Limited tumor infiltration by activated T effector cells restricts the therapeutic activity of regulatory T cell depletion against established melanoma

Interference with inhibitory immunological checkpoints controlling T cell activation provides new opportunities to augment cancer immunotherapies. Whereas cytotoxic T lymphocyte–associated antigen-4 blockade has shown promising preclinical and clinical results, therapeutic CD4+CD25+ T reg cell depletion has failed to consistently enhance immune-based therapies. Using B16/BL6, a transplantable murine melanoma model, we show a dichotomy between the effects of T reg cell depletion on tumor rejection dependent on whether depletion occurs before (prophylactic) or after (therapeutic) tumor engraftment. Failure to promote rejection with therapeutic depletion is not related to lack of T reg cell depletion, to elimination of CD25+ effector T cells, or to a failure to enhance systemic antitumor T cell responses, but correlates with failure of effector cells to infiltrate the tumor and increase the intratumor ratio of effector T cell/T reg cell. Finally, systemic antitumor responses generated upon therapeutic T reg cell depletion are significantly stronger than those generated in the presence of T reg cells, and are capable of eliciting rejection of established tumors after transfer into immunoablated recipients receiving combination immunotherapy. The data demonstrate a dissociation between measurable systemic responses and tumor rejection during CD25-directed T reg cell depletion, and suggest an alternative, clinically applicable strategy for the treatment of established tumors

Donor whole blood DNA methylation is not a strong predictor of acute graft versus host disease in unrelated donor allogeneic haematopoietic cell transplantation

Allogeneic hematopoietic cell transplantation (HCT) is used to treat many blood-based disorders and malignancies. While this is an effective treatment, it can result in serious adverse events, such as the development of acute graft-versus-host disease (aGVHD). This study aimed to develop a donor-specific epigenetic classifier that could be used in donor selection in HCT to reduce the incidence of aGVHD. The discovery cohort of the study consisted of 288 donors from a population receiving HLA-A, -B, -C and -DRB1 matched unrelated donor HCT with T cell replete peripheral blood stem cell grafts for treatment of acute leukaemia or myelodysplastic syndromes after myeloablative conditioning. Donors were selected based on recipient aGVHD outcome; this cohort consisted of 144 cases with aGVHD grades III-IV and 144 controls with no aGVHD that survived at least 100 days post-HCT matched for sex, age, disease and GVHD prophylaxis. Genome-wide DNA methylation was assessed using the Infinium Methylation EPIC BeadChip (Illumina), measuring CpG methylation at >850,000 sites across the genome. Following quality control, pre-processing and exploratory analyses, we applied a machine learning algorithm (Random Forest) to identify CpG sites predictive of aGVHD. Receiver operating characteristic (ROC) curve analysis of these sites resulted in a classifier with an encouraging area under the ROC curve (AUC) of 0.91. To test this classifier, we used an independent validation cohort (n=288) selected using the same criteria as the discovery cohort. Different attempts to validate the classifier using the independent validation cohort failed with the AUC falling to 0.51. These results indicate that donor DNA methylation may not be a suitable predictor of aGVHD in an HCT setting involving unrelated donors, despite the initial promising results in the discovery cohort. Our work highlights the importance of independent validation of machine learning classifiers, particularly when developing classifiers intended for clinical use

AKT inhibition generates potent polyfunctional clinical grade AUTO1 CAR T-cells, enhancing function and survival

BACKGROUND: AUTO1 is a fast off-rate CD19-targeting chimeric antigen receptor (CAR), which has been successfully tested in adult lymphoblastic leukemia. Tscm/Tcm-enriched CAR-T populations confer the best expansion and persistence, but Tscm/Tcm numbers are poor in heavily pretreated adult patients. To improve this, we evaluate the use of AKT inhibitor (VIII) with the aim of uncoupling T-cell expansion from differentiation, to enrich Tscm/Tcm subsets. METHODS: VIII was incorporated into the AUTO1 manufacturing process based on the semiautomated the CliniMACS Prodigy platform at both small and cGMP scale. RESULTS: AUTO1 manufactured with VIII showed Tscm/Tcm enrichment, improved expansion and cytotoxicity in vitro and superior antitumor activity in vivo. Further, VIII induced AUTO1 Th1/Th17 skewing, increased polyfunctionality, and conferred a unique metabolic profile and a novel signature for autophagy to support enhanced expansion and cytotoxicity. We show that VIII-cultured AUTO1 products from B-ALL patients on the ALLCAR19 study possess superior phenotype, metabolism, and function than parallel control products and that VIII-based manufacture is scalable to cGMP. CONCLUSION: Ultimately, AUTO1 generated with VIII may begin to overcome the product specific factors contributing to CD19+relapse

