Igor Puzanov

Inhibition of Mutated, Activated BRAF in Metastatic Melanoma

BACKGROUND The identification of somatic mutations in the gene encoding the serine-threonine protein kinase B-RAF (BRAF) in the majority of melanomas offers an opportunity to test oncogene-targeted therapy for this disease. METHODS We conducted a multicenter, phase 1, dose-escalation trial of PLX4032 (also known as RG7204), an orally available inhibitor of mutated BRAF, followed by an extension phase involving the maximum dose that could be administered without adverse effects (the recommended phase 2 dose). Patients received PLX4032 twice daily until they had disease progression. Pharmacokinetic analysis and tumor-response assessments were conducted in all patients. In selected patients, tumor biopsy was performed before and during treatment to validate BRAF inhibition. RESULTS A total of 55 patients (49 of whom had melanoma) were enrolled in the dose-escalation phase, and 32 additional patients with metastatic melanoma who had BRAF with the V600E mutation were enrolled in the extension phase. The recommended phase 2 dose was 960 mg twice daily, with increases in the dose limited by grade 2 or 3 rash, fatigue, and arthralgia. In the dose-escalation cohort, among the 16 patients with melanoma whose tumors carried the V600E BRAF mutation and who were receiving 240 mg or more of PLX4032 twice daily, 10 had a partial response and 1 had a complete response. Among the 32 patients in the extension cohort, 24 had a partial response and 2 had a complete response. The estimated median progression-free survival among all patients was more than 7 months. CONCLUSIONS Treatment of metastatic melanoma with PLX4032 in patients with tumors that carry the V600E BRAF mutation resulted in complete or partial tumor regression in the majority of patients. (Funded by Plexxikon and Roche Pharmaceuticals.)

Combined BRAF and MEK Inhibition in Melanoma with BRAF V600 Mutations

BACKGROUND Resistance to therapy with BRAF kinase inhibitors is associated with reactivation of the mitogen-activated protein kinase (MAPK) pathway. To address this problem, we conducted a phase 1 and 2 trial of combined treatment with dabrafenib, a selective BRAF inhibitor, and trametinib, a selective MAPK kinase (MEK) inhibitor. METHODS In this open-label study involving 247 patients with metastatic melanoma and BRAF V600 mutations, we evaluated the pharmacokinetic activity and safety of oral dabrafenib (75 or 150 mg twice daily) and trametinib (1, 1.5, or 2 mg daily) in 85 patients and then randomly assigned 162 patients to receive combination therapy with dabrafenib (150 mg) plus trametinib (1 or 2 mg) or dabrafenib monotherapy. The primary end points were the incidence of cutaneous squamous-cell carcinoma, survival free of melanoma progression, and response. Secondary end points were overall survival and pharmacokinetic activity. RESULTS Dose-limiting toxic effects were infrequently observed in patients receiving combination therapy with 150 mg of dabrafenib and 2 mg of trametinib (combination 150/2). Cutaneous squamous-cell carcinoma was seen in 7% of patients receiving combination 150/2 and in 19% receiving monotherapy (P=0.09), whereas pyrexia was more common in the combination 150/2 group than in the monotherapy group (71% vs. 26%). Median progression-free survival in the combination 150/2 group was 9.4 months, as compared with 5.8 months in the monotherapy group (hazard ratio for progression or death, 0.39; 95% confidence interval, 0.25 to 0.62; P<0.001). The rate of complete or partial response with combination 150/2 therapy was 76%, as compared with 54% with monotherapy (P=0.03). CONCLUSIONS Dabrafenib and trametinib were safely combined at full monotherapy doses. The rate of pyrexia was increased with combination therapy, whereas the rate of proliferative skin lesions was nonsignificantly reduced. Progression-free survival was significantly improved. (Funded by GlaxoSmithKline; ClinicalTrials.gov number, NCT01072175.).

