Immune checkpoints refer to a plethora of inhibitory pathways of the immune system that play a crucial role in maintaining self-tolerance and in tuning the duration and amplitude of physiological immune responses to minimize collateral tissue damages. The breakdown of this delicate balance leads to pathological conditions, including cancer. Indeed, tumor cells can develop multiple mechanisms to escape from immune system defense, including the activation of immune checkpoint pathways. The development of monoclonal antibodies, targeting inhibitory immune checkpoints, has provided an immense breakthrough in cancer therapy. Immune checkpoint inhibitors (ICI), initially developed to reverse functional exhaustion in T cells, recently emerged as important actors in natural killer (NK)-cell-based immunotherapy. Moreover, the discovery that also helper innate lymphoid cells (ILCs) express inhibitory immune checkpoints, suggests that these molecules might be targeted on ILCs, to modulate their functions in the tumor microenvironment. Recently, other strategies to achieve immune checkpoint blockade have been developed, including miRNA exploiting systems. Herein, we provide an overview of the current knowledge on inhibitory immune checkpoints on NK cells and ILCs and we discuss how to target these innate lymphocytes by ICI in both solid tumors and hematological malignancies.

Metabolic reprogramming is emerging as a cancer vulnerability that could be therapeutically exploitable using different approaches, including amino acid depletion for those tumors that rely on exogenous amino acids for their maintenance. ʟ-Asparaginase (ASNase) has contributed to a significant improvement in acute lymphoblastic leukemia outcomes; however, toxicity and resistance limit its clinical use in other tumors. Here, we report that, in multiple myeloma (MM) cells, the DNA methylation status is significantly associated with reduced expression of ASNase-related gene signatures, thus suggesting ASNase sensitivity for this tumor. Therefore, we tested the effects of ASNase purified from Erwinia chrysanthemi (Erw-ASNase), combined with the next-generation proteasome inhibitor (PI) carfilzomib. We observed an impressive synergistic effect on MM cells, whereas normal peripheral blood mononuclear cells were not affected. Importantly, this effect was associated with increased reactive oxygen species (ROS) generation, compounded mitochondrial damage, and Nrf2 upregulation, regardless of the c-Myc oncogenic-specific program. Furthermore, the cotreatment resulted in genomic instability and DNA repair mechanism impairment via increased mitochondrial oxidative stress, which further enhanced its antitumor activity. Interestingly, carfilzomib-resistant cells were found to be highly dependent on amino acid starvation, as reflected by their higher sensitivity to Erw-ASNase treatment compared with isogenic cells. Overall, by affecting several cellular programs, Erw-ASNase makes MM cells more vulnerable to carfilzomib, providing proof of concept for clinical use of this combination as a novel strategy to enhance PI sensitivity in MM patients.

CPX-351 has been approved for patients with therapy-related acute myeloid leukemia (t-AML) or AML with myelodysplasia-related changes (MRC-AML). No extensive data are available on measurable residual disease (MRD) and long-term clinical outcome using CPX-351 in AML in real life. We retrospectively collected data from 168 patients in 36 centers in France and Italy who had received 1 or 2 cycles of induction with CPX-351. All patients were aged >18 years and had newly diagnosed, untreated t-AML or MRC-AML. With a median follow-up of 3 years, the median overall survival (OS) was 13.3 months. The median OS was 20.4 months vs 12.9 months for patients with MRD below or above 10–3, respectively (P = .006). In a multivariate analysis, only MRD >10–3 was associated with a poorer OS (hazard ratio, 2.6; 95% confidence interval, 1.2-5.5; P = .013). We also observed a trend toward a better median OS in patients who underwent hematopoietic stem cell transplantation with MRD <10–3 (not reached vs 26.0 months; P = .06). Achievement of MRD negativity contributed to the improvement of OS in the overall population and, maybe, in patients receiving transplant. These data provide the rationale for the 2 ongoing studies evaluating CPX-351 vs 7+3 in non–MRC-AML and non–t-AML using MRD as the primary end point for ALFA-2101 phase 2 clinical trial and event-free survival for AMLSG 30-18 phase 3 clinical trial.

The mutations of NPM1 and FLT3-ITD represent the most frequent genetic aberration in acute myeloid leukemia. Indeed, the presence of an NPM1 mutation reduces the negative prognostic impact of FLT3-ITD in patients treated with conventional “3+7” induction. However, little information is available on their prognostic role with intensified regimens. Here, we investigated the efficacy of a fludarabine, high-dose cytarabine and idarubicin induction (FLAI) in 149 consecutive fit AML patients (median age 52) carrying the NPM1 and/or FLT3-ITD mutation, treated from 2008 to 2018. One-hundred-and-twenty-nine patients achieved CR (86.6%). After a median follow up of 68 months, 3-year overall survival was 58.6%. Multivariate analysis disclosed that both NPM1mut (p < 0.05) and ELN 2017 risk score (p < 0.05) were significant predictors of survival. NPM1-mutated patients had a favorable outcome, with no significant differences between patients with or without concomitant FLT3-ITD (p = 0.372), irrespective of FLT3-ITD allelic burden. Moreover, in landmark analysis, performing allogeneic transplantation (HSCT) in first CR proved to be beneficial only in ELN 2017 high-risk patients. Our data indicate that FLAI exerts a strong anti-leukemic effect in younger AML patients with NPM1mut and question the role of HSCT in 1st CR in NPM1mut patients with concomitant FLT3-ITD.