Immunotherapy in gastric cancer with liver metastasis: Challenges and opportunities.

In this editorial, we review the article by Liu et al published in the World Journal of Gastrointestinal Surgery investigating the efficacy and safety of immunotherapy in patients with gastric cancer (GC) and liver metastasis. GC, the fifth most commonly diagnosed malignancy worldwide, presents a significant challenge due to its multifactorial etiology and a grim prognosis for unresectable or recurrent cases. The advent of immune checkpoint inhibitors (ICIs) has revolutionized oncology; yet liver metastasis has been associated with reduced response rates, progression-free survival, and overall survival in various malignancies. The CheckMate-649 and KEYNOTE-859 trials demonstrated promising results with ICIs in advanced GC, particularly in patients with liver metastasis. However, a meta-analysis of liver metastatic solid tumors revealed worse outcomes with ICIs, highlighting the need for further investigation. While combined therapies, including ICIs with local treatments, show promise in improving outcomes, the nuanced landscape of ICIs in liver metastatic GC necessitates continued research for robust conclusions. The current contradictions in the literature underscore the importance of cautious interpretation and the exploration of tailored approaches to enhance clinical efficacy in this challenging patient population.

Real-World Efficacy and Safety of First-Line Nivolumab Plus Chemotherapy in Patients with Advanced Gastric, Gastroesophageal Junction, and Esophageal Adenocarcinoma: A Nationwide Observational Turkish Oncology Group (TOG) Study.

Based on the CheckMate 649 trial, nivolumab plus chemotherapy is the recommended first-line treatment for HER2-negative unresectable advanced or metastatic gastric, gastroesophageal junction (GEJ), or esophageal adenocarcinoma. This nationwide, multicenter, retrospective study evaluated the real-world effectiveness of this regimen in Turkish patients and identified subgroups that may experience superior outcomes. Conducted across 16 oncology centers in Turkey, this study retrospectively reviewed the clinical charts of adult patients diagnosed with HER2-negative unresectable advanced or metastatic gastric, GEJ, or esophageal adenocarcinoma from 2016 to 2023. This study included 111 patients (54 women, 57 men) with a median age of 58 years. The median progression-free survival (PFS) and overall survival (OS) were 11.7 months and 18.2 months, respectively, whereas the objective response rate (ORR) was 70.3%. Multivariable analyses revealed that previous curative surgery was a favorable independent prognostic factor for both PFS and OS. Conversely, an Eastern Cooperative Oncology Group performance status of 2 emerged as an adverse independent prognostic factor for OS. The safety profile of nivolumab plus chemotherapy was found to be manageable. Our findings support the use of nivolumab plus chemotherapy for the first-line treatment of Turkish patients with HER2-negative unresectable advanced or metastatic gastric, GEJ, or esophageal adenocarcinoma. Patient selection based on clinical characteristics is crucial for optimizing treatment outcomes.

Comparison of anthracycline-containing and anthracycline-free regimens in neoadjuvant HER-2 positive breast cancer treatment.

While some clinics have adopted abbreviated neoadjuvant treatment for HER2-positive breast cancer, there remains a shortage of comprehensive clinical data to support this practice. This is a retrospective, multicenter study. A total of 142 patients were included in the study who are HER2-positive breast cancer, aged ≤ 65 years, with left ventricular ejection fraction ≥ 50%, received neoadjuvant chemotherapy and underwent surgery at 10 different oncology centers in Türkiye between October 2016 and December 2022. The treatment arms were divided into 4-6 cycles of docetaxel/trastuzumab/pertuzumab for arm A, 4 cycles of adriamycin/cyclophosphamide followed by 4 cycles of taxane/TP for arm B. There were 50 patients (35.2%) in arm A and 92 patients (64.8%) in arm B. The median follow-up of all of the patients was 19.9 months (95% CI 17.5-22.3). The 3-year DFS rates for treatment arms A and B were 90.0% and 83.8%, respectively, and the survival outcomes between the groups were similar (p = 0.34). Furthermore, the pathologic complete response rates were similar in both treatment arms, at 50.0% and 51.1%, respectively (p = 0.90). This study supports shortened neoadjuvant treatment of HER2-positive breast cancer, a common practice in some clinics.