Survival in BRAF V600–Mutant Advanced Melanoma Treated with Vemurafenib

BACKGROUND Approximately 50% of melanomas harbor activating (V600) mutations in the serine-threonine protein kinase B-RAF (BRAF). The oral BRAF inhibitor vemurafenib (PLX4032) frequently produced tumor regressions in patients with BRAF V600-mutant metastatic melanoma in a phase 1 trial and improved overall survival in a phase 3 trial. METHODS We designed a multicenter phase 2 trial of vemurafenib in patients with previously treated BRAF V600-mutant metastatic melanoma to investigate the efficacy of vemurafenib with respect to overall response rate (percentage of treated patients with a tumor response), duration of response, and overall survival. The primary end point was the overall response rate as ascertained by the independent review committee; overall survival was a secondary end point. RESULTS A total of 132 patients had a median follow-up of 12.9 months (range, 0.6 to 20.1). The confirmed overall response rate was 53% (95% confidence interval [CI], 44 to 62; 6% with a complete response and 47% with a partial response), the median duration of response was 6.7 months (95% CI, 5.6 to 8.6), and the median progression-free survival was 6.8 months (95% CI, 5.6 to 8.1). Primary progression was observed in only 14% of patients. Some patients had a response after receiving vemurafenib for more than 6 months. The median overall survival was 15.9 months (95% CI, 11.6 to 18.3). The most common adverse events were grade 1 or 2 arthralgia, rash, photosensitivity, fatigue, and alopecia. Cutaneous squamous-cell carcinomas (the majority, keratoacanthoma type) were diagnosed in 26% of patients. CONCLUSIONS Vemurafenib induces clinical responses in more than half of patients with previously treated BRAF V600-mutant metastatic melanoma. In this study with a long follow-up, the median overall survival was approximately 16 months. (Funded by Hoffmann-La Roche; ClinicalTrials.gov number, NCT00949702.).

Clinical efficacy of a RAF inhibitor needs broad target blockade in BRAF -mutant melanoma

B-RAF is the most frequently mutated protein kinase in human cancers. The finding that oncogenic mutations in BRAF are common in melanoma, followed by the demonstration that these tumours are dependent on the RAF/MEK/ERK pathway, offered hope that inhibition of B-RAF kinase activity could benefit melanoma patients. Herein, we describe the structure-guided discovery of PLX4032 (RG7204), a potent inhibitor of oncogenic B-RAF kinase activity. Preclinical experiments demonstrated that PLX4032 selectively blocked the RAF/MEK/ERK pathway in BRAF mutant cells and caused regression of BRAF mutant xenografts. Toxicology studies confirmed a wide safety margin consistent with the high degree of selectivity, enabling Phase 1 clinical trials using a crystalline formulation of PLX4032 (ref. 5). In a subset of melanoma patients, pathway inhibition was monitored in paired biopsy specimens collected before treatment initiation and following two weeks of treatment. This analysis revealed substantial inhibition of ERK phosphorylation, yet clinical evaluation did not show tumour regressions. At higher drug exposures afforded by a new amorphous drug formulation, greater than 80% inhibition of ERK phosphorylation in the tumours of patients correlated with clinical response. Indeed, the Phase 1 clinical data revealed a remarkably high 81% response rate in metastatic melanoma patients treated at an oral dose of 960 mg twice daily. These data demonstrate that BRAF-mutant melanomas are highly dependent on B-RAF kinase activity.

Survival, Durable Tumor Remission, and Long-Term Safety in Patients With Advanced Melanoma Receiving Nivolumab

PURPOSE Programmed cell death 1 (PD-1) is an inhibitory receptor expressed by activated T cells that downmodulates effector functions and limits the generation of immune memory. PD-1 blockade can mediate tumor regression in a substantial proportion of patients with melanoma, but it is not known whether this is associated with extended survival or maintenance of response after treatment is discontinued. PATIENTS AND METHODS Patients with advanced melanoma (N = 107) enrolled between 2008 and 2012 received intravenous nivolumab in an outpatient setting every 2 weeks for up to 96 weeks and were observed for overall survival, long-term safety, and response duration after treatment discontinuation. RESULTS Median overall survival in nivolumab-treated patients (62% with two to five prior systemic therapies) was 16.8 months, and 1- and 2-year survival rates were 62% and 43%, respectively. Among 33 patients with objective tumor regressions (31%), the Kaplan-Meier estimated median response duration was 2 years. Seventeen patients discontinued therapy for reasons other than disease progression, and 12 (71%) of 17 maintained responses off-therapy for at least 16 weeks (range, 16 to 56+ weeks). Objective response and toxicity rates were similar to those reported previously; in an extended analysis of all 306 patients treated on this trial (including those with other cancer types), exposure-adjusted toxicity rates were not cumulative. CONCLUSION Overall survival following nivolumab treatment in patients with advanced treatment-refractory melanoma compares favorably with that in literature studies of similar patient populations. Responses were durable and persisted after drug discontinuation. Long-term safety was acceptable. Ongoing randomized clinical trials will further assess the impact of nivolumab therapy on overall survival in patients with metastatic melanoma.

