Effector Mechanisms of Rejection

International audienceOrgan transplantation appears today to be the best alternative to replace the loss of vital organs induced by various diseases. Transplants can, however, also be rejected by the recipient. In this review, we provide an overview of the mechanisms and the cells/molecules involved in acute and chronic rejections. T cells and B cells mainly control the antigen-specific rejection and act either as effector, regulatory, or memory cells. On the other hand, nonspecific cells such as endothelial cells, NK cells, macrophages, or polymorphonuclear cells are also crucial actors of transplant rejection. Last, beyond cells, the high contribution of antibodies, chemokines, and complement molecules in graft rejection is discussed in this article. The understanding of the different components involved in graft rejection is essential as some of them are used in the clinic as biomarkers to detect and quantify the level of rejection

Cell therapy using tolerogenic dendritic cells in transplantation

International audienceOrgan transplantation is the main alternative to the loss of vital organ function from various diseases. However, to avoid graft rejection, transplant patients are treated with immunosuppressive drugs that have adverse side effects. A new emerging approach to reduce the administration of immunosuppressive drugs is to co-treat patients with cell therapy using regulatory cells. In our laboratory, as part of a European project, we plan to test the safety of tolerogenic dendritic cell (TolDC) therapy in kidney transplant patients. In this mini-review, we provide a brief summary of the major protocols used to derive human TolDC, and then focus on the granulocyte macrophage-TolDC generated by our own team. Proof of safety of TolDC therapy in the clinic has already been demonstrated in patients with diabetes. However, in transplantation, DC therapy will be associated with the administration of immunosuppressive drugs, and interactions between drugs and DC are possible. Finally, we will discuss the issue of DC origin, as we believe that administration of autologous TolDC is more appropriate, as demonstrated by our experiments in animal models

Machine learning algorithm to predict response to immunotherapy in real-life settings for patients with advanced melanoma

International audienceBackground: Melanoma is one of the most fatal forms of skin cancer. Defining relevant biomarkers to predict treatment outcome based on immune checkpoint inhibitors (ICIs) is needed in order to increase overall survival of metastatic melanoma patients (MM).Objectives: This study compared different machine learning models in terms of performance to identify biomarkers from clinical diagnosis and follow-up of MM patients, to predict treatment response to ICIs under real-life conditions.Materials & methods: Clinical data from melanoma patients with an AJCC status of III C/D or IV, having received ICIs, were extracted from the RIC-MEL database for this pilot study. Light Gradient Boosting Machine, linear regression, Random Forest (RF), Support Vector Machine and Extreme Gradient Boosting were compared in terms of performance. The SHAP (SHapley Additive exPlanations) method was used to assess the link between the different clinical features investigated and the prediction of response to ICIs.Results: RF showed the highest scores for accuracy (0.63) and sensitivity (0.64) and high scores for precision (0.61) and specificity (0.63). AJCC stage (0.076) showed the highest SHAP mean value, thus being the most suitable feature to predict response to treatment. The number of metastatic sites per year (0.049), number of months since first treatment initiation and the Breslow index (both 0.032) were less predictive, but still showed relatively high predictive power.Conclusion: This machine learning approach confirms that a certain number of biomarkers may enable prediction of treatment success with ICIs

Panniculitis does not predict clinical response in patients with advanced melanoma under targeted therapy

International audienceBackground: BRAF and MEK inhibitors have changed the landscape of treatment for advanced melanoma. Among their side effects, panniculitis has been hypothesized to be associated with better survival.Objectives: In this study, we aimed to explore the association between the occurrence of panniculitis during targeted therapy and outcome of metastatic melanoma.Materials & methods: This was a retrospective single-centre comparative study from 2014 to 2019. An English literature review was also conducted to further our understanding of the mechanism(s) involved and identify characteristics of this association, in order to support better management.Results: Ten patients who developed panniculitis during treatment were matched to 26 controls based on potential confounders at treatment introduction. The prevalence of panniculitis was 5.3%. Median progression-free survival (PFS) for all patients was 8.5 months (range: 3.0-94.0). The median PFS for the group with panniculitis was 10.5 months (7.0-undefined) and 7.0 months (6.0-32.0) for controls (p=0.39). According to the scientific literature, panniculitis occurring during targeted therapy affects mainly young people, predominantly women, with variable delay to onset (with half reported cases occurring in the first month). In addition, panniculitis usually only affects the lower limbs or is associated with other clinical signs (fever, arthralgia), without histological specificity. Discontinuation of targeted therapy is not required as spontaneous remission is usually experienced. Symptomatic treatment may be administered but systemic corticosteroids have not been proven to be effective.Conclusion: In contrast to the belief that there is a link between panniculitis and clinical response to targeted therapy according to the literature, our results show that there is no significant association between the two