Treatment outcomes and prognostic factors in patients with driver mutant non-small cell lung cancer and de novo brain metastases.

Central nervous system (CNS) metastases can be seen at a rate of 30% in advanced stages for patients with non-small cell lung cancer (NSCLC). Growing evidence indicates the predictive roles of driver gene mutations in the development of brain metastases (BM) in recent years, meaning that oncogene-driven NSCLC have a high incidence of BM at diagnosis. Today, 3rd generation targeted drugs with high intracranial efficacy, which can cross the blood-brain barrier, have made a positive contribution to survival for these patients with an increased propensity to BM. It is important to update the clinical and pathological factors reflected in the survival with real-life data. A multi-center, retrospective database of 306 patients diagnosed with driver mutant NSCLC and initially presented with BM between between November 2008 and September 2022 were analyzed. The median progression-free survival (mPFS) was 12.25 months (95% CI, 10-14.5). While 254 of the patients received tyrosine kinase inhibitor (TKI), 51 patients received chemotherapy as first line treatment. The median intracranial PFS (iPFS) was 18.5 months (95% CI, 14.8-22.2). The median overall survival (OS) was 29 months (95% CI, 25.2-33.0). It was found that having 3 or less BM and absence of extracranial metastases were significantly associated with better mOS and iPFS. The relationship between the size of BM and survival was found to be non-significant. Among patients with advanced NSCLC with de novo BM carrying a driver mutation, long-term progression-free and overall survival can be achieved with the advent of targeted agents with high CNS efficacy with more conservative and localized radiotherapy modalities.

Effect of HER2/CEP17 ratio on survival in metastatic HER2-positive gastric cancer, multicenter study.

AIM: HER2-positive metastatic gastric cancer is still a highly fatal disease despite advances. We aimed to investigate the relationship between HER2/CEP17 ratio and survival in patients with HER2-positive metastatic gastric cancer. METHODS: A total of 99 patients from 8 different centers in Turkey were included in the study. Patients with HER2-positive metastatic gastric cancer and whose HER2/CEP17 ratio was examined were included in the study. Patients were divided into two groups according to HER2/CEP17 values, and survival analysis was performed. RESULTS: The median age was 64 (24-83) years. There were 74 (74.8%) male and 25 (25.2%) female patients. OS in the high HER2/CEP17 ratio group was 21.97 months (95% CI: 16.36-27.58), and in the low ratio group was 16.17 months (95% CI: 10.95-21.38) (p = 0.015). OS was 17.7 months (95% CI: 7.02-28.37) in the high HER2 gene copy number group and 10.13 months (5.55-14.71) in the group with low copy number (p = 0.03). PFS was 10.94 months (95% CI: 7.55-14.33) in the group with high HER2 gene copy number and 7.56 months (4.62-10.49) in the low copy number group (p = 0.06). CONCLUSION: Patients with both high HER2 gene amplification and high HER2/CEP17 ratio had better OS. The PFS of the group with high HER2 gene amplification was also better. To our knowledge, this is the first study in the literature showing that the HER2/CEP17 ratio affects survival in patients with metastatic gastric cancer.

Efficacy and safety of bevacizumab in patients with low-grade serous ovarian cancer.

Aim: To investigate the efficacy and safety of bevacizumab in patients with recurrent low-grade serous ovarian carcinoma. Materials & methods: The data of patients who received at least two cycles of bevacizumab in combination with chemotherapy were retrospectively recorded. Results: The median age of 51 patients was 56 (range: 33-75) years. The complete response rate was 10.4% and the partial response rate was 43.7%. The objective response rate was 54.1%. Median progression-free survival was 15.9 months (95% CI: 9.1-22.6) and median overall survival was 42.5 months (95% CI: 37.2-47.8). Conclusion: Bevacizumab with chemotherapy is an effective option for treating recurrent ovarian low-grade serous carcinoma.

