Faculty Bibliography

PURPOSE: Dabrafenib is a selective, potent ATP-competitive inhibitor of the BRAFV600-mutant kinase that has demonstrated efficacy in clinical trials. We report the rationale for dose selection in the first-in-human study of dabrafenib, including pharmacokinetics, tissue pharmacodynamics, 2[18F]fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) pharmacodynamics, and dose-response relationship. EXPERIMENTAL DESIGN: Dabrafenib was administered orally once, twice (BID), or three times daily (TID). Selected dose cohorts were expanded to collect adequate data on safety, pharmacokinetics, or pharmacodynamics. A recommended phase II dose (RP2D) was chosen based on safety, pharmacokinetic, pharmacodynamic, and response data. RESULTS: One hundred and eighty-four patients were enrolled and treated with doses ranging from 12 mg once daily to 300 mg BID in 10 cohorts. Pharmacokinetic assessment of dabrafenib demonstrated a less-than-dose-proportional increase in exposure after repeat dosing above 150 mg BID. Similar to parent drug concentrations, exposure for all metabolites demonstrated less-than-dose-proportional increases. Predicted target inhibition of pERK (>80%) was achieved at 150 mg BID, with a similar magnitude of inhibition at higher doses in BRAFV600 mutation melanoma biopsy samples. Although there was large variability between patients, FDG uptake decreased with higher daily doses in patients with BRAFV600 mutation-positive melanoma. A favorable activity and tolerability profile was demonstrated at 150 mg BID. There was no improvement with TID dosing compared with BID dosing, based on FDG-PET and tumor response analyses in patients with melanoma. CONCLUSION: The RP2D of dabrafenib was determined to be 150 mg BID after considering multiple factors, including pharmacokinetics, tissue pharmacodynamics, FDG-PET pharmacodynamics, and the dose-response relationship. A maximum tolerated dose for dabrafenib was not determined. Clin Cancer Res; 20(17); 4449-58. (c)2014 AACR.

Neural infiltration in primary melanoma is a histopathologic feature that has been associated with desmoplastic histopathologic subtype and local recurrence in the literature. We tested the hypothesis that improved detection and characterization of neural infiltration into peritumoral or intratumoral location and perineural or intraneural involvement could have a prognostic relevance. We studied 128 primary melanoma cases prospectively accrued and followed at New York University using immunohistochemical detection with antihuman neurofilament protein and routine histology with hematoxylin and eosin. Neural infiltration, defined as the presence of tumor cells involving or immediately surrounding nerve foci, was identified and characterized using both detection methods. Neural infiltration rate of detection was enhanced by immunohistochemistry for neurofilament in matched-pair design (47% by immunohistochemistry versus 25% by routine histology). Immunohistochemical detection of neural infiltration was significantly associated with ulceration (P = .021), desmoplastic and acral lentiginous histologic subtype (P = .008), and head/neck/hands/feet tumor location (P = .037). Routinely detected neural infiltration was significantly associated with local recurrence (P = .010). Immunohistochemistry detected more intratumoral neural infiltration cases compared with routine histology (30% versus 3%, respectively). Peritumoral and intratumoral nerve location had no impact on clinical outcomes. Using a multivariate model controlling for stage, neither routinely detected neural infiltration nor enhanced immunohistochemical characterization of neural infiltration was significantly associated with disease-free or overall survival. Our data demonstrate that routinely detected neural infiltration is associated with local recurrence in all histologic subtypes but that improved detection and characterization of neural infiltration with immunohistochemistry in primary melanoma does not add to prognostic relevance.

