Time-to-event surrogate end-points in multiple myeloma randomised trials from 2005 to 2019: A surrogacy analysis

Outcomes in randomized controlled trials of therapeutic interventions for multiple myeloma: A systematic review

PURPOSE

Many clinical trials of therapeutic interventions for multiple myeloma do not use patient important outcomes and rely on the use of surrogate endpoints. The aim of this systematic review was to depict the landscape of randomized controlled trials in myeloma research and compile the endpoints utilized.

METHODS

We searched Embase, PubMed, and the Cochrane Library for randomized controlled trials in myeloma published in English up to October 2023. We included trials exploring efficacy of therapeutic modalities for myeloma itself or supportive care interventions.

RESULTS

A total of 2181 records, reporting data from 624 trials (448 comparing anti-myeloma treatments and 176 comparing supportive interventions) were deemed eligible. The most common primary outcome reported was disease response, followed by progression free survival (PFS) and overall survival (OS). Across all trials, 119 (19.1 %) used OS as the primary endpoint, while 316 (50.6 %) listed it as a secondary endpoint. Quality of life was less commonly prioritized, featured as primary endpoint only in seven studies (1.1 %) and as secondary endpoint in 115 studies (18.4 %). Studies funded by the pharmaceutical industry were more likely (Odds Ratio [OR] 3.85, 95 % CI 2.41-6.35) to use PFS as primary outcome. Similarly, studies with authors that had conflicts of interest with the funding source were more likely (OR 4.57, 95 % CI 2.72-7.92) to use PFS as the primary outcome.

CONCLUSION

While randomized controlled trials for multiple myeloma predominantly rely on surrogate endpoints, particularly PFS, the importance of OS as an outcome should not be overlooked.

Isatuximab plus carfilzomib-dexamethasone versus carfilzomib-dexamethasone in patients with relapsed multiple myeloma (IKEMA): overall survival analysis of a phase 3, randomised, controlled trial

BACKGROUND

Isatuximab is an anti-CD38 monoclonal antibody approved for the treatment of relapsed or refractory multiple myeloma. Previous analyses of the IKEMA trial showed prolonged progression-free survival in patients with this disease who received isatuximab in combination with carfilzomib-dexamethasone as compared with those who received carfilzomib-dexamethasone alone. Herein, we report the analysis of overall survival from the IKEMA trial.

METHODS

This prospective, randomised, open-label, active-controlled, phase 3 study included patients with relapsed or refractory multiple myeloma aged 18 years or older, who had received one to three previous lines of treatment from 69 study centres in 16 countries across North America, South America, Europe, and the Asia-Pacific region. Patients were randomly allocated (3:2) to treatment with either isatuximab plus carfilzomib-dexamethasone (isatuximab group) or carfilzomib-dexamethasone (control group). In the isatuximab group, patients received intravenous isatuximab (10 mg/kg on days 1, 8, 15, and 22 of the first 28-day cycle, and days 1 and 15 of subsequent 28-day cycles). In both treatment groups, intravenous carfilzomib (20 mg/m2 on days 1 and 2 of the first cycle; and 56 mg/m2 on days 8, 9, 15, and 16 of the first cycle, and days 1, 2, 8, 9, 15, and 16 of subsequent cycles) and intravenous or oral dexamethasone (20 mg on days 1, 2, 8, 9, 15, 16, 22, and 23) were administered. The primary endpoint of the trial was progression-free survival, which was reported previously. Treatment continued until progression, unacceptable toxicity, or patient request to discontine. The overall survival analysis reported here was planned to be conducted 3 years after the primary progression-free survival analysis in the intention-to-treat population. Additional analyses were conducted on the secondary endpoints of time to next treatment and second-progression-free survival. Reported p values are non-inferential due to hierarchical testing. This trial is registered with ClinicalTrials.gov (NCT03275285).

FINDINGS

Between Nov 15, 2017, and March 21, 2019, 302 patients were enrolled and randomly allocated: 179 (59%) to the isatuximab group and 123 (41%) to the control group. 169 (56%) patients were male, 133 (44%) were female, 214 (71%) were White, 50 (17%) were Asian, nine (3%) were Black or African American, and three (1%) were multiracial. At data cutoff for this overall survival analysis (Feb 7, 2023), 79 (44%) overall survival events in the isatuximab group and 59 (48%) in the control group had occurred (median follow-up 56·61 months [IQR 54·90-58·02]). Median overall survival (in months) was not reached (NR; 95% CI 52·17-NR) in the isatuximab group and was 50·60 months (38·93-NR) in the control group (hazard ratio [HR] 0·855 [95% CI 0·608-1·202], nominal one-sided p=0·18). Survival probability at 48 months was 59·7% (95% CI 52·0-66·7) in the isatuximab group and 52·2% (95% CI 42·7-60·8) in the control group (based on Kaplan-Meier analysis). Improvements in time to next treatment (HR 0·583 [95% CI 0·429-0·792], nominal one-sided p=0·0002) and second-progression-free survival (0·663 [0·491-0·895], nominal one-sided p=0·0035) were observed in the isatuximab group. The most common treatment-emergent adverse events were infusion reactions (82 [46%] patients in the isatuximab group and four [3%] in the control group) and upper respiratory tract infections (71 [40%] and 34 [28%], respectively). Discontinuations due to treatment-emergent adverse events were similar between treatment groups (24 [14%] in the isatuximab group and 22 [18%] in the control group), despite an additional 30 weeks of exposure in the isatuximab group. 12 (7%) patients in the isatuximab group and six (5%) patients in the control group had a treatment-related adverse event with a fatal outcome during study treatment.

