Integrated exposure-response analysis of efficacy and safety of lurbinectedin to support the dose regimen in small-cell lung cancer

Real-world use, effectiveness, and safety of second-line lurbinectedin monotherapy in small cell lung cancer

AIM

Assess real-world outcomes of lurbinectedin and other second-line treatments (OST) in adults with small cell lung cancer that progressed on/after chemotherapy.

PATIENTS & METHODS

US-based electronic medical data from Flatiron Health (01/01/2013-03/31/2022) were used. Baseline characteristics, including chemotherapy-free interval (CTFI), in patients receiving lurbinectedin or OST were balanced using propensity score (PS) overlap weighting.

RESULTS

Before PS-weighting, median (95% confidence interval [CI]) real-world progression-free survival (rwPFS) was 2.46 months (2.07-2.73), and real-world response rate (rwRR) was 27.5% (23.1-32.4) in 374 eligible lurbinectedin-treated patients. After PS-weighting, median rwPFS was 2.73 months (2.33-3.32) and 2.53 months (2.23-2.99) in 291 lurbinectedin-treated patients and 261 OST-treated patients, respectively; rwRR was 30.9% and 31.8% (relative risk, 0.97). Lurbinectedin demonstrated numerically improved median rwPFS (3.61 versus 3.02 months) and rwRR (38.7% versus 36.1%) versus OST in patients with CTFI ≥90 days but not in patients with CTFI <90 days (2.00 months both; 20.5% versus 26.1%). Lurbinectedin-treated patients reported less grade ≥3 thrombocytopenia (11.7%) and anemia (6.5%) versus OST (27.2% and 20.3%, respectively); prevalence by CTFI status were similar.

CONCLUSION

Lurbinectedin demonstrated comparable real-world effectiveness with OST with a favorable safety profile; however, these findings are limited by small sample size.

CYP3A Genotype Is Associated With Variability in the Exposure and Clearance of the Novel Oncogenic Transcription Inhibitor Lurbinectedin

Lurbinectedin is an oncogenic transcription inhibitor indicated for the treatment of small cell lung cancer (SCLC), which has also shown activity against other malignancies. In this work, two independent cohorts of 180 (discovery cohort) and 719 (validation cohort) cancer patients receiving lurbinectedin in Phases I, II, or III clinical trials were enrolled. Using a population pharmacokinetic (popPK) model of the discovery cohort, patients with extremely high (n = 10, cohort 1) and low (n = 10, cohort 2) etaCL values (i.e., a variable used as a surrogate of unexplained CL interindividual variability) were identified. They were sequenced for 42 candidate genes involved in lurbinectedin pharmacokinetics. A total of 34 variants located in 20 genes were significantly associated with lurbinectedin etaCL; the best nine hits (located in CYP3A5, CYP3A4, ABCB1, ARNT, NR5A2, NR1H4, and FOXA3) were subsequently genotyped in the validation cohort. A strong additive association between CYP3A4 and CYP3A5 genotypes (informed as a CYP3A activity score [AS] variable) and lurbinectedin clearance (CL) and exposure was confirmed, for example, patients with an AS of 3, 2, or 1 showed a 2.3-, 1.6-, and 1.5-fold higher total lurbinectedin CL compared to those with an AS of 0 and 2.3-, 1.8-, and 1.6-fold higher unbound lurbinectedin CL. In conclusion, preemptive CYP3A genotyping may offer a valuable approach for personalizing treatment with lurbinectedin in cancer patients.

Lurbinectedin Plus Pembrolizumab in Relapsed SCLC: The Phase I/II LUPER Study

INTRODUCTION

SCLC has limited second-line treatment options after chemotherapy. We assessed the efficacy and safety of lurbinectedin combined with pembrolizumab in relapsed SCLC patients who had not received prior immunotherapy, aiming to prevent early progression and achieve sustained responses.

METHODS

The LUPER trial (NCT04358237) is a phase I/II, single-arm, open-label, multicenter study. Phase I established the recommended phase II dose. The primary endpoint of phase II was the investigator-confirmed objective response rate. Secondary endpoints included duration of response, progression-free survival (PFS), overall survival (OS), and safety. Patients were categorized as platinum-sensitive (chemotherapy-free interval ≥ 90 d) or platinum-resistant (<90 d).

