Peter F. Lebowitz

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.).

Dabrafenib in patients with melanoma, untreated brain metastases, and other solid tumours: a phase 1 dose-escalation trial.

BACKGROUND Dabrafenib is an inhibitor of BRAF kinase that is selective for mutant BRAF. We aimed to assess its safety and tolerability and to establish a recommended phase 2 dose in patients with incurable solid tumours, especially those with melanoma and untreated, asymptomatic brain metastases. METHODS We undertook a phase 1 trial between May 27, 2009, and March 20, 2012, at eight study centres in Australia and the USA. Eligible patients had incurable solid tumours, were 18 years or older, and had adequate organ function. BRAF mutations were mandatory for inclusion later in the study because of an absence of activity in patients with wild-type BRAF. We used an accelerated dose titration method, with the first dose cohort receiving 12 mg dabrafenib daily in a 21-day cycle. Once doses had been established, we expanded the cohorts to include up to 20 patients. On the basis of initial data, we chose a recommended phase 2 dose. Efficacy at the recommended phase 2 dose was studied in patients with BRAF-mutant tumours, including those with non-Val600Glu mutations, in three cohorts: metastatic melanoma, melanoma with untreated brain metastases, and non-melanoma solid tumours. This study is registered with ClinicalTrials.gov, number NCT00880321. FINDINGS We enrolled 184 patients, of whom 156 had metastatic melanoma. The most common treatment-related adverse events of grade 2 or worse were cutaneous squamous-cell carcinoma (20 patients, 11%), fatigue (14, 8%), and pyrexia (11, 6%). Dose reductions were necessary in 13 (7%) patients. No deaths or discontinuations resulted from adverse events, and 140 (76%) patients had no treatment-related adverse events worse than grade 2. Doses were increased to 300 mg twice daily, with no maximum tolerated dose recorded. On the basis of safety, pharmacokinetic, and response data, we selected a recommended phase 2 dose of 150 mg twice daily. At the recommended phase 2 dose in 36 patients with Val600 BRAF-mutant melanoma, responses were reported in 25 (69%, 95% CI 51·9-83·7) and confirmed responses in 18 (50%, 32·9-67·1). 21 (78%, 57·7-91·4) of 27 patients with Val600Glu BRAF-mutant melanoma responded and 15 (56%, 35·3-74·5) had a confirmed response. In Val600 BRAF-mutant melanoma, responses were durable, with 17 patients (47%) on treatment for more than 6 months. Responses were recorded in patients with non-Val600Glu BRAF mutations. In patients with melanoma and untreated brain metastases, nine of ten patients had reductions in size of brain lesions. In 28 patients with BRAF-mutant non-melanoma solid tumours, apparent antitumour activity was noted in a gastrointestinal stromal tumour, papillary thyroid cancers, non-small-cell lung cancer, ovarian cancer, and colorectal cancer. INTERPRETATION Dabrafenib is safe in patients with solid tumours, and an active inhibitor of Val600-mutant BRAF with responses noted in patients with melanoma, brain metastases, and other solid tumours. FUNDING GlaxoSmithKline.

Activity of the oral MEK inhibitor trametinib in patients with advanced melanoma: a phase 1 dose-escalation trial

BACKGROUND MEK is a member of the MAPK signalling cascade that is commonly activated in melanoma. Direct inhibition of MEK blocks cell proliferation and induces apoptosis. We aimed to analyse safety, efficacy, and genotyping data for the oral, small-molecule MEK inhibitor trametinib in patients with melanoma. METHODS We undertook a multicentre, phase 1 three-part study (dose escalation, cohort expansion, and pharmacodynamic assessment). The main results of this study are reported elsewhere; here we present data relating to patients with melanoma. We obtained tumour samples to assess BRAF mutational status, and available tissues underwent exploratory genotyping analysis. Disease response was measured by Response Evaluation Criteria in Solid Tumors, and adverse events were defined by common toxicity criteria. This study is registered with ClinicalTrials.gov, number NCT00687622. FINDINGS 97 patients with melanoma were enrolled, including 81 with cutaneous or unknown primary melanoma (36 BRAF mutant, 39 BRAF wild-type, six BRAF status unknown), and 16 with uveal melanoma. The most common treatment-related adverse events were rash or dermatitis acneiform (n=80; 82%) and diarrhoea (44; 45%), most of which were grade 2 or lower. No cutaneous squamous-cell carcinomas were recorded. Of 36 patients with BRAF mutations, 30 had not received a BRAF inhibitor before; two complete responses (both confirmed) and ten partial responses (eight confirmed) were noted in this subgroup (confirmed response rate, 33%). Median progression-free survival of this subgroup was 5·7 months (95% CI 4·0-7·4). Of the six patients who had received previous BRAF inhibition, one unconfirmed partial response was recorded. Of 39 patients with BRAF wild-type melanoma, four partial responses were confirmed (confirmed response rate, 10%). INTERPRETATION Our data show substantial clinical activity of trametinib in melanoma and suggest that MEK is a valid therapeutic target. Differences in response rates according to mutations indicate the importance of mutational analyses in the future. FUNDING GlaxoSmithKline.

