Duration of and time to response in oncology clinical trials from the perspective of the estimand framework

Duration of response (DOR) and time to response (TTR) are typically evaluated as secondary endpoints in early-stage clinical studies in oncology when efficacy is assessed by the best overall response and presented as the overall response rate. Despite common use of DOR and TTR in particular in single-arm studies, the definition of these endpoints and the questions they are intended to answer remain unclear. Motivated by the estimand framework, we present relevant scientific questions of interest for DOR and TTR and propose corresponding estimand definitions. We elaborate on how to deal with relevant intercurrent events which should follow the same considerations as implemented for the primary response estimand. A case study in mantle cell lymphoma illustrates the implementation of relevant estimands of DOR and TTR. We close the paper with practical recommendations to implement DOR and TTR in clinical study protocols.

Early Increase in Circulating PD-1+CD8+ T Cells Predicts Favorable Survival in Patients with Advanced Gastric Cancer Receiving Chemotherapy

The clinical significance of PD-1 expression in circulating CD8+ T cells in patients with gastric cancer (GC) receiving chemotherapy remains unelucidated. Therefore, we aimed to examine its prognostic significance in blood samples of 68 patients with advanced GC who received platinum-based chemotherapy. The correlation between peripheral blood mononuclear cells, measured using fluorescence-activated cell sorting, was evaluated. Patients were divided into two groups according to the changes in PD-1+CD8+ T-cell frequencies between day 0 and 7. They were categorized as increased or decreased PD-1+CD8+ T-cell groups. The increased PD-1+CD8+ T-cell group showed longer progression-free survival (PFS) and overall survival (OS) than the decreased PD-1+CD8+ T-cell group (PFS: 8.7 months vs. 6.1 months, p = 0.007; OS: 20.7 months vs. 10.8 months, p = 0.003). The mean duration of response was significantly different between the groups (5.7 months vs. 2.5 months, p = 0.041). Multivariate analysis revealed that an increase in PD-1+CD8+ T-cell frequency was an independent prognostic factor. We concluded that the early increase in PD-1+CD8+ T-cell frequency is a potential predictor of favorable prognoses and durable responses in patients with advanced GC receiving chemotherapy.

Late relapse after CAR-T cell therapy for adult patients with hematologic malignancies: a definite evidence from Systematic Review and Meta-Analysis on individual data

Chimeric Antigen Receptor (CAR)-modified T lymphocytes represent one of the most innovative and promising approaches to treating hematologic malignancies. CAR-T cell therapy is currently being used for the treatment of relapsed/refractory (r/r) B-cell malignancies including Acute Lymphoblastic Leukemia, Large B-Cell Lymphoma, Follicular Lymphoma, Multiple Myeloma and Mantle Cell Lymphoma. Despite the unprecedented clinical success, one of the major issues of the approved CAR-T cell therapy - tisagenlecleucel, axicabtagene, lisocabtagene, idecabtagene, ciltacabtagene and brexucabtagene - is the uncertainty about its persistence which in turn could lead to weak or no response to therapy with malignancy recurrence. Here we show that the prognosis of patients who do not respond to CAR-T cell therapy is still an unmet medical need. We performed a systematic review and meta-analysis collecting individual data on Duration of Response from at least 12-month follow-up studies. We found that the pooled prevalence of relapse within the first 12 months after CAR-T infusion was 61% (95% CI, 43%-78%); moreover, one year after the infusion, the analysis highlighted a pooled prevalence of relapse of 24% (95% CI, 11%-42%). Our results suggest that identifying potential predictive biomarkers of response to CAR-T therapy, especially for patients affected by the advanced stage of blood malignancies, could lead to stratification of the eligible population to that therapy, recognizing which patients will benefit and which will not, helping regulators to make decision in that way.

Utilizing restricted mean duration of response for efficacy evaluation of cancer treatments

In oncology clinical trials, response-based endpoints (time to response, objective response, duration of response [DOR]) are commonly used to detect therapeutic effect to support proof-of-concept or submission decisions. The restricted mean DOR (RMDOR) was recently proposed as a composite nonparametric method to efficiently quantify the treatment effect related to tumor reductions, which offers an intuitive way to perform statistical inference in cross-arm comparison and has since been applied in some Phase III studies. In this paper, we provide further technical details and asymptotic properties of the RMDOR method and discuss the selection of the truncation time. A simulation study is conducted comparing the performance of the proposed method with existing standard methods in hypothesis testing and quantification of treatment efficacy. We use two oncology Phase III examples to illustrate the method. An R package PBIR and a SAS macro are available to perform statistical inference based on the RMDOR.

