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The therapeutic benefit of approved BRAF and MEK inhibitors (BRAFi/MEKi) in patients with brain metastatic BRAF V600E/K-mutated melanoma is limited and transient. Resistance largely occurs through the restoration of MAPK signaling via paradoxical BRAF activation, highlighting the need for more effective therapeutic options. Aiming to address this clinical challenge, we characterized the activity of a potent, brain-penetrant paradox breaker BRAFi (compound 1a, C1a) as first-line therapy and following progression upon treatment with approved BRAFi and BRAFi/MEKi therapies. C1a activity was evaluated in vitro and in vivo in melanoma cell lines and patient-derived models of BRAF V600E-mutant melanoma brain metastases following relapse after treatment with BRAFi/MEKi. C1a showed superior efficacy compared with approved BRAFi in both subcutaneous and brain metastatic models. Importantly, C1a manifested potent and prolonged antitumor activity even in models that progressed on BRAFi/MEKi treatment. Analysis of mechanisms of resistance to C1a revealed MAPK reactivation under drug treatment as the predominant resistance-driving event in both subcutaneous and intracranial tumors. Specifically, BRAF kinase domain duplication was identified as a frequently occurring driver of resistance to C1a. Combination therapies of C1a and anti-PD-1 antibody proved to significantly reduce disease recurrence. Collectively, these preclinical studies validate the outstanding antitumor activity of C1a in brain metastasis, support clinical investigation of this agent in patients pretreated with BRAFi/MEKi, unveil genetic drivers of tumor escape from C1a, and identify a combinatorial treatment that achieves long-lasting responses., Significance: A brain-penetrant BRAF inhibitor demonstrates potent activity in brain metastatic melanoma, even upon relapse following standard BRAF inhibitor therapy, supporting further investigation into its clinical utility., (©2022 American Association for Cancer Research.)

Purpose: Most hyperprogression disease (HPD) definitions are based on tumor growth rate (TGR). However, there is still no consensus on how to evaluate this phenomenon., Patients and Methods: We investigated two independent cohorts of patients with advanced solid tumors treated in phase I trials with (i) programmed cell death 1 (PD-1)/PD-L1 antibodies in monotherapy or combination and (ii) targeted agents (TA) in unapproved indications. A Response Evaluation Criteria in Solid Tumors (RECIST) 1.1-based definition of hyperprogression was developed. The primary endpoint was the assessment of the rate of HPD in patients treated with ICIs or TAs using both criteria (RECIST and TGR) and the impact on overall survival (OS) in patients who achieved PD as best response., Results: Among 270 evaluable patients treated with PD-1/PD-L1 inhibitors, 29 PD-1/PD-L1-treated patients (10.7%) had HPD by RECIST definition. This group had a significantly lower OS (median of 5.23 months; 95% CI, 3.97-6.45) when compared with the non-HPD progressor group (median, 7.33 months; 95% CI, 4.53-10.12; HR = 1.73, 95% CI, 1.05-2.85; P = 0.04). In a subset of 221 evaluable patients, 14 (6.3%) were categorized as HPD using TGR criteria, differences in median OS (mOS) between this group (mOS 4.2 months; 95% IC, 2.07-6.33) and non-HPD progressors ( n = 44) by TGR criteria (mOS 6.27 months; 95% CI, 3.88-8.67) were not statistically significant (HR 1.4, 95% IC, 0.70-2.77; P = 0.346). Among 239 evaluable patients treated with TAs, 26 (10.9%) were classified as having HPD by RECIST and 14 using TGR criteria in a subset of patients. No differences in OS were observed between HPD and non-HPD progressors treated with TAs., Conclusions: HPD measured by TGR or by RECIST was observed in both cohorts of patients; however, in our series, there was an impact on survival only in the immune-checkpoint inhibitor cohort when evaluated by RECIST. We propose a new way to capture HPD using RECIST criteria that is intuitive and easy to use in daily clinical practice., (©2019 American Association for Cancer Research.)

Purpose: Atezolizumab [anti-programmed death-ligand 1 (PD-L1)] selectively targets PD-L1 to block its interaction with receptors programmed death 1 and B7.1, thereby reinvigorating antitumor T-cell activity. We evaluated the long-term safety and activity of atezolizumab, along with biological correlates of clinical activity endpoints, in a cohort of patients with melanoma in an ongoing phase Ia study (NCT01375842)., Patients and Methods: Patients with unresectable or metastatic melanoma were enrolled to receive atezolizumab 0.1 to 20 mg/kg or ≥10 mg/kg every 3 weeks. Primary study objectives were safety and tolerability. Secondary objectives included investigator-assessed efficacy measures; pharmacodynamic and predictive biomarkers of antitumor activity were explored., Results: Forty-five patients were enrolled and were evaluable for safety. Most treatment-related adverse events (AE) were grade 1/2 (60%). Fatigue (44%), pruritus (20%), pyrexia (18%), and rash (18%) were the most common treatment-related AEs of any grade. No treatment-related deaths occurred. Overall response rate was 30% among 43 efficacy- evaluable patients, with a median duration of response of 62 months [95% CI, 35-not estimable (NE)]. Clinically meaningful long-term survival was observed, with a median overall survival of 23 months (95% CI, 9-66). Baseline biomarkers of tumor immunity [PD-L1 expression on immune cells, T effector (Teff), and antigen presentation gene signatures) and tumor mutational burden (TMB) were associated with improved response, progression-free survival, and overall survival., Conclusions: Atezolizumab was well tolerated, with durable responses and survival in patients with melanoma. PD-L1 expression, TMB, and Teff signatures may indicate improved benefit with atezolizumab in these patients., (©2019 American Association for Cancer Research.)