The prognostic factors in patients with advanced hepatocellular carcinoma: impact of treatment sequencing.

The prognosis of patients with advanced HCC can vary widely depending on factors such as the stage of the cancer, the patient's overall health, and treatment regimens. This study aimed to investigate survival outcomes and associated factors in patients with hepatocellular carcinoma (HCC). In this retrospective study, data from 23 medical oncology clinics were analyzed. Progression-free survival (PFS) and overall survival (OS) values were estimated using the Kaplan-Meier method. Prognostic factors associated with survival which were identified in univariate analysis were subsequently evaluated in a multivariate Cox-regression survival analysis was conducted using the backward stepwise (Conditional LR) method to determine the independent predictors of PFS and OS. Of 280 patients, 131 received chemotherapy and 142 received sorafenib, 6 received atezolizumab plus bevacizumab and 1 received nivolumab for first-line setting. The median follow-up time was 30.4 (95%CI 27.1-33.6) months. For-first line, median PFS was 3.1 (95%CI2.7-3.5) months, and it was significantly longer in patients who received sorafenib or atezolizumab-bevacizumab or nivolumab (PFS 5.8 (95%CI 4.2-7.5) than in those received chemotherapy (PFS 2.1 (95%CI 1.9-2.3) in the first-line setting (p < 0.001). Multivariate analysis revealed that male gender (HR: 2.75, 95% CI: 1.53-4.94, p = 0.01), poor ECOG performance score (HR: 1.88, 95% CI: 1.10-3.21, p = 0.02), higher baseline AFP level (HR: 2.38, 95% CI: 1.54-3.67, p < 0.001) and upfront sorafenib treatment (HR,0.38; 95% CI: 0.23-0.62, p < 0.001) were significantly associated with shorter PFS. The median OS was 13.2 (95%CI 11.1-15.2) months. It was significantly longer in patients who received sorafenib or atezolizumab-bevacizumab or nivolumab in the first-line setting followed by TKIs (sorafenib or regorafenib, OS 18.6 (95%CI 13.8-23.5)) compared to those who received chemotherapy (OS 10.3 (95%CI 6.6-14.1)) in the first-line setting. The multivariate analysis revealed that upfront chemotherapy treatment approach, male gender (HR: 1.77, 95% CI: 1.07-2.94, p = 0.02), poor ECOG performance score (HR: 1.96, 95% CI: 1.24-3.09, p = 0.004) and Child-Pugh score, presence of extrahepatic disease (HR: 1.54, 95% CI: 1.09-2.18, p = 0.01), and higher baseline AFP value (HR: 1.50, 95% CI: 1.03-2.19, p = 0.03) were significantly associated with poor prognosis. Additionally, regarding of treatment sequence, upfront sorafenib followed by regorafenib showed a significantly lower risk of mortality (HR: 0.40, 95% CI: 0.25-0.66, p < 0.001). Sorafenib followed by regorafenib treatment was associated with a significantly lower risk of mortality rather than upfront sorafenib followed by BSC group or upfront chemotherapy followed by TKIs. These findings underscore the importance of the optimal treatment sequences to improve survival in patients with advanced HCC.

Treatment Outcomes and Prognostic Factors in N3 Stage Gastric Cancer After Curative Resection: A Real World Data.

