Immunotherapy and Biomarkers in Sarcoma

OPINION STATEMENT

Sarcoma describes a rare and heterogeneous group of diseases. Current treatment options for metastatic sarcoma are quite limited. Conventional treatments with chemotherapy or anti-angiogenic agents result in a non-durable response and a survival rate of approximately 12 to 18 months. In addition, the benefits of such treatments remain limited in some sarcoma subtypes only. Immunotherapy is an emerging treatment for several cancer types with promising outcomes. Studies at the cellular level have shown a relatively high immunogenicity in some subtypes of sarcoma. It is therefore hypothesized that sarcoma may respond to immunotherapy. However, sarcoma is a heterogeneous disease and differences in terms of immunogenicity exist. A multitude of immune-based treatment approaches for sarcoma have been explored. This includes immune checkpoint inhibitors, therapeutic vaccines, and adoptive cell therapy. Single-agent immunotherapy has exhibited efficacy against some sarcoma subtypes, including alveolar soft-part sarcoma, angiosarcoma, and undifferentiated pleomorphic sarcoma. Combination immunotherapy appears superior to single-agent immunotherapy in terms of response, and several ongoing studies of immunotherapy using single/combination immune checkpoint inhibitors and combination with anti-angiogenesis have begun to report beneficial results. Predictive and prognostic biomarkers are also under active investigations, with particular interest in tumor-infiltrating lymphocytes or high tumor mutational burden levels. However, the information is still limited and further studies are needed.

Association of Bevacizumab Plus Oxaliplatin-Based Chemotherapy With Disease-Free Survival and Overall Survival in Patients With Stage II Colon Cancer: A Secondary Analysis of the AVANT Trial

IMPORTANCE

In the pivotal Bevacizumab-Avastin Adjuvant (AVANT) trial, patients with high-risk stage II colon cancer (CC) had 5-year and 10-year overall survival (OS) rates of 88% and 75%, respectively, with adjuvant fluorouracil and oxaliplatin-based chemotherapy; however, the trial did not demonstrate a disease-free survival (DFS) benefit of adding bevacizumab to oxaliplatin-based chemotherapy in stage III CC and suggested a detrimental effect on OS. The Long-term Survival AVANT (S-AVANT) study was designed to collect extended follow-up for patients in the AVANT trial.

OBJECTIVE

To explore the efficacy of adjuvant bevacizumab combined with oxaliplatin-based chemotherapy in patients with high-risk, stage II CC.

DESIGN, SETTING, AND PARTICIPANTS

This prespecified secondary end point analysis of the AVANT and S-AVANT studies included 573 patients with curatively resected high-risk stage II CC and at least 1 of the following criteria: stage T4, bowel obstruction or perforation, blood and/or lymphatic vascular invasion and/or perineural invasion, age younger than 50 years, or fewer than 12 nodes analyzed. The AVANT study was a multicenter randomized stage 3 clinical trial. Data were collected from December 2004 to February 2019, and data for this study were analyzed from March to September 2019.

INTERVENTION

Patients were randomly assigned to receive 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX4), FOLFOX4 with bevacizumab, or capecitabine and oxaliplatin (XELOX) with bevacizumab.

MAIN OUTCOMES AND MEASURES

The primary end points of this secondary analysis were DFS and OS in patients with high-risk stage II CC.

