Clinical Benefit from Docetaxel +/− Ramucirumab Is Not Associated with Mutation Status in Metastatic Non-Small-Cell Lung Cancer Patients Who Progressed on Platinum Doublets and Immunotherapy

Simple Summary Docetaxel +/− ramucirumab is now frequently used as the standard chemotherapeutic regimen for patients with metastatic non-small-cell lung cancer (NSCLC) after progression on platinum doublets and immune checkpoint inhibitors (ICIs), regardless of the tumor histology. However, these regimens only lead to short-lived disease control with substantial toxicity, and there is an unmet need for more treatment options in this setting. Our study investigated whether the cancer gene mutation status is associated with clinical benefits from docetaxel +/− ramucirumab by analyzing treatment and outcomes by genomic status. We also explored whether platinum/taxane-based regimens offered a better clinical benefit in this patient population. The results of this study showed that the benefit from docetaxel +/− ramucirumab was not dependent on the cancer gene mutation status. Our exploratory analysis also suggested that platinum-/taxane-based regimens could be reasonable alternative treatment options with better efficacy and comparable tolerability. Abstract Docetaxel +/− ramucirumab remains the standard-of-care therapy for patients with metastatic non-small-cell lung cancer (NSCLC) after progression on platinum doublets and immune checkpoint inhibitors (ICIs). The aim of our study was to investigate whether the cancer gene mutation status was associated with clinical benefits from docetaxel +/− ramucirumab. We also investigated whether platinum/taxane-based regimens offered a better clinical benefit in this patient population. A total of 454 patients were analyzed (docetaxel +/− ramucirumab n=381; platinum/taxane-based regimens n=73). Progression-free survival (PFS) and overall survival (OS) were compared among different subpopulations with different cancer gene mutations and between patients who received docetaxel +/− ramucirumab versus platinum/taxane-based regimens. Among patients who received docetaxel +/− ramucirumab, the top mutated cancer genes included TP53 (n=167), KRAS (n=127), EGFR (n=65), STK11 (n=32), ERBB2 (HER2) (n=26), etc. None of these cancer gene mutations or PD-L1 expression was associated with PFS or OS. Platinum/taxane-based regimens were associated with a significantly longer mQS (13.00 m, 95% Cl: 11.20–14.80 m versus 8.40 m, 95% Cl: 7.12–9.68 m, LogRank P=0.019) than docetaxel +/− ramcirumab. Key prognostic factors including age, histology, and performance status were not different between these two groups. In conclusion, in patients with metastatic NSCLC who have progressed on platinum doublets and ICIs, the clinical benefit from docetaxel +/− ramucirumab is not associated with the cancer gene mutation status. Platinum/taxane-based regimens may offer a superior clinical benefit over docetaxel +/− ramucirumab in this patient population.


