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Abstract Patients with relapsed/refractory multiple myeloma (RRMM) have a poor prognosis and a need remains for novel effective therapies. Belantamab mafodotin, an anti–B-cell maturation antigen antibody-drug conjugate, was granted accelerated/conditional approval for patients with RRMM who have received at least 4 prior lines of therapy, based on response rates observed in DREAMM-1/DREAMM-2. Despite the 41% response rate and durable responses observed with belantamab mafodotin in the Phase III confirmatory DREAMM-3 trial, the marketing license for belantamab mafodotin was later withdrawn from US and European markets when the trial did not meet its primary endpoint of superiority for progression-free survival compared with pomalidomide and dexamethasone. This review reflects on key lessons arising from the clinical journey of belantamab mafodotin in RRMM. It considers how incorporating longer follow-up in DREAMM-3 may have better captured the clinical benefits of belantamab mafodotin, particularly given its multimodal, immune-related mechanism of action with responses deepening over time. A non-inferiority hypothesis may have been more appropriate rather than superiority in the context of a monotherapy versus an active doublet therapy. Further, anticipation of, and planning for, non-proportional hazards arising from response heterogeneity may have mitigated loss of statistical power. With the aim of improving the efficacy of belantamab mafodotin, other Phase III trials in the RRMM development program (DREAMM-7 and DREAMM-8) proceeded to evaluate the synergistic potential of combination regimens in earlier lines of treatment. The aim was to increase the proportion of patients responding to belantamab mafodotin (and thus the likelihood of seeing a clear separation of the progression-free survival curve versus comparator regimens). Protocol amendments reflecting DREAMM-3 learnings could also be implemented prospectively on the combinations trials to optimize the follow-up duration and mitigate risk. The wider implications of the lessons learned for clinical research in RRMM and in earlier treatment settings are discussed.

Early endpoints, such as progression-free survival (PFS), are increasingly used as surrogates for overall survival (OS) to accelerate approval of novel oncology agents. Compiling trial-level data from randomized controlled trials (RCTs) could help to develop a predictive framework to ascertain correlation trends between treatment effects for early and late endpoints. Through trial-level correlation and random-effects meta-regression analysis, we assessed the relationship between hazard ratio (HR) OS and (1) HR PFS and (2) odds ratio (OR) PFS at 4 and 6 months, stratified according to the mechanism of action of the investigational product. Using multiple source databases, we compiled a data set including 81 phase II–IV RCTs (35 drugs and 156 observations) of patients with non-small-cell lung cancer. Low-to-moderate correlations were generally observed between treatment effects for early endpoints (based on PFS) and HR OS across trials of agents with different mechanisms of action. Moderate correlations were seen between treatment effects for HR PFS and HR OS across all trials, and in the programmed cell death-1/programmed cell death ligand-1 and epidermal growth factor receptor trial subsets. Although these results constitute an important step, caution is advised, as there are some limitations to our evaluation, and an additional patient-level analysis would be needed to establish true surrogacy.