INTERPRETATION

At the time of the current analysis, a difference in overall survival could not be detected between the treatment groups, and no new safety signals were observed. Collectively, the evidence suggests that isatuximab plus carfilzomib-dexamethasone is a key treatment for patients with relapsed or refractory multiple myeloma.

FUNDING

Sanofi.

Evaluating early intervention in smoldering myeloma clinical trials: a systematic review

BACKGROUND

Smoldering multiple myeloma (SMM), an asymptomatic precursor of multiple myeloma (MM), carries a variable risk of progression to MM. There is little consensus on the efficacy or optimal timing of treatment in SMM. We systematically reviewed the landscape of all clinical trials in SMM. We compared the efficacy of treatment regimens studied in SMM to results from these regimens when used in newly diagnosed multiple myeloma (NDMM), to determine whether the data suggest deeper responses in SMM versus NDMM.

METHODS

All prospective interventional clinical trials for SMM, including published studies, meeting abstracts, and unpublished trials listed on ClinicalTrials.gov up to April 1, 2023, were identified. Trial-related variables were captured, including treatment strategy and efficacy results. Relevant clinical endpoints were defined as overall survival (OS) and quality of life.

RESULTS

Among 45 SMM trials identified, 38 (84.4%) assessed active myeloma drugs, while 7 (15.6%) studied bone-modifying agents alone. Of 18 randomized trials in SMM, only one (5.6%) had a primary endpoint of OS; the most common primary endpoint was progression-free survival (n = 7, 38.9%). Among 32 SMM trials with available results, 9 (28.1%) met their prespecified primary endpoint, of which 5 were single-arm studies. Six treatment regimens were tested in both SMM and NDMM; 5 regimens yielded a lower rate of very good partial response rate or better (≥VGPR) in SMM compared to the corresponding NDMM trial (32% vs 63%, 43% vs 53%, 40% vs 63%, 86% vs 89%, 92% vs 95%, and 94% vs 87%, respectively).

CONCLUSION

In this systematic review of all prospective interventional clinical trials in SMM, we found significant variability in trial design, including randomization status, primary endpoints, and types of intervention used. Despite the statistical limitations, comparison of treatment regimens revealed no compelling evidence that the treatment is more effective when introduced early in SMM compared to NDMM.

Comparative Meta-Analysis of Triplet vs. Quadruplet Induction Regimens in Newly Diagnosed, Treatment Naïve, Multiple Myeloma

The use of 4-drug induction regimens for treatment naïve newly diagnosed multiple myeloma (NDMM) is associated with improved depth of response and progression-free survival (PFS). However, head-to-head trials of 4-drug combinations are lacking, and instead, these regimens are typically compared to 3-drug backbones; limiting the ability to discern whether any additional benefit (or toxicity) is simply additive or represents a synergy (or interaction). We conducted a meta-analysis of phase 2 and phase 3 clinical trials that randomized treatment naïve NDMM patients to either a 4-drug or 3-drug induction regimen. We included 11 trials which represented 6509 unique patients. PFS for all trials in the meta-analysis was 54 months with a 4-drug induction and 8.9 months with a 3-drug induction (HR: 0.49; 95% CI: 0.45; 0.54), but there was no benefit to using a 4-drug induction that did not include an anti-CD38 antibody (PFS 4-drug 8.1 months, PFS 3-drug 8.0 months; HR 0.95; 95% CI 0.86; 1.06). Adverse events were more frequent with the quadruplet regimens but were predominately mild. High-grade (≥3) adverse events (AEs) that were more common with 4-drug regimens were infections (RR: 1.34; 95% CI 1.17; 1.54) and thrombocytopenia (RR: 1.39; 95% CI 1.12; 1.74). This study suggests that 4-drug induction regimens which include an anti-CD38 antibody improve efficacy although with additional toxicity in NDMM patients.