Systematic Evaluation of the Immune Environment of Small Intestinal Neuroendocrine Tumours

BACKGROUND: The immune tumour microenvironment and the potential therapeutic opportunities for immunotherapy in small intestinal neuroendocrine tumours (siNET) have not been fully defined. METHODS: Herein, we studied 40 patients with primary and synchronous metastatic siNETs , and matched blood and normal tissue obtained during surgery. We interrogated the immune checkpoint landscape using multi-parametric flow cytometry. Additionally, matched FFPE tissue was obtained for multi-parametric immunohistochemistry (IHC) to determine the relative abundance and distribution of T-cell infiltrate. Tumour mutational burden (TMB) was also assessed and correlated with immune infiltration. RESULTS: Effector tumour infiltrating lymphocytes had a higher expression of PD-1 in the tumour microenvironment compared to the periphery. Additionally, CD8+ tumour infiltrating lymphocytes had a significantly higher co-expression of PD-1/ICOS and PD-1/CTLA-4 and higher levels of PD-1 expression compared to normal tissue. IHC revealed that the majority of cases have {less than or equal to}10% intratumoural T cells but a higher number of peritumoural T cells, demonstrating an "exclusion" phenotype. Finally, we confirmed that siNETs have a low TMB compared to other tumour types in the TCGA database but did not find a correlation between TMB and CD8/Treg ratio. CONCLUSIONS: Taken together, these results suggest that a combination therapy approach will be required to enhance the immune response, using PD-1 as a checkpoint immunomodulator backbone in combination with other checkpoint targeting molecules (CTLA-4 or ICOS), or with drugs targeting other pathways to recruit "excluded" T cells into the tumour microenvironment to treat patients with siNETs

Tumor-reactive CD4+ T cells develop cytotoxic activity and eradicate large established melanoma after transfer into lymphopenic hosts

Adoptive transfer of large numbers of tumor-reactive CD8+ cytotoxic T lymphocytes (CTLs) expanded and differentiated in vitro has shown promising clinical activity against cancer. However, such protocols are complicated by extensive ex vivo manipulations of tumor-reactive cells and have largely focused on CD8+ CTLs, with much less emphasis on the role and contribution of CD4+ T cells. Using a mouse model of advanced melanoma, we found that transfer of small numbers of naive tumor-reactive CD4+ T cells into lymphopenic recipients induces substantial T cell expansion, differentiation, and regression of large established tumors without the need for in vitro manipulation. Surprisingly, CD4+ T cells developed cytotoxic activity, and tumor rejection was dependent on class II–restricted recognition of tumors by tumor-reactive CD4+ T cells. Furthermore, blockade of the coinhibitory receptor CTL-associated antigen 4 (CTLA-4) on the transferred CD4+ T cells resulted in greater expansion of effector T cells, diminished accumulation of tumor-reactive regulatory T cells, and superior antitumor activity capable of inducing regression of spontaneous mouse melanoma. These findings suggest a novel potential therapeutic role for cytotoxic CD4+ T cells and CTLA-4 blockade in cancer immunotherapy, and demonstrate the potential advantages of differentiating tumor-reactive CD4+ cells in vivo over current protocols favoring in vitro expansion and differentiation

Misalignment evaluation of superconducting magnets in the relativistic heavy ion collider

In this paper, we first present the procedures for aligning and installing RHIC superconducting magnets, and then discuss the effects and compensation methods for the remaining misalignments

Immunotherapy with CD25/CD71-allodepleted T cells to improve T-cell reconstitution after matched unrelated donor hematopoietic stem cell transplant: a randomized trial