Purpose: N3 gastric cancer is characterized by a fairly high lymph node metastasis burden and poor outcome despite optimal therapy. Given the limitations of TNM classification, a comprehensive evaluation tool is necessary to predict the prognosis of patients with N3 gastric cancer who underwent curative surgery. This study aims to explore the outcomes and clinicopathologic prognostic factors affecting the overall survival (OS) of patients with N3 gastric cancer after surgery. Methods: Data on patients with N3 gastric cancer who underwent (sub)total gastrectomy and regional lymph node dissection between November 2005 and September 2018 (n = 169) were analyzed by Cox regression to determine the independent prognostic factors for OS. Results: The multivariable analysis established that gender, patient performance status, metastatic lymph node ratio (MLNR), tumor grade, and adjuvant chemotherapy are significantly associated with OS. The five-year OS of the study population was 15%. Adjuvant chemoradiotherapy was applied to 72% of the patients, which resulted in an improvement in recurrence-free survival but not OS. Recurrence occurred in 103 (75%) patients, in which the most frequent recurrence site was distant metastasis. Conclusion: Male gender, poor performance status, grade 3 tumor, MLNR > 0.37, and not receiving adjuvant chemotherapy are predictors of poor prognosis in N3 gastric cancer after curative resection. Considering the high recurrence rates of this group, prospective studies are needed to optimize treatment strategies.

Efficacy of adjuvant CDK4/6 inhibitors in hormone receptor-positive breast cancer: a systematic review and meta-analysis.

BACKGROUND: The combination of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors and standard endocrine therapy (ET) in the adjuvant treatment of hormone receptor (HR)-positive/HER2-negative breast cancer (BC) has yielded conflicting results. We performed a pooled analysis of the adjuvant efficacy of CDK4/6 inhibitors by including data from the NATALEE trial, the most recent trial on this topic. METHODS: We searched major databases and congress proceedings until 7 June 2023 to identify randomized controlled trials (RCT) comparing adjuvant CDK4/6 inhibitor plus ET combination versus ET in HR-positive/HER2-negative early-stage BC. RESULTS: Four RCTs involving a total of 17,749 patients were included. According to the pooled analysis of these four studies, significant improvement in invasive disease-free survival (iDFS) was observed with the addition of CDK4/6 inhibitors to standard ET (HzR: 0.81, 95% CI 0.67-0.97). IDFS benefit was irrespective from menopausal status, Ki-67 index, tumor grade, and previous chemotherapy. CDK4/6 inhibitors plus ET had a significant improvement in iDFS in stage 3 whereas there was a trend toward better iDFS in stage 2 (HzR for stage 3: 0.67, 95% CI 0.58-0.78; HzR for stage 2: 0.74, 95% CI 0.55-1.01). CONCLUSIONS: Addition of CDK4/6 inhibitors to standard ET in the adjuvant treatment of HR-positive/HER2-negative early-stage BC improves iDFS.

The Prognostic and Functional Impact of Sprouty 2 Expression in Non-small Cell Lung Cancer.

OBJECTIVE: We represent Sprouty 2 (Spry2) expression analysis and its association with key driver mutations and clinical features of patients with non-small cell lung cancer as the largest ex vivo data. METHODS: The strength of Spry2 expression was evaluated using the immunoreactivity score (IRS), which was calculated using the following formula: IRS=(staining intensity score) SI×(percentage of positively stained cells) PP. The median IRS score was defined as the cutoff value. Patients were grouped as "weak immunoreactivity score" (IRS: 0 to 4) or "strong immunoreactivity score" (IRS: ≥4) with respect to the IRS score. RESULTS: The intensity and percentage of Spry2 staining were significantly lower in tumor tissues than in normal lung tissues ( P <0.0001). Patients' characteristics were similar for both groups, except for smoking status and, brain and lymph node metastasis. Overall survival of patients with a strong immunoreactivity score was significantly lower than those with a weak immunoreactivity score among metastatic patients (6.9 mo vs. 13.6, P =0.023) and adenocarcinoma histology (7.0 mo vs. not reached, P =0.003). CONCLUSION: Spry2 expression was lower in tumor tissues than in normal lung parenchyma. Increased expression of Spry2 is associated with poor prognosis. There were no significant associations between epidermal growth factor receptor, anaplastic lymphoma kinase, or c-ros oncogene 1 rearrangement and Spry2 expression. Despite the absence of KRAS mutational analysis, the clinical and epidemiological features of patients suggested that KRAS mutation might be an underlying determinant factor of the functional role of Spry2 in non-small cell lung cancer.