Introduction
Lung cancer is the leading cause of cancer-related death worldwide [1].Platinum-based chemotherapies have been the standard first-line treatments for patients with metastatic/ advanced-stage non-small-cell lung cancer (NSCLC) [2].Immune checkpoint inhibitors (ICIs) targeting programmed cell death protein 1 (PD-1)/programmed death ligand 1 (PD-L1) produce an unrivaled durable clinical response, and first-line strategies for advanced NSCLC patients without a molecular driver have been shifted from traditional doublet chemotherapy to immunotherapy-based treatments with and without chemotherapy [3][4][5][6][7][8][9].However, a durable response to ICIs is only achieved in a small subset of NSCLC patients, and most patients will develop resistance and disease progression [6,[10][11][12].
For patients with metastatic NSCLC, who have progressed after platinum doublets and ICIs, subsequent therapy options include docetaxel (± ramucirumab), albumin-bound paclitaxel, gemcitabine, or pemetrexed (for nonsquamous only), depending on which agent has not been previously administered [13], among which docetaxel +/ramucirumab is the recommended salvage therapy regardless of tumor histology, based on the data of the REVEL study [14].However, docetaxel +/− ramucirumab only leads to short-lived disease control and is associated with substantial toxicity.In the landmark REVEL study, the progression-free survival (PFS) was only 3.0 months for docetaxel monotherapy and 4.5 months for docetaxel + ramucirumab, while over 70% of patients had grade 3 or higher adverse events (79% for docetaxel + ramucirumab and 71% for docetaxel monotherapy) [14].Therefore, precision patient selection and alternative salvage regimens are needed for this patient population.
Platinum-plus-taxane-based regimens have been well established as treatment options for metastatic NSCLC.Recently, multiple studies have investigated the clinical safety and efficacy of platinum/taxane in combination with ICIs [8,[15][16][17][18].The IMPOWER150 study demonstrated that the addition of atezolizumab to carboplatin/paclitaxel/bevacizumab chemotherapy improved the PFS and OS as the first-line treatment in patients with metastatic non-squamous NSCLC, without showing a detrimental effect on quality of life [18].However, platinum/taxane-based regimens have not been systemically tested in the salvage setting in patients with metastatic NSCLC who have progressed on platinum doublets and ICIs.Another not fully addressed question is whether the cancer gene mutation status, which is known to profoundly impact the cancer biology and clinical presentation of NSCLCs, including the benefit from ICIs [19,20], impacts the benefits of docetaxel +/− ramucirumab.In this study, we investigated whether platinum/taxanebased regimens offered another salvage option in this patient population.we also sought to investigate whether different cancer gene mutation statuses were associated with different benefits of docetaxel +/ramucirumab in patients with metastatic NSCLC after progression on concomitant or sequential platinum-based chemotherapy and ICIs.

Clinical Endpoints
Real-world PFS and OS were primary outcomes for this study.PFS was defined as the time of initiation of each treatment until disease progression or death (whichever occurred first).Disease progression was determined based on pathologic confirmation or clinical progression determined by the treating physician based on imaging reports or through clinical assessment.OS was measured from the date of initiation of each treatment to the date of death from any cause.

Statistical Analysis
Standard descriptive statistics such as the median and range, frequencies, and percentages were used for the baseline characteristics of the patients.Continuous variables were summarized using medians and interquartile ranges.Categorical variables were calculated as frequencies or percentages.The Kaplan-Meier method was used for the estimation of PFS and OS, and differences were compared through the log-rank test.Cox proportional hazards regression models were used to evaluate the associations between clinical-genomic factors and PFS/OS; hazard ratios (HRs) and 95% confidence intervals (Cls) were obtained.Clinical features were selected for multivariate analysis if they were significant in the univariate analysis for PFS and OS.Statistical analyses for continuous and categorical variables and comparisons of the characteristics between the two groups, as well as the associations between the mutational status and response, were assessed by Student's t-test, the Mann-Whitney U test, Pearson's and Spearman's chi-squared tests, or the Fisher exact test, as appropriate.In the exploratory subgroup analysis of the overall population, Cox proportional hazard regression models were used to adjust for relevant clinicopathological variables in the multivariable analysis.Statistical analyses were performed using SPSS version 29.0 and GraphPad Prism version 9.0.