ABSTRACT: Background: Historically, the standard of care for patients with unresectable, Stage III non–small cell lung cancer had been concurrent chemoradiotherapy. However, outcomes had been poor, with approximately 15% to 32% of patients alive at 5 years. In the placebo-controlled Phase III A PACIFIC trial, consolidation treatment with durvalumab after concurrent chemoradiotherapy significantly improved overall survival (OS) and progression-free survival in patients with unresectable, Stage III non–small cell lung cancer, establishing this regimen as a new standard of care in this setting. In the PACIFIC trial, crossover between treatment arms (durvalumab or placebo) was not permitted. However, after discontinuation from study treatment, patients from both arms of PACIFIC could switch to subsequent anticancer therapy, including durvalumab and other immunotherapies, which is known to influence standard intention-to-treat analysis of OS, potentially underestimating the effect of an experimental drug. Moreover, the introduction of immunotherapies has demonstrated marked improvements in the postprogression, metastatic non–small cell lung cancer setting. Objective: To examine the influence of subsequent immunotherapy on OS in the PACIFIC trial. Methods: Both a Rank Preserving Structural Failure Time Model (RPSFTM) and modified 2-stage method were used. RPSFTM assumes that a patient's survival time with no immunotherapy (counterfactual survival time) is equal to the observed time influenced by immunotherapy, multiplied by an acceleration factor, plus the time not influenced. The modified 2-stage method estimates the effect of immunotherapy by comparing postsubsequent-treatment-initiation survival times between patients with and without subsequent immunotherapy. In both models, OS was adjusted to reflect a hypothetical scenario in which no patients received subsequent immunotherapy. RPSFTM was also used for scenarios in which subsequent immunotherapy was received by increasing proportions of placebo patients but none of the durvalumab patients. Results: In the intention-to-treat analysis (3-year follow-up), durvalumab improved OS versus placebo (stratified hazard ratio = 0.69; 95% CI, 0.55–0.86). Overall, 10% and 27% of durvalumab and placebo patients, respectively, received subsequent immunotherapy. With subsequent immunotherapy removed from both arms, estimated hazard ratio was 0.66 (95% CI, 0.53–0.84) with RPSFTM and 0.68 (95% CI, 0.54–0.85) with the modified 2-stage method. With subsequent immunotherapy removed from the durvalumab arm only (RPSFTM), estimated hazard ratio increased as the proportion of placebo patients receiving subsequent immunotherapy increased, up to 0.75 (95% CI, 0.60–0.94) maximum (assuming all placebo patients with subsequent treatment received immunotherapy). Conclusions: Results were consistent with the intention-to-treat analysis, supporting the conclusion that durvalumab after chemoradiotherapy provides substantial OS benefit in patients with Stage III, unresectable non–small cell lung cancer. ClinicalTrials.gov identifier: NCT02125461 (Curr Ther Res Clin Exp. 2021; 82:XXX–XXX)

BackgroundStudies have indicated that programmed death ligand 1 (PD-L1) expression may have utility as a predictive biomarker in patients with advanced/metastatic urothelial carcinoma (UC). Different immunohistochemical (IHC) assays are in development to assess PD-L1 expression on tumor cells (TCs) and tumor-infiltrating immune cells (ICs).MethodsIn this post hoc analysis of the single-arm, phase 1/2 Study 1108 (NCT01693562), PD-L1 expression was evaluated from tumor samples obtained prior to second-line treatment with durvalumab in patients with advanced/metastatic UC using the VENTANA (SP263) IHC Assay. The primary objective was to determine whether the TC ≥ 25%/IC ≥ 25% algorithm (i.e., cutoff of ≥ 25% TC or ≥ 25% IC with PD-L1 staining at any intensity above background) was optimal for predicting response to durvalumab. PD-L1 expression data were available from 188 patients.ResultsAfter a median follow-up of 15.8 and 14.6 months, higher PD-L1 expression was associated with longer overall survival (OS) and progression-free survival (PFS), respectively, with significant separation in survival curves for PD-L1-high and-low expressing patients for the TC ≥ 25%/IC ≥ 25% cutoff (median OS: 19.8 vs 4.8 months; hazard ratio: 0.46; 90% confidence interval: 0.33, 0.639). OS was also prolonged for PD-L1-high compared with-low patients when samples were categorized using TC/IC combined positive score ≥ 10 and IC≥ 5% cutoffs. In multivariate analysis, IC but not TC PD-L1 expression was significantly associated with OS, PFS, and objective response rate (P < 0.001 for each), although interaction analysis showed similar directionality of benefit for ICs and TCs.ConclusionsThese findings support the utility of a combined TC/IC algorithm for predicting response to durvalumab in patients with UC, with the TC≥ 25%/IC≥ 25% cutoff optimal when used with the VENTANA (SP263) IHC Assay.