Chemotherapy efficacy after first-line immunotherapy in 18 advanced melanoma patients

International audienceIn BRAF wild type advanced melanoma, immune checkpoint blockers such as anti-PD1 (anti-programmed cell death 1) are usually continued beyond progression for a hypothetical rare further response. Chemotherapy as a second-line option is considered ineffective by many practitioners based on historical data. Continuing anti-PD1 beyond progression has a high health-economic impact and is not recommended by the FDA. This study aimed to describe the efficacy and survival of advanced melanoma patients who received second-line (or more) chemotherapy after immunotherapy failure. This was a retrospective single center study conducted in a French University Hospital during an 11-month period. All advanced melanoma patients treated with chemotherapy after immunotherapy failure were included. Eighteen patients were analyzed. Therapeutic response to chemotherapy was evaluable in 16 patients: partial response was achieved in 3/16 (19%), stable disease in 1/16 (6%) and progressive disease in 12/16 (75%). Median overall survival from chemotherapy start was 12 months. Median progression-free survival was 5.4 months. The 6-month overall survival rate was 81% and the 6-month progression-free survival rate was 40%. Although the disease control rate with chemotherapy was low (25%), survival data in our study are far superior to those previously published. This could be linked to a high proportion of patients treated with anti-PD1 just prior to chemotherapy, which may suggest a potential synergy between immunotherapy and chemotherapy

Positive margins after surgical excision of locoregional cutaneous melanoma metastasis and their impact on patient outcome

International audienceFor melanoma patients, surgery is a standard treatment for locoregional skin metastasis (LSM). To assess the frequency and risk factors for positive margins after excision of LSM and their impact on patient overall survival (OS) and progression-free survival (PFS). A monocentric, retrospective observational study was performed including 87 patients with LSM who had undergone surgical excision. Positive margins were found in 45% of patients after excision. After additional excision, 28% of patients still had positive margins. Interestingly, there was no difference in PFS or OS for clear margins after the first or additional excision or for margins that remained positive without additional excision. LSM size was the only identified predictive factor for positive margins. This is the first reported study investigating the frequency of, and risk factors for positive margins of cutaneous LSM, which raises the question of whether additional excision should be performed following positive margin excision

Circulating Tumor DNA Early Kinetics Predict Response of Metastatic Melanoma to Anti-PD1 Immunotherapy: Validation Study

International audienceThe ability of early (first weeks of treatment) ctDNA kinetics to identify primary resistance to anti-PD1 immunotherapies was evaluated with a validation cohort of 49 patients treated with anti-PD1 for metastatic BRAF or NRAS-mutated melanoma, alone and pooled with the 53 patients from a previously described derivation cohort. BRAF or NRAS mutations were quantified on plasma DNA by digital PCR at baseline and after two or four weeks of treatment. ctDNA kinetics were interpreted according to pre-established biological response criteria. A biological progression (bP, i.e., a significant increase in ctDNA levels) at week two or week four was associated with a lack of benefit from anti-PD1 (4-month PFS = 0%; 1-year OS = 13%; n = 12/102). Patients without initial bP had significantly better PFS and OS (4-month PFS = 78%; 1-year OS = 73%; n = 26/102), as did patients whose ctDNA kinetics were not evaluable, due to low/undetectable baseline ctDNA (4-month PFS = 80%; 1-year OS = 81%; n = 64/102). ctDNA detection at first-line anti-PD1 initiation was an independent prognostic factor for OS and PFS in multivariate analysis. Overall, early ctDNA quantitative monitoring may allow the detection of primary resistances of metastatic melanoma to anti-PD1 immunotherapies

Quantitative monitoring of circulating tumor DNA predicts response of cutaneous metastatic melanoma to anti-PD1 immunotherapy