Discussion
The management of patients with metastatic NSCLC, who have progressed on platinum doublets and ICIs, remains an unmet clinical need.These ongoing efforts entail biomarker-based patient selection for existing SOC treatment options and the development of novel therapeutic strategies.Docetaxel +/− ramucirumab is still the most used chemotherapy regimen in this population and there are currently no reliable biomarkers to identify patients who may or may not benefit from these treatments.Cancer gene mutations and PD-L1 levels are known to be associated with the benefit from various therapies, which promoted us to investigate whether these biomarkers are associated with benefits from docetaxel +/− ramucirumab.
PD-L1 is the most used biomarker to guide decisions regarding ICI regimens for patients with metastatic NSCLC, and it has been reported to be positively associated with a benefit from ICIs [19,20].Multiple studies have investigated the role of PD-L1 expression in the survival of patients who receive docetaxel monotherapy or docetaxel + ramucirumab.In a study by Yoshimura et al., PD-L1 expression was not found to be associated with the efficacy of docetaxel + ramucirumab in NSCLC patients who progressed on platinum-based chemotherapy [22].In our study, the benefit from docetaxel +/− ramucirumab was not associated with the level of PD-L1 expression in patients who had progressed on platinum doublets and ICIs.Taken together, these results indicate that the PD-L1 expression status may not impact docetaxel +/− ramucirumab in the salvage setting and novel predictive biomarkers are needed in this patient population.
In the search for alternative treatments to docetaxel +/− ramucirumab in NSCLC patients who had progressed on platinum doublets and ICIs, we found that platinum/taxane-based regimens provided a numerically longer PFS (PFS: 3.80 m 95% CI: 3.31 m-4.29 m versus 5.50 m 95% Cl: 4.19 m-6.81 m, p = 0.092) and significantly longer OS (mOS: 8.40 m 95% Cl: 7.12 m-9.68 m versus 13.00 m 95% Cl: 11.20 m-14.80 m p = 0.019), suggesting that platinum/taxane-based regimens could be one of the most promising strategies to further improve NSCLC patients' outcomes after progressing on first-line chemoimmunotherapy.
Platinum agents exert their therapeutic effect by forming covalent bonds with DNA, leading to the creation of DNA cross-links that hinder DNA replication, ultimately resulting in cell cycle arrest and the cessation of tumor cell proliferation [50].In contrast, taxanes such as paclitaxel and docetaxel disrupt the cell cycle by binding to the β tubulin subunit, stabilizing microtubules, inducing mitotic arrest, and ultimately triggering apoptosis in tumor cells [51][52][53].The combination of platinum and taxane agents is widely used in clinical practice due to their additive and synergistic effects, as supported by both in vitro data and clinical studies.Phase III clinical trials have demonstrated that this combination therapy extends the median survival to 8-11 months and yields 1-year survival rates ranging from 31% to 46% [54][55][56][57].Despite this, there is a lack of systematic studies evaluating platinum/taxane-based regimens in advanced NSCLC patients who have progressed on previous platinum doublets and immunotherapy.Our data indicate promising clinical efficacy in this patient population, suggesting that the additive and synergistic effects between platinum and taxane agents may still be relevant in this context.Another plausible explanation is that platinum/taxane-based regimens may only be offered to patients who are healthier (better PS), have better prognostic factors, or have tumors that are very sensitive to platinum.However, our data demonstrated that there was no significant difference in key prognostic factors such as age, gender, ECOG PS, and baseline metastatic patterns between patients who received SOC docetaxel +/ramucirumab versus those treated with platinum/taxane-based regimens.Additionally, in the subgroup of patients who had disease progression 2-4 months after discontinuing platinum, platinum/taxane-based regimens still demonstrated significantly longer OS than docetaxel +/− ramucirumab, indicating that the observed superior benefit from platinum/taxane-based regimens was unlikely due to a greater portion of patients with platinum-sensitive tumors in this group.Importantly, the rate of treatment discontinuation due to adverse effects was also no different between these two regimen groups.Taken together, these data suggest that in patients with metastatic NSCLC who have progressed on platinum doublets and ICIs, platinum/taxane-based regimens could be reasonable options with comparable tolerability and possibly better clinical efficacy compared to SOC docetaxel +/− ramucirumab.
As a real-world study, our work has important limitations.First, due to its retrospective nature, we were limited by the inadequate control for potential confounding factors that may have impacted the clinical benefit, such as metastatic patterns and prior treatment history.Second, the sample size was still relatively small, which might be the reason for the lack of significance in PFS and OS between the docetaxel + ramucirumab group and the docetaxel monotherapy group.Third, due to the relatively small sample size, we included all eligible patients without a pre-determined power analysis to detect differences between subgroups.Therefore, this study serves as an exploratory analysis of overall outcomes, rather than a definitive assessment of the differences among specific subgroups.Fourth, all patients in this study were treated at comprehensive cancer centers, which may limit the generalizability of our findings.Real-world practices can vary significantly between academic centers and community settings.While academic centers often offer access to cutting-edge treatments and clinical trials, community practices may serve a more diverse patient population with varying levels of access to resources and specialized care.Therefore, the findings from our study may not fully reflect the diversity of realworld clinical practice.Moreover, differences in patient demographics, genetic factors, and healthcare infrastructure could also impact the generalizability of our study findings.It is essential to consider these factors when interpreting and applying our results to different patient populations.On the other hand, while randomized clinical trials are the gold standard in providing evidence in clinical practice, conducting such trials may not always be practical, especially in certain circumstances.For example, although our data demonstrated the superiority of platinum/taxane-based regimens over docetaxel +/− ramucirumab, conducting randomized trials to directly compare these two regimens in the salvage setting can be challenging both practically and financially, and biomarker-based novel agents may offer a more feasible approach to improve the clinical outcomes of this patient population.Real-world data can also provide valuable insights to guide treatment decision making until novel trials change the standard-of-care practice.