RESULTS

The recommended phase II dose was 3.2 mg/m2 lurbinectedin and 200 mg pembrolizumab IV every three weeks. Phase II included 28 patients, 50% of whom were platinum-resistant. The objective response rate was 46.4% (95% confidence interval: 27.5-66.1, p < 0.001), including three complete responses, with two complete metabolic responses post-treatment completion at 35 cycles. The median duration of response was 7.8 months, with 40% of patients maintaining responses for 12 months or longer. The median PFS was 4.6 months, and the median OS was 10.5 months. Platinum-sensitive patients had significantly better PFS (8.0 versus 2.8 mo, p = 0.012) and numerically superior OS (15.7 versus 7.1 mo, p = 0.058). Grade 3 or higher treatment-related adverse events occurred in 71.4% of patients, with transient neutropenia being the most common. Immune-related adverse events were consistent with prior pembrolizumab studies.

CONCLUSIONS

Lurbinectedin plus pembrolizumab reported promising efficacy in relapsed SCLC, particularly for platinum-sensitive patients, with a known and manageable safety profile. These results support further exploration of this combination in SCLC treatment.

Exposure-Response-Based Multiattribute Clinical Utility Score Framework to Facilitate Optimal Dose Selection for Oncology Drugs

PURPOSE

The advent of new therapeutic modalities highlighted deficiencies in the traditional maximum tolerated dose approach for oncology drug dose selection and prompted the Food and Drug Administration (FDA)'s Project Optimus initiative, which suggests that sponsors take a holistic approach, including efficacy, safety, and pharmacokinetic (PK) and pharmacodynamic data, in conjunction with integrated exposure-response (ER) analyses. However, this method comes with an inherent challenge of the collation of the multisource data. To address this issue, an ER-based clinical utility score (CUS) framework, combining benefit and risk into a single measurement, was developed.

METHODS

Model-predicted outcomes for each clinically relevant end point, informed by ER modeling, are converted to a CUS using a user-defined utility function. Thereafter, individual CUS is integrated into a single score with user-defined weighting for each end point. The user-defined weighting feature allows the user to incorporate expert knowledge/understanding into weighing the product's benefit versus risk profile.

RESULTS

To validate the framework, data were leveraged from over 50 oncology programs from 2019 to 2023 on the basis of FDA new drug application/biologics license application review packages and/or related literature studies. Five representative cases were selected for in-depth evaluation. Results showed that the optimal benefit-risk ratio (highest CUS) was consistently observed at PK exposures synonymous with recommended doses. A recurring theme across cases was a greater emphasis on safety over efficacy in oncology drug dose determination.

CONCLUSION

The ER-based CUS framework offers a strategic tool to navigate the complexities of dose selection in oncology programs. It serves as a pillar to the importance of integrative data analysis, aligning with the vision of Project Optimus, and demonstrates its potential in guiding dose optimization by balancing therapeutic benefits against risk.

Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) methods for the therapeutic drug monitoring of cytotoxic anticancer drugs: An update

In the era of precision medicine, there is increasing evidence that conventional cytotoxic agents may be suitable candidates for therapeutic drug monitoring (TDM)- guided drug dosage adjustments and patient's tailored personalization of non-selective chemotherapies. To that end, many liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) assays have been developed for the quantification of conventional cytotoxic anticancer chemotherapies, that have been comprehensively and critically reviewed. The use of stable isotopically labelled internal standards (IS) of cytotoxic drugs was strikingly uncommon, accounting for only 48 % of the methods found, although their use could possible to suitably circumvent patients' samples matrix effects variability. Furthermore, this approach would increase the reliability of cytotoxic drug quantification in highly multi-mediated cancer patients with complex fluctuating pathophysiological and clinical conditions. LC-MS/MS assays can accommodate multiplexed analyses of cytotoxic drugs with optimal selectivity and specificity as well as short analytical times and, when using stable-isotopically labelled IS for quantification, provide concentrations measurements with a high degree of certainty. However, there are still organisational, pharmacological, and medical constraints to tackle before TDM of cytotoxic drugs can be more largely adopted in the clinics for contributing to our ever-lasting quest to improve cancer treatment outcomes.