Progression-free survival as a surrogate endpoint in myeloma clinical trials: an evolving paradigm

Measurement of overall survival (OS) remains the gold standard for interpreting the impact of new therapies for multiple myeloma in phase 3 trials. However, as outcomes have improved, it is increasingly challenging to use OS as the primary endpoint if timely approval of novel agents is to be ensured to enable maximum benefit for patients. Surrogate endpoints of OS, such as progression-free survival (PFS) and response to treatment, have contributed to approval decisions by the Food and Drug Administration (FDA) and European Medicines Agency as endpoints demonstrating clinical benefit, and the FDA has recently supported the use of minimal residual disease (MRD) as an accelerated approval endpoint in multiple myeloma. This review aims to address situations in which the use of PFS as a surrogate endpoint warrants careful interpretation especially for specific subgroups of patients and considers ways to ensure that studies can be designed to account for possible discordance between PFS and OS. The utility of subgroup analyses, including the potential for those not pre-specified, to identify target populations for new agents is also discussed.

UK Stakeholder Perspectives on Surrogate Endpoints in Cancer, and the Potential for UK Real-World Datasets to Validate Their Use in Decision-Making

Duration of overall survival in patients with cancer has lengthened due to earlier detection and improved treatments. However, these improvements have created challenges in assessing the impact of newer treatments, particularly those used early in the treatment pathway. As overall survival remains most decision-makers' preferred primary endpoint, therapeutic innovations may take a long time to be introduced into clinical practice. Moreover, it is difficult to extrapolate findings to heterogeneous populations and address the concerns of patients wishing to evaluate everyday quality and extension of life. There is growing interest in the use of surrogate or interim endpoints to demonstrate robust treatment effects sooner than is possible with measurement of overall survival. It is hoped that they could speed up patients' access to new drugs, combinations, and sequences, and inform treatment decision-making. However, while surrogate endpoints have been used by regulators for drug approvals, this has occurred on a case-by-case basis. Evidence standards are yet to be clearly defined for acceptability in health technology appraisals or to shape clinical practice. This article considers the relevance of the use of surrogate endpoints in cancer in the UK context, and explores whether collection and analysis of real-world UK data and evidence might contribute to validation.

Progression-free survival is a weakly predictive surrogate end-point for overall survival in follicular lymphoma: A systematic review and meta-analysis

Although progression-free survival (PFS) is a commonly used surrogate end-point for clinical trials of follicular lymphoma (FL), no analyses have evaluated the strength of surrogacy for PFS with overall survival (OS). A systematic review was performed and 20 studies (total participants, 10 724) met final inclusion criteria. PFS was weakly associated with OS (correlation coefficient; 0.383, p < 0.001). The coefficient of determination was 0.15 (95% CI: 0.002-0.35) suggesting 15% of OS variance could be explained by changes in PFS. This challenges the role for PFS as a surrogate end-point for clinical trials and drug approvals.

Nomograms Predict PFS and OS for SCLC Patients After Standardized Treatment: A Real-World Study

Purpose

This study aims to investigate the process of small cell lung cancer (SCLC) patients from achieving optimal efficacy to experiencing disease progression until death. It examines the predictive value of the treatment response on progression free survival (PFS) and overall survival (OS) of SCLC patients.

Patients and Methods

We conducted a retrospective analysis on 136 SCLC patients diagnosed from 1992 to 2018. Important prognostic factors were identified to construct nomogram models. The predictive performance of the models was evaluated using the receiver operating characteristic curves and calibration curves. Survival differences between groups were compared using Kaplan-Meier survival curves. Subsequently, an independent cohort consisting of 106 SCLC patients diagnosed from 2014 to 2021 was used for validation.

Results

We constructed two nomograms to predict first-line PFS (PFS1) and OS of SCLC. The area under the receiver operating characteristic curves for the PFS1 nomogram predicting PFS at 3-, 6-, and 12-months were 0.919 (95% CI: 0.867-0.970), 0.908 (95% CI: 0.860-0.956) and 0.878 (95% CI: 0.798-0.958), and for the OS nomogram predicting OS at 6-, 12-, and 24-months were 0.814 (95% CI: 0.736-0.892), 0.819 (95% CI: 0.749-0.889) and 0.809 (95% CI: 0.678-0.941), indicating those two models with a high discriminative ability. The calibration curves demonstrated the models had a high degree of consistency between predicted and observed values. According to the risk scores, patients were divided into high-risk and low-risk groups, showing a significant difference in survival rate. And these findings were validated in another independent validation cohort.

Conclusion

Based on the patients' treatment response after standardized treatment, we developed and validated two nomogram models to predict PFS1 and OS of SCLC. The models demonstrated good accuracy, reliability and clinical applicability by validating in an independent cohort.

Measurable Residual Disease and Decision-Making in Multiple Myeloma

Measurable (minimal) residual disease (MRD) has already proven to be one of the most important prognostic factors in multiple myeloma (MM). Each improvement in the depth of MRD testing has led to superior discrimination of outcomes, and sustained MRD negativity seems to be paramount to durable responses. Peripheral blood assays to assess for MRD are still under investigation but hold promise as complementary tools to bone marrow MRD assays such as next-generation sequencing and flow cytometry. Herein, the authors explore the evidence and potential benefits and drawbacks of MRD-adapted clinical decision-making in MM.