RAS mutations in cutaneous squamous-cell carcinomas in patients treated with BRAF inhibitors.

BACKGROUND Cutaneous squamous-cell carcinomas and keratoacanthomas are common findings in patients treated with BRAF inhibitors. METHODS We performed a molecular analysis to identify oncogenic mutations (HRAS, KRAS, NRAS, CDKN2A, and TP53) in the lesions from patients treated with the BRAF inhibitor vemurafenib. An analysis of an independent validation set and functional studies with BRAF inhibitors in the presence of the prevalent RAS mutation was also performed. RESULTS Among 21 tumor samples, 13 had RAS mutations (12 in HRAS). In a validation set of 14 samples, 8 had RAS mutations (4 in HRAS). Thus, 60% (21 of 35) of the specimens harbored RAS mutations, the most prevalent being HRAS Q61L. Increased proliferation of HRAS Q61L-mutant cell lines exposed to vemurafenib was associated with mitogen-activated protein kinase (MAPK)-pathway signaling and activation of ERK-mediated transcription. In a mouse model of HRAS Q61L-mediated skin carcinogenesis, the vemurafenib analogue PLX4720 was not an initiator or a promoter of carcinogenesis but accelerated growth of the lesions harboring HRAS mutations, and this growth was blocked by concomitant treatment with a MEK inhibitor. CONCLUSIONS Mutations in RAS, particularly HRAS, are frequent in cutaneous squamous-cell carcinomas and keratoacanthomas that develop in patients treated with vemurafenib. The molecular mechanism is consistent with the paradoxical activation of MAPK signaling and leads to accelerated growth of these lesions. (Funded by Hoffmann-La Roche and others; ClinicalTrials.gov numbers, NCT00405587, NCT00949702, NCT01001299, and NCT01006980.).

Talimogene Laherparepvec Improves Durable Response Rate in Patients With Advanced Melanoma

PURPOSE Talimogene laherparepvec (T-VEC) is a herpes simplex virus type 1-derived oncolytic immunotherapy designed to selectively replicate within tumors and produce granulocyte macrophage colony-stimulating factor (GM-CSF) to enhance systemic antitumor immune responses. T-VEC was compared with GM-CSF in patients with unresected stage IIIB to IV melanoma in a randomized open-label phase III trial. PATIENTS AND METHODS Patients with injectable melanoma that was not surgically resectable were randomly assigned at a two-to-one ratio to intralesional T-VEC or subcutaneous GM-CSF. The primary end point was durable response rate (DRR; objective response lasting continuously ≥ 6 months) per independent assessment. Key secondary end points included overall survival (OS) and overall response rate. RESULTS Among 436 patients randomly assigned, DRR was significantly higher with T-VEC (16.3%; 95% CI, 12.1% to 20.5%) than GM-CSF (2.1%; 95% CI, 0% to 4.5%]; odds ratio, 8.9; P < .001). Overall response rate was also higher in the T-VEC arm (26.4%; 95% CI, 21.4% to 31.5% v 5.7%; 95% CI, 1.9% to 9.5%). Median OS was 23.3 months (95% CI, 19.5 to 29.6 months) with T-VEC and 18.9 months (95% CI, 16.0 to 23.7 months) with GM-CSF (hazard ratio, 0.79; 95% CI, 0.62 to 1.00; P = .051). T-VEC efficacy was most pronounced in patients with stage IIIB, IIIC, or IVM1a disease and in patients with treatment-naive disease. The most common adverse events (AEs) with T-VEC were fatigue, chills, and pyrexia. The only grade 3 or 4 AE occurring in ≥ 2% of T-VEC-treated patients was cellulitis (2.1%). No fatal treatment-related AEs occurred. CONCLUSION T-VEC is the first oncolytic immunotherapy to demonstrate therapeutic benefit against melanoma in a phase III clinical trial. T-VEC was well tolerated and resulted in a higher DRR (P < .001) and longer median OS (P = .051), particularly in untreated patients or those with stage IIIB, IIIC, or IVM1a disease. T-VEC represents a novel potential therapy for patients with metastatic melanoma.