BACKGROUND: To evaluate the efficacy and safety of ramucirumab (IMC-1121B; LY3009806), a fully human monoclonal antibody targeting the vascular endothelial growth factor receptor-2, alone and in combination with dacarbazine in chemotherapy-naive patients with metastatic melanoma (MM). METHODS: Eligible patients received ramucirumab (10mg/kg) + dacarbazine (1000mg/m2) (Arm A) or ramucirumab only (10mg/kg) (Arm B) every 3weeks. The primary end-point was progression-free survival (PFS); secondary end-points included overall survival (OS), overall response and safety. FINDINGS: Of 106 randomised patients, 102 received study treatment (Arm A, N=52; Arm B, N=50). Baseline characteristics were similar in both arms. Median PFS was 2.6months (Arm A) and 1.7months (Arm B); median 6-month PFS rates were 30.7% and 17.9% and 12-month PFS rates were 23.7% and 15.6%, respectively. In Arm A, 9 (17.3%) patients had partial response (PR) and 19 (36.5%), stable disease (SD); PR and SD in Arm B were 2 (4.0%) and 21 (42.0%), respectively. Median OS was 8.7months in Arm A and 11.1months in Arm B. Patients in both arms tolerated the treatment with limited Grade 3/4 toxicities. INTERPRETATION: Ramucirumab alone or in combination with dacarbazine was associated with an acceptable safety profile in patients with MM. Although the study was not powered for comparison between treatment arms, PFS appeared greater with combination therapy. Sustained disease control was observed on both study arm.

BACKGROUND: Addition of a MEK inhibitor to a BRAF inhibitor enhances tumour growth inhibition, delays acquired resistance, and abrogates paradoxical activation of the MAPK pathway in preclinical models of BRAF-mutated melanoma. We assessed the safety and efficacy of combined BRAF inhibition with vemurafenib and MEK inhibition with cobimetinib in patients with advanced BRAF-mutated melanoma. METHODS: We undertook a phase 1b study in patients with advanced BRAF(V600)-mutated melanoma. We included individuals who had either recently progressed on vemurafenib or never received a BRAF inhibitor. In the dose-escalation phase of our study, patients received vemurafenib 720 mg or 960 mg twice a day continuously and cobimetinib 60 mg, 80 mg, or 100 mg once a day for either 14 days on and 14 days off (14/14), 21 days on and 7 days off (21/7), or continuously (28/0). The primary endpoint was safety of the drug combination and to identify dose-limiting toxic effects and the maximum tolerated dose. Efficacy was a key secondary endpoint. All patients treated with vemurafenib and cobimetinib were included in safety and efficacy analyses (intention-to-treat). The study completed accrual and all analyses are final. This study is registered with ClinicalTrials.gov, number NCT01271803. FINDINGS: 129 patients were treated at ten dosing regimens combining vemurafenib and cobimetinib: 66 had recently progressed on vemurafenib and 63 had never received a BRAF inhibitor. Dose-limiting toxic effects arose in four patients. One patient on a schedule of vemurafenib 960 mg twice a day and cobimetinib 80 mg once a day 14/14 had grade 3 fatigue for more than 7 days; one patient on a schedule of vemurafenib 960 mg twice a day and cobimetinib 60 mg once a day 21/7 had a grade 3 prolongation of QTc; and two patients on a schedule of vemurafenib 960 mg twice a day and cobimetinib 60 mg 28/0 had dose-limiting toxic effects-one developed grade 3 stomatitis and fatigue and one developed arthralgia and myalgia. The maximum tolerated dose was established as vemurafenib 960 mg twice a day in combination with cobimetinib 60 mg 21/7. Across all dosing regimens, the most common adverse events were diarrhoea (83 patients, 64%), non-acneiform rash (77 patients, 60%), liver enzyme abnormalities (64 patients, 50%), fatigue (62 patients, 48%), nausea (58 patients, 45%), and photosensitivity (52 patients, 40%). Most adverse events were mild-to-moderate in severity. The most common grade 3 or 4 adverse events were cutaneous squamous-cell carcinoma (12 patients, 9%; all grade 3), raised amounts of alkaline phosphatase (11 patients, 9%]), and anaemia (nine patients, 7%). Confirmed objective responses were recorded in ten (15%) of 66 patients who had recently progressed on vemurafenib, with a median progression-free survival of 2.8 months (95% CI 2.6-3.4). Confirmed objective responses were noted in 55 (87%) of 63 patients who had never received a BRAF inhibitor, including six (10%) who had a complete response; median progression-free survival was 13.7 months (95% CI 10.1-17.5). INTERPRETATION: The combination of vemurafenib and cobimetinib was safe and tolerable when administered at the respective maximum tolerated doses. The combination has promising antitumour activity and further clinical development is warranted in patients with advanced BRAF(V600)-mutated melanoma, particularly in those who have never received a BRAF inhibitor; confirmatory clinical testing is ongoing. FUNDING: F Hoffmann-La Roche/Genentech.

