PD-1 blockade and CDK4/6 inhibition augment nonoverlapping features of T cell activation in cancer

Phase I study of ribociclib (CDK4/6 inhibitor) with spartalizumab (PD-1 inhibitor) with and without fulvestrant in metastatic hormone receptor-positive breast cancer or advanced ovarian cancer

BACKGROUND

Preclinical evidence suggests that cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors enhance antitumor immunity. We conducted a phase I trial of ribociclib (CDK4/6 inhibitor) plus spartalizumab (PD-1 inhibitor) in patients with hormone receptor (HR)-positive/HER2-negative metastatic breast cancer (MBC) or advanced ovarian cancer (AOC). The combination was also evaluated with fulvestrant in MBC.

METHODS

In Cohort A, ribociclib was administered on Days 1-21 (28-day cycle) starting at 400 mg, and spartalizumab at 400 mg on Day 1. Dose escalation was followed by expansion in AOC. Fulvestrant was added (Cohort B) with a safety run-in followed by expansion in MBC. Primary objectives were to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D), and safety and tolerability of the combinations.

RESULTS

33 patients enrolled (n=18, Cohort A; n=15, Cohort B). The RP2D of ribociclib in both cohorts was 600 mg. Treatment-related adverse events in >20% of patients in either cohort were neutropenia, fatigue, anemia, thrombocytopenia, hypertransaminasemia, maculopapular rash, fatigue, and nausea. Hypertransaminasemia occurred in 66.7% (AST) and 46.7% (ALT) of patients in Cohort B, including 46.7% and 40.0%, respectively, of grade 3 or 4 events. Two confirmed partial responses were observed (13.3%) in Cohort B, in patients with low baseline serum thymidine kinase activity, coupled with an increase on-treatment. Peripheral blood flow cytometry across patients demonstrated on-target drug binding with increases in PD-1 occupancy and activated CD8+ T cells during treatment, irrespective of response. PD-L1-positivity, tumor-infiltrating lymphocytes, or tumor mutational burden did not correlate with progression-free survival (PFS). Several copy-number variations detected with next-generation sequencing correlated with PFS.

CONCLUSIONS

Ribociclib with spartalizumab and fulvestrant showed limited efficacy and elevated hepatotoxicity, precluding further development. Correlative analyses revealed treatment-induced immunological effects, and genomic alterations associated with PFS.

Biomimetic Targeted Co-Delivery System Engineered from Genomic Insights for Precision Treatment of Osteosarcoma

The high heterogeneity and severe side effects of chemotherapy are major factors contributing to the failure of osteosarcoma treatment. Herein, a comprehensive genomic analysis is conducted, and identified two prominent characteristics of osteosarcoma: significant cyclin-dependent kinases 4 (CDK4) amplification and homologous recombination repair deficiency. Based on these findings, a co-delivery system loaded with CDK4/6 inhibitors and poly ADP-ribose polymerase (PARP) inhibitors is designed. By employing metal-organic frameworks (MOFs) as carriers, issue of drug insolubility is effectively addressed, while also enabling controlled release in response to the tumor microenvironment. To enhance targeting capability and biocompatibility, the MOFs are further coated with a bio-membrane targeting B7H3. This targeted biomimetic co-delivery system possesses several key features: 1) it can precisely target osteosarcoma with high B7H3 expression; 2) the combination of CDK4/6 inhibitors and PARP inhibitors exhibits synergistic effects, significantly impairing tumor's DNA repair capacity; and 3) the system has the potential for combination with photodynamic therapy, amplifying DNA repair defects to maximize tumor cell eradication. Furthermore, it is observed that this co-delivery system can activate immune microenvironment, increasing CD8+ T cell infiltration and converting osteosarcoma from an immune-cold to an immune-hot tumor. In summary, the co-delivery system is an effective therapeutic strategy and holds promise as a novel approach for osteosarcoma treatment.

Efficacy and safety of PD-1 and PD-L1 inhibitors in advanced colorectal cancer: a meta-analysis of randomized controlled trials

BACKGROUND

PD-1 and PD-L1 inhibitors have emerged as promising therapies for advanced colorectal cancer (CRC), but their efficacy and safety profiles require further evaluation. This meta-analysis aims to assess the efficacy and safety of PD-1/PD-L1 inhibitors in this patient population.