BACKGROUND AND AIMS: Delayed immune reconstitution is a major challenge after matched unrelated donor (MUD) stem cell transplant (SCT). In this randomized phase 2 multi-center trial, Adoptive Immunotherapy with CD25/71 allodepleted donor T cells to improve immunity after unrelated donor stem cell transplant (NCT01827579), the authors tested whether allodepleted donor T cells (ADTs) can safely be used to improve immune reconstitution after alemtuzumab-based MUD SCT for hematological malignancies. METHODS: Patients received standard of care or up to three escalating doses of ADTs generated through CD25+/CD71+ immunomagnetic depletion. The primary endpoint of the study was circulating CD3+ T-cell count at 4 months post-SCT. Twenty-one patients were treated, 13 in the ADT arm and eight in the control arm. RESULTS: The authors observed a trend toward improved CD3+ T-cell count at 4 months in the ADT arm versus the control arm (230/µL versus 145/µL, P = 0.18), and three ADT patients achieved normal CD3+ T-cell count at 4 months (>700/µL). The rates of significant graft-versus-host disease (GVHD) were comparable in both cohorts, with grade ≥2 acute GVHD in seven of 13 and four of eight patients and chronic GVHD in three of 13 and three of eight patients in the ADT and control arms, respectively. CONCLUSIONS: These data suggest that adoptive transfer of ADTs is safe, but that in the MUD setting the benefit in terms of T-cell reconstitution is limited. This approach may be of more use in the context of more rigorous T-cell depletion

Outcomes after alemtuzumab-containing reduced-intensity allogeneic transplantation regimen for relapsed and refractory non-Hodgkin lymphoma

18-60 months) , the actuarial overall survival (OS) rates at 3 years were 34% for HG-NHL, 60% for MCL, and 73% for LG-NHL (P < .001). The 100-day and 3-year transplant-related mortality (TRM) rates for patients with LG-NHL were 2% and 11%, respectively, and were better (P ‫؍‬ .01) than they were for patients with HG-NHL (27% and 38%, respectively). The actuarial current progression-free survival (PFS) rate at 3 years, including the rate for patients who achieved remission after donor lymphocyte infusion (DLI) for progression, was 65% for LG-NHL, 50% for MCL, and 34% for HG-NHL (P ‫؍‬ .002)

Dual targeting of CD19 and CD22 with Bicistronic CAR-T cells in Patients with Relapsed/Refractory Large B Cell Lymphoma

Relapse following CD19-directed chimeric antigen receptor T-cells (CAR-T) for relapsed/refractory large B-cell lymphoma (r/r LBCL) is commonly ascribed to antigen loss or CAR-T exhaustion. Multi-antigen targeting and PD-1 blockade are rational approaches to prevent relapse. Here, we test CD19/22 dual-targeting CAR-T (AUTO3) plus pembrolizumab in r/r LBCL as inpatient or outpatient therapy (NCT03289455, https://clinicaltrials.gov/ct2/show/NCT03289455). Endpoints include toxicity (primary) and response rates (secondary). AUTO3 was manufactured for 62 patients using autologous leukapheresis, modified with a bicistronic transgene. 52 patients received AUTO3 (7/52,50x106; 45/52,150-450x106) and 48/52 received pembrolizumab. Median age was 59 years (range,27-83) and 46/52 had stage III/IV disease. Median follow-up was 21.6 months (range,15.1-51.3) at last data cut (Feb 28, 2022). AUTO3 was safe: grade 1-2 and grade 3 CRS affected 18/52 (34.6%) and 1/52 (1.9%) patients, neurotoxicity arose in 4 patients (2/4, grade 3-4), HLH affected 2 patients, and no Pembrolizumab-associated autoimmune sequalae were observed. On this basis, outpatient administration was tested in 20 patients, saving a median of 14 hospital days/patient. AUTO3 was effective: overall response rates were 66% (48.9%, CR; 17%, PR). For patients with CR, median DOR was not reached, with 54.4% (CI: 32.8, 71.7) projected to remain progression-free beyond 12 months after onset of remission. DOR for all responding patients was 8.3 months (95% CI: 3.0, NE) with 42.6% projected to remain progression-free beyond 12 months after onset of remission. Overall, AUTO3 +/- pembrolizumab for r/r LBCL was safe, lending itself to outpatient administration, and delivered durable remissions in 54.4% of complete responders, associated with robust CAR-T expansion. Neither dual-targeting CAR-T nor pembrolizumab prevented relapse in a significant proportion of patients, and future developments include next-generation-AUTO3, engineered for superior expansion/persistence in vivo, and selection of CAR binders active at low antigen densities