Cyclic adenosine monophosphate involvement in low-dose cyclophosphamide-reversed immune evasion in a mouse lymphoma model

Metronomic chemotherapy in hematology: Lessons from preclinical and clinical studies to build a solid rationale for future schedules

Metronomic chemotherapy (mCHEMO), based on frequent, regular administration of low, but pharmacologically active drug doses, optimizes antitumor efficacy by targeting multiple targets and reducing toxicity of antineoplastic drugs. This minireview will summarize preclinical and clinical studies on cytotoxic drugs given at weekly, daily, or at continuous metronomic schedules alone or in combination with novel targeted agents for hematological malignancies, including lymphoma, multiple myeloma, and leukemia. Most of the preclinical in vitro and in vivo studies have reported a significant benefit of both mCHEMO monotherapy and combinatorial regimens compared with chemotherapy at the maximum tolerated dose. However, the combination of mCHEMO with targeted drugs is still little explored in the hematologic clinical setting. Data obtained from preclinical studies on low dose metronomic chemotherapy in hematological malignancies clearly suggested the possibility to clinically investigate more tolerable and effective strategies for the treatment of patients with advanced hematological malignancies, or at least for those frail and elderly patients, who are not eligible or resistant to standard treatments.

Combination low-dose cyclophosphamide with check-point blockade and ionizing radiation promote an abscopal effect in mouse models of melanoma

PURPOSE

The complex strategy of hypo-fractionated radiotherapy (HFRT) in combination with an immune checkpoint inhibitor (ICI) can stimulate a potential systemic antitumor response; however, the abscopal effect is always precluded by the tumor microenvironment, which may limit sufficient T-cell infiltration of distant nonirradiated tumors for certain kinds of inhibitory factors, such as regulatory T-cells (Tregs). Additionally, low-dose cyclophosphamide (LD-CYC) can specifically kill regulatory Tregs and strongly synergize antigen-specific immune responses, which could promote an abscopal effect.

MATERIALS AND METHODS

We explored whether a triple regimen consisting of HFRT, ICI, and LD-CYC could achieve a better systemic antitumor response in bilateral mouse tumor models.

RESULT

Our data demonstrate that LD-CYC combined with HFRT and antiprogrammed cell death ligand 1 (PDL-1) therapy could enhance the abscopal effect than only HFRT/antiPDL-1 or HFRT alone. Surprisingly, repeat CYC doses cannot further restrain tumor proliferation but can prolong murine overall survival, as revealed by the major pathologic responses. These results are associated with increased CD8 + effector T-cell infiltration, although LD-CYC did not upregulate PDL-1 expression in the tumor.

CONCLUSIONS

Compared with traditional strategies, for the first time, we demonstrated that a triple treatment strategy remarkably increased the number of radiation-induced tumor-infiltrating CD8 + T-cells, effectively decreasing infiltrating Tregs, and promoting an abscopal effect. Thus, we describe a novel and effective therapeutic approach by combining multiple strategies to target several tumor-mediated immune inhibitory mechanisms.

Metronomic chemotherapy regimens and targeted therapies in non-Hodgkin lymphoma: The best of two worlds

Novel drugs are rapidly moving forward the treatment-paradigm of non-Hodgkin-lymphomas (NHLs). Notwithstanding, especially in aggressive subtypes, chemotherapy remains the pillar of treatment. Indeed, the combination of highly effective Maximum-Tolerated-Dose Chemotherapy (MTD-CHEMO) + "novel drugs", has so far, fallen short from expectations, often because it caused excessive toxicity. Metronomic chemotherapy (mCHEMO), which is the frequent, long-term administration of low dose cytotoxic drugs, may allow more effective and tolerable combinations. mCHEMO pharmacodynamics, has been described as pleiotropic. In fact, it may have different cellular and molecular targets, when drugs or their schedules are modified. Although mCHEMO has been little explored in NHLs, pre-clinical studies - in lymphoma models - which addressed the activity of mCHEMO in combination with novel drugs, have shown very promising results. These included inhibitors of histone deacetylase, mTOR and PI3K/mTOR, as well as the immune checkpoint inhibitor anti-PD-L1. Moreover, a few impressive reports have recently shown all-oral mCHEMO schedules, with or without rituximab, can effectively shrink both B and T-cell aggressive NHLs. Indeed, these regimens allowed elderly-frail patients to achieve sustained remission, while toxicity proved manageable. In our opinion, all-oral mCHEMO, is an active, easy-to start, well-tolerated, and inexpensive therapeutic approach, which deserves further investigation. Most importantly, mCHEMO, holds promise to empower the activity of novel targeted therapies, without causing excessive toxicity.

Identification of potential biomarkers associated with immune infiltration in papillary renal cell carcinoma

Background

Immunotherapeutic approaches have recently emerged as effective treatment regimens against various types of cancer. However, the immune‐mediated mechanisms surrounding papillary renal cell carcinoma (pRCC) remain unclear. This study aimed to investigate the tumor microenvironment (TME) and identify the potential immune‐related biomarkers for pRCC.

Methods

The CIBERSORT algorithm was used to calculate the abundance ratio of immune cells in each pRCC samples. Univariate Cox analysis was used to select the prognostic‐related tumor‐infiltrating immune cells (TIICs). Multivariate Cox regression analysis was performed to develop a signature based on the selected prognostic‐related TIICs. Then, these pRCC samples were divided into low‐ and high‐risk groups according to the obtained signature. Analyses using Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) were performed to investigate the biological function of the DEGs (differentially expressed genes) between the high‐ and low‐risk groups. The hub genes were identified using a weighted gene co‐expression network analysis (WGCNA) and a protein‐protein interaction (PPI) analysis. The hub genes were subsequently validated by multiple clinical traits and databases.