OPINION STATEMENT: The management of high-risk melanoma has historically included primary surgical resection with or without lymphadenectomy followed by an array of adjuvant options including radiation therapy or immunomodulatory therapies such as interferon-alpha, granulocyte macrophage colony-stimulating factor, and a multitude of vaccines. There has been a long-standing interest in the development of vaccines in high-risk and metastatic melanoma, and clinical trials have been ongoing for decades. Given that melanoma is identified as one of the most immunogenic solid tumors, there is continued hope that vaccine therapies will improve clinical outcomes. Despite intense interest in this field, few clinical trials to-date have demonstrated significant benefit from melanoma vaccines in high-risk disease. Several trials have even documented a detrimental effect on outcomes after vaccine administration. While the role of vaccines in the adjuvant setting of high-risk melanoma presently remains unclear, recent advances in immunotherapy for melanoma including development of cytotoxic T-lymphocyte antigen 4 (CTLA-4) and programmed cell death 1 (PD-1) monoclonal antibodies have demonstrated meaningful clinical responses. With further study and focus on mechanisms of immune regulation, there remains promise for the role of vaccines in combination with other immune-stimulatory agents in high-risk melanoma.

Background: BRIM7 is a phase 1B study evaluating the safety and efficacy of combined BRAF and MEK inhibition with vemurafenib + cobimetinib. The utility of FDG-PET as an early predictor of clinical benefit was also evaluated in this study. Materials and methods: Eligible patients (pts) had advanced BRAF^V600-mutated melanoma and ECOG PS 0-1 and were either naive to BRAF inhibitor (BRAFi-naive) or had disease progression on vemurafenib (vem-progressor). Pts in the dose-escalation portion received vemurafenib 720 or 960 mg BID continuously and cobimetinib 60, 80, or 100 mg QD 14 days (d) on/14 d off (14/14); 21 d on/7 d off (21/7); or continuously (28/0). Two dose levels were expanded: vemurafenib (720 mg and 960 mg BID) + cobimetinib 60 mg QD 21/7. FDG-PET scans were performed at baseline and on Day 15 of Cycles 1 and 2. Correlation between tumor glucose metabolism changes, baseline tumor burden and target lesion responses were evaluated. Results: 128 pts were treated with vemurafenib + cobimetinib as of 21 June 2013; male 60%, median age 55 y (19-88), stage M1c 76% and BRAFi-naive 49%. Median duration of follow-up in vem-progressor and BRAFi-naive pts was 3 and 10 months, respectively. Most adverse events (AE) were mild to moderate in severity and vem-progressor pts reported fewer AEs compared to BRAFi-naive pts. Most common AEs in BRAFi-naive pts (n=63) were nonacneiform rash (89%), diarrhea (81%), photosensitivity/sunburn (70%), fatigue (67%) and liver test abnormality (59%). Most frequent grade >3 AEs in BRAFi-naive pts were liver test abnormality (19%), non-acneiform rash (13%), arthralgia (11%) and fatigue (10%). BRAFi-naive pts attained 85% confirmed response rate (RR), including 10% complete responses; median PFS was not reached at 10 months follow-up. Vem-progressor pts attained 15% confirmed RR, stable disease of 43%, and median PFS of 2.8 months. Preliminary FDG-PET analysis showed that the magnitude of reduction in tumor glucose uptake correlated with maximal tumor reduction, but the degree of correlation varied across time and in BRAFi-naive and Vem-progressor pts. Conclusions: Vemurafenib + cobimetinib can be safely administered at the respective single-agent MTDs of vemurafenib (960 mg BID) and cobimetinib (60 mg 21/7). Preliminary efficacy of the combination is encouraging in BRAFi-naive patients. FDG-PET is a potentially useful marker of early biologic response to the combination

