Calreticulin exposure on malignant blasts correlates with improved natural killer cell-mediated cytotoxicity in acute myeloid leukemia patients.

In some settings, cancer cells responding to treatment undergo an immunogenic form of cell death that is associated with the abundant emission of danger signals in the form of damage-associated molecular patterns. Accumulating preclinical and clinical evidence indicates that danger signals play a crucial role in the (re-)activation of antitumor immune responses in vivo, thus having a major impact on patient prognosis. We have previously demonstrated that the presence of calreticulin on the surface of malignant blasts is a positive prognostic biomarker for patients with acute myeloid leukemia (AML). Calreticulin exposure not only correlated with enhanced T-cell-dependent antitumor immunity in this setting but also affected the number of circulating natural killer (NK) cells upon restoration of normal hematopoiesis. Here, we report that calreticulin exposure on malignant blasts is associated with enhanced NK cell cytotoxic and secretory functions, both in AML patients and in vivo in mice. The ability of calreticulin to stimulate NK-cells relies on CD11c+CD14high cells that, upon exposure to CRT, express higher levels of IL-15Rα, maturation markers (CD86 and HLA-DR) and CCR7. CRT exposure on malignant blasts also correlates with the upregulation of genes coding for type I interferon. This suggests that CD11c+CD14high cells have increased capacity to migrate to secondary lymphoid organs, where can efficiently deliver stimulatory signals (IL-15Rα/IL-15) to NK cells. These findings delineate a multipronged, clinically relevant mechanism whereby surface-exposed calreticulin favors NK-cell activation in AML patients.

Phase 1 study of lenalidomide plus dose-adjusted EPOCH-R in patients with aggressive B-cell lymphomas with deregulated MYC and BCL2.

BACKGROUND: Dual translocation of MYC and BCL2 or the dual overexpression of these proteins in patients with aggressive B-cell lymphomas (termed double-hit lymphoma [DHL] and double-expressor lymphoma [DEL], respectively) have poor outcomes after chemoimmunotherapy with the combination of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). Retrospective reports have suggested improved outcomes with dose-intensified regimens. In the current study, the authors conducted a phase 1 study to evaluate the feasibility, toxicity, and preliminary efficacy of adding lenalidomide to dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin with rituximab (DA-EPOCH-R) in patients with DHL and DEL. METHODS: The primary objective of the current study was to determine the maximum tolerated dose of lenalidomide in combination with DA-EPOCH-R. A standard 3+3 design was used with lenalidomide administered on days 1 to 14 of each 21-day cycle (dose levels of 10 mg, 15 mg, and 20 mg). Patients attaining a complete response after 6 cycles of induction therapy proceeded to maintenance lenalidomide (10 mg daily for 14 days every 21 days) for 12 additional cycles. RESULTS: A total of 15 patients were enrolled, 10 of whom had DEL and 5 of whom had DHL. Two patients experienced dose-limiting toxicities at a lenalidomide dose of 20 mg, consisting of grade 4 sepsis. The maximum tolerated dose of lenalidomide was determined to be 15 mg. The most common nonhematologic grade ≥3 adverse events included thromboembolism (4 patients; 27%) and hypokalemia (2 patients; 13%) (toxicities were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.0]). The preliminary efficacy of the regimen was encouraging, especially in the DEL cohort, in which all 10 patients achieved durable and complete metabolic responses with a median follow-up of 24 months. CONCLUSIONS: The combination of lenalidomide with DA-EPOCH-R appears to be safe and feasible in patients with DHL and DEL. These encouraging results have prompted an ongoing phase 2 multicenter study.

Therapeutic activity of high-dose intratumoral IFN-ß requires direct effect on the tumor vasculature.

Endogenous type I IFN production after innate immune recognition of tumor cells is critical for generating natural adaptive immune responses against tumors in vivo. We recently have reported that targeting low doses of IFN-ß to the tumor microenvironment using tumor-specific mAbs can facilitate antitumor immunity, which could be augmented further with PD-L1/PD-1 blockade. However, sustained high doses of type I IFNs in the tumor microenvironment, which are potently therapeutic alone, may function through distinct mechanisms. In the current report, we demonstrate that high-dose intratumoral type I IFNs indeed exerted a profound therapeutic effect in the murine B16 model, which unexpectedly did not increase T cell responses. Moreover, bone marrow chimeras revealed a role for type I IFN signaling on nonhematopoietic cells, and most of the therapeutic effect was retained in mice deficient in T, B, and NK cells. Rather, the tumor vasculature was ablated with high-dose intratumoral IFN-ß, and conditional deletion of IFN-α/ßR in Tie2-positive vascular endothelial cells eliminated most of the antitumor activity. Therefore, the major component of the antitumor activity of sustained high doses of type I IFNs occurs through a direct antiangiogenic effect. Our data help resolve conditions under which distinct antitumor mechanisms of type I IFNs are operational in vivo.