RESULTS

The AVANT study included 3451 patients, of whom 573 (16.6%) had high-risk stage II CC (192 [33.5%] randomized to FOLFOX4 group; 194 [33.9%] randomized to FOLFOX4 with bevacizumab group; 187 [32.6%] randomized to XELOX with bevacizumab group). With a median (interquartile range) age of 57.0 (47.2-65.7) years, the study population comprised 325 men (56.7%) and 248 women (43.3%). After a median (interquartile range) follow-up of 6.9 (6.1-11.3) years, the 3-year DFS and 5-year OS rates were 88.2% (95% CI, 83.7%-93.0%) and 89.7% (95% CI, 85.4%-94.2%) in the FOLFOX4 group, 86.6% (95% CI, 81.8%-91.6%) and 89.7% (95% CI, 85.4%-94.2%) in the FOLFOX4 with bevacizumab group, and 86.7% (95% CI, 81.8%-91.8%) and 93.2% (95% CI, 89.6%-97.0%) in the XELOX with bevacizumab group, respectively. The DFS hazard ratio was 0.94 (95% CI, 0.59-1.48; P = .78) for FOLFOX4 with bevacizumab vs FOLFOX4 and 1.07 (95% CI, 0.69-1.67; P = .76) for XELOX with bevacizumab vs FOLFOX4. The OS hazard ratio was 0.92 (95% CI, 0.55-1.55; P = .76) for FOLFOX4 with bevacizumab vs FOLFOX4 and 0.85 (95% CI, 0.50-1.44; P = .55) for XELOX with bevacizumab vs FOLFOX4.

CONCLUSIONS AND RELEVANCE

In this secondary analysis of data from the AVANT trial, adding bevacizumab to oxaliplatin-based chemotherapy was not associated with longer DFS or OS in patients with high-risk stage II CC. The findings suggest that the definition of high-risk stage II CC needs to be revisited.

TRIAL REGISTRATION

ClinicalTrial.gov Identifiers: AVANT (NCT00112918); S-AVANT (NCT02228668).

Role of BIM Deletion Polymorphism and BIM Expression as Predictive Biomarkers to Maximize the Benefit of EGFR-TKI Treatment in EGFR-Positive NSCLC

Objective:

BIM is a modulator of apoptosis that is triggered by EGFR-TKIs. This study evaluated the role of BIM deletion and its expression as predictor of EGFR-TKI treatment outcome.

Methods:

The medical record of 185 EGFR-positive advanced non-small cell lung cancer (NSCLC) patients with/ without EGFR-TKI treatment between 9/2012 and 12/2014 were retrospectively reviewed. BIM deletion polymorphism and expression were tested by RT-PCR and immunohistochemistry, respectively. Survival outcomes in EGFR-TKI-treated patients were analyzed according to treatment sequence and EGFR mutation. The correlation between BIM deletion polymorphism, expression, response rate (as a function of EGFR-TKI treatment) and schedule was also explored.

Result:

EGFR-TKIs were administered to 139 (75.1%) of the 185 patients: as the first-line in 52 (37.4%) patients and as later-line treatment in 87 (62.6%) patients. Median overall survival (mOS) was significantly longer in EGFR-TKIs treated patients (28.9 vs. 7.4 months, P<0.001). Among L858R-mutated patients, median progression-free survival (mPFS) was significantly longer in first-line EGFR TKI treatment than a later-line (12.6 vs. 6.3 months, P=0.03). BIM deletion polymorphism and expression was detected in 20.2% and 52.7%, respectively. Patients without BIM deletion polymorphism had a significantly longer mOS when treated with a first-line than with a later-line EGFR-TKI (28.9 vs. 20.7 months, P= 0.04). Patients without BIM expression had a significantly longer mPFS (9.6 vs. 7.3 months, P=0.01) better mOS and response rate (RR).

Conclusion:

BIM deletion polymorphism and expression may predict an EGFR-TKI response in patients with EGFR-positive during therapy.

Healthcare coverage affects survival of EGFR-mutant Thai lung cancer patients

Background

Despite significant benefits of epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) treatment in patients with EGFR-mutated NSCLC, access remains limited in Thailand and elsewhere.

Methods

Retrospective analysis of patients with locally advanced/recurrent NSCLC and known EGFR mutation (EGFRm) status treated at Ramathibodi Hospital (2012-2017). Prognostic factors for overall survival (OS), including treatment type and healthcare coverage, were analyzed using Cox regression.