Ipilimumab in patients with melanoma and brain metastases: an open-label, phase 2 trial.

BACKGROUND Brain metastases commonly develop in patients with melanoma and are a frequent cause of death of patients with this disease. Ipilimumab improves survival in patients with advanced melanoma. We aimed to investigate the safety and activity of this drug specifically in patients with brain metastases. METHODS Between July 31, 2008, and June 3, 2009, we enrolled patients with melanoma and brain metastases from ten US centres who were older than 16 years into two parallel cohorts. Patients in cohort A were neurologically asymptomatic and were not receiving corticosteroid treatment at study entry; those in cohort B were symptomatic and on a stable dose of corticosteroids. Patients were to receive four doses of 10 mg/kg intravenous ipilimumab, one every 3 weeks. Individuals who were clinically stable at week 24 were eligible to receive 10 mg/kg intravenous ipilimumab every 12 weeks. The primary endpoint was the proportion of patients with disease control, defined as complete response, partial response, or stable disease after 12 weeks, assessed with modified WHO criteria. Analyses of safety and efficacy included all treated patients. This trial is registered with ClinicalTrials.gov, number NCT00623766. FINDINGS We enrolled 72 patients: 51 into cohort A and 21 into cohort B. After 12 weeks, nine patients in cohort A exhibited disease control (18%, 95% CI 8-31), as did one patient in cohort B (5%, 0·1-24). When the brain alone was assessed, 12 patients in cohort A (24%, 13-38) and two in cohort B (10%, 1-30) achieved disease control. We noted disease control outside of the brain in 14 patients (27%, 16-42) in cohort A and in one individual (5%, 0·1-24) in cohort B. The most common grade 3 adverse events in cohort A were diarrhoea (six patients [12%]) and fatigue (six [12%]); in cohort B, they were dehydration (two individuals [10%]), hyperglycaemia (two [10%]), and increased concentrations of serum aspartate aminotransferase (two [10%]). One patient in each cohort had grade 4 confusion. The most common grade 3 immune-related adverse events were diarrhoea (six patients [12%]) and rash (one [2%]) in cohort A, and rash (one individual [5%]) and increased concentrations of serum aspartate aminotransferase (two [10%]) in cohort B. One patient in cohort A died of drug-related complications of immune-related colitis. INTERPRETATION Ipilimumab has activity in some patients with advanced melanoma and brain metastases, particularly when metastases are small and asymptomatic. The drug has no unexpected toxic effects in this population. FUNDING Bristol-Myers Squibb.

Dabrafenib in patients with Val600Glu or Val600Lys BRAF-mutant melanoma metastatic to the brain (BREAK-MB): a multicentre, open-label, phase 2 trial

