Bayesian interpretation of immunotherapy trials with dynamic treatment effects.

INTRODUCTION: The mechanism of action of immune checkpoints inhibitors hinders the writing of rational statistical analysis plans for phase III randomised clinical trials (RCTs) because of their unpredictable dynamic effects. The purpose is to illustrate the advantages of Bayesian reporting of treatment efficacy analysis in immunotherapy RCTs, in contrast to frequentist reporting. METHOD: Fourteen RCTs (one with two pairwise comparisons) that failed to achieve their primary objective (overall survival, OS) were selected. These RCTs were reanalysed using Bayesian Cox models with dynamic covariate coefficients and time-invariant models. RESULTS: The RCTs that met inclusion criteria were 7 lung cancer trials, various other tumours, with antiPD1, antiPDL1 or antiCTLA4 therapies. The minimum detectable effect (δS) was superior to the true benefit observed in all cases, in conditions of non-proportional hazards. Schoenfeld tests indicated the existence of PH assumption violations (p<0.05) in 6/15 cases. The Bayesian Cox models revealed a probability of benefit >79% in all the RCTs, with the therapeutic equivalence hypothesis unlikely. The OS curves diverged after a median of 9.1 months. Since the divergency, no non-proportionality was evinced in 13/15, while the Wald tests achieved p<0.05 in 12/15 datasets. In all cases, the Bayesian Cox models with dynamic coefficients detected fluctuations of the hazard ratio, and increased 2-year OS was the most likely hypothesis. CONCLUSION: We recommend progressively implementing Bayesian and dynamic analyses in all RCTs of immunotherapy to interpret and assess the credibility of frequentist results.

Critical reappraisal of phase III trials with immune checkpoint inhibitors in non-proportional hazards settings.

BACKGROUND: The dynamic effects of immune checkpoint inhibitors (ICIs) are a challenge when designing and analysing data in non-proportional hazards (PH) scenarios. Herein, we present the risk of making type II errors, affecting pharmacotherapeutic development when methods that assume constant effects are applied. PATIENTS AND METHODS: Individual patient data from six clinical trials (KEYNOTE-062/061, IMvigor211, CA184-143 y CheckMate-057/037) were extracted. The most relevant time-varying effects were examined using the Royston-Parmar spline model (RPSM), time-driven analyses and weighted log-rank and Renyi tests. RESULTS: The RPSM yields an appropriate fit in non-PH contexts, enabling dynamic descriptions of the hazard rate, and time-varying differences of overall survival (OS)/progression-free survival. In the KEYNOTE-061, CheckMate-057 and 037 trials, 12-, 18-, and 24-month OS rates were higher with immunotherapy (differences of some 10%) (P-value <0.05). In KEYNOTE-062, CA184-043 and IMvigor-211 trials, OS rate differences were significant for past 20 months. Flemming-Harrington and Renyi tests with late weighting (e.g. with ρ-value = 0 and γ-value = 1) captured the existence of significant differences on all curves. The Cox models and log-rank tests were inefficient at detecting the effect. CONCLUSION: This analysis highlights the risk of declaring studies with ICIs negative, despite associating substantial OS benefits. Effort and consensus are needed with respect to methodology to design and evaluate trials with ICIs in non-PH settings.

Does active smoking worsen Covid-19?

Probably it does.

Intratumoral Immunotherapy with XCL1 and sFlt3L Encoded in Recombinant Semliki Forest Virus-Derived Vectors Fosters Dendritic Cell-Mediated T-cell Cross-Priming.

: Multiple lines of evidence indicate a critical role of antigen cross-presentation by conventional BATF3-dependent type 1 classical dendritic cells (cDC1) in CD8-mediated antitumor immunity. Flt3L and XCL1, respectively, constitute a key growth/differentiation factor and a potent and specific chemoattractant for cDC1. To exploit their antitumor functions in local immunotherapy, we prepared Semliki Forest Virus (SFV)-based vectors encoding XCL1 and soluble Flt3L (sFlt3L). These vectors readily conferred transgene expression to the tumor cells in culture and when engrafted as subcutaneous mouse tumor models. In syngeneic mice, intratumoral injection of SFV-XCL1-sFlt3L (SFV-XF) delayed progression of MC38- and B16-derived tumors. Therapeutic activity was observed and exerted additive effects in combination with anti-PD-1, anti-CD137, or CTLA-4 immunostimulatory mAbs. Therapeutic effects were abolished by CD8ß T-cell depletion and were enhanced by CD4 T-cell depletion, but not by T regulatory cell predepletion with anti-CD25 mAb. Antitumor effects were also abolished in BATF3- and IFNAR-deficient mice. In B16-OVA tumors, SFV-XF increased the number of infiltrating CD8 T cells, including those recognizing OVA. Consistently, following the intratumoral SFV-XF treatment courses, we observed increased BATF3-dependent cDC1 among B16-OVA tumor-infiltrating leukocytes. Such an intratumoral increase was not seen in MC38-derived tumors, but both resident and migratory cDC1 were boosted in SFV-XF-treated MC38 tumor-draining lymph nodes. In conclusion, viral gene transfer of sFlt3L and XCL1 is feasible, safe, and biologically active in mice, exerting antitumor effects that can be potentiated by CD4 T-cell depletion. SIGNIFICANCE: These findings demonstrate that transgenic expression of sFLT3L and XCL1 in tumor cells mediates cross-priming of, and elicits potent antitumor activity from, CD8 T lymphocytes, particularly in combination with CD4 T-cell depletion.

Cellular immunotherapies for cancer.

Lessons learned over decades on the use of gene and cell therapies have found clinical applicability in the field of cancer immunotherapy. On December 16th, 2016 a symposium was held in Pamplona (Spain) to analyze and discuss the critical points for the clinical success of adoptive cell transfer strategies in cancer immunotherapy. Cellular immunotherapy is being currently exploited for the development of new cancer vaccines using ex vivo manipulated dendritic cells or to enhance the number of effector cells, transferring reinvigorated NK cells or T cells. In this meeting report, we summarize the main topics covered and provide an overview of the field of cellular immunotherapy.