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Background This open-label, phase 1 trial (NCT02316197) aimed to determine the maximum-tolerated dose (MTD) and/or recommended phase 2 dose (RP2D) of peposertib (formerly M3814), a DNA-dependent protein kinase (DNA-PK) inhibitor in patients with advanced solid tumours. Secondary/exploratory objectives included safety/tolerability, pharmacokinetic/pharmacodynamic profiles and clinical activity. Methods Adult patients with advanced solid tumours received peposertib 100–200 mg once daily or 150–400 mg twice daily (BID) in 21-day cycles. Results Thirty-one patients were included (median age 66 years, 61% male). One dose-limiting toxicity, consisting of mainly gastrointestinal, non-serious adverse events (AEs) and long recovery duration, was reported at 300 mg BID. The most common peposertib-related AEs were nausea, vomiting, fatigue and pyrexia. The most common peposertib-related Grade 3 AEs were maculopapular rash and nausea. Peposertib was quickly absorbed systemically (median Tmax 1.1–2.5 h). The p-DNA-PK/t-DNA-PK ratio decreased consistently in peripheral blood mononuclear cells 3–6 h after doses ≥100 mg. The best overall response was stable disease (12 patients), lasting for ≥12 weeks in seven patients. Conclusions Peposertib was well-tolerated and demonstrated modest efficacy in unselected tumours. The MTD was not reached; the RP2D was declared as 400 mg BID. Further studies, mainly with peposertib/chemo-radiation, are ongoing. Clinical trial registration NCT02316197

Background Recently, two phase II trials showed intracranial activity of the immune checkpoint inhibitors nivolumab and ipilimumab in patients with melanoma brain metastases. However, it is generally assumed that large molecules like monoclonal antibodies nivolumab and ipilimumab cannot penetrate and pass an intact blood brain barrier (BBB). In this systematic review we provide a pharmacodynamic and pharmacokinetic consideration of the clinical activity of the immune checkpoint inhibitors nivolumab and ipilimumab in melanoma brain metastases. Methods Pubmed was systematically searched for prospective phase II and III studies on nivolumab and ipilimumab in melanoma brain metastases and cerebrospinal fluid (CSF) levels of nivolumab and ipilimumab. Results were discussed and a perspective on the pharmacodynamics and pharmacokinetics for the intracranial activity of these agents was given. Results Two phase II studies with the combination nivolumab and ipilimumab and one phase II study with ipilimumab monotherapy in melanoma brain metastases were included in this review. One article reported drug levels of nivolumab in CSF. Intracranial responses were achieved in 16 of 35 patients (46%; 95% confidence interval (CI) 29–63) in a phase II study cohort treated with nivolumab and ipilimumab. In a second phase II study in 94 patients, the rate of intracranial clinical benefit was 57% (95% CI 47–68). The CSF/serum ratio of nivolumab was 0.88–1.9% in a cohort of metastatic melanoma patients treated with nivolumab 1–3 mg/kg. Nivolumab concentrations ranged from 35 to 150 ng/ml in CSF of these patients, which is in the range of the half maximal effective concentration (EC50) of 0.64 nM. Conclusions Ipilimumab and nivolumab are active in melanoma brain metastases. Nivolumab penetrates into the CSF. Based on the described findings the general consensus that monoclonal antibodies do not penetrate into the central nervous system (CNS) and cannot have a direct intracranial effect needs to be reconsidered.

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