Results

Of 750 patients, 56.3% were EGFRm-positive. After first-line therapy (n=646), 29.4% received no subsequent (second-line) treatment. EGFR-TKI-treated EGFRm-positive patients survived significantly longer than EGFRm-negative patients without EGFR-TKIs (median OS [mOS] 36.4 vs. 11.9 months; hazard ratio HR=0.38 [95%CI 0.32-0.46], P<0.001). Cox regression indicated significantly longer OS in patients with comprehensive healthcare coverage that included reimbursement of EGFR-TKIs, versus basic coverage (mOS 27.2 vs. 18.3 months; adjusted HR=0.73 [95%CI 0.59-0.90]). Compared with best supportive care (BSC; reference), EGFR-TKI-treated patients survived significantly longer (mOS 36.5 months; adjusted HR (aHR)=0.26 [95%CI 0.19-0.34]), and versus chemotherapy alone (14.5 months; aHR=0.60 [95%CI 0.47-0.78]). In EGFRm-positive patients (n=422), relative survival benefit of EGFR-TKI treatment remained highly significant (aHR[EGFR-TKI]=0.19 [95%CI 0.12-0.29]; aHR(chemotherapy only)=0.50 [95%CI 0.30-0.85]; reference:BSC), indicating that healthcare coverage (reimbursement) affected treatment choice and survival.

Conclusion

Our analysis describes EGFRm prevalence and survival benefit of EGFR-TKI therapy for EGFRm-positive NSCLC patients treated from 2012-2017, one of the largest such Thai datasets. Together with research by others, these findings contributed evidence supporting the decision to broaden erlotinib access on healthcare schemes in Thailand from 2021, demonstrating the value of local real-world outcome data for healthcare policy decision-making.

Real World Experience of Long Term Treatment Outcome in Hormone Receptor-positive Metastatic Breast Cancer with or without Everolimus and Exemestane after Prior Aromatase Inhibitor

Background: Everolimus/exemestane has been shown to improve progression-free survival in patients with endocrine-resistant metastatic breast cancer. The regimen has been well-accepted despite lack of survival benefit. In real-life setting, patients were not well-selected and hence benefit of such treatment may not be as robust. Method: This is a retrospective review of 143 hormone receptor (HR) positive, HER-2 negative MBC patients who progressed on nonsteroidal aromatase inhibitors. Patients who received everolimus/exemestane in any treatment lines (EE group) were compared to patients who never received everolimus (NE group). Primary end point was survival adjusted to prognostic factors. Results: There were 52 patients in EE group and 91 in NE group with mean age of 58.6 years. Median follow-up time was 51 months. Unadjusted median OS was significantly longer in EE [33 vs 25 months, HR 0.66 (95%CI 0.44-0.998); p = 0.049]. In univariate analysis, factors affecting survival included numbers of metastatic sites, bone metastasis, EE treatment and numbers of treatment lines. Independent factors that remained significant in multivariate analysis were treatment lines [HR 0.71 (95%CI 0.63-0.79); p < 0.05] and numbers of metastatic sites. Median numbers of treatment line after NSAI failure was 5.2 vs 3.6 lines in EE and NE, respectively.Conclusion: In this real-life practice data, pts with HR positive, HER-2 negative MBC who had progressed on NSAI, sequential use of multiple treatment regimens of endocrine and chemotherapy is essential to longer survival. Everolimus/exemestane may have contributed, to a lesser extent, to this improvement in survival. 

Dynamic changes in immune repertoire profiles in patients with stage III unresectable non-small cell lung cancer during consolidation treatment with immunotherapy

BACKGROUND

One-year of immune checkpoint inhibitor (ICI) treatment after concurrent chemoradiation (CCRT) in unresectable stage III non-small cell lung cancer (NSCLC) is a standard of care. The precise predictive biomarkers are under investigations either immunological markers or clinical characteristics. Here, we explored immune repertoire of T cell receptor β-chain (TCRβ) during ICI treatment.

