PD-L1 in Breast Cancer: The Road to the Perfect BiomarkerIs Fraught With Uncertainty

Constructing Hypoxia-Tolerant and Host Tumor-Enriched Aggregation-Induced Emission Photosensitizer for Suppressing Malignant Tumors Relapse and Metastasis

Photodynamic immunotherapy is a promising treatment strategy that destroys primary tumors and inhibits the metastasis and relapse of distant tumors. As reactive oxygen species are an intermediary for triggering immune responses, photosensitizers (PSs) that can actively target and efficiently trigger oxidative stress are urgently required. Herein, pyrrolo[3,2-b]pyrrole as an electronic donor is introduced in acceptor-donor-acceptor skeleton PSs (TP-IS1 and TP-IS2) with aggregation-induced emission properties and high absorptivity. Meanwhile, pyrrolo[3,2-b]pyrrole derivatives innovatively prove their ability of type I photoreaction, indicating their promising hypoxia-tolerant advantages. Moreover, M1 macrophages depicting an ultrafast delivery through the cell-to-cell tunneling nanotube pathway emerge to construct TP-IS1@M1 by coating the photosensitizer TP-IS1. Under low concentration of TP-IS1@M1, an effective immune response of TP-IS1@M1 is demonstrated by releasing damage-associated molecular patterns, maturating dendritic cells, and vanishing the distant tumor. These findings reveal insights into developing hypoxia-tolerant PSs and an efficient delivery method with unprecedented performance against tumor metastasis.

Addition of immunotherapy to chemotherapy for metastatic triple-negative breast cancer: A systematic review and meta-analysis of randomized clinical trials

BACKGROUND

One of the front treatment regimens used for metastatic triple-negative breast cancer (mTNBC) is treatment with programmed death-1 (PD-1) or programmed death ligand-1 (PD-L1) blockade combine with chemotherapy. However, the results of such studies have been controversial.

METHODS

A systematic searched of PubMed, Embase, Cochrane Library, and the proceedings of the last 5 years of several meetings until February 18, 2021. The primary endpoint was the progression-free survival (PFS) of PD-L1-positive patients treated with PD1/PD-L1 blockade plus chemotherapy compare with chemotherapy.

RESULTS

Overall, 4 studies that included a total of 3007 mTNBC patients were analyzed in this meta-analysis. PFS was significantly improved in the PD1/PD-L1 blockade plus chemotherapy group compared with the chemotherapy group in PD-L1-positive mTNBC patients (hazard ratios, (HR), 0.69; 95% CI, 0.59-0.80; P < .001), also in intention-to-treat (ITT) population (HR, 0.82; 95% CI, 0.74-0.90; P < .001). However, no significant benefit in overall survival (OS) was observed regardless of PD-L1 status or ITT population. The immunotherapy plus chemotherapy has higher adverse events (AEs) compared with chemotherapy (all AEs, Odds ratios (ORs), 2.33; 95% CI, 1.50-3.62; P < .001; grade 3-5 AEs, OR, 1.27; 95% CI, 1.04-1.55; P = .019).

CONCLUSIONS

This meta-analysis showed that the addition of PD1/PD-L1 blockade to chemotherapy improved PFS in PD-L1 positive mTNBC patients, also in the ITT population. However, no significant benefit in OS was observed in patients of PD-L1 positive or in the ITT population after adding PD1/PD-L1 blockade. We found a higher rate of AEs with the addition of PD1/PD-L1 blockers to chemotherapy.

Multiplexed immunofluorescence identifies high stromal CD68+PD-L1+ macrophages as a predictor of improved survival in triple negative breast cancer

Triple negative breast cancer (TNBC) comprises 10-15% of all breast cancers and has a poor prognosis with a high risk of recurrence within 5 years. PD-L1 is an important biomarker for patient selection for immunotherapy but its cellular expression and co-localization within the tumour immune microenvironment and associated prognostic value is not well defined. We aimed to characterise the phenotypes of immune cells expressing PD-L1 and determine their association with overall survival (OS) and breast cancer-specific survival (BCSS). Using tissue microarrays from a retrospective cohort of TNBC patients from St George Hospital, Sydney (n = 244), multiplexed immunofluorescence (mIF) was used to assess staining for CD3, CD8, CD20, CD68, PD-1, PD-L1, FOXP3 and pan-cytokeratin on the Vectra Polaris™ platform and analysed using QuPath. Cox multivariate analyses showed high CD68+PD-L1+ stromal cell counts were associated with improved prognosis for OS (HR 0.56, 95% CI 0.33-0.95, p = 0.030) and BCSS (HR 0.47, 95% CI 0.25-0.88, p = 0.018) in the whole cohort and in patients receiving chemotherapy, improving incrementally upon the predictive value of PD-L1+ alone for BCSS. These data suggest that CD68+PD-L1+ status can provide clinically useful prognostic information to identify sub-groups of patients with good or poor prognosis and guide treatment decisions in TNBC.