Optimization of Metabolic Tumor Volume as a Prognostic Marker in CAR T-Cell Therapy for Aggressive Large B-cell NHL.

BACKGROUND: CD19-targeted chimeric antigen receptor (CAR) T-cell therapy has become a standard of care in relapsed/refractory (R/R) aggressive large B-cell non-Hodgkin lymphomas (B-NHL) though the majority of recipients do not receive durable disease benefit, prompting the need to better define risk factors for relapse/progression. OBJECTIVES: We performed a single-center, retrospective analysis of patients treated with commercial CAR T-cell therapy to evaluate the impact of tumor burden, as measured by whole-body metabolic tumor volume (MTV) from 18F fluorodeoxyglucose PET imaging, on treatment outcomes. STUDY DESIGN: Sixty-one patients treated with CAR T-cell therapy for R/R B-NHL between May 2016 and November 2021 were included. RESULTS: Using a receiver operating characteristic curve-based MTV optimization cutoff of 450 mL, 1-year progression-free survival (PFS) was 22% for high MTV versus 54% for low MTV (P < .01), and 1-year overall survival (OS) was 37% and 73%, respectively (P = .01). In a subset of 46 patients, residual MTV of less than 106 mL at the day 30 (D30) disease assessment was associated with significantly improved outcomes (1-year OS 85% vs. 13%, P < .01). Incorporation of pretreatment MTV to the International Prognostic Index (IPI) scoring system significantly distinguished 2-year PFS and OS outcomes by 3 risk groups. CONCLUSIONS: Our findings suggest that both pretreatment and D30 MTV are predictive of outcomes among R/R B-NHL patients treated with CAR T-cell therapy. These data indicate that efforts to reduce pretreatment tumor burden may improve longitudinal clinical outcomes. Furthermore, D30 postinfusion MTV quantification may aid clinicians in optimally identifying patients at high-risk for progression, and in whom closer disease monitoring should be considered. MTV also adds prognostic value to patients with high-risk IPI and holds promise for incorporation in novel risk scoring systems which can identify patients prior to CAR T-cell therapy at highest risk of adverse outcomes.

FLT3 inhibitor maintenance after allogeneic stem cell transplantation in FLT3-mutated acute myeloid leukemia (AML) patients.

Background: The somatic mutation of fms-like tyrosine kinase 3 (FLT3) in acute myeloid leukemia (AML) is associated with increased risk of relapse and lower survival rates. FLT3i as maintenance after allogeneic hematopoietic stem cell transplant (allo-HSCT) are under study to prevent disease relapse, but real-world data are lacking. Methods: We performed a single center, retrospective cohort study and analyzed patients who had FLT3-mutated AML and underwent allogeneic-HSCT between January 2011 to June 2022 at the University of Chicago. We identified 23 patients who received FLT3i maintenance therapy post-allo-HSCT and compared their outcomes against 57 patients who did not. Primary outcome was disease-free survival (DFS). Secondary outcomes include overall survival (OS) and relapse rate. Results: FLT3i maintenance therapy was started at a median 59 days (range, 29-216 days) after allo-HSCT with median duration of 287 days (range, 15-1,194 days). Maintenance therapy was well tolerated. Overall, the improvement in DFS rates for patients after they were placed on FLT3i maintenance therapy was not significant [hazard ratio (HR) for relapse or death =0.65, 95% confidence interval (CI): 0.32-1.31, P=0.23]. However, when adjusted for the conditioning regimen and donor status, the differences were statistically significant with improvement in DFS and OS for patients on FLT3i maintenance (HR for OS =0.42, 95% CI: 0.18-0.95, P=0.04). Conclusions: When adjusting for conditioning regimen and donor status, there was a significant improvement in DFS and OS for patients who received FLT3i maintenance therapy compared to those who did not. Randomized prospective studies may provide more insight.

TIGIT is a key inhibitory checkpoint receptor in lymphoma.

