Efficacy of Cabozantinib in Metastatic MiT Family Translocation Renal Cell Carcinomas

BACKGROUND

MiT family translocation renal cell carcinoma (TRCC) is a rare and aggressive subgroup of renal cell carcinoma harboring high expression of c-MET. While TRCC response rates to VEGF receptor tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors are limited, efficacy of cabozantinib (a VEGFR, MET, and AXL inhibitor) in this subgroup is unclear.

METHODS

We performed a multicenter, retrospective, international cohort study of patients with TRCC treated with cabozantinib. The main objectives were to estimate response rate according to RECIST 1.1 and to analyze progression-free survival (PFS) and overall survival (OS).

RESULTS

Fifty-two patients with metastatic TRCC treated in the participating centers and evaluable for response were included. Median age at metastatic diagnosis was 40 years (IQR 28.5-53). Patients' IMDC risk groups at diagnosis were favorable (9/52), intermediate (35/52), and poor (8/52). Eleven (21.2%) patients received cabozantinib as frontline therapy, 15 (28.8%) at second line, and 26 (50%) at third line and beyond. The proportion of patients who achieved an objective response was 17.3%, including 2 complete responses and 7 partial responses. For 26 (50%) patients, stable disease was the best response. With a median follow-up of 25.1 months (IQR 12.6-39), median PFS was 6.8 months (95%CI 4.6-16.3) and median OS was 18.3 months (95%CI 17.0-30.6). No difference of response was identified according to fusion transcript features.

CONCLUSION

This real-world study provides evidence of the activity of cabozantinib in TRCC, with more durable responses than those observed historically with other VEGFR-TKIs or ICIs.

Personalizing First-Line Management of Metastatic Renal Cell Carcinoma: Leveraging Current and Novel Therapeutic Options

The treatment of metastatic renal cell carcinoma (RCC) has been revolutionized by advances in immunotherapeutic and targeted agents. Therapeutic approaches to RCC in these categories have recently evolved to include immune checkpoint inhibitors, novel vascular endothelial growth factor receptor-targeting tyrosine kinase inhibitors, and combinations of those agents. Multiple regimens within each category have been approved for use in the first-line treatment of clear cell and non-clear cell RCC. However, few of these regimens have been directly compared, leading to a new clinical challenge for physicians: how to select a first-line treatment regimen for an individual patient from among multiple approved options. In the modern era of RCC management, the initial treatment selection therefore becomes highly personalized and depends on numerous patient-specific factors, including histopathologic and clinical features of the disease, comorbid conditions, and psychosocial and economic factors. This review details current first-line treatment options for the management of metastatic RCC and proposes a framework whereby treatment selection can be optimized for individual patients.

Emergent immunotherapy approaches for brain metastases

Brain metastases from solid tumors are increasing in incidence, especially as outcomes of systemic therapies continue to extend patients’ overall survival. The long-held notion that the brain is an immune sanctuary has now been largely refuted with increasing evidence that immunotherapy can induce durable responses in brain metastases. Single agent immune checkpoint inhibition with anti-CTLA4 and anti-PD1 antibodies induces durable responses in 15%–20% in melanoma brain metastases as long as patients are asymptomatic and do not require corticosteroids. The combination of anti-CTLA4 with anti-PD-1 antibodies induces an intracranial response in over 50% of asymptomatic melanoma patients, and much lower rate of otherwise durable responses (20%) in symptomatic patients or those on steroids. Data in other cancers, such as renal cell carcinoma, are accumulating indicating a role for immunotherapy. Emerging immunotherapy approaches will have to focus on increasing response rates, decreasing toxicity, and decreasing steroid dependency. The path to those advances will have to include a better understanding of the mechanisms of response and resistance to immunotherapy in brain metastases, the use of novel agents such as anti-LAG3 checkpoint inhibitors, targeted therapy (oncogene directed or TKIs), and possibly surgery and SRS to improve the outcomes of patients with brain metastases.

Challenges and advances for the treatment of renal cancer patients with brain metastases: From immunological background to upcoming clinical evidence on immune-checkpoint inhibitors

The introduction of checkpoint inhibitors (ICIs) in renal cell carcinoma (RCC) treatment landscape, resulted in improvements in overall survival (OS) in metastatic patients. Brain metastases (BMs) are a specific metastatic site of interest representing a predictive factor of poor prognosis. Patients with BMs were usually excluded from prospective clinical trials in the past. Despite recent evidence suggest the efficacy and safety of ICIs, the BMs treatment remains a challenge; the immunotherapy responsiveness seems to be multifactorial and dependent on several factors, such as the genetic intratumor heterogeneity and the immunosuppressive role of the brain tumor microenvironment. This review, starting from the immunological background in RCC BMs, provide an overview of the upcoming evidence from clinical trials, address the issues related to the neuroradiological immunotherapy response evaluation and, with a look to the future, describes how the epigenetic modulation of immune evasion could represent a background for new therapeutic strategies.

Prognostic Factors and Current Treatment Strategies for Renal Cell Carcinoma Metastatic to the Brain: An Overview

Renal cell carcinoma (RCC) is one of primary cancers that frequently metastasize to the brain. Brain metastasis derived from RCC has the propensity of intratumoral hemorrhage and relatively massive surrounding edema. Moreover, it confers a grim prognosis in a great percentage of cases with a median overall survical (mOS) around 10 months. The well-recognized prognostic factors for brain metastatic renal cell carcinoma (BMRCC) are Karnofsky Performance Status (KPS), the number of brain metastasis (BM), the presence of a sarcomatoid component and the presence of extracranial metastasis. Therapeutic strategies are multimodal and include surgical resection, radiotherapy, such as stereotactic radiosurgery due to the radioresistance of RCC and systemic strategies with tyrosin kinase inhibitors (TKI) or Immune checkpoint inhibitors (ICI) whose efficacy is not well-established in this setting of patients due to their exclusion from most clinical trials. To date, in case of positive prognostic factors and after performing local radical therapies, such as complete resection of BM or stereotactic radiosurgery (SRS), the outcome of these patients significantly improves, up to 33 months in some patients. As a consequence, tailored clinical trials designed for BMRCC are needed to define the correct treatment strategy even in this poor prognostic subgroup of patients.