METHODS

A systematic review and meta-analysis were conducted following PRISMA guidelines, with data sourced from PubMed, Embase, CENTRAL, Web of Science, and CNKI up to August 3, 2024. Nine randomized controlled trials (RCTs) involving 1680 patients were included. The primary outcomes were overall survival (OS), progression-free survival (PFS) and objective response rate (ORR), while safety was assessed through adverse events (AEs) and grade ≥ 3 AEs. Effect sizes were calculated using mean differences (MD) and risk ratios (RR) with 95% confidence intervals (CIs).

RESULTS

Overall, the meta-analysis showed that PD-1/PD-L1 inhibitors did not significantly extend OS (MD = 0.86, 95% CI: -0.55, 2.27), but they significantly improved PFS (MD = 2.53, 95% CI: 0.92, 4.15). Additionally, PD-1/PD-L1 inhibitors did not significantly increase the ORR compared to controls (RR = 1.19, 95% CI: 0.99, 1.44). In terms of safety, PD-1/PD-L1 inhibitors did not significantly increase the incidence of overall AEs. Subgroup analysis further indicated that PD-1 inhibitors significantly improved OS (MD = 1.24, 95% CI: 0.20, 2.29) and PFS (MD = 6.27, 95% CI: 0.56, 11.97), while PD-L1 inhibitors did not have a significant impact on these outcomes. Additionally, PD-L1 inhibitors were associated with a higher risk of grade ≥ 3 AEs (RR = 1.29, 95% CI: 1.07, 1.57), a risk not observed with PD-1 inhibitors.

CONCLUSION

PD-1 inhibitors significantly improve PFS and OS in advanced CRC, making them a preferable option over PD-L1 inhibitors, which show limited efficacy and a higher risk of severe AEs. These findings support prioritizing PD-1 inhibitors in clinical practice for this patient group, while caution is warranted with PD-L1 inhibitors due to their safety concerns.

TRIAL REGISTRATION

PROSPERO (CRD42024611696).

Blockade of IL1β and PD1 with Combination Chemotherapy Reduces Systemic Myeloid Suppression in Metastatic Pancreatic Cancer with Heterogeneous Effects in the Tumor

Innate inflammation promotes tumor development, although the role of innate inflammatory cytokines in established human tumors is unclear. Herein, we report clinical and translational results from a phase Ib trial testing whether IL1β blockade in human pancreatic cancer would alleviate myeloid immunosuppression and reveal antitumor T-cell responses to PD1 blockade. Patients with treatment-naïve advanced pancreatic ductal adenocarcinoma (n = 10) were treated with canakinumab, a high-affinity monoclonal human antiinterleukin-1β (IL1β), the PD1 blocking antibody spartalizumab, and gemcitabine/n(ab)paclitaxel. Analysis of paired peripheral blood from patients in the trial versus patients receiving multiagent chemotherapy showed a modest increase in HLA-DR+CD38+ activated CD8+ T cells and a decrease in circulating monocytic myeloid-derived suppressor cells (MDSC) by flow cytometry for patients in the trial but not in controls. Similarly, we used patient serum to differentiate monocytic MDSCs in vitro and showed that functional inhibition of T-cell proliferation was reduced when using on-treatment serum samples from patients in the trial but not when using serum from patients treated with chemotherapy alone. Within the tumor, we observed few changes in suppressive myeloid-cell populations or activated T cells as assessed by single-cell transcriptional profiling or multiplex immunofluorescence, although increases in CD8+ T cells suggest that improvements in the tumor immune microenvironment might be revealed by a larger study. Overall, the data indicate that exposure to PD1 and IL1β blockade induced a modest reactivation of peripheral CD8+ T cells and decreased circulating monocytic MDSCs; however, these changes did not lead to similarly uniform alterations in the tumor microenvironment.

ALK5/VEGFR2 dual inhibitor TU2218 alone or in combination with immune checkpoint inhibitors enhances immune-mediated antitumor effects