BACKGROUND: PD-1 checkpoint blockade therapy (CBT) has greatly benefited patients with select solid tumors and lymphomas but has limited efficacy against diffuse large B-cell lymphoma (DLBCL). Because numerous inhibitory checkpoint receptors have been implicated in driving tumor-specific T cell dysfunction, we hypothesized that combinatorial CBT would enhance the activity of anti-PD-1-based therapy in DLBCL. T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT) is a coinhibitory receptor expressed on dysfunctional tumor-infiltrating T cells, and TIGIT blockade has demonstrated encouraging activity in combination with PD-1 blockade in murine tumor models and in clinical studies. However, the degree to which TIGIT mediates T cell dysfunction in DLBCL has not been fully explored. RESULTS: Here, we demonstrate that TIGIT is broadly expressed on lymphoma-infiltrating T cells (LITs) across a variety of human lymphomas and is frequently coexpressed with PD-1. TIGIT expression is particularly common on LITs in DLBCL, where TIGIT+ LITs often form distinct cellular communities and exhibit significant contact with malignant B cells. TIGIT+/PD-1+ LITs from human DLBCL and murine lymphomas exhibit hypofunctional cytokine production on ex vivo restimulation. In mice with established, syngeneic A20 B-cell lymphomas, TIGIT or PD-1 mono-blockade leads to modest delays in tumor outgrowth, whereas PD-1 and TIGIT co-blockade results in complete rejection of A20 lymphomas in most mice and significantly prolongs survival compared with mice treated with monoblockade therapy. CONCLUSIONS: These results provide rationale for clinical investigation of TIGIT and PD-1 blockade in lymphomas, including DLBCL.

TIM-3 levels correlate with enhanced NK cell cytotoxicity and improved clinical outcome in AML patients.

Accumulating evidence indicates that immune checkpoint inhibitors (ICIs) can restore CD8+ cytotoxic T lymphocyte (CTL) functions in preclinical models of acute myeloid leukemia (AML). However, ICIs targeting programmed cell death 1 (PDCD1, best known as PD-1) and cytotoxic T lymphocyte-associated protein 4 (CTLA4) have limited clinical efficacy in patients with AML. Natural killer (NK) cells are central players in AML-targeting immune responses. However, little is known on the relationship between co-inhibitory receptors expressed by NK cells and the ability of the latter to control AML. Here, we show that hepatitis A virus cellular receptor 2 (HAVCR2, best known as TIM-3) is highly expressed by NK cells from AML patients, correlating with improved functional licensing and superior effector functions. Altogether, our data indicate that NK cell frequency as well as TIM-3 expression levels constitute prognostically relevant biomarkers of active immunity against AML.

Antigen-Multimers: Specific, Sensitive, Precise, and Multifunctional High-Avidity CAR-Staining Reagents.

Although chimeric antigen receptor (CAR) T-cell therapy has transformed cancer treatment, high-quality and universal CAR-staining reagents are urgently required to manufacture CAR T cells, predict therapy response, decipher CAR biology, and engineer new CARs. Here, we developed tetrameric and dodecameric forms of a multifunctional and extensible category of high-avidity CAR-staining reagents: antigen-multimers. Antigen-multimers detected CARs against CD19, HER2, and Tn-glycoside with significantly higher specificity, sensitivity, and precision than existing reagents. In addition to accurate CAR T-cell detection by flow cytometry, antigen-multimers also enabled ≥100-fold magnetic enrichment of rare CAR T cells, selective CAR T-cell stimulation, and high-dimensional CAR T-cell profiling by single-cell multi-omics analyses. Finally, antigen-multimers accurately captured clinical anti-CD19 CAR T cells from patients' cellular infusion products, post-infusion peripheral blood, and tumor biopsies. Antigen-multimers can be readily extended to other CAR systems by switching its antigen ligand. As such, antigen-multimers have broad clinical and research applications.

Recommendations and outcomes from a geriatric assessment guided multidisciplinary clinic prior to autologous stem cell transplant in older patients.

BACKGROUND: Autologous hematopoietic stem cell transplant (autoHCT) is a mainstay of treatment for multiple myeloma and non-Hodgkin lymphoma but is underutilized in older adults. We investigated the association of vulnerabilities identified by a geriatric assessment (GA)-guided multidisciplinary clinic (MDC) on the receipt of autoHCT and evaluated its ability to predict outcomes in older autoHCT candidates. METHODS: Patients 50+ years received GA-informed optimization recommendations: 'decline' if unlikely to realize benefits of autoHCT, 'defer' if optimization necessary before autoHCT, and 'proceed' if autoHCT could proceed without delay. We compared characteristics and outcomes of autoHCT recipients (n = 62) to non-autoHCT patients (n = 29) and evaluated GA deficits on outcomes. RESULTS: 91 patients were evaluated; the MDC recommendation was 'decline' for 5 (6%), 'defer' for 25 (27%), and 'proceed' for 61 (67%). AutoHCT recipients had fewer GA-rated impairments relative to non-autoHCT patients, as did patients with a 'proceed' recommendation relative to 'defer'. Among autoHCT recipients, 1-year and 3-year non-relapse morality (NRM) was 0% and 5%, and there was no difference in length of hospitalization, readmission rate, or mortality after transplant by MDC recommendation. Frail grip strength and poor performance status were associated with inferior post-autoHCT progression-free survival and overall survival. CONCLUSIONS: Patients pursuing autoHCT after MDC-directed optimization achieved excellent outcomes, including patients deferred but ultimately receiving autoHCT. GA-identified functional deficits, especially frail grip strength, may improve risk stratification in older autoHCT candidates. Employing a GA earlier in the disease trajectory to inform early referral to an MDC may increase autoHCT safety and utilization in older patients.

