Metabolic interventions combined with CTLA-4 and PD-1/PD-L1 blockade for the treatment of tumors: mechanisms and strategies / 医学前沿

Immunotherapies based on immune checkpoint blockade (ICB) have significantly improved patient outcomes and offered new approaches to cancer therapy over the past decade. To date, immune checkpoint inhibitors (ICIs) of CTLA-4 and PD-1/PD-L1 represent the main class of immunotherapy. Blockade of CTLA-4 and PD-1/PD-L1 has shown remarkable efficacy in several specific types of cancers, however, a large subset of refractory patients presents poor responsiveness to ICB therapy; and the underlying mechanism remains elusive. Recently, numerous studies have revealed that metabolic reprogramming of tumor cells restrains immune responses by remodeling the tumor microenvironment (TME) with various products of metabolism, and combination therapies involving metabolic inhibitors and ICIs provide new approaches to cancer therapy. Nevertheless, a systematic summary is lacking regarding the manner by which different targetable metabolic pathways regulate immune checkpoints to overcome ICI resistance. Here, we demonstrate the generalized mechanism of targeting cancer metabolism at three crucial immune checkpoints (CTLA-4, PD-1, and PD-L1) to influence ICB therapy and propose potential combined immunotherapeutic strategies co-targeting tumor metabolic pathways and immune checkpoints.

Assessment of the safety and efficacy of combination chemotherapy and PD-1/PD-L1 inhibitor treatment of breast cancer: A meta-analysis / 中华医学杂志(英文版)

BACKGROUND@#As the efficacy of programmed cell death-1/programmed death-ligand 1 (PD-1/PD-L1) inhibitors combined with chemotherapy in curing breast cancer is still controversial, this meta-analysis compares the efficacy and safety of PD-1/PD-L1 inhibitors combined with chemotherapy and chemotherapy alone in the treatment of breast cancer, which provides guidance for the clinical treatment.@*METHODS@#Relevant studies published as of April 2022 in the various databases including EMBASE, PubMed, and Cochrane Library were selected. Randomized controlled trials (RCTs) in which control patients underwent chemotherapy alone and experimental group patients underwent combination chemotherapy and PD-1/PD-L1 inhibitor treatment were included in this investigation. Investigations without complete information, researches from which information could not be extracted, duplicate articles, animal studies, review articles, and systematic reviews were excluded. STATA 15.1 was employed for all statistical analyses.@*RESULTS@#In total, eight eligible studies were identified, revealing that combination chemotherapy and PD-1/PD-L1 inhibitor treatment was linked to significant increases in progression-free survival (PFS) relative to chemotherapy alone (hazard ratio [HR] = 0.83, 95% confidence interval [CI]: 0.70-0.99, P = 0.032) but not overall survival (HR = 0.92, 95% CI: 0.80-1.06, P = 0.273). Pooled adverse event rates were also increased within the group of combination treatment relative to the chemotherapy group (risk ratio [RR] = 1.08, 95% CI: 1.03-1.14, P = 0.002). Specifically, nausea rates were lesser within the group of combination treatment relative to the group of chemotherapy (RR = 0.48, 95% CI: 0.25-0.92, P = 0.026). Subgroup analyses indicated that the PFS of patients who underwent combination atezolizumab or pembrolizumab and chemotherapy treatment were substantially longer than those of patients who underwent chemotherapy alone (HR = 0.79, 95% CI: 0.69-0.89, P ≤0.001; HR = 0.79, 95% CI: 0.67-0.92, P = 0.002).@*CONCLUSIONS@#The pooled results suggest that combination chemotherapy and PD-1/PD-L1 inhibitor treatment approaches help prolong PFS in breast cancer patients, but have no statistically significant effect on overall survival (OS). Additionally, combination therapy can significantly improve complete response rate (CRR) compared with chemotherapy alone. However, combination therapy was associated with greater rates of adverse events.

Immunotherapy treatment against cervical cancer

ABSTRACT Cervical cancer (CC) is one of the most common gynecological tumors and an important health problem, especially in developing countries. The vast majority of patients in early stages are cured of the disease with surgical treatment and with concomitant chemoradiotherapy in locally advanced stages. However, in patients with recurrent, persistent, or metastatic cervical CC, the effectiveness of treatment is limited, except for the combination of chemotherapy based on platinum doublets plus bevacizumab, the treatment that has achieved the best results to date. Programmed cell death-1/PD ligand-1 (PD-1/PD-L1) inhibitors could be a novel and cutting-edge therapeutic option to improve clinical outcomes in this group of patients. Thus far, there are a few Phase I/II clinical trials that have assessed the usefulness of pembrolizumab and nivolumab in this group of patients; these include the KEYNOTE 028, KEYNOTE 158, and CHECKMATE 358 trials, in which clinical benefit has been proven with PD-1/PD-L1 inhibitors in recurrent, persistent, or metastatic CC, as second-line treatment. There are also some ongoing trials that could provide further evidence on the PD-1/PD-L1 pathway as a therapeutic target in CC. In this review, we will focus on the usefulness of these PD-1/PDL1 inhibitors in CC, as well as on trials that are still in the recruitment phase, to confirm their effectiveness in this clinical setting.

