Neoantigen vaccine generates intratumoral T cell responses in phase Ib glioblastoma trial.

Neoantigens, which are derived from tumour-specific protein-coding mutations, are exempt from central tolerance, can generate robust immune responses1,2 and can function as bona fide antigens that facilitate tumour rejection3. Here we demonstrate that a strategy that uses multi-epitope, personalized neoantigen vaccination, which has previously been tested in patients with high-risk melanoma4-6, is feasible for tumours such as glioblastoma, which typically have a relatively low mutation load1,7 and an immunologically 'cold' tumour microenvironment8. We used personalized neoantigen-targeting vaccines to immunize patients newly diagnosed with glioblastoma following surgical resection and conventional radiotherapy in a phase I/Ib study. Patients who did not receive dexamethasone-a highly potent corticosteroid that is frequently prescribed to treat cerebral oedema in patients with glioblastoma-generated circulating polyfunctional neoantigen-specific CD4+ and CD8+ T cell responses that were enriched in a memory phenotype and showed an increase in the number of tumour-infiltrating T cells. Using single-cell T cell receptor analysis, we provide evidence that neoantigen-specific T cells from the peripheral blood can migrate into an intracranial glioblastoma tumour. Neoantigen-targeting vaccines thus have the potential to favourably alter the immune milieu of glioblastoma.

Hypoxemic Respiratory Failure Following Ruxolitinib Discontinuation in Allogeneic Hematopoietic Cell Transplantation Recipients.

Ruxolitinib, a selective inhibitor of Janus kinases 1 and 2, is increasingly being used in allogeneic hematopoietic cell transplantation (HCT) recipients following its approval by the U.S. Food and Drug Administration for the treatment of steroid-refractory acute graft-versus-host disease. Although there is extensive experience using ruxolitinib for patients with myeloproliferative neoplasms, the biologic effects and clinical implications of its dosing, tapering, and discontinuation for allogeneic HCT recipients are incompletely characterized. We describe three allogeneic HCT recipients who developed acute hypoxemic respiratory failure within 3 months of ruxolitinib discontinuation. Radiographic findings included marked bilateral ground-glass opacities. Systemic corticosteroids and reinitiation of ruxolitinib resulted in rapid clinical improvement in all three patients. All three patients achieved a significant clinical response, with decrease in oxygen requirement and improvement in radiographic changes. Given the increasing use of ruxolitinib in allogeneic HCT recipients, there is significant impetus to characterize the biologic and clinical effects resulting from discontinuation of ruxolitinib, to better tailor treatment plans and prevent potential adverse effects.

Multiorgan failure in a fatal case of autoimmune hemolytic anemia.

BACKGROUND: Autoimmune hemolytic anemia (AIHA) results in red blood cell destruction by auto-antibodies directed against surface antigens and is rarely fatal. Here we describe a case of AIHA, refractory to both standard and experimental therapies, complicated by multiorgan failure, and rapidly leading to death. CASE REPORT AND RESULTS: A 65 year-old man who presented with progressive dyspnea and jaundice was found to have hemolytic anemia. Diagnostic work-up revealed a positive direct antiglobulin test and a strong pan-reactive antibody in the plasma reacting to a titer of 1:1024 with strongest reactivity at 37 °C Coombs' phase with reagent anti-IgG. The red cell eluate contained a pan-agglutinin. The patient received multiple lines of treatment including glucocorticoids, intravenous immunoglobulin, rituximab, eculizumab, splenectomy and etoposide. Despite these interventions, he continued to experience brisk hemolysis and remained transfusion dependent. Repeat testing on day 16 demonstrated persistent high titer IgG auto-antibodies, suggesting minimal suppressive effect of therapy. His course was complicated by acute renal and liver failure, venous thrombosis, and worsening coagulopathy, and he ultimately died from multiorgan failure on day 18. CONCLUSION: Severe cases of AIHA can result in multiorgan failure and a fatal outcome. The rapid development of liver failure in this setting has been described in only few case reports to date, and represents an important complication for clinicians to be aware of when treating patients with AIHA.

A cloning and expression system to probe T-cell receptor specificity and assess functional avidity to neoantigens.

