Metronomic cyclophosphamide attenuates mTOR-mediated expansion of regulatory T cells, but does not impact clinical outcome in patients with metastatic renal cell cancer treated with everolimus

"Cyclophosphamide and analogues; a matter of dose and schedule for dual anticancer activities"

Cyclophosphamide and ifosfamide are major alkylating agents but their therapeutics uses are limiting by the toxicity due to several toxicities. Indeed conventional chemotherapies are generally used with the maximum tolerated dose. In contrast, metronomic schedule aims to get a minimum dose for efficacy with a good safety. Depending on the dose, their mechanisms of action are different and offer a dual activity: at high dose, cyclophosphamide is mainly used in graft conditioning for its immunosuppressive properties, while at metronomic dose it is used as an immunoactive agent. Currently, at metronomic dose, cyclophosphamide is studied in clinic against various types of cancer, alone or in combination with others anticancer drugs (anti-angiogenic, immune-modulating agents, immune checkpoints blockers, vaccines, radiotherapy, others conventional anticancer agents), as a nth-line or first-line treatment. More than three quarters of clinical studies show promising results, mostly in breast, ovarian and prostate cancers. Taking advantage of the immune system, use dual antitumor action's chemotherapy is clearly a therapeutic strategy that deserves to be confirmed in order to improve the efficacy/toxicity balance of anticancer treatments, and to use CPM or analogues as a standard of care.

Cancer immunometabolism: advent, challenges, and perspective

For decades, great strides have been made in the field of immunometabolism. A plethora of evidence ranging from basic mechanisms to clinical transformation has gradually embarked on immunometabolism to the center stage of innate and adaptive immunomodulation. Given this, we focus on changes in immunometabolism, a converging series of biochemical events that alters immune cell function, propose the immune roles played by diversified metabolic derivatives and enzymes, emphasize the key metabolism-related checkpoints in distinct immune cell types, and discuss the ongoing and upcoming realities of clinical treatment. It is expected that future research will reduce the current limitations of immunotherapy and provide a positive hand in immune responses to exert a broader therapeutic role.

Regulatory T cells: Their role in triple-negative breast cancer progression and metastasis

Triple-negative breast cancer (TNBC) is an aggressive and immunogenic subtype of breast cancer. This tumorigenicity is independent of hormonal or HER2 pathways because of a lack of respective receptor expression. TNBC is extremely prone to drug resistance and early recurrence because of T-regulatory cell (Treg) infiltration into the tumor microenvironment (TME) in addition to other mechanisms like genomic instability. Tumor-infiltrating Tregs interact with both tumor and stromal cells as well as extracellular matrix components in the TME and induce an immune-suppressive phenotype. Hence, treatment of TNBC with conventional therapies remains challenging. Understanding the protective mechanism of Tregs in shielding TNBC from antitumor immune responses in the TME will pave the way for developing novel, immune-based therapeutics. The current review focuses on the role of tumor-infiltrating Tregs in tumor progression and metabolic reprogramming of the TME. The authors have extended their focus to oncotargeting Treg-mediated immune suppression in breast cancer. Because of its potential role in the TME, modulating Treg activity may provide a novel strategic intervention to combat TNBC. Both under laboratory conditions and in clinical trials, currently available anticancer drugs and natural therapeutics as potential agents for targeting Tregs are explored.

Trial watch: chemotherapy-induced immunogenic cell death in immuno-oncology

The term ‘immunogenic cell death’ (ICD) denotes an immunologically unique type of regulated cell death that enables, rather than suppresses, T cell-driven immune responses that are specific for antigens derived from the dying cells. The ability of ICD to elicit adaptive immunity heavily relies on the immunogenicity of dying cells, implying that such cells must encode and present antigens not covered by central tolerance (antigenicity), and deliver immunostimulatory molecules such as damage-associated molecular patterns and cytokines (adjuvanticity). Moreover, the host immune system must be equipped to detect the antigenicity and adjuvanticity of dying cells. As cancer (but not normal) cells express several antigens not covered by central tolerance, they can be driven into ICD by some therapeutic agents, including (but not limited to) chemotherapeutics of the anthracycline family, oxaliplatin and bortezomib, as well as radiation therapy. In this Trial Watch, we describe current trends in the preclinical and clinical development of ICD-eliciting chemotherapy as partner for immunotherapy, with a focus on trials assessing efficacy in the context of immunomonitoring.