METHODS

During August 2019 and September 2021, stage III NSCLC, post CCRT patients from Ramathibodi Hospital was enrolled. All patients were treated by durvalumab after CCRT. Blood samples were collected together with clinical data and tumor assessment every 3-4 months until disease progression or discontinuation of treatment due to adverse events. CDR3 region and TCRΒ polymorphisms was explored by RNA sequencing using Next-Generation Sequencing (NGS) TCR beta short-read assay. Bioinformatic analysis was performed to analyze clonal diversity, TCR convergence frequency and the Shannon diversity from each timepoint. Immune repertoire and clinical correlation were explored using Spearman's correlation and Pearson's correlation. RStudio software version 2021 build 372 was used for analyses. A significance level was at P < 0.05.

RESULTS

Forty-four blood samples from 12 patients were analyzed. Mean duration of durvalumab treatment was 284 days. After durvalumab treatment, increasing of TCR convergence frequency was found compared to baseline (R = 0.36). Interestingly, it was also significantly higher in non-progressive disease (non-PD) patients compared with progressive disease (PD) patients (P = 0.011). Furthermore, Shannon diversity was higher increasing in PD patients compared with non-PD patients. Taken together, our study found that increasing of TCR convergence with less T-cell diversity in non-PD patients probably demonstrated a T cell-specific clonal expansion response to durvalumab treatment in this population.

CONCLUSIONS

TCRβ repertoire is the potential biomarker for predicting durvalumab treatment response in post CCRT stage III NSCLC patients. However, a larger cohort with long-read assay should be explored.

Optimizing outcomes for patients with metastatic prostate cancer: insights from South East Asia Expert Panel

AIMS

Clinical decision making is challenging in men with metastatic prostate cancer (mPC), as heterogeneity in treatment options and patient characteristics have resulted in multiple scenarios with little or no evidence. The South East Asia Expert Panel 2019 addressed some of these challenges.

METHODS

Based on evidence in the literature and expert interviews, 19 statements were formulated for key challenges in the treatment of men with castration-sensitive and -resistant prostate cancer in clinical practice. A modified Delphi process was used to reach consensus among experts in the panel and develop clinical practice recommendations.

RESULTS

The majority of the panel preferred a risk-based stratification and recommended abiraterone or enzalutamide as first-line therapy for symptomatic chemotherapy naïve patients. Abiraterone is preferred over enzalutamide as a first-line treatment in these patients. However, the panel did not support the use of abiraterone in high risk lymph-node positive only (N+M0) or in non-metastatic (N0M0) patients. In select patients, low dose abiraterone with food may be used to optimize clinical outcomes. Androgen receptor gene splice variant status may be a useful guide to therapy. In addition, generic versions of approved therapies may improve access to treatment to a broader patient population. The choice of treatment, as well as sequencing are guided by both patient and disease characteristics, preferences, drug access, cost, and compliance.

CONCLUSION

Expert recommendations are key to guidance for the optimal management of mPC. Appropriate choice, timing, and sequence of treatment options can help to tailor therapy to maximize outcomes in men with mPC.

Cost-utility and budget impact analysis of neoadjuvant dual HER2 targeted therapy for HER2-positive breast cancer in Sri Lanka

This study aimed to assess the cost-utility and budget impact of dual to single HER2 targeted neoadjuvant therapy for HER2-positive breast cancer in Sri Lanka. A five-health state Markov model with lifetime horizon was used to assess the cost-utility of neoadjuvant trastuzumab (T) plus pertuzumab (P) or lapatinib (L) compared to single therapy of T with chemotherapy (C), in public healthcare system and societal perspectives. Input parameters were estimated using local data, network meta-analysis, published reports and literature. Costs were adjusted to year 2021 (1USD = LKR194.78). Five-year budget impact for public healthcare system was assessed. Incremental cost-effectiveness ratios in societal perspective for neoadjuvantLTC plus adjuvantT (strategy 3), neoadjuvantPTC plus adjuvantT (strategy 2), neoadjuvantLTC plus adjuvantLT (strategy 5), and neoadjuvantPTC plus adjuvantPT (strategy 4) compared to neoadjuvantTC plus adjuvantT (strategy 1) were USD2716, USD5600, USD6878, and USD12127 per QALY gained, respectively. One GDP per-capita (USD3815) was considered as the cost-effectiveness threshold for the analysis. Even though only the ICER for strategy 3 was cost-effective, uncertainty of efficacy parameter was revealed. For strategy 2 neoadjuvant PTC plus adjuvant T, a 25% reduction of neoadjuvant regimen cost was required to be cost effective for use in early HER2 positive breast cancer.