Recent studies have highlighted the promise of targeting tumor neoantigens to generate potent antitumor immune responses and provide strong motivation for improving our understanding of antigen-T-cell receptor (TCR) interactions. Advances in single-cell sequencing technologies have opened the door for detailed investigation of the TCR repertoire, providing paired information from TCRα and TCRß, which together determine specificity. However, a need remains for efficient methods to assess the specificity of discovered TCRs. We developed a streamlined approach for matching TCR sequences with cognate antigen through on-demand cloning and expression of TCRs and screening against candidate antigens. Here, we first demonstrate the system's capacity to identify viral-antigen-specific TCRs and compare the functional avidity of TCRs specific for a given antigen target. We then apply this system to identify neoantigen-specific TCR sequences from patients with melanoma treated with personalized neoantigen vaccines and characterize functional avidity of neoantigen-specific TCRs. Furthermore, we use a neoantigen-prediction pipeline to show that an insertion-deletion mutation in a putative chronic lymphocytic leukemia (CLL) driver gives rise to an immunogenic neoantigen mut-MGA, and use this approach to identify the mut-MGA-specific TCR sequence. This approach provides a means to identify and express TCRs, and then rapidly assess antigen specificity and functional avidity of a reconstructed TCR, which can be applied for monitoring antigen-specific T-cell responses, and potentially for guiding the design of effective T-cell-based immunotherapies.

Evolutionary history of transformation from chronic lymphocytic leukemia to Richter syndrome.

Richter syndrome (RS) arising from chronic lymphocytic leukemia (CLL) exemplifies an aggressive malignancy that develops from an indolent neoplasm. To decipher the genetics underlying this transformation, we computationally deconvoluted admixtures of CLL and RS cells from 52 patients with RS, evaluating paired CLL-RS whole-exome sequencing data. We discovered RS-specific somatic driver mutations (including IRF2BP2, SRSF1, B2M, DNMT3A and CCND3), recurrent copy-number alterations beyond del(9p21)(CDKN2A/B), whole-genome duplication and chromothripsis, which were confirmed in 45 independent RS cases and in an external set of RS whole genomes. Through unsupervised clustering, clonally related RS was largely distinct from diffuse large B cell lymphoma. We distinguished pathways that were dysregulated in RS versus CLL, and detected clonal evolution of transformation at single-cell resolution, identifying intermediate cell states. Our study defines distinct molecular subtypes of RS and highlights cell-free DNA analysis as a potential tool for early diagnosis and monitoring.

Directing Traffic: How to Effectively Drive T Cells into Tumors.

Although immune checkpoint inhibitors (ICI) have demonstrated clinical activity in multiple tumor types, the majority of patients do not respond to ICI monotherapy. Mounting evidence suggests that ICI-mediated clinical responses rely upon tumor infiltration by T cells that are able to recognize and kill cancer cells. Here, we review therapeutic modalities that have been shown to promote T-cell infiltration into human tumors in studies to date, and discuss emerging data guiding how these modalities can be sequenced in order to optimize T-cell effector function and memory T-cell generation, while minimizing overactivation and potential toxicity. SIGNIFICANCE: The lack of preexisting T-cell inflammation in tumors is a major barrier to effective cancer immunity. A deep understanding of the mechanisms that prevent T cells from trafficking into the tumor in a given individual will be critical for tailoring immunotherapy combinations that can overcome resistance to ICI in patients with cancer.

The regulation of growth and metabolism of kidney stem cells with regional specificity using extracellular matrix derived from kidney.

Native extracellular matrix (ECM) that is secreted and maintained by resident cells is of great interest for cell culture and cell delivery. We hypothesized that specialized bioengineered niches for stem cells can be established using ECM-derived scaffolding materials. Kidney was selected as a model system because of the high regional diversification of renal tissue matrix. By preparing the ECM from three specialized regions of the kidney (cortex, medulla, and papilla; whole kidney, heart, and bladder as controls) in three forms: (i) intact sheets of decellularized ECM, (ii) ECM hydrogels, and (iii) solubilized ECM, we investigated how the structure and composition of ECM affect the function of kidney stem cells (with mesenchymal stem cells, MSCs, as controls). All three forms of the ECM regulated KSC function, with differential structural and compositional effects. KSCs cultured on papilla ECM consistently displayed lower proliferation, higher metabolic activity, and differences in cell morphology, alignment, and structure formation as compared to KSCs on cortex and medulla ECM, effects not observed in corresponding MSC cultures. These data suggest that tissue- and region-specific ECM can provide an effective substrate for in vitro studies of therapeutic stem cells.