Clinical efficacy of immune checkpoint inhibitors in patients with brain metastases

The Role of Microglia in Brain Metastases: Mechanisms and Strategies

Brain metastases and related complications are one of the major fatal factors in cancer. Patients with breast cancer, lung cancer, and melanoma are at a high risk of developing brain metastases. However, the mechanisms underlying the brain metastatic cascade remain poorly understood. Microglia, one of the major resident macrophages in the brain parenchyma, are involved in multiple processes associated with brain metastasis, including inflammation, angiogenesis, and immune modulation. They also closely interact with metastatic cancer cells, astrocytes, and other immune cells. Current therapeutic approaches against metastatic brain cancers, including small-molecule drugs, antibody-coupled drugs (ADCs), and immune-checkpoint inhibitors (ICIs), have compromised efficacy owing to the impermeability of the blood-brain barrier (BBB) and complex brain microenvironment. Targeting microglia is one of the strategies for treating metastatic brain cancer. In this review, we summarize the multifaceted roles of microglia in brain metastases and highlight them as potential targets for future therapeutic interventions.

An Overview of Systemic Targeted Therapy in Renal Cell Carcinoma, with a Focus on Metastatic Renal Cell Carcinoma and Brain Metastases

The most commonly diagnosed malignancy of the urinary system is represented by renal cell carcinoma. Various subvariants of RCC were described, with a clear-cell type prevailing in about 85% of all RCC tumors. Patients with metastases from renal cell carcinoma did not have many effective therapies until the end of the 1980s, as long as hormonal therapy and chemotherapy were the only options available. The outcomes were unsatisfactory due to the poor effectiveness of the available therapeutic options, but then interferon-alpha and interleukin-2 showed treatment effectiveness, providing benefits but only for less than half of the patients. However, it was not until 2004 that targeted therapies emerged, prolonging the survival rate. Currently, new technologies and strategies are being developed to improve the actual efficacy of available treatments and their prognostic aspects. This article summarizes the mechanisms of action, importance, benefits, adverse events of special interest, and efficacy of immunotherapy in metastatic renal cell carcinoma, with a focus on brain metastases.

Risk Factors of Second Local Recurrence in Surgically Treated Recurrent Brain Metastases: An Exploratory Analysis

BACKGROUND

A first local recurrence is common after resection or radiotherapy for brain metastasis (BM). However, patients with BMs can develop multiple local recurrences over time. Published data on second local recurrences are scarce. This study aimed to report predictors associated with a second local recurrence in patients with BMs who underwent a craniotomy for a first locally recurrent BM.

METHODS

Patients were identified from a database at Brigham and Women's Hospital in Boston. Hazard ratios and 95% confidence intervals for predictors of a second local recurrence were computed using a Cox proportional hazards model.

RESULTS

Of 170 identified surgically treated first locally recurrent lesions, 74 (43.5%) progressed to second locally recurrent lesions at a median of 7 months after craniotomy. Subtotal resection of the first local BM recurrence was significantly associated with shorter time to second local recurrence (hazard ratio = 2.09; 95% confidence interval, 1.27-3.45). Infratentorial location was associated with a worse second local recurrence prognosis (hazard ratio = 2.22; 95% confidence interval, 1.24-3.96).

CONCLUSIONS

A second local recurrence occurred after 43.5% of craniotomies for first recurrent lesions. Subtotal resection and infratentorial location were the strongest risk factors for worse second local recurrence prognosis following resection of first recurrent BM.

Efficacy of PD-1/L1 inhibitors in brain metastases of non-small-cell lung cancer: pooled analysis from seven randomized controlled trials

Background: The efficacy of PD-1 or PD-L1 inhibitors in patients with brain metastases of non-small-cell lung cancer (BM-NSCLC) is inconclusive. Materials & methods: An electronic search was performed. Randomized controlled trials RCTs that compared the efficacy of PD-1- or PD-L1-inhibitor-based regimens with non-PD-1/L1 inhibitor regimens in patients with NSCLC and reported the data of subgroup patients with brain metastases were eligible for inclusion. The hazard ratios (HRs) for progression-free survival and overall survival were pooled in BM-NSCLC. Results: Seven RCTs with 472 BM-NSCLC cases are included. The pooled HRs indicated that PD-1 or PD-L1 inhibitor-based regimens reduced risk of disease progression by 44% and reduced risk of death of BM-NSCLC patients by 29% compared with non-PD-1/L1 inhibitor regimens. Conclusion: This meta-analysis indicates that PD-1 or PD-L1 inhibitors can reduce risk of both disease progression and death of patients with brain metastases of NSCLC, who have been pretreated with local therapies and/or are asymptomatic for the brain lesions.

Is Molecular Tailored-Therapy Changing the Paradigm for CNS Metastases in Breast Cancer?

Breast cancer (BC) is the second most common tumour spreading to the central nervous system (CNS). The prognosis of patients with CNS metastases depends on several parameters including the molecular assessment of the disease. Although loco-regional treatment remains the best approach, systemic therapies are acquiring a role leading to remarkable long-lasting responses. The efficacy of these compounds diverges between tumours with different molecular assessments. Promising agents under investigation are drugs targeting the HER2 pathways such as tucatinib, neratinib, pyrotinib, trastuzumab deruxtecan. In addition, there are several promising agents under investigation for patients with triple-negative brain metastases (third-generation taxane, etirinotecan, sacituzumab, immune-checkpoint inhibitors) and hormone receptor-positive brain metastases (CDK 4/5, phosphoinositide-3-kinase-mammalian target of rapamycin [PI3K/mTOR] inhibitors). Also, the systemic treatment of leptomeningeal metastases, which represents a very negative prognostic site of metastases, is likely to change as several compounds are under investigation, some with interesting preliminary results. Here we performed a comprehensive review focusing on the current management of CNS metastases according to molecular subtypes, site of metastases (leptomeningeal vs brain), and systemic treatments under investigation.

Glioblastoma: Emerging Treatments and Novel Trial Designs

Simple Summary

Nowadays, very few systemic agents have shown clinical activity in patients with glioblastoma, making the research of novel therapeutic approaches a critical issue. Fortunately, the availability of novel compounds is increasing thanks to better biological knowledge of the disease. In this review we want to investigate more promising ongoing clinical trials in both primary and recurrent GBM. Furthermore, a great interest of the present work is focused on novel trial design strategies.

Abstract

Management of glioblastoma is a clinical challenge since very few systemic treatments have shown clinical efficacy in recurrent disease. Thanks to an increased knowledge of the biological and molecular mechanisms related to disease progression and growth, promising novel treatment strategies are emerging. The expanding availability of innovative compounds requires the design of a new generation of clinical trials, testing experimental compounds in a short time and tailoring the sample cohort based on molecular and clinical behaviors. In this review, we focused our attention on the assessment of promising novel treatment approaches, discussing novel trial design and possible future fields of development in this setting.