Comparison of the Efficacy and Safety of 3 Months of CAPOX Followed by 3 Months of Capecitabine and 6 Months of CAPOX/FOLFOX in the Adjuvant Treatment of Low-Risk Stage III Colon Cancer Treated Surgically.

INTRODUCTION: In the adjuvant treatment of low-risk stage III colon cancer treated surgically, 3 months of CAPOX followed by 3 months of capecitabine is not a common clinical practice. Since there are no data on this practice in the literature, we have no idea how often it is used. However, it should be noted that this application is used in some centers due to the cumulative neurotoxicity of oxaliplatin but there are insufficient data in the literature on its efficacy. METHODS: The data of patients with colon cancer treated surgically who were followed up in 12 different oncology centers in Turkey between November 2004 and June 2022 were analyzed retrospectively. RESULTS: The study included 194 patients. The treatment arms were as follows: 3 months of CAPOX followed by 3 months of capecitabine = arm A and CAPOX/FOLFOX (6 months) = arm B. There were 78 patients (40.2%) in arm A and 116 patients (59.8%) in arm B. The median age and sex distribution were similar between the treatment arms. The median follow-up period of all patients was 34.4 months (95% confidence interval, 29.1-39.7). When arm A was compared with arm B, 3-year disease-free survival (DFS) was 75.3% versus 88.4% and 5-year DFS was 75.3% versus 82.8%, respectively. There were similar DFS outcomes between the treatment arms (p = 0.09). Rates of any grade of neuropathy were numerically lower in arm A, but the difference between the treatment arms was not statistically significant (51.3% vs. 56.9%; p = 0.44). The frequency of neutropenia was similar between the treatment arms. CONCLUSION: In this study, the efficacy and safety of the 3 months of CAPOX followed by 3 months of capecitabine chemotherapy regimen in the adjuvant treatment of low-risk stage III colon cancer treated surgically were proven. This result may also support the discontinuation of oxaliplatin at 3 months while continuing fluoropyrimidines, which is a common clinical practice but lacks sufficient data.

The Effect of HER2-Low Status on Pathological Complete Response and Survival in Triple-Negative Breast Cancer: A Systemic Review and Meta-Analysis.

This meta-analysis conducted a comprehensive analysis of research investigating the correlation between HER2 expression levels and treatment outcomes in early-stage triple-negative breast cancer (TNBC) patients. We systematically searched major databases for studies published up to January 01, 2023. The data from various studies examined the relationship between HER2-zero and HER2-low tumors in terms of pathological complete response (pCR) rates, disease-free survival (DFS), and overall survival (OS) outcomes. The odds ratio (OR) and 95% confidence interval (CI) by the number of events were calculated using the Mantel-Haenszel method to analyze pCR. The hazard ratio and 95% CI were calculated using the inverse variance method for DFS and OS. In all comparisons, I2 was 0% and no heterogeneity was detected. A total of 12 retrospective studies involving 4094 patients were included. Thirty-six percent of the patients were in the HER2-low group. All 12 studies were included in the pooled analysis for pCR, and there was no difference between HER2-zero and HER2-low (40% vs. 38%, respectively; pooled OR:1.01 95% CI 0.88-1.16; I2: 0%). Four studies were included in the pooled analysis for DFS and 3 in the OS analysis. DFS and OS were significantly better in the HER2-low group (pooled hazard ratio: 0.67 for DFS, 0.64 for OS). There was no difference between HER2-low and HER2-zero in terms of pCR in early-stage TNBC. However, HER2-low was found to be associated with prolonged DFS and OS. PROSPERO REGISTRATION NUMBER: CRD42023391002.