International audienceImmunotherapies have changed the medical management of metastatic melanoma. However, the early detection of patients who do not respond to these treatments is a key issue. We evaluated the quantitative monitoring of circulating tumor DNA (ctDNA) as an early predictor of response to anti-PD1. Patients treated with anti-PD1 for metastatic mutated melanoma were selected. The somatic alteration detected on the tumor tissue was quantified on plasma DNA by digital PCR (dPCR) at treatment initiation, after 2 and 4 weeks of treatment, and then every 4 weeks until progression. The absence of biological response (defined as a significant decrease in the amount of ctDNA relative to the baseline level) after 2 weeks of treatment was associated with a lack of clinical benefit under anti-PD1. In the presence of a biological response at week 2, detection of subsequent biological progression (significant increase in the amount of ctDNA relative to its nadir) was 100% predictive of progressive disease, on average 75 days prior to radiological detection. Patients with a persistent biological response beyond week 16 did not experience any progressive disease and exhibited sustained responses. In conclusion, we show that quantitative monitoring of ctDNA, using criteria accounting for dPCR measurement imprecision, allows the early and specific detection of patients who do not respond to anti-PD1 therapy

Emergence of High-Avidity Melan-A–Specific Clonotypes as a Reflection of Anti–PD-1 Clinical Efficacy

International audienceTherapeutic strategies using anti-PD-1-blocking antibodies reported unparalleled effectiveness for melanoma immunotherapy, but deciphering immune responses modulated by anti-PD-1 treatment remains a crucial issue. Here, we analyzed the composition and functions of the large Melan-A-specific T-cell repertoire in the peripheral blood of 9 melanoma patients before and after 2 months of treatment with anti-PD-1. We observed amplification of Melan-A-specific Vß subfamilies undetectable before therapy (thereafter called emerging Vß subfamilies) in responding patients, with a predominant expansion in patients with a complete response. These emerging Vß subfamilies displayed a higher functional avidity for their cognate antigen than Vß subfamilies not amplified upon anti-PD-1 therapy and could be identified by a sustained coexpression of PD-1 and TIGIT receptors. Thus, in addition to the emergence of neoantigen-specific T cells previously documented upon anti-PD-1 therapy, our work describes the emergence of high-avidity Melan-A-specific clonotypes as a surrogate marker of treatment efficacy

Profile of vemurafenib-induced severe skin toxicities

International audienceBACKGROUND: Vemurafenib, a BRAF inhibitor, is commonly associated with skin toxicity. The impact of severe forms is unknown.OBJECTIVE: To determine the rate of permanent vemurafenib discontinuation due to grade 3-4 skin toxicity, features of these toxicities, their recurrence rate after a switch to dabrafenib and their impact on overall survival.METHODS: Retrospective cohort study of 131 patients treated with vemurafenib for melanoma between November 2010 and December 2014. Data on skin toxicities, the need for vemurafenib adjustment and the impact of switching to dabrafenib were collected. Regarding survival analysis, a conditional landmark analysis was performed to correct lead-time bias.RESULTS: Among the 131 vemurafenib-treated patients, 26% developed grade 3-4 skin toxicity. Forty-four percent of them permanently discontinued their treatment, mainly due to rash and classic skin adverse reactions (Steven-Johnson syndrome, Drug Reaction with Eosinophilia and Systemic Symptoms). Conversely, photosensitivity and carcinomas rarely required treatment adjustment. Grade 3-4 rashes were associated with clinical or biological abnormalities in 94% of patients. Among the 10 patients who subsequently switched to dabrafenib, skin toxicity recurred only in one patient. Overall survival was significantly prolonged in case of severe skin toxicity emerging within the first 4 (P = 0.014) and 8 weeks (P = 0.038) on vemurafenib, with only a trend at 12 weeks (P = 0.052). Median overall survival was also prolonged in case of severe rash.CONCLUSION: In this study, vemurafenib was continued in 56% of patients with grade 3-4 skin toxicity, which was associated with prolonged overall survival when emerging within the first 4 and 8 weeks of treatment. While developing severe skin adverse reactions permanently contraindicates vemurafenib use, other rashes should lead to retreatment attempts with dose reduction. In case of recurrence, dabrafenib seems to be an interesting option. For other skin toxicities, including photosensitivity and cutaneous carcinoma, treatment adjustment is usually not needed