Pan-Asian adapted ESMO Clinical Practice Guidelines for the diagnosis, treatment and follow-up of patients with endometrial cancer

The most recent version of the European Society for Medical Oncology (ESMO) Clinical Practice Guidelines for the diagnosis, treatment and follow-up of patients with endometrial cancer was published in 2022. It was therefore decided, by both the ESMO and the Indian Society of Medical and Paediatric Oncology (ISMPO), to convene a virtual meeting in July 2022 to adapt the ESMO 2022 guidelines to take into account the variations in the management of endometrial cancer in Asia. These guidelines represent the consensus opinion of a panel of Asian experts representing the oncological societies of China (CSCO), India (ISMPO), Indonesia (ISHMO), Japan (JSMO), Korea (KSMO), Malaysia (MOS), the Philippines (PSMO), Singapore (SSO), Taiwan (TOS) and Thailand (TSCO). Voting was based on scientific evidence and was conducted independently of the current treatment practices and treatment access constraints in the different Asian countries, which were discussed when appropriate. The aim of this guideline manuscript is to provide guidance for the optimisation and harmonisation of the management of patients with endometrial cancer across the different regions of Asia, drawing on the evidence provided by Western and Asian trials whilst respecting the variations in clinical presentation, diagnostic practices including molecular profiling and disparities in access to therapeutic options, including drug approvals and reimbursement strategies.

Molecular alterations and clinical prognostic factors in resectable non-small cell lung cancer

BACKGROUND

EGFR inhibitor and immunotherapy have been approved for adjuvant treatment in resectable non-small cell lung cancer (NSCLC). Limited reports of molecular and clinical characteristics as prognostic factors in NSCLC have been published.

METHODS

Medical records of patients with resectable NSCLC stage I-III diagnosed during 2015-2020 were reviewed. Real time-PCR (RT-PCR) was performed for EGFR mutations (EGFRm). Immunohistochemistry staining was conducted for ALK and PD-L1 expression. Categorical variables were compared using chi-square test and Fisher's exact test. Survival analysis was done by cox-regression method.

RESULTS

Total 441 patients were included. The prevalence of EGFRm, ALK fusion, and PD-L1 expression were 57.8%, 1.9%, and 20.5% (SP263), respectively. The most common EGFRm were Del19 (43%) and L858R (41%). There was no significant difference of recurrence free survival (RFS) by EGFRm status whereas patients with PD-L1 expression (PD-L1 positive patients) had lower RFS compared to without PD-L1 expression (PD-L1 negative patients) (HR = 1.75, P = 0.036). Patients with both EGFRm and PD-L1 expression had worse RFS compared with EGFRm and PD-L1 negative patients (HR = 3.38, P = 0.001). Multivariable analysis showed higher CEA at cut-off 3.8 ng/ml, pT4, pN2, pStage II, and margin were significant poor prognostic factors for RFS in the overall population, which was similar to EGFRm population (exception of pT and pStage). Only pStage was a significant poor prognostic factor for PD-L1 positive patients. The predictive score for predicting of recurrence were 6 for all population (63% sensitivity and 86% specificity) and 5 for EGFRm population (62% sensitivity and 93% specificity).

CONCLUSION

The prevalence and types of EGFRm were similar between early stage and advanced stage NSCLC. While lower prevalence of PD-L1 expression was found in early stage disease. Patients with both EGFRm and PD-L1 expression had poorer outcome. Thus PD-L1 expression would be one of the prognostic factor in EGFRm patients. Validation of the predictive score should be performed in a larger cohort.