Efficacy and safety of concomitant chemo-endocrine therapy in neoadjuvant treatment of hormone-positive HER2-negative breast cancer: a systemic review and meta-analysis.

BACKGROUND: The rate of pathological complete response (pCR) with both chemotherapy alone (CT) and endocrine therapy (ET) in the neoadjuvant (Na) treatment of hormone receptor (HR)-positive/HER2-negative breast cancer (BC) is unsatisfactory. Limited data on neoadjuvant concomitant chemotherapy and endocrine therapy (NaCET) are available. RESEARCH DESIGN AND METHODS: In this meta-analysis analyzed the efficacy and safety of randomized controlled trials (RCT) comparing the use of NaCET in HR-positive/HER2-negative BC. A comprehensive search was performed on PubMed, Cochrane Library and EMBASE databases, and congress paper lists for studies published/presented until 1 December 2022. RESULTS: Five RCTs involving a total of 630 patients were included. A pooled analysis of the five studies demonstrated that the pCR ratio was numerically higher in the NaCET arm than in the NaCT arm, but the difference was not statistically significant (6.5% vs. 3.8%; OR:1.72, 95% CI 0.82-3.62). Nonetheless, the NaCET arm exhibited a significantly higher objective response rate (ORR) (82% vs. 72.7%; OR:1.77, 95% CI 1.20-2.62). There was no difference between the arms in terms of grade 3-5 adverse events. CONCLUSIONS: In HR-positive/HER2-negative BC, NaCET significantly increases ORR without an increase in serious adverse events. Although the pCR rate increased numerically, it was not statistically significant.

Real-world outcomes of pazopanib in metastatic soft tissue sarcoma: a retrospective Turkish oncology group (TOG) study.

AIM: Description of patient characteristics, effectiveness and safety in Turkish patients treated with pazopanib for metastatic soft tissue sarcoma (STS). PATIENTS AND METHODS: This multicenter study is based on retrospective review of hospital medical records of patients (≥ 18 years) treated with pazopanib for non-adipocytic metastatic STS at 37 Oncology clinics across Turkey. Objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS) and overall survival (OS) were evaluated with further analysis of data on the three most common histological subtypes (leiomyosarcoma [LMS], undifferentiated pleomorphic sarcoma [UPS], synovial sarcoma [SS]) in the cohort. RESULTS: Data of 552 adults (57.6% women, median age: 52 years) were analyzed. DCR and ORR were 43.1% and 30.8%, respectively. Median PFS was 6.7 months and OS was 13.8 months. For LMS, UPS and SS, median PFSs were 6.1, 5.9 and 7.53 months and median OSs were 15.03, 12.87 and 12.27 months, respectively. ECOG ≥ 2 was associated with poor PFS and OS. Liver metastasis was only a factor for progression. Second-line use of pazopanib (vs. front-line) was associated with better PFS, its use beyond third line predicted worse OS. Adverse events (AE) occurred in 82.7% of patients. Most common AEs were fatigue (58.3%) and anorexia (52.3%) which were graded as ≥ 3 in 8.2% and 7.4% of patients, respectively. CONCLUSION: Pazopanib is effective and well-tolerated in treatment of non-adipocytic metastatic STS. Its earlier use (at second-line), good performance status may result in better outcomes. Worldwide scientific collaborations are important to gain knowledge on rarer STS subtypes by conducting studies in larger patient populations.

Comparison of HER2-zero and HER2-low in terms of clinicopathological factors and survival in early-stage breast cancer: A systematic review and meta-analysis.