BACKGROUND Brain metastases are common in patients with metastatic melanoma and median overall survival from their diagnosis is typically 17-22 weeks. We assessed dabrafenib in patients with Val600Glu or Val600Lys BRAF-mutant melanoma metastatic to the brain. METHODS We undertook a multicentre, open-label, phase 2 trial in 24 centres in six countries. We enrolled patients with histologically confirmed Val600Glu or Val600Lys BRAF-mutant melanoma and at least one asymptomatic brain metastasis (≥5 mm and ≤40 mm in diameter). Eligible patients were aged 18 years or older, had an Eastern Cooperative Oncology Group performance status of 0 or 1, and had adequate organ function. Patients were split into two cohorts: those in cohort A had not received previous local treatment for brain metastases and those in cohort B had progressive brain metastases after previous local treatments. Patients received 150 mg oral dabrafenib twice a day until disease progression, death, or unacceptable adverse events. The primary endpoint was the proportion of patients with Val600Glu BRAF-mutant melanoma who achieved an overall intracranial response, which was defined as a complete response or partial response assessed with a modified form of Response Evaluation Criteria in Solid Tumors (RECIST 1.1). We included patients who received at least one dose of dabrafenib in efficacy and safety analyses. This study is registered with ClinicalTrials.gov, number NCT01266967. FINDINGS Between Feb 2, 2011, and Aug 5, 2011, we enrolled 172 patients: 89 (52%) in cohort A and 83 (48%) in cohort B. 139 (81%) had Val600Glu BRAF-mutant melanoma. 29 (39·2%, 95% CI 28·0-51·2) of 74 patients with Val600Glu BRAF-mutant melanoma in cohort A achieved an overall intracranial response, as did 20 (30·8%, 19·9-43·4) of 65 in cohort B. One (6·7%, 0·2-31·9) of 15 patients with Val600Lys BRAF-mutant melanoma achieved an overall intracranial response in cohort A, as did four (22·2%, 6·4-47·6) of 18 such patients in cohort B. Treatment-related adverse events of grade 3 or worse occurred in 38 (22%) patients. Eleven (6%) patients developed squamous-cell carcinoma (five [6%] patients in cohort A, of whom one also had keratoacanthoma; six [7%] in cohort B). Four grade 4 treatment-related adverse events occurred in cohort A: one blood amylase increase, one convulsion, one lipase increase, and one neutropenia. Two grade 4 events occurred in cohort B: one agranulocytosis and one intracranial haemorrhage. 51 (30%) patients had a serious adverse event. The three most frequent serious adverse events were pyrexia (ten [6%] patients), intracranial haemorrhage (ten [6%]; one treatment-related), and squamous-cell carcinoma (11 [6%]). INTERPRETATION Dabrafenib has activity and an acceptable safety profile in patients with Val600Glu BRAF-mutant melanoma and brain metastases irrespective of whether they are untreated or have been previously treated but have progressed. FUNDING GlaxoSmithKline.

Phase I, Pharmacokinetic, and Pharmacodynamic Study of AMG 479, a Fully Human Monoclonal Antibody to Insulin-Like Growth Factor Receptor 1

PURPOSE To determine the maximum-tolerated dose (MTD) and to assess the safety, pharmacokinetics, and evidence of antitumor activity of AMG 479, a fully human monoclonal antibody to insulin-like growth factor receptor 1 (IGF-1R). PATIENTS AND METHODS Patients with advanced solid malignancies or non-Hodgkins lymphoma received escalating doses of AMG 479 intravenously (IV) every 2 weeks (Q2W). Blood samples were assayed to determine pharmacokinetic parameters and IGF-1R occupancy on neutrophils; fluorodeoxyglucose-positron emission tomography scans were used to assess tumor metabolic effects. RESULTS Fifty-three patients received 312 infusions of AMG 479 Q2W. Overall, the most common grades 1 to 2 toxicities were fatigue, thrombocytopenia, fever, rash, chills, and anorexia. One dose-limiting toxicity (ie, grade 3 thrombocytopenia) occurred in a patient at 20 mg/kg during course 1; grade 3 thrombocytopenia (n = 8) and grade 3 transaminitis elevations (n = 1) also were reported but not in the escalation phase. The maximum-planned dose of 20 mg/kg was safely administered; thus, an MTD was not reached. High levels of neutrophil IGF-1R binding and increases from baseline in serum IGF-1 levels were observed in the 12- and 20-mg/kg cohorts. Tumor responses included one durable complete response (CR) and one unconfirmed partial response (PR) in two patients with Ewing/primitive neuroectodermal tumors and included one PR and one minor response in two patients with neuroendocrine tumors. The patients with Ewing/PNET who had a CR have remained disease free on therapy after 28 months. CONCLUSION AMG 479 can be administered safely at 20 mg/kg IV Q2W. The absence of severe toxicities, attainment of serum concentrations associated with high levels of IGF-1R binding on neutrophils, and provocative antitumor activity warrant additional studies of this agent.