A pivotal bridging study of lurbinectedin as second-line therapy in Chinese patients with small cell lung cancer

This single-arm, multi-center clinical trial aimed to evaluate the safety, tolerability, DLT, recommended dose (RD), preliminary efficacy, and pharmacokinetics (PK) characteristics of lurbinectedin, a selective inhibitor of oncogenic transcription, in Chinese patients with advanced solid tumors, including relapsed SCLC. Patients with advanced solid tumors were recruited in the dose-escalation stage and received lurbinectedin in a 3 + 3 design (two cohorts: 2.5 mg/m2 and 3.2 mg/m2, IV, q3wk). The RD was expanded in the following dose-expansion stage, including relapsed SCLC patients after first-line platinum-based chemotherapy. The primary endpoints included safety profile, tolerability, DLT, RD, and preliminary efficacy profile, while the secondary endpoints included PK characteristics. In the dose-escalation stage, ten patients were included, while one patient had DLT in the 3.2 mg/m2 cohort, which was also the RD for the dose-expansion stage. At cutoff (May 31, 2022), 22 SCLC patients were treated in the ongoing dose-expansion stage, and the median follow-up was 8.1 months (range 3.0-11.7). The most common grade ≥ 3 treatment-related adverse events (TRAEs) included neutropenia (77.3%), leukopenia (63.6%), thrombocytopenia (40.9%), anemia (18.2%), and ALT increased (18.2%). The most common severe adverse events (SAEs) included neutropenia (27.3%), leukopenia (22.7%), thrombocytopenia (18.2%), and vomiting (9.1%). No treatment-related deaths occurred. The Independent Review Committee (IRC)-assessed ORR was 45.5% (95% CI 26.9-65.3). Lurbinectedin at the RD (3.2 mg/m2) showed manageable safety and acceptable tolerability in Chinese patients with advanced solid tumors, and demonstrates promising efficacy in Chinese patients with SCLC as second-line therapy.Trial registration: This study was registered with ClinicalTrials.gov NCT04638491, 20/11/2020.

A model-based head-to-head comparison of single-agent lurbinectedin in the pivotal ATLANTIS Study

Introduction

Lurbinectedin is a selective inhibitor of oncogenic transcription U.S. Food and Drug Administration (FDA)-approved for patients with relapsed small cell lung cancer (SCLC) as monotherapy at 3.2 mg/m² every 3 weeks (q3wk). ATLANTIS was a phase 3 study in SCLC with lurbinectedin 2.0 mg/m² plus doxorubicin 40 mg/m² q3wk vs physician's choice, with overall survival (OS) as the primary endpoint and objective response rate (ORR) as the secondary endpoint. This work aimed to dissect the contribution of lurbinectedin and doxorubicin to antitumor effects in SCLC, and to predict the efficacy of single-agent lurbinectedin at 3.2 mg/m² in ATLANTIS to allow for a head-to-head comparison with the control arm.

Methods

The dataset included exposure and efficacy data from 387 patients with relapsed SCLC (ATLANTIS, n=288; study B-005, n=99). Patients in the ATLANTIS control arm (n=289) were used for comparison. Unbound plasma lurbinectedin area under the concentration-time curve (AUC_u) and total plasma doxorubicin area under the concentration-time curve (AUC_DOX) were used as exposure metrics. Univariate and multivariate analyses were conducted to determine the best predictors and predictive model for OS and ORR. OS baseline hazard was best described by a log-logistic distribution, with chemotherapy-free interval (CTFI), lactate dehydrogenase, albumin, brain metastases, neutrophils/lymphocytes ratio, AUC_u, and the interaction between AUC_u and AUC_DOX as predictors. Effect of AUC_u on ORR best fitted to a sigmoid-maximal response (E_max) logistic model, where E_max was dependent on CTFI.

Results

Head-to-head comparisons with predicted 3.2 mg/m² lurbinectedin resulted in a positive outcome in ATLANTIS, with hazard ratio (95% prediction intervals [95% PI]) for OS of 0.54 (0.41, 0.72), and odds ratio (95% PI) for ORR of 0.35 (0.25, 0.5).

Conclusion

These results support the superiority of lurbinectedin monotherapy for relapsed SCLC over other approved therapies.

Lurbinectedin-induced thrombocytopenia: the role of body surface area

Lurbinectedin is an alkylating agent approved for the second-line treatment of small cell lung cancer. Although initial studies showed no association between body surface area (BSA) and drug clearance, the recommended dose is 3.2 mg/m² every 3 weeks. This recommendation was based on an exposure-response study, which demonstrated that patients with lower BSA had a higher incidence of thrombocytopenia. Herein we present the factors associated with BSA and thrombopoiesis, which may have contributed to the observed relationship.