A Bayesian hierarchical monitoring design for phase II cancer clinical trials: Incorporating information on response duration into monitoring rules

We propose a Bayesian hierarchical monitoring design for single-arm phase II clinical trials of cancer treatments that incorporates the information on the duration of response (DOR) into the monitoring rules. To screen a new treatment by evaluating its preliminary therapeutic effect, futility monitoring rules are commonly used in phase II clinical trials to make "go/no-go" decisions timely and efficiently. These futility monitoring rules are usually focused on a single outcome (eg, response rate), although a single outcome may not adequately determine the efficacy of the experimental treatment. For example, targeted agents with a long response duration but a similar response rate may be worth further evaluation in cancer research. To address this issue, we propose Bayesian hierarchical futility monitoring rules to consider both the response rate and duration. The first level of monitoring evaluates whether the response rate provides evidence that the experimental treatment is worthy of further evaluation. If the evidence from the response rate does not support continuing the trial, the second level monitoring rule, which is based on the DOR, will be triggered. If both stopping rules are satisfied, the trial will be stopped for futility. We conducted simulation studies to evaluate the operating characteristics of the proposed monitoring rules and compared them to those of standard method. We illustrated the proposed design with a single-arm phase II cancer clinical trial to assess the safety and efficacy of combined treatment of nivolumab and azacitidine in patients with relapsed/refractory acute myeloid leukemia. The proposed design avoids an aggressive early termination for futility when the experimental treatment substantially prolongs the DOR but fails to improve the response rate.

Clinical impact of immunotherapy in Merkel cell carcinoma patients: A systematic review and meta-analysis

BACKGROUND

Immunotherapy is emerging as an alternative treatment for Merkel cell carcinoma, but its long-term effects on response, survival, and safety are not well established. High-quality evidence is needed to estimate the efficacy of this treatment and to review the characteristics of patients and tumors that might improve outcomes.

OBJECTIVE

To summarize efficacy and safety of immunotherapy in patients with Merkel cell carcinoma.

METHODS

A systematic review was performed for studies published in MEDLINE, Web of Science, Scopus, and EMBASE. Two reviewers examined the literature and data extraction in duplicate. We estimated the proportions for objective responses, progression-free survival, overall survival, and treatment-related adverse events. Associations between objective response rate and immunobiologic markers were analyzed.

RESULTS

Six clinical trials of 201 patients treated with immunotherapy were included. The objective response rate was 51% (95% confidence interval, 0.40-0.62; I² = 37.1%) and grade ≥3 treatment-related adverse events were observed in 18% (95% confidence interval, 0.11-0.29; I² = 49.5%) of patients. No significant difference was observed between response rates and immunobiologic characteristics.

CONCLUSIONS

A significantly reduced tumor diameter with durable response rates and a safe profile are obtained with immunotherapy. Similar response rates achieved on either subgroup of viral status or programmed death ligand 1 expression suggests that it might act on multiple, unexplored pathways.

Response Efficacy of PD-1 and PD-L1 Inhibitors in Clinical Trials: A Systematic Review and Meta-Analysis

Background

Immune checkpoint inhibitors targeting the PD-1/PD-L1 pathway have demonstrated promise in treating a variety of advanced cancers; however, little is known regarding their efficacy under various clinical situations, including different cancer types, treatment lines, drug combinations, and therapeutic regimens.

Methods

Published articles and conference abstracts (in English) in PubMed, Embase, the Cochrane Central Register, and Web of Science were searched up to February 10, 2020. The data were analyzed by the meta-analysis program in Stata.