Calreticulin arms NK cells against leukemia.

Calreticulin (CALR) exposed on the surface of cancer cells succumbing to therapy delivers robust phagocytic signals that support the activation of adaptive anticancer immune responses. Recent data from our group demonstrate that spontaneous CARL exposure on leukemic blasts also supports innate anticancer immunity by natural killer (NK) cells via an indirect mechanism relying on myeloid CD11c+CD14+ cells.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of lymphoma.

The recent development and clinical implementation of novel immunotherapies for the treatment of Hodgkin and non-Hodgkin lymphoma have improved patient outcomes across subgroups. The rapid introduction of immunotherapeutic agents into the clinic, however, has presented significant questions regarding optimal treatment scheduling around existing chemotherapy/radiation options, as well as a need for improved understanding of how to properly manage patients and recognize toxicities. To address these challenges, the Society for Immunotherapy of Cancer (SITC) convened a panel of experts in lymphoma to develop a clinical practice guideline for the education of healthcare professionals on various aspects of immunotherapeutic treatment. The panel discussed subjects including treatment scheduling, immune-related adverse events (irAEs), and the integration of immunotherapy and stem cell transplant to form recommendations to guide healthcare professionals treating patients with lymphoma.

T-cell-depleted allogeneic transplant without donor leukocyte infusions results in excellent long-term survival in patients with multiply relapsed Lymphoma. Predictors for survival after transplant relapse.

We analyzed 67 patients with lymphoma who received alemtuzumab-based conditioning regimens for allogeneic stem cell transplant and no post-transplant DLI. The median age was 54 (24-70), 43% had unrelated donors, 34% had chemotherapy refractory disease, and 25% had an elevated LDH. With a median follow-up for survivors of 35 months, the estimated 3-year progression-free survival (PFS) and overall survival (OS) were 30% and 47%, respectively. Chemosensitivity by CT and pre-transplant LDH were independent prognostic factors for both overall survival and progression-free survival. Patient age, performance status, donor type, lymphoma subtype, disease sensitivity by PET, and conditioning regimen did not correlate with PFS and OS. Patients who relapsed greater than 6 months after allogeneic transplant were frequently able to re-enter a subsequent durable remission. Our experience confirms the curative potential of alemtuzumab-containing RIC regimens for allogeneic HCT in patients with relapsed lymphoma without prophylactic DLI. An elevated pre-transplant LDH and chemorefractory disease prior to transplant confer a worse prognosis, while PET scan findings do not have this same implication. Patients who relapse greater than 6 months after their transplant are likely to achieve a subsequent remission with any of a variety of interventions, suggesting that GVL effects can be operative even after recurrence. Our outcomes challenge the utility of the common practice of prophylactic DLI after T-depleted transplant for lymphoma.

Clofarabine in the treatment of acute myeloid leukaemia and acute lymphoblastic leukaemia: a review.

Clofarabine, a synthesised adenosine nucleoside, has recently demonstrated single-agent activity in the acute leukaemias. Originally developed to capture the best qualities of cladribine and fludarabine, clofarabine contains halogenated carbons, rendering it resistant to inactivating enzymes and maintaining its stability in acidic environments. Like other adenosine nucleosides, clofarabine acts by inhibiting ribonucleotide reductase and DNA polymerase, thereby depleting the amount of intracellular deoxynucleoside triphosphates available for DNA replication and also resulting in premature DNA chain termination. Clofarabine has also been shown to induce apoptosis in transformed cell lines, indicating that clofarabine results in cell death in both cycling and non-cycling cells. Interest in the development of clofarabine was initially hampered by the availability of other active nucleoside analogues for the treatment of haematological malignancies. However, the results of several early-phase trials evaluating the use of clofarabine in acute leukaemias in adults and children have rekindled enthusiasm for further investigation into its use. This article describes the development, pharmacology, toxicity and clinical activity of clofarabine, as well as discuss its potential role in the treatment of acute leukaemia.