Transforming growth factor β (TGFβ) is present in blood of patients who do not respond to anti-programmed cell death (ligand) 1 [PD-(L)1] treatment, and through synergy with vascular endothelial growth factor (VEGF), it helps to create an environment that promotes tumor immune evasion and immune tolerance. Therefore, simultaneous inhibition of TGFβ/VEGF is more effective than targeting TGFβ alone. In this study, the dual inhibitory mechanism of TU2218 was identified through in vitro analysis mimicking the tumor microenvironment, and its antitumor effects were analyzed using mouse syngeneic tumor models. TU2218 directly restored the activity of damaged cytotoxic T lymphocytes (CTLs) and natural killer cells inhibited by TGFβ and suppressed the activity and viability of regulatory T cells. The inactivation of endothelial cells induced by VEGF stimulation was completely ameliorated by TU2218, an effect not observed with vactosertib, which inhibits only TGFβ signaling. The combination of TU2218 and anti-PD1 therapy had a significantly greater antitumor effect than either drug alone in the poorly immunogenic B16F10 syngeneic tumor model. The mechanism of tumor reduction was confirmed by flow cytometry, which showed upregulated VCAM-1 expression in vascular cells and increased influx of CD8 + CTLs into the tumor. As another strategy, combination of anti-CTLA4 therapy and TU2218 resulted in high complete regression (CR) rates in CT26 and WEHI-164 tumor models. In particular, immunological memory generated by the combination of anti-CTLA4 and TU2218 in the CT26 model prevented the development of tumors after additional tumor cell transplantation, suggesting that the TU2218-based combination has therapeutic potential in immunotherapy.

Blocking the CTLA-4 and PD-1 pathways during pulmonary paracoccidioidomycosis improves immunity, reduces disease severity, and increases the survival of infected mice

Immune checkpoint pathways, i.e., coinhibitory pathways expressed as feedback following immune activation, are crucial for controlling an excessive immune response. Cytotoxic T lymphocyte antigen-4 (CTLA-4) and programmed cell death protein-1 (PD-1) are the central classical checkpoint inhibitory (CPI) molecules used for the control of neoplasms and some infectious diseases, including some fungal infections. As the immunosuppression of severe paracoccidioidomycosis (PCM), a chronic granulomatous fungal disease, was shown to be associated with the expression of coinhibitory molecules, we hypothesized that the inhibition of CTLA-4 and PD-1 could have a beneficial effect on pulmonary PCM. To this end, C57BL/6 mice were infected with Paracoccidioides brasiliensis yeasts and treated with monoclonal antibodies (mAbs) α-CTLA-4, α-PD-1, control IgG, or PBS. We verified that blockade of CTLA-4 and PD-1 reduced the fungal load in the lungs and fungal dissemination to the liver and spleen and decreased the size of pulmonary lesions, resulting in increased survival of mice. Compared with PBS-treated infected mice, significantly increased levels of many pro- and anti-inflammatory cytokines were observed in the lungs of α-CTLA-4-treated mice, but a drastic reduction in the liver was observed following PD-1 blockade. In the lungs of α-CPI and IgG-treated mice, there were no changes in the frequency of inflammatory leukocytes, but a significant reduction in the total number of these cells was observed. Compared with PBS-treated controls, α-CPI- and IgG-treated mice exhibited reduced pulmonary infiltration of several myeloid cell subpopulations and decreased expression of costimulatory molecules. In addition, a decreased number of CD4+ and CD8+ T cells but sustained numbers of Th1, Th2, and Th17 T cells were detected. An expressive reduction in several Treg subpopulations and their maturation and suppressive molecules, in addition to reduced numbers of Treg, TCD4+, and TCD8+ cells expressing costimulatory and coinhibitory molecules of immunity, were also detected. The novel cellular and humoral profiles established in the lungs of α-CTLA-4 and α-PD-1-treated mice but not in control IgG-treated mice were more efficient at controlling fungal growth and dissemination without causing increased tissue pathology due to excessive inflammation. This is the first study demonstrating the efficacy of CPI blockade in the treatment of pulmonary PCM, and further studies combining the use of immunotherapy with antifungal drugs are encouraged.

PD-1 Blockade Induces Reactivation of Nonproductive T-Cell Responses Characterized by NF-κB Signaling in Patients with Pancreatic Cancer

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) trials have evaluated CTLA-4 and/or PD-(L)1 blockade in patients with advanced disease in which bulky tumor burden and limited time to develop antitumor T cells may have contributed to poor clinical efficacy. Here, we evaluated peripheral blood and tumor T cells from patients with PDAC receiving neoadjuvant chemoradiation plus anti-PD-1 (pembrolizumab) versus chemoradiation alone. We analyzed whether PD-1 blockade successfully reactivated T cells in the blood and/or tumor to determine whether lack of clinical benefit could be explained by lack of reactivated T cells versus other factors.