Immunotherapy with PD-1 and PD-L1 inhibitors for prostate cancer / 中华男科学杂志

Prostate cancer (PCa) has become one of the common malignant diseases in elderly men, and its incidence is increasing year by year. Apart from surgery, radiotherapy and chemotherapy, immunotherapy, as with the programmed death receptor-1 (PD-1) or the programmed death ligand-1 (PD-L1) inhibitor, is a most promising new strategy for the treatment of PCa. PD-1 and PD-L1 inhibitors restore the activity of T cells by blocking the PD-1/PD-L1 signaling pathway in tumor cells, reverse the mechanism of tumor immune escape, recover the immune system and directly kill tumor cells. This review focuses on the current progress in the studies of PD-1 and PD-L1 inhibitors in the treatment of PCa.

Novel thioredoxin reductase inhibitor butaselen inhibits tumorigenesis by down-regulating programmed death-ligand 1 expression / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

The thioredoxin system plays a role in a variety of physiological functions, including cell growth, differentiation, apoptosis, tumorigenesis, and immunity. We previously confirmed that butaselen (BS), a novel thioredoxin reductase inhibitor, can inhibit the growth of various human cancer cell lines, yet the underlying mechanism remains elusive. In this study, we investigated the anti-tumor effect of BS in vivo through regulating the immune system of KM mice. We found that BS inhibits tumor proliferation by promoting the activation of splenic lymphocytes in mice. BS can elevate the percentage of CD4-CD8+ T lymphocytes and the secretion of downstream cytokines in mice via down-regulating the expression of programmed death-ligand 1 (PD-L1) on the tumor cells' surface in vivo. Further study in HepG2 and BEL-7402 cells showed that decrease of PD-L1 level after BS treatment was achieved by inhibiting signal transducer and activator of transcription 3 (STAT3) phosphorylation. Taken together, our results suggest that BS has a role in promoting the immune response by reducing PD-L1 expression via the STAT3 pathway, and subsequently suppresses tumorigenesis.

Perspectives on the clinical development of immunotherapy in prostate cancer / 亚洲男科学杂志(英文版)

Despite impressive survival benefits with immunotherapy in patients with various solid tumors, the full potential of these agents in prostate cancer has yet to be realized. Sipuleucel-T demonstrated a survival benefit in this population, indicating that prostate cancer is an immunoresponsive disease; however, these results have not been matched by other agents. A large trial with ipilimumab in prostate cancer failed to meet its primary objective, and small trials with PD-1/PD-L1 inhibitors did not yield a significant improvement in overall response. However, several late-stage clinical trials are underway with other vaccines in prostate cancer. Reports of clinical benefit with immunotherapies, particularly when used in combination or a select population, have provided the framework to develop sound clinical trials. Understanding immunogenic modulation, antigen spread, biomarkers, and DNA-repair defects will also help mold future strategies. Through rational patient selection and evidence-based combination approaches, patients with prostate cancer may soon derive durable survival benefits with immunotherapies.

Effects of lung cancer cell-associated B7-H1 on T-cell proliferation in vitro and in vivo

B7 homolog 1 (B7-H1) is the most potent immunoinhibitory molecule in the B7 family. In this study, we examined the effects of tumor-associated B7-H1 on T-cell proliferation in lung cancer. The expression of B7-H1 in human adenocarcinoma A549 and mouse Lewis lung carcinoma (LLC) cells were examined by flow cytometry. To assess the in vitro effect of tumor-associated B7-H1 on T-cell proliferation, we isolated T cells from peripheral blood mononuclear cells (PBMCs) of healthy individuals, labeled them with carboxyfluorescein succinimidyl ester, and co-cultured them with A549 cells in the absence or presence of anti-B7-H1 antibody. For in vivo analysis, LLC cells were subcutaneously injected into mice treated or not with anti-B7-H1 antibody. T-cell proliferation in both in vitro and in vivo assays was analyzed by flow cytometry. In vitro, co-culturing T cells with A549 cells significantly inhibited the proliferation of the former compared with the proliferation of T cells alone (P<0.01), and the addition of B7-H1 blocking antibody dramatically reversed the inhibition of T-cell proliferation by A549 cells. Similarly, in mice bearing LLC-derived xenograft tumors, in vivo administration of anti-B7-H1 antibody significantly increased the total number of spleen and tumor T cells compared to levels in control mice that did not receive anti-B7-H1 antibody. Functionally, in vivo administration of anti-B7-H1 antibody markedly reduced tumor growth. Tumor-associated B7-H1 may facilitate immune evasion by inhibiting T-cell proliferation. Targeting of this mechanism offers a promising therapy for cancer immunotherapy.