Phase I Dose Escalation and Pharmacokinetic Study of Lapatinib in Combination With Trastuzumab in Patients With Advanced ErbB2-Positive Breast Cancer

PURPOSE The combination of lapatinib and trastuzumab has been observed to have a synergistic, antiproliferative effect against ErbB2-positive breast cancer cells in vitro. This phase I study assessed the safety, clinical feasibility, optimally tolerated regimen (OTR), pharmacokinetics (PK), and preliminary clinical activity of this combination in patients with ErbB2-positive advanced breast cancer. PATIENTS AND METHODS Cohorts of three patients with ErbB2-positive advanced breast cancer were treated with escalating doses of lapatinib (750 to 1,500 mg) administered once daily (continuous) in combination with trastuzumab (4 mg/kg loading dose then 2 mg/kg weekly) to determine the OTR. Once the OTR was determined, additional patients were enrolled to provide the PK profile of both agents alone and in combination. RESULTS A total of 54 patients were treated: 27 in the dose-escalation group and 27 in the PK group. Overall, adverse events were mild to moderate in severity, with no drug-related grade 4 events. The most frequent drug-related grade 3 events included diarrhea (17%), fatigue (11%), and rash (6%). The OTR was 1,000 mg lapatinib with standard weekly trastuzumab. One patient had a complete response and seven patients had partial responses. The PK parameters (maximum concentration in plasma and area under the curve) of lapatinib and trastuzumab in combination were not significantly different than when either was administered alone. CONCLUSION The OTR of the lapatinib/trastuzumab combination was lapatinib 1,000 mg per day with standard weekly trastuzumab. At these doses, the regimen was well tolerated and clinically active in this heavily pretreated ErbB2-positive breast cancer population.

Tumor genetic analyses of patients with metastatic melanoma treated with the BRAF inhibitor dabrafenib (GSK2118436)

Purpose: Dabrafenib is a selective inhibitor of V600-mutant BRAF kinase, which recently showed improved progression-free survival (PFS) as compared with dacarbazine, in metastatic melanoma patients. This study examined potential genetic markers associated with response and PFS in the phase I study of dabrafenib. Experimental Design: Baseline (pretreatment or archival) melanoma samples were evaluated in 41 patients using a custom genotyping melanoma-specific assay, sequencing of PTEN, and copy number analysis using multiplex ligation amplification and array-based comparative genomic hybridization. Nine patients had on-treatment and/or progression samples available. Results: All baseline patient samples had BRAFV600E/K confirmed. Baseline PTEN loss/mutation was not associated with best overall response to dabrafenib, but it showed a trend for shorter median PFS [18.3 (95% confidence interval, CI, 9.1–24.3) vs. 32.1 weeks (95% CI, 24.1–33), P = 0.059]. Higher copy number of CCND1 (P = 0.009) and lower copy number of CDKN2A (P = 0.012) at baseline were significantly associated with decreased PFS. Although no melanomas had high-level amplification of BRAF, the two patients with progressive disease as their best response had BRAF copy gain in their tumors. Conclusions: Copy number changes in CDKN2A, CCND1, and mutation/copy number changes in PTEN correlated with the duration of PFS in patients treated with dabrafenib. The results suggest that these markers should be considered in the design and interpretation of future trials with selective BRAF inhibitors in advanced melanoma patients. Clin Cancer Res; 19(17); 4868–78. ©2013 AACR.

Deep sequencing of gastric carcinoma reveals somatic mutations relevant to personalized medicine

BackgroundGlobally, gastric cancer is the second most common cause of cancer-related death, with the majority of the health burden borne by economically less-developed countries.MethodsHere, we report a genetic characterization of 50 gastric adenocarcinoma samples, using affymetrix SNP arrays and Illumina mRNA expression arrays as well as Illumina sequencing of the coding regions of 384 genes belonging to various pathways known to be altered in other cancers.ResultsGenetic alterations were observed in the WNT, Hedgehog, cell cycle, DNA damage and epithelial-to-mesenchymal-transition pathways.ConclusionsThe data suggests targeted therapies approved or in clinical development for gastric carcinoma would be of benefit to ~22% of the patients studied. In addition, the novel mutations detected here, are likely to influence clinical response and suggest new targets for drug discovery.

A Phase II Trial of Neoadjuvant Docetaxel and Capecitabine for Locally Advanced Breast Cancer

Purpose: This study evaluated the toxicity and efficacy of docetaxel/capecitabine as neoadjuvant treatment for stage 2/3 breast cancer. Experimental Design: Subjects with newly diagnosed invasive stage 2 and 3 breast cancer were eligible. The first cohort of patients was treated at dose A with neoadjuvant docetaxel (75 mg/m2 i.v. day 1) and capecitabine (1000 mg/m2 orally twice daily days 2–15) for four cycles. A second cohort of subjects was treated with a reduced dose, dose B, of docetaxel (60 mg/m2 i.v. day 1) and capecitabine (937.5 mg/m2 orally twice daily days 2–15). Results: Thirty patients were enrolled. Eight of 10 patients treated at dose A required dose reductions of either docetaxel or capecitabine secondary to grade 3 or 4 toxicities: mucositis (1), hand-foot syndrome (3), diarrhea (2), perirectal abscess (1), and neutropenia (2). Because of a high rate of dose reductions, the next 20 patients were treated at dose B. The mean cumulative administered dose of docetaxel was 285 and 231 mg/m2 at dose A and dose B, respectively. For capecitabine, the mean cumulative dose at dose A and B were similar at 1585 and 1