BACKGROUND: The prognostic differences between HER2-zero and HER2-low breast cancer (BC) remain unclear. Purpose of this meta-analysis is to investigate the differences between HER2-low and HER2-zero in terms of clinicopathological factors and survival outcomes in early-stage BC. METHODS: We searched major databases and congress proceedings until November 1, 2022 to identify studies comparing HER2-zero and HER2-low in early-stage BC. HER2-zero immunohistochemically (IHC) was defined as score 0, while HER2-low was defined as IHC 1+ or 2+/in situ hybridization negative. RESULT: A total of 23 retrospective studies involving 636,535 patients were included. HER2-low rate was 67.5% in the hormone receptor (HR)-positive group, while this rate was 48.6% in the HR-negative group. In the analysis of clinicopathological factors by HR status, the proportion of premenopausal patients within the HR-positive group was greater in the HER2-zero arm (66.5% vs 61.8%), whereas grade 3 tumors (74.2% vs 71.5%), patients younger than 50 years of age (47.3% vs 39.6%), and T3-T4 tumors (7.7% vs 6.3%) within the HR-negative group was higher in the HER2-zero arm. In both the HR-positive and HR-negative groups, the HER2-low arm showed significantly improved results for disease-free survival (DFS) and overall survival (OS). The hazard ratios for DFS and OS in the HR-positive group were 0.88 (95% CI 0.83-0.94) and 0.87 (95% CI 0.78-0.96), respectively. In the HR-negative group, the hazard ratios for DFS and OS were 0.87 (95% CI 0.79-0.97) and 0.86 (95% CI 0.84-0.89), respectively. CONCLUSION: In early-stage BC, HER2-low is associated with better DFS and OS compared to HER2-zero, regardless of HR status.

Efficacy of subsequent treatments in patients with hormone-positive advanced breast cancer who had disease progression under CDK 4/6 inhibitor therapy.

BACKGROUND: There is no standard treatment recommended at category 1 level in international guidelines for subsequent therapy after cyclin-dependent kinase 4/6 inhibitor (CDK4/6) based therapy. We aimed to evaluate which subsequent treatment oncologists prefer in patients with disease progression under CDKi. In addition, we aimed to show the effectiveness of systemic treatments after CDKi and whether there is a survival difference between hormonal treatments (monotherapy vs. mTOR-based). METHODS: A total of 609 patients from 53 centers were included in the study. Progression-free-survivals (PFS) of subsequent treatments (chemotherapy (CT, n:434) or endocrine therapy (ET, n:175)) after CDKi were calculated. Patients were evaluated in three groups as those who received CDKi in first-line (group A, n:202), second-line (group B, n: 153) and ≥ 3rd-line (group C, n: 254). PFS was compared according to the use of ET and CT. In addition, ET was compared as monotherapy versus everolimus-based combination therapy. RESULTS: The median duration of CDKi in the ET arms of Group A, B, and C was 17.0, 11.0, and 8.5 months in respectively; it was 9.0, 7.0, and 5.0 months in the CT arm. Median PFS after CDKi was 9.5 (5.0-14.0) months in the ET arm of group A, and 5.3 (3.9-6.8) months in the CT arm (p = 0.073). It was 6.7 (5.8-7.7) months in the ET arm of group B, and 5.7 (4.6-6.7) months in the CT arm (p = 0.311). It was 5.3 (2.5-8.0) months in the ET arm of group C and 4.0 (3.5-4.6) months in the CT arm (p = 0.434). Patients who received ET after CDKi were compared as those who received everolimus-based combination therapy versus those who received monotherapy ET: the median PFS in group A, B, and C was 11.0 vs. 5.9 (p = 0.047), 6.7 vs. 5.0 (p = 0.164), 6.7 vs. 3.9 (p = 0.763) months. CONCLUSION: Physicians preferred CT rather than ET in patients with early progression under CDKi. It has been shown that subsequent ET after CDKi can be as effective as CT. It was also observed that better PFS could be achieved with the subsequent everolimus-based treatments after first-line CDKi compared to monotherapy ET.