Results

A total of 16,400 patients from 91 clinical trials were included in this meta-analysis. PD-1/PD-L1 inhibitors had a mean ORR of 19.56% (95% CI: 15.09–24.03), a median TTR of 2.05 months (m) (95%CI: 1.85–2.26), and a median DOR of 10.65 m (95%CI: 7.78–13.52). First-line treatment had a higher ORR (36.57% vs. 13.18%) but a shorter DOR (9.00 m vs. 13.42 m) compared to the second-line or subsequent treatment. Immunotherapy combined with chemotherapy (I+C) (46.81% [95%CI: 36.02–57.60]) had a statistically significant higher ORR compared to immunotherapy (I) (17.75% [95%CI: 14.47–21.03]) or immunotherapy combined with immunotherapy (I+O) (12.25% [95%CI: 1.56–22.94]), while I+C (8.09 m [95%CI: 6.86–9.32]) appeared to reduce the DOR compared to I (12.39 m [95%CI: 7.60–17.18]). PD-1 inhibitors were associated with better ORR (21.65% vs. 17.60%) and DOR (11.26 m vs. 10.03 m) compared to PD-L1 inhibitors. There were no significant differences in TTR under different situations.

Conclusions

PD-1/PD-L1 inhibitors were promising immunotherapeutic agents to achieve satisfactory response efficacies with different cancer types, treatment lines, drug combinations, and therapeutic regimens. This comprehensive summary of the response efficacy of PD-1/PD-L1 inhibitors serves as a reference for clinicians to make evidence-based decisions.

Pomalidomide Plus Low-Dose Dexamethasone in Relapsed/Refractory Multiple Myeloma Patients: Results of the Real-World "POWERFUL" Study

The “POWERFUL” multicenter, retrospective, and prospective study investigated the effectiveness of pomalidomide plus low-dose dexamethasone (POM/LoDex) therapy in relapsed/refractory multiple myeloma in routine care in Greece. Ninety-nine eligible adult patients treated with POM/LoDex according to the approved label after having received ≥2 prior therapies, including lenalidomide and bortezomib, were consecutively enrolled between 16 November 2017 and 21 February 2019 in 18 hematology departments. Fifty patients (50.5%) started POM/LoDex as third-line treatment. During the treatment period (median: 8.3 months; range: 0.3–47.6 months), the median POM dose was 4 mg/day, and 31.3% of the patients received additional antimyeloma agents. The overall response rate was 32.3%. During a median follow-up period of 13.8 months (Kaplan–Meier estimate), the median progression-free survival (PFS) was 10.5 months (95% CI: 7.4–14.4). The PFS was not significantly different between patients receiving POM/LoDex in the third versus later line of therapy, nor between patients receiving concomitant antimyeloma therapy versus POM/LoDEx doublet. During the prospective safety data collection period (median: 7.6 months) among patients with prospective follow-up (N = 75), POM-related adverse event incidence rate was 42.7% (serious: 18.7%; grade  ≥  3 hematological POM-related adverse events: 8.0%). Only neutropenia (13.3%) was reported at a frequency ≥10%. In conclusion, in this real-world study, POM/LoDex displayed a long PFS with no new safety signals emerging.

Duration of Symptom Relief Between Injections for AbobotulinumtoxinA (Dysport®) in Spastic Paresis and Cervical Dystonia: Comparison of Evidence From Clinical Studies

Background: Botulinum toxin-A is a well-established treatment for adult and pediatric spastic paresis and cervical dystonia. While guidelines and approved labels indicate that treatment should not occur more frequently than every 12 weeks, studies and real-world evidence show that the timing of symptom recurrence between treatments may vary. Methods: We report retreatment criteria and response duration (retreatment intervals) from four pivotal, double-blind, placebo-controlled studies with open-label extensions involving patients treated with abobotulinumtoxinA (aboBoNTA) for upper limb (NCT01313299) or lower limb (NCT01249404) spastic paresis in adults, lower limb spastic paresis in children (NCT01249417), and cervical dystonia in adults (NCT00257660). We review results in light of recently available preclinical data. Results: In spastic paresis, 24.0-36.9% of upper limb patients treated with aboBoNTA and 20.1-32.0% of lower limb patients did not require retreatment before 16 weeks. Moreover, 72.8-93.8% of aboBoNTA-treated pediatric patients with lower limb spastic paresis did not require retreatment before 16 weeks (17.7-54.0% did not require retreatment before 28 weeks). In aboBoNTA-treated patients with cervical dystonia, 72.6-81.5% did not require retreatment before 16 weeks. Conclusion: AboBoNTA, when dosed as recommended, offers symptom relief beyond 12 weeks to many patients with spastic paresis and cervical dystonia. From recently available preclinical research, the amount of active neurotoxin administered with aboBoNTA might be a factor in explaining this long duration of response.