Conclusions
To our knowledge, this is the largest multi-institute real-world study that has systematically investigated the associations of different molecular alterations and the benefits obtained from the most prescribed SOC regimen, docetaxel +/− ramucirumab, in metastatic NSCLC patients after progression on concomitant or sequential platinum-based chemotherapy and ICIs.Furthermore, our analyses suggest that platinum/taxane-based regimens may be an option in this patient population, with comparable tolerability and possibly better clinical efficacy compared to docetaxel +/− ramucirumab.

Supplementary Materials:
The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/cancers16050935/s1.Table S1.Baseline Numbers of Patients in Each Treatment Group.Table S2.Mono-Variate Analysis for Selected Factors for PFS and OS of Patients with Docetaxel+/−Ramucirumab Treatment.Table S3.Multi-variate Analysis for Selected Factors for PFS and OS of Patients with Docetaxel+/−Ramucirumab Treatment.Table S4.Survival of Patients in Different Groups Based on Demographic Factors.Table S5.Justified HRs for Selected Molecular Markers in Patients with Docetaxel+/−Ramucirumab Treatment.Table S6.Comparison of Distribution of Significant Factors Between Docetaxel+/−Ramucirumab and Platinum-Taxane Groups.Figure S1.Kaplan-Meier curve for PFS and OS in NSCLC patients with docetaxel+/−ramucirumab treatments(N = 381).Figure S2.Kaplan-Meier curve for PFS and OS in patients with adenocarcinoma with positive and negative EGFR alterations in each treatment group.Figure S3.Kaplan-Meier curve for PFS and OS in patients with adenocarcinoma with different subtype of EGFR alterations in each treatment group.Figure S4.Kaplan-Meier curve for PFS and OS in patients with adenocarcinoma with positive and negative KRAS alterations in each treatment group.Figure S5.Percent of patients with different PD-L1 status (TPS < 1%, TPS1-49%, TPS > 50%, unknown) with docetaxel+/−ramucirumab treatment(N = 381).Figure S6.Kaplan-Meier curve for PFS and OS in patients with different PD-L1 status (TPS score at 1% and 50% cutoff) in each treatment group.Figure S7.Kaplan-Meier curve for PFS and OS in patients with different PD-L1 status (TPS at 1% cutoff) in each treatment group.Figure S8.Kaplan-Meier curve for PFS and OS in patients with different PD-L1 status (TPS at 50% cutoff) in each treatment group.Figure S9.Kaplan-Meier curve for PFS and OS in patients with different PD-L1 status (TPS known vs. unknown) in each treatment group.

Institutional Review Board Statement:
The study was conducted in accordance with the Declaration of Helsinki.The study was approved by the institutional review board at the MD Anderson Cancer Center (approval date: 15 February 2016; approval number: PA16-0061) and the Mayo Clinic (approval date: 7 October 2016, approval number: 16-007597).
Informed Consent Statement: Written informed consent was obtained from all patients at the MD Anderson Cancer Center and was waived due to the retrospective nature of the study for patients at the Mayo Clinic.

Figure 2 .
Figure 2. Comparison of PFS and OS in patients treated with docetaxel +/− ramucirumab versus platinum/taxane-based regimens.(A) PFS and (B) OS of patients treated with docetaxel + ramucirumab

Funding:
This work was supported by the generous philanthropic contributions to the University of Texas MD Anderson's Lung Cancer Moon Shot Program and the MD Anderson Cancer Center Support Grant P30 CA016672.