First-line pazopanib in intermediate- and poor-risk patients with metastatic renal cell carcinoma: Final results of the FLIPPER trial

Temsirolimus has long been the only approved first-line standard of care (SOC) with overall survival (OS) benefit in poor-risk patients with advanced or metastatic renal cell cancer (mRCC). However, tyrosine kinase inhibitors are also commonly used in clinical practice. Pazopanib is an SOC for first-line mRCC treatment, but for poor-risk patients data are scarce. The FLIPPER (First-Line Pazopanib in Poor-Risk Patients with Metastatic Renal Cell Carcinoma) study aimed to assess efficacy and safety of first-line pazopanib in poor-risk mRCC patients. FLIPPER was a single-arm, multicenter, Phase IV trial. Key inclusion criteria were treatment-naive clear cell, inoperable advanced or mRCC, poor-risk according to MSKCC with slight modification, Karnofsky performance status (KPS) ≥60% and adequate organ function. Oral pazopanib 800 mg was given daily. Primary endpoint was the 6-month progression-free survival rate (PFS6). Secondary endpoints included PFS, OS, overall response rate (ORR), duration of response (DOR) and safety. For analysis, descriptive statistics were used. Between 2012 and 2016, 60 patients had been included. Forty-three patients qualified for safety analyses, 34 for efficacy. Median age was 66 years, 64.7% of patients were poor-risk, 82.4% had a KPS ≤70%. PFS6 was 35.3% (95% CI, 19.7-53.5). Median PFS and OS were 4.5 months (95% CI, 3.6-7.8) and 9.3 months (95% CI, 6.6-22.2), respectively. ORR was 32.4% (95% CI, 17.4-50.5), median DOR 9.7 months (95% CI, 1.8-12.4). The most common treatment-related grade 3/4 adverse event reported in 4.7% of patients was hypertension. No treatment-related death occurred. Since pazopanib is active and well tolerated in poor-risk patients with clear cell mRCC, our results support its use as first-line treatment in this setting.

[Molecular tumor board-renal cell carcinoma]

The introduction of molecular targeted agents has fundamentally changed the treatment of metastatic renal cell carcinoma. A first wave of development was based on the improved understanding of tumor biology since the discovery of the importance of the von Hippel-Lindau gene as the key driver of the disease and paved the way for antiangiogenic agents. Of relevance is the overexpression of proangiogenic and proliferation-promoting factors (VEGF, vascular endothelial growth factor; PDGF, platelet-derived growth factor) as well as an overactivation of the PI3K-Akt signaling pathway: the target structure is the "mammalian target of rapamycin" (mTOR) molecule, which is involved in the regulation of cell proliferative processes. VEGF-, PDGF-, and mTOR-signals and signaling pathways are central targets of current targeted substances. A second wave is certainly to be seen in the development of therapeutic approaches with the targeted activation and modulation of the immune system, which has brought "immunotherapy" back into the focus of interest. Central development is the application of immune-checkpoint inhibitors, with the help of which (re-)activation of the cellular defense, especially of T cells, takes place, which per se holds the potential of a cytoreductive therapy by killing the tumor cells. Even though the prognosis has improved significantly due to the rapid development of recent years, treatment remains challenging as most patients experience progress, and long-term survival is only achieved in about 20% of cases because some patients are primarily refractory or do not respond. The more intensive interlocking of molecular biology, pathology, clinical research, and interdisciplinary uro-oncology, as is the claim of molecular tumor boards, can contribute to the individual selection of a suitable therapy strategy and, thus, establish the latest findings and developments for the benefit of patients in the clinic.