The impact of cytogenetics on duration of response and overall survival in patients with relapsed multiple myeloma (long-term follow-up results from BSBMT/UKMF Myeloma X Relapse [Intensive]): a randomised, open-label, phase 3 trial

The Myeloma X trial (ISCRTN60123120) registered patients with relapsed multiple myeloma. Participants were randomised between salvage autologous stem cell transplantation (ASCT) or weekly cyclophosphamide following re‐induction therapy. Cytogenetic analysis performed at trial registration defined t(4;14), t(14;16) and del(17p) as high‐risk. The effect of cytogenetics on time to progression (TTP) and overall survival was investigated. At 76 months median follow‐up, ASCT improved TTP compared to cyclophosphamide (19 months (95% confidence interval [95% CI] 16–26) vs. 11 months (9–12), hazard ratio [HR]: 0·40, 95% CI: 0·29–0·56, P < 0·001), on which the presence of any single high‐risk lesion had a detrimental impact [likelihood ratio test (LRT): P = 0·011]. ASCT also improved OS [67 months (95% CI 59‐not reached) vs. 55 months (44–67), HR: 0·64, 95% CI: 0·42–0·99, P = 0·0435], with evidence of a detrimental impact with MYC rearrangement (LRT: P = 0·021). Twenty‐one (24·7%) cyclophosphamide patients received an ASCT post‐trial, median OS was not reached (95% CI: 39‐not reached) for these participants compared to 31 months (22–39), in those who did not receive a post‐trial ASCT. The analysis further supports the benefit of salvage ASCT, which may still be beneficial after second relapse in surviving patients. There is evidence that this benefit reduces in cytogenetic high‐risk patients, highlighting the need for targeted study in this patient group.

Prolonged duration of response in lenvatinib responders with thyroid cancer

We present an updated analysis of lenvatinib in radioiodine-refractory differentiated thyroid cancer (RR-DTC) with new duration of response (DOR) data unavailable for the primary analysis. In this randomized, double-blind, multicenter, placebo-controlled phase 3 study, patients ≥18 years old with measurable, pathologically confirmed RR-DTC with independent radiologic confirmation of disease progression within the previous 13 months were randomized 2:1 to oral lenvatinib 24 mg/day or placebo. The main outcome measures for this analysis are DOR and progression-free survival (PFS). The median DOR for all lenvatinib responders (patients with complete or partial responses; objective response rate: 60.2%; 95% confidence interval (CI) 54.2-66.1) was 30.0 months (95% CI 18.4-36.7) and was generally similar across subgroups. DOR was shorter in patients with greater disease burden and with brain and liver metastases. Updated median PFS was longer in the overall lenvatinib group vs placebo (19.4 vs 3.7 months; hazard ratio (HR) 0.24; 99% CI 0.17-0.35; nominal P < 0.0001). In lenvatinib responders, median PFS was 33.1 months (95% CI 27.8-44.6) vs 7.9 months (95% CI 5.8-10.7) in non-responders. The median DOR of 30.0 months seen with patients who achieved complete or partial responses with lenvatinib (60.2%) demonstrates that lenvatinib responders can have prolonged, durable and clinically meaningful responses. Prolonged PFS (33.1 months) was also observed in these lenvatinib responders.

Assessing treatment efficacy in the subset of responders in a randomized clinical trial

Background

Durability of response is a clinically relevant dimension of the treatment effect in randomized clinical trials; it is often measured by comparing among the responders the duration of response between the treatment arms. However, since the comparison groups are defined by response (a post-randomization event), it is subject to analysis-by-responder bias, especially if the proportion of responders differs between the arms.

