T-cell receptor diversity as a prognostic biomarker in melanoma patients.

There is increasing evidence that T-cell receptor (TCR) repertoire diversity can be a predictive biomarker of immune responses in cancer patients. However, the characteristics of the T-cell repertoire together with its prognostic significance in melanoma patients and impact on disease progression remain unknown. We investigated the combinatorial TCR repertoire diversity by semi-quantitative multi-N-plex PCR in peripheral blood samples from 44 melanoma patients together with seven matched metastatic lymph nodes and explored its potential predictive value on clinical prognosis. The diversity was quantified by calculating both richness (number of different specificities) and evenness (relative abundance of the different specificities). Our results revealed that a higher TCR repertoire diversity in blood of patients was associated with a longer PFS, while divpenia (low repertoire diversity) was linked with poor prognosis. The diversity was significantly higher in patients undergoing late relapse and long survival compared to patients who progressed rapidly. Interestingly, the TCR repertoire diversity in tumor may have a potential prognostic value. Thus, our study highlights that the TCR repertoire diversity is a prognostic indicator of clinical outcome in patients with melanoma.

Long-Term Safety and Efficacy of Single or Repeated Intra-Articular Injection of Allogeneic Neonatal Mesenchymal Stromal Cells for Managing Pain and Lameness in Moderate to Severe Canine Osteoarthritis Without Anti-inflammatory Pharmacological Support: Pilot Clinical Study.

Objective: To explore the long-term safety and efficacy of canine allogeneic mesenchymal stromal cells (MSC) administered intra-articularly as single or repeated injections in appendicular joints of dogs affected by moderate to severe refractory osteoarthritis. Study Design: 22 pet dogs were recruited into a non-randomized, open and monocentric study initially administering one cellular injection. A second injection was offered after 6 months to owners if the first injection did not produce expected results. Materials and Methods: Anti-inflammatory treatment (if prescribed) was discontinued at last one week before the onset of treatment. Each injection consisted of at least 10 million viable neonatal allogeneic mesenchymal stromal cells obtained from fetal adnexa. Medical data was collected from veterinary clinical evaluations of joints up to 6 months post-injection and owner's assessment of their dog's mobility and well-being followed for a further 2 years when possible. Results: Mild, immediate self-limiting inflammatory joint reactions were observed in 5/22 joints after the first injection, and in almost all dogs having a subsequent injection. No other MSC-related adverse medical events were reported, neither during the 6 months follow up visits, nor during the long-term (2-years) safety follow up. Veterinary clinical evaluation showed a significant and durable clinical improvement (up to 6 months) following MSC administration. Eight dogs (11 joints) were re-injected 6 months apart, sustaining clinical benefits up to 1 year. Owner's global satisfaction reached 75% at 2 years post-treatment Conclusion: Our data suggest that a single or repeated intra-articular administration of neonatal MSC in dogs with moderate to severe OA is a safe procedure and confer clinical benefits over a 24-month period. When humoral response against MSC is investigated by flow cytometry, a positive mild and transient signal was detected in only one dog from the studied cohort, this dog having had a positive clinical outcome.

Peripheral Blood TCR Repertoire Profiling May Facilitate Patient Stratification for Immunotherapy against Melanoma.

Many metastatic melanoma patients experience durable responses to anti-PD1 and/or anti-CTLA4; however, a significant proportion (over 50%) do not benefit from the therapies. In this study, we sought to assess pretreatment liquid biopsies for biomarkers that may correlate with response to checkpoint blockade. We measured the combinatorial diversity evenness of the T-cell receptor (TCR) repertoire (the DE50, with low values corresponding to more clonality and lack of TCR diversity) in pretreatment peripheral blood mononuclear cells from melanoma patients treated with anti-CTLA4 (n = 42) or anti-PD1 (n = 38) using a multi-N-plex PCR assay on genomic DNA (gDNA). A receiver operating characteristic curve determined the optimal threshold for a dichotomized analysis according to objective responses as defined by RECIST1.1. Correlations between treatment outcome, clinical variables, and DE50 were assessed in multivariate regression models and confirmed with Fisher exact tests. In samples obtained prior to treatment initiation, we showed that low DE50 values were predictive of a longer progression-free survival and good responses to PD-1 blockade, but, on the other hand, predicted a poor response to CTLA4 inhibition. Multivariate logistic regression models identified DE50 as the only independent predictive factor for response to anti-CTLA4 therapy (P = 0.03) and anti-PD1 therapy (P = 0.001). Fisher exact tests confirmed the association of low DE50 with response in the anti-CTLA4 (P = 0.041) and the anti-PD1 cohort (P = 0.0016). Thus, the evaluation of basal TCR repertoire diversity in peripheral blood, using a PCR-based method, could help predict responses to anti-PD1 and anti-CTLA4 therapies.

Decreased T-cell repertoire diversity in sepsis: a preliminary study.

OBJECTIVE: Septic syndromes are the leading causes of mortality in intensive care units. In patients, the occurrence of sepsis-induced immune suppression is associated with delayed mortality, although the exact role of lymphocyte dysfunctions is not well established. The objective of this study was to investigate T-cell receptor diversity, an important feature of T-cell response, in patients with septic shock. DESIGN: Preliminary prospective observational study. SETTING: Adult intensive care units in a university hospital. SUBJECTS: Patients with septic shock (n = 41) sampled twice after the onset of shock (early after inclusion [day 1] and at the end of the first week [day 7]). MEASUREMENTS AND MAIN RESULTS: Using a novel molecular biology technique, the combinatorial diversity of human T-cell receptor ß-chain (TRB locus) was measured in peripheral blood. Patients with septic shock presented with a marked decreased T-cell receptor diversity after the onset of shock in comparison with normal values. Importantly, in paired samples, a very steep recovery slope of T-cell receptor diversity, never described in other clinical situations, was observed between day 1 and day 7 (p < 0.0001, Wilcoxon's paired test). Decreased T-cell receptor diversity was associated with mortality (log-rank test, p = 0.0058; hazard ratio = 4.48; 95% confidence interval 1.96-53.32), and the development of nosocomial infections (p < 0.05, Mann-Whitney U test). CONCLUSION: Our results show for the first time that septic patients present with a marked decreased T-cell receptor diversity that returned rapidly toward normal values over time. This opens novel cognitive research perspectives that deserve to be investigated in experimental models of sepsis. After confirmation in larger cohorts of these preliminary results, T-cell receptor diversity measurements may become a crucial tool to monitor immune functions in ICU patients.