Clinical Treatment Score Post-5 Years as a Tool for Risk Estimation of Late Recurrence in Thai Patients With Estrogen-Receptor-Positive, Early Breast Cancer: A Validation Study

Background

The risk of late distant recurrence (LDR) of estrogen receptor (ER)-positive breast cancer continues even after 5 years of endocrine treatment. Clinical Treatment Score after 5 years (CTS5) was developed and validated as a tool to assess the risk of LDR using data from Tamoxifen, Arimidex Alone or in Combinations (ATAC) and Breast International Group 1-98 (BIG1-98) trials. This study aimed to externally validate CTS5 in a real-world cohort of patients treated at an academic center in Thailand.

Methods

The study was a retrospective analytical research study of early-stage, ER-positive breast cancer patients. The primary endpoint was LDR. The risk of LDR was determined using the CTS5 calculator. Cox regression model and Kaplan-Meier survival analysis were applied for prognostic validation of CTS5. Calibration was performed by comparing observed LDR to expected LDR using the Hosmer-Lemeshow (H-L) test.

Results

A total of 323 women were included with a median follow-up period of 11.6 years. The rate of LDR was 10.8%. The CTS5 was prognostic for LDR. C-index of the area under the ROC curve was 0.672. There was no significant difference between actual and expected numbers of LDR with an observed (O) LDR events to expected (E) number of LDR events ratio of 0.99 (0.86-1.12) (H-L P = .79) indicating a proper calibration in this cohort.

Conclusions

Our study validated that CTS5 is accurate in predicting the risk of LDR in ER-positive breast cancer cases in Thai patients. Its performance seemed to be better in postmenopausal patients. CTS5 could be applied in routine clinical practice to improve decisions regarding prolonged endocrine therapy, particularly in resource-limited countries where molecular profiling are inaccessible.

Disparities in Access to Systemic Treatment for Breast Cancer in Thailand and Major Asian Territories

Purpose

Methods

Results

Conclusion

Pan-Asian adapted ESMO Clinical Practice Guidelines for the diagnosis, treatment and follow-up of patients with early breast cancer

The European Society for Medical Oncology (ESMO) Clinical Practice Guidelines for the diagnosis, treatment and follow-up of patients with early breast cancer were updated and published online in 2023, and adapted, according to previously established standard methodology, to produce the Pan-Asian adapted (PAGA) ESMO consensus guidelines for the management of Asian patients with early breast cancer. The adapted guidelines presented in this manuscript represent the consensus opinions reached by a panel of Asian experts in the treatment of patients with breast cancer representing the oncological societies of China (CSCO), Indonesia (ISHMO), India (ISMPO), Japan (JSMO), Korea (KSMO), Malaysia (MOS), the Philippines (PSMO), Singapore (SSO), Taiwan (TOS) and Thailand (TSCO), co-ordinated by ESMO and KSMO. The voting was based on scientific evidence and was independent of the current treatment practices, drug access restrictions and reimbursement decisions in the different Asian regions represented by the 10 oncological societies. The latter are discussed separately in the manuscript. The aim is to provide guidance for the optimisation and harmonisation of the management of patients with early breast cancer across the different regions of Asia, drawing on the evidence provided by both Western and Asian trials, whilst respecting the differences in screening practices, molecular profiling, as well as the age and stage at presentation. Attention is drawn to the disparity in the drug approvals and reimbursement strategies, between the different regions of Asia.

Incidence and Prognostic Values in Human Epidermal Growth Factor Receptor 2-Low Expression Metastatic Breast Cancer in Southeast Asian Population: A 10-Year Retrospective Study

PURPOSE

Breast cancer progression varies across molecular subtypes, and treatment options for human epidermal growth factor receptor 2 (HER2)-low expression tumors are limited compared with those of HER2 overexpression tumors. Comprehensive information regarding the epidemiology and clinical outcomes of metastatic HER2-low expression breast cancer in a Southeast Asian population is lacking.