Results

According to our analyses, nine immune cells play a vital role in the TME of pRCC. Our analyses also obtained nine potential immune‐related biomarkers for pRCC, including TOP2A, BUB1B, BUB1, TPX2, PBK, CEP55, ASPM, RRM2, and CENPF.

Conclusion

In this study, our data revealed the crucial TIICs and potential immune‐related biomarkers for pRCC and provided compelling insights into the pathogenesis and potential therapeutic targets for pRCC.

Rituximab treatment circumvents the prognostic impact of tumor-infiltrating T-cells in follicular lymphoma patients

Previous immunohistochemical (IHC) studies showed controversial data about the prognostic value of tumor-infiltrating lymphocytes (TILs) in follicular lymphoma (FL). To clarify this issue, a large series of FL samples from rituximab-treated patients enrolled in the randomized PRIMA trial was examined. IHC was quantified using automated image analysis in 417, 287, 418, 406, 379, and 369 patients for CD3, CD4, CD8, PD1, ICOS, and FOXP3, respectively. RNAseq analysis was used to quantify TIL-related mRNA transcripts from 148 patients. When each IHC marker was used as a continuous variable in the whole cohort, high CD3 counts were associated with better progression-free survival (PFS) (P = .025). When an optimal IHC cut point was applied to the whole patient population, high CD3 counts and high PD1 counts were associated with better PFS (P = .011 and P = .044, respectively), whereas none of the other TIL markers had any significant correlation with outcome. When a stringent analysis was performed by dividing the whole cohort into a training set and a validation set, none of the TIL markers showed a prognostic significance in both groups. RNAseq analysis showed a significant correlation between high levels of CD3 and CD8 transcripts and better PFS (P = .001 and P = .037, respectively). No prognostic correlation was found as to the level of other immune gene transcripts. These results suggest that the IHC prognostic value of TILs is circumvented by rituximab treatment, although there is a trend for high numbers of CD3+ TILs to correlate with better PFS.

Follicular B Lymphomas Generate Regulatory T Cells via the ICOS/ICOSL Pathway and Are Susceptible to Treatment by Anti-ICOS/ICOSL Therapy

The prognosis of follicular lymphoma (FL) patients is suspected to be influenced by tumor-infiltrating regulatory T cells (Treg). The mechanism of Treg enrichment in FL and their impact on malignant FL B cells remains to be elucidated. We analyzed 46 fresh lymph node biopsy samples, including FL (n = 20), diffuse large B-cell lymphoma (n = 10), classical Hodgkin lymphoma (n = 9), and reactive lymphadenitis (n = 7). Using multicolor flow cytometry and cell sorting, we observed an accumulation of CD25(high)CD127(low/neg) Tregs in FL tissues. These Tregs comprised activated ICOS(+) Tregs that were able to suppress not only conventional T cells, but also FL B cells. These FL B cells were able to express ICOSL in vitro and to generate CD25(high)FoxP3(high) Tregs expressing ICOS. Treg generation was associated with ICOS/ICOSL engagement and was abrogated by antagonist anti-ICOS and anti-ICOSL antibodies. Interactions between Tregs and FL B cells resulted in ICOSL downregulation on FL B cells. Our results highlight a key role for Tregs in FL pathogenesis and suggest that targeting the ICOS/ICOSL pathway may be a promising immunotherapy for FL treatment. Cancer Res; 76(16); 4648-60. ©2016 AACR.

Combining low-dose or metronomic chemotherapy with anticancer vaccines: A therapeutic opportunity for lymphomas

Therapeutic vaccination is regarded as a promising strategy against multiple hematological malignancies including lymphoma. However, this approach alone possesses limited potential for the treatment of established tumors. As several anticancer regimens relies on the combination of multiple drugs, it is reasonable to predict that also cancer vaccination will be most effective in the context of multimodal approaches. In particular, low-dose or metronomic chemotherapy could be coupled to anticancer vaccines to improve the efficacy of this immunotherapeutic interventions. This review summarizes recent findings in support of the use of anticancer vaccines combined with low-dose or metronomic chemotherapy for the treatment and management of lymphoid malignancies.

A bystander cell-based GM-CSF secreting vaccine synergized with a low dose of cyclophosphamide presents therapeutic immune responses against murine hepatocellular carcinoma

Granulocyte-macrophage colony-stimulating factor (GM-CSF) secreting cellular tumor vaccines contribute to the induction of potent antitumor immune responses in murine models and patients suffering from cancers. Hepatocellular carcinoma (HCC) is one of the most frequent and malignant cancers in China. We describe, for the first time, a GM-CSF releasing vaccine strategy that represents a step toward combating this type of cancer. In this study, a bystander cell-based GM-CSF secreting vaccine against murine HCC, Hepa1-6/B78H1-GM-CSF, was co-administered with a low dose of cyclophosphamide (CY). After challenging with tumor and vaccination, immunological assays demonstrated that the cellular antitumor immune responses were efficiently activated and that tumor development was significantly retarded, which was dependent on synergy with CY. The promising outcome of the anti-HCC vaccine in the murine model demonstrates the feasibility of a future clinical application for this treatment in HCC patients.