Overestimated treatment effects in randomised phase II trials: What's up doctor?

Intranasal Esketamine versus Intravenous Ketamine: An observational pilot study assessing efficacy and tolerability of two novel 'standard of care' treatments for treatment resistant depression in naturalistic clinical practice. Protocol for an observational pilot study (Preprint)

Background

Intravenous (IV) ketamine and intranasal (IN) esketamine have been studied as novel alternatives to manage treatment-resistant depression (TRD). The objective of this observational pilot study is to compare the real-world effectiveness and tolerability of IV ketamine and IN esketamine in the management of unipolar TRD.

Objective

To compare the effectiveness (primary outcome measure) and tolerability (secondary outcome measure) of racemic ketamine and esketamine in the management of TRD in adults and provide an expert qualitative commentary on the application of IV ketamine and IN esketamine in clinical practice (exploratory objective), focusing on the recruitment process, patient retention, effectiveness, and tolerability of the treatments.

Methods

This is a multicenter prospective observational study of naturalistic clinical practice. We expect to recruit 10 patients per treatment arm—IV ketamine or IN esketamine per center (2 centers, total 40 subjects). Patients experiencing moderate to severe TRD and who are candidates for receiving low-dose IV ketamine treatments or IN esketamine as part of their standard-of-care treatments will be recruited. We will measure the effectiveness of each treatment arm by measuring the severity of depression symptoms using the Montgomery and Åsberg Depression Rating Scale; tolerability, side effects, and the appearance of dissociation symptoms using the simplified 6-item version of the Clinician Administered Dissociative Symptom Scale (CADSS-6); and potential for abuse using a Likeability and Craving Questionnaire. Logistic regression will examine odds ratios, number needed to treat for response and remission, number needed to harm, and likelihood to be helped or harmed of each treatment. Covariate analysis will assess the impact of site and demographic variables on treatment efficacy.

Results

This observational trial was approved by the Queen’s University Health Science and Affiliated Teaching Hospital’s Research Ethics Board in February 2021. The two research centers involved have started patient recruitment. Our research center (Providence Care Hospital, Kingston, Ontario) has recruited 9 patients so far. We expect to finalize data gathering by August 2022. The manuscript is expected to be published by December 2022.

Conclusions

We hypothesize that both treatments will have comparable rapid and robust antidepressant effects and similar tolerability profiles in a real-world setting for the management of TRD.

International Registered Report Identifier (IRRID)

DERR1-10.2196/34711

Validation of Progression-Free Survival Rate at 6 Months and Objective Response for Estimating Overall Survival in Immune Checkpoint Inhibitor Trials: A Systematic Review and Meta-analysis

IMPORTANCE

Progression-free survival (PFS) rate at 6 months has been proposed as a potential surrogate for overall survival (OS) rate at 12 months for immune checkpoint inhibitor (ICI) trials but requires further assessment for validation.

OBJECTIVE

To validate 6-month PFS and objective response rate (ORR) as estimators of 12-month OS in the ICI arms of randomized clinical trials (RCTs).

DATA SOURCES

Electronic databases (Medline, EMBASE, and the Cochrane Central Register of Controlled Trials) were searched for ICI RCTs published between January 2000 and June 2019.

STUDY SELECTION

Eligible studies were phase 2 and phase 3 ICI RCTs in advanced solid cancers that reported ORR, PFS, and OS. A total of 99 articles (from 60 studies) of 2502 articles were selected by consensus.

DATA EXTRACTION AND SYNTHESIS

Data were screened and extracted independently. Estimation models for 12-month OS and to assess correlation coefficient between end points were developed using linear regression. Data were extracted in July 2019, and analyses were conducted in September 2019. This study is reported following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline.

MAIN OUTCOMES AND MEASURES

Validation of previously reported 6-month PFS and ORR estimation models for 12-month OS using contemporary RCTs. Calibration of 6-month PFS and ORR model-estimated vs observed 12-month OS in ICI arms were assessed by correlation coefficient (r) and weighted Brier scores. Secondary analyses were performed for subgroups (ie, ICI-only, ICI-combination, line of therapy, programmed cell death 1 ligand 1 selected, and unselected).

RESULTS

Data from 60 RCTs with 74 experimental ICI arms were used. The development data set included 25 arms from studies published January 2000 to January 2017. The estimation model for 12-month OS using 6-month PFS was: (1.06 × PFS6) + 0.16 + (0.04 × melanoma) - (0.03 × NSCLC) + (0 × other tumors), in which PFS6 indicates 6-month PFS and NSCLC indicates non-small cell lung cancer. The estimation model for 12-month OS using ORR was (0.15 × ORR) + 0.52 + (0 × melanoma) - (0.02 × NSCLC) - (0.01 × other tumors). A total of 49 arms from studies published after January 2017 to June 2019 formed the validation data set. When the models were applied on the validation data set, calibration between the 6-month PFS model estimated vs observed 12-month OS was good (r = 0.89; Brier score, 0.008), but poor for the ORR model (r = 0.47; Brier score, 0.03). Findings were similar across all subgroups.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that the estimation model using 6-month PFS could reliably estimate 12-month OS in ICI trials. This study could assist in better selection and prioritization of ICI agents for testing in RCTs based on phase 2 single-arm RCT results.