METHODS

This retrospective cohort study was performed to analyze data from patients with de novo advanced breast cancer, including HER2 expression, tumor stage, and metastatic pattern. Statistical analyses, including chi-square tests and survival analyses, were used to compare HER2-low expression and HER2-negative groups.

RESULTS

Of the 491 patients, 21.2% had HER2-low expression, 30% had HER2 overexpression, and 50% had HER2-negative expression. Among the hormone receptor (HR)-positive patients, 34% had HER2-low expression; in the triple-negative patients, the HER2-low incidence was 20.6%. No significant differences in clinical characteristics between HER2-low and HER2-negative groups were observed, except for more HR-positive patients in the HER2-low group. HER2-low patients had a longer overall survival (OS) than HER2-negative patients (43 v 23 months; hazard ratio, 0.7; P < .001), especially in HR-positive patients. After adjusting for HR status, HER2-low patients maintained improved outcomes. HR-positive HER2-low patients showed nonsignificant OS gains compared with HR-positive HER2-negative patients, regardless of first-line chemotherapy or endocrine therapy.

CONCLUSION

This study revealed the incidence and clinical outcomes of HER2-low expression in de novo advanced breast cancer, suggesting favorable outcomes, particularly in HR-positive breast cancer. These findings may inform personalized treatment strategies. Further research into the mechanisms and implications of HER2-low expression in breast cancer is required.

Comparative effectiveness analysis of survival with first-line palbociclib or ribociclib plus AI in HR + /HER2- advanced breast cancer (CEPRA study): preliminary analysis of real-world data from Thailand

BACKGROUND

The current standard first-line treatment for hormone receptor-positive/human epidermal growth factor receptor 2 negative (HR + /HER2 -) advanced breast cancer (ABC) is a combination of aromatase inhibitor (AI) plus CDK4/6 inhibitors (CDK4/6i). Direct comparison trials of different CDK4/6i are scarce. This real-world study compared the effectiveness of first-line AI plus ribociclib versus palbociclib.

METHODS

This multicenter retrospective cohort study, conducted in six cancer centers in Thailand, enrolled patients with HR + /HER2 - ABC treated with first-line AI, and either ribociclib or palbociclib. Propensity score matching (PSM) was performed. The primary endpoint was overall survival (OS). Secondary endpoints included progression-free survival (PFS), overall response rate (ORR), time to chemotherapy (TTC), and adverse events.

RESULTS

Of the 250 patients enrolled, 134 patients with ribociclib and 49 patients with palbociclib were captured after PSM. Baseline characteristics were well-balanced between groups. Median PFS in patients receiving ribociclib and palbociclib were 27.9 and 31.8 months, respectively (hazard ratio: 0.87; 0.55-1.37). The median OS in the AI + ribociclib arm was 48.7 months compared to 59.1 months in the AI + palbociclib arm (hazard ratio: 0.55; 0.29-1.05). The median TTC in the AI + palbociclib group was 56 months, but not reached in the AI + ribociclib group (p = 0.42). The ORR of AI + ribociclib and AI + palbociclib were comparable (40.5% vs. 53.6%, p = 0.29). Patients receiving palbociclib demonstrated a higher proportion of neutropenia compared to those receiving ribociclib, despite a similar dose reduction rate (p = 0.28). Hepatitis rate was similar between the ribociclib (21%) and palbociclib groups (22%). Additionally, a low incidence of QT prolongation was observed in both the ribociclib (5%) and palbociclib groups (4%).

CONCLUSION

This preliminary analysis of a real-world study demonstrated the comparable effectiveness of ribociclib and palbociclib with AI as an initial therapy for HR + /HER2 - ABC. No statistically significant difference in PFS, OS, and TTC was found in patients treated with AI combined with palbociclib or ribociclib. Longer follow-up and further prospective randomized head-to-head studies are warranted.