 Anas Zayed,1 Tala Ghatasheh,1 Tala Radaideh1 1Department of Internal Medicine, Section of Hematology and Medical Oncology, King Hussein Cancer Center, Amman, Jordan; 2School of Medicine, the University of Jordan, Amman, Jordan; 3Office of Scientific Affairs and Research. King Hussein Cancer Center, Amman, JordanCorrespondence: Hikmat Abdel-Razeq, Department of Internal Medicine, Section of Hematology and Medical OncologyKing Hussein Cancer Center, 202 Queen Rania Al Abdullah Street, P.O. Box: 1269, Amman, 11941, Jordan, Tel: +962-6 5300460, Email habdelrazeq@khcc.joBackground: Cyclin-dependent kinase (CDK) 4/6 inhibitors have revolutionized the treatment landscape of hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2 −) metastatic breast cancer (MBC). Here, we present the real-world clinical outcomes and toxicity data of patients treated at a single cancer center.Methods: A retrospective analysis was conducted on patients with HR+/HER2− MBC treated with ribociclib plus endocrine therapy (ET). Outcomes measured included progression-free survival (PFS), overall survival (OS), and adverse events.Results: A total of 356 patients (median age 52, range 27– 91 years) were enrolled, all with metastatic disease; 204 (57.5%) had de novo metastasis, and 183 (51.4%) had visceral metastasis. Ribociclib was combined with aromatase inhibitors in 321 patients (90.2%) and with fulvestrant in 35 patients (9.8%). Dose reduction was needed in 101 patients (28.4%), primarily due to neutropenia (21.3%) and abnormal liver enzymes (5.9%). After a median follow-up of 36.3 months, median PFS was 27.3 months (95% CI: 21.3– 31.7). PFS was significantly better in patients receiving ribociclib as first-line therapy (32.1 months, 95% CI: 27.7– 42.1, p < 0.0001) and those with non-visceral metastasis (38.6 months, 95% CI: 29.8–NR, p < 0.0001). Similarly, OS was significantly better in first-line treatment (48.6 months, 95% CI: 39.1–NR) and non-visceral metastasis cases (NR, 95% CI: 40.6–NR, p < 0.0001). No significant differences in 3-year PFS and OS were found between patients with and without dose reductions.Conclusion: In real-world settings, and away from the stringency of controlled clinical trials, endocrine therapy in combination with ribociclib in patients with HR-positive/HER2-negative MBC is an effective and well-tolerated therapy with a manageable toxicity profile and a low drug discontinuation rate. Dose reduction due to toxicity did not worsen the outcome.Keywords: metastatic breast cancer, MBC, CDK4/6 inhibitors, ribociclib, aromatase inhibitors, fulvestrant

BACKGROUND: Disparities in survival and clinical outcomes between African American and White patients with breast cancer (BC) are well documented, but African American patients have not been well represented in randomized clinical trials of CDK4/6 inhibitors. Real-world studies can provide evidence for effective treatment strategies for underreported patient populations. PATIENTS AND METHODS: This retrospective analysis of African American patients with HR+/HER2- metastatic breast cancer (mBC) from the Flatiron Health longitudinal database evaluated treatments for patients with BC in routine clinical practice in the US. Patients initiated first-line therapy with palbociclib plus an aromatase inhibitor (AI) or AI alone between February 2015 and March 2020. Outcomes assessed included overall survival (OS) and real-world progression-free survival (rwPFS) until September 2020. RESULTS: Of 270 eligible patients, 127 (median age 64 years) were treated with palbociclib + AI, and 143 (median age 68 years) were treated with an AI. Median follow-up was 24.0 months for palbociclib + AI and 18.2 months for AI-treated patients. Median OS was not reached (NR; 95% CI, 38.2-NR) in the palbociclib + AI group versus 28.2 months (95% CI, 19.2-52.8) in the AI group (adjusted HR, 0.56; 95% CI, 0.36-0.89; P = .013). Median rwPFS was 18.0 months (95% CI, 12.4-26.7) in the palbociclib + AI group and 10.5 months (95% CI, 7.0-13.4) in the AI group (adjusted HR, 0.74; 95% CI, 0.47-1.17; P = .199). CONCLUSION: This comparative analysis of palbociclib + AI versus AI alone indicates that palbociclib combined with endocrine therapy in the first line is associated with improved effectiveness for African American patients with HR+/HER2- mBC in real-world settings. TRIAL NUMBER: NCT05361655.