PURPOSE: This open-label, multicenter study was designed to allow access to vemurafenib for patients with metastatic melanoma, bridging the time between end of enrollment in the phase III registration trial (December 2010) and commercial availability following US Food and Drug Administration approval of vemurafenib for the treatment of unresectable or metastatic BRAF-mutated melanoma (August 2011). PATIENTS AND METHODS: Eligible patients had metastatic melanoma with a BRAF mutation (detected by the cobas 4800 BRAF V600 Mutation Test). Unlike previous vemurafenib trials, patients with poor performance status (PS) and treated brain metastases were permitted. Enrolled patients received oral vemurafenib 960 mg twice daily. RESULTS: Of 374 patients enrolled at 29 US sites (December 2010 to October 2011), 371 patients received vemurafenib and were followed up for a median of 2.8 months (the study had a prespecified end upon vemurafenib approval and commercial availability). At baseline, most patients (75%) had stage M1c disease, and 19% had an Eastern Cooperative Oncology Group PS of 2 or 3; 72% of patients had received prior systemic therapy for metastatic melanoma, 27% received prior ipilimumab, and 29% radiotherapy for prior brain metastases. Because reassessment data to confirm response were not available for most patients, point estimates of objective response rate (ORR) are reported. Among 241 efficacy-evaluable patients, the ORR was 54% (median time to response, 1.9 months). The ORR in non-central nervous system sites in patients with previously treated brain metastases (n = 68) was 53%. The ORR in prior ipilimumab-treated patients (n = 68) was 52%. For patients with PS of 0 or 1 (n = 210) and 2 or 3 (n = 31), the ORRs were 55%, and 42%, respectively. The safety profile observed was consistent with that reported in previous studies. The number of patients with grade 3 or 4 treatment-related adverse events was higher in patients with PS 2 or 3 than in those with PS 0 or 1 (10% vs. 5%, respectively). Adverse events requiring a dose reduction (at least 1 level) occurred in 11% of patients, and 9 patients (2%) experienced events leading to vemurafenib withdrawal, including 2 with repeated QT interval prolongation. DISCUSSION: This study confirmed the established rapid and high tumor response rate achievable with vemurafenib in BRAF mutation-positive metastatic melanoma. Several groups not included in previous studies, including patients with previously treated brain metastases, Eastern Cooperative Oncology Group PS 2 to 3, or previous ipilimumab treatment had benefitted from vemurafenib similar to the overall population. No new safety signals were detected.

Previous reports have demonstrated a role for hedgehog signaling in melanoma progression, prompting us to explore the therapeutic benefit of targeting this pathway in melanoma. We profiled a panel of human melanoma cell lines and control melanocytes for altered expression of hedgehog pathway members and determined the consequences of both genetic and pharmacological inhibition of the hedgehog pathway activator Smoothened (SMO) in melanoma, both in vitro and in vivo. We also examined the relationship between altered expression of hedgehog pathway mediators and survival in a well-characterized cohort of metastatic melanoma patients with prospectively collected follow up information. Studies revealed that over 40% of the melanoma cell lines examined harbored significantly elevated levels of the hedgehog pathway mediators SMO, GLI2, and PTCH1 compared to melanocytes (p < 0.05). SMO inhibition using siRNA and the small molecule inhibitor, NVP-LDE-225, suppressed melanoma growth in vitro, particularly in those cell lines with moderate SMO and GLI2 expression. NVP-LDE-225 also induced apoptosis in vitro and inhibited melanoma growth in a xenograft model. Gene expression data also revealed evidence of compensatory up-regulation of two other developmental pathways, Notch and WNT, in response to hedgehog pathway inhibition. Pharmacological and genetic SMO inhibition also downregulated genes involved in human embryonic stem cell pluripotency. Finally, increased SMO expression and decreased expression of the hedgehog pathway repressor GLI3 correlated with shorter post recurrence survival in metastatic melanoma patients. Our data demonstrate that hedgehog pathway inhibition might be a promising targeted therapy in appropriately selected metastatic melanoma patients.