EXPERIMENTAL DESIGN

We used single-cell transcriptional profiling and TCR clonotype tracking to identify TCR clonotypes from blood that match clonotypes in the tumor.

RESULTS

PD-1 blockade increases the flux of TCR clonotypes entering cell cycle and induces an IFNγ signature like that seen in patients with other GI malignancies who respond to PD-1 blockade. However, these reactivated T cells have a robust signature of NF-κB signaling not seen in cases of PD-1 antibody response. Among paired samples between blood and tumor, several of the newly cycling clonotypes matched activated T-cell clonotypes observed in the tumor.

CONCLUSIONS

Cytotoxic T cells in the blood of patients with PDAC remain sensitive to reinvigoration by PD-1 blockade, and some have tumor-recognizing potential. Although these T cells proliferate and have a signature of IFN exposure, they also upregulate NF-κB signaling, which potentially counteracts the beneficial effects of anti-PD-1 reinvigoration and marks these T cells as non-productive contributors to antitumor immunity. See related commentary by Lander and DeNardo, p. 474.

Changes in T lymphocyte subsets predict the efficacy of atezolizumab in advanced non-small cell lung cancer: a retrospective study

Background

It has remained unclear how programmed cell death ligand 1 (PD-L1) inhibitors affect peripheral blood lymphocyte (PBL) subsets in patients with advanced non-small cell lung cancer (NSCLC). This study assessed the predictive and prognostic value of PBL subsets in patients with advanced NSCLC who were treated with atezolizumab.

Methods

A total of 30 patients with advanced NSCLC treated with atezolizumab were selected as the observation group, and 30 healthy individuals were chosen as the control group during same period. Flow cytometry was used to detect lymphocyte subsets before and after treatment. The relationship between the changes of lymphocyte subsets and atezolizumab in the treatment of NSCLC was analyzed and calculated.

Results

Before treatment, compared with the control group, the number of CD3+, CD4+ T, and CD4+/CD8+ indexes in the observation group were significantly decreased, whereas the level of CD8+ was significantly increased. The number of CD3+, CD4+ T, and CD4+/CD8+ indexes gradually increased with the process of atezolizumab treatment, whereas the number of CD8+ T gradually decreased. After the 4 cycles, the number of CD3+, CD4+ T, and CD4+/CD8+ indexes were significantly increased, and the number of CD8+ was significantly decreased. In the observation group, 22 patients achieved partial response (PR)/stable disease (SD) and 8 patients achieved progressive disease (PD) after 4 cycles of atezolizumab treatment. Before treatment, there were no significant differences in the level of lymphocyte subsets between those who achieved PR/SD or PD. However, a significant difference in the level of lymphocyte subsets appeared after 4 cycles of atezolizumab treatment. Among the 22 patients who achieved PR/SD, the number of CD3+, CD4+ T, and CD4+/CD8+ indexes were significantly increased, whereas the number of CD8+ T lymphocytes was significantly decreased. Meanwhile, the 8 patients who achieved PD displayed different results. In addition, ROC curve combined detection of CD3+, CD4+, and CD8+ T [area under the curve (AUC) =0.9018, P<0.0001] showed good predictive ability for the efficacy of atezolizumab in advanced NSCLC.

Conclusions

Atezolizumab may alter the level of lymphocyte subsets in patients with advanced NSCLC, and the changes in lymphocyte subsets may predict the efficacy of atezolizumab for these patients.

The correlation between gut and intra-tumor microbiota and PDAC: Etiology, diagnostics and therapeutics

Pancreatic ductal adenocarcinoma (PDAC) is one of the lethal cancers in the world and its 5-year survival rate is <10%. Due to the unique TME and dense tissue structure, its curative efficacy is far from satisfactory，the immunotherapy is even more invalid. According to the recent studies, the gut and tumor microbiota have been proved to play a key role in the development, progression and prognosis of PDAC. Based on the differences of microbiome composition observed in PDAC patients and normal pancreas, many researches have been made focusing on the latent communication between gut and intra-tumor microbiota and PDAC. In this review, we will demonstrate the potential mechanism of the oncogenic effects of GM and IM and their crucial effects on modulating the TME. Besides, we focus on their interaction with chemotherapeutic and immunotherapeutic drugs and inducing the drug resistance, thus enlightening the promising role to be used to monitor the occurrence of PDAC, accurately modulate the immune environment to promote the therapeutic efficacy and predict the prognosis.