Methods

Two simple methods are developed that use tumor shrinkage measurements in order to lessen analysis-by-responder bias by generating more comparable patient subsets in the control and experimental arms of the trial. These subsets are then used to estimate between-arm differences in response duration. In the subtraction method, responding patients with the least tumor shrinkage in the treatment arm with more responders are removed from the patient subset for that arm. In the addition method, non-responding patients with the most tumor shrinkage in the treatment arm with fewer responders are added to the patient subset for that arm. In both methods, the numbers of patients subtracted or added are such that the proportion of patients in the modified patient subset is the same as the proportion of responders in the other treatment arm.

Results

The methods are demonstrated on a hypothetical dataset where they are shown to eliminate analysis-by-responder bias, and on two published analyses of randomized trials that compared the duration of response between the treatment arms.

Conclusions

The proposed methods can lessen the analysis-by-responder bias. These methods to compare duration of response between treatment arms may provide a useful exploratory analysis to measure treatment efficacy among responders.

Pattern Recognition in Pharmacodynamic Data Analysis

Pattern recognition is a key element in pharmacodynamic analyses as a first step to identify drug action and selection of a pharmacodynamic model. The essence of this process is going from data to insight through exploratory data analysis. There are few formal strategies that scientists typically use when the experiment has been done and data collected. This report attempts to ameliorate this deficit by identifying the properties of a pharmacodynamic model via dissection of the pattern revealed in response-time data. Pattern recognition in pharmacodynamic analyses contrasts with pharmacokinetic analyses with respect to time course. Thus, the time course of drug in plasma usually differs markedly from the time course of the biomarker response, as a consequence of a myriad of interactions (transport to biophase, binding to target, activation of target and downstream mediators, physiological response, cascade and amplification of biosignals, homeostatic feedback) between the events of exposure to test compound and the occurrence of the biomarker response. Homing in on this important-but less often addressed-element, 20 datasets of varying complexity were analyzed, and from this, we summarize a set of points to consider, specifically addressing baseline behavior, number of phases in the response-time course, time delays between concentration- and response-time courses, peak shifts in response with increasing doses, saturation, and other potential nonlinearities. These strategies will hopefully give a better understanding of the complete pharmacodynamic response-time profile.

Relative efficacy and interchangeability ofvarious clobetasol propionate vehicles in the management of steroid-responsive dermatoses

BACKGROUND

Topical corticosteroids have long been the cornerstone in thetreatment of steroid-responsive dermatoses. Despite the effectiveness of these formulations, there is a misperception that drugs delivered via ointments are more potent than those delivered via other vehicles. Potency, however, is a complex function of the physical and chemical properties of both the active ingredient and its vehicle. Studies have determined that newer vehicles (eg, lotions), particularly those in the super-high-potency class, not only heighten the ability of the active ingredient to penetrate skin but also are preferred by patients over ointments and creams.

OBJECTIVE

This review of the literature investigates the effectiveness andtolerability of a high-potency corticosteroid lotion compared with cream or emollient cream formulations in treating moderate to severe plaque-type psoriasis and atopic dermatitis.

METHODS

A literature search was conducted of US and international published clinical trials (1975 to November 2004) comparing all potencies of topical corticosteroid cream and lotion formulations using MEDLINE and the Web sites of individual dermatologic journals. No specific study designs were excluded from this search. Search terms included corticosteroid-responsive dermatoses, creams versus lotions, topical corticosteroid clinical trials, plaque-type psoriasis, atopic dermatitis, clobetasol propionate, drug bioavailability, Class I topical agents, and vasoconstriction. The primary diagnoses were moderate to severe plaque-type psoriasis and atopic dermatitis. Two unpublished clinical investigations comparing clobetasol propionate lotion 0.05% with clobetasol propionate cream 0.05% and emollient cream 0.05% in a total of 421 patients were also included.

RESULTS

In the 20 published and 2 unpublished trials identified and reviewed, the response rates were comparable between the lotion and cream formulations. In addition, in a psoriasis study, clobetasol lotion received significantly better cosmetic-acceptability ratings compared with clobetasol cream (P < 0.05).

CONCLUSION

In the studies reviewed, the effectiveness and tolerability of clobetasollotion were comparable to those of clobetasol cream and emollient cream in studies in adults with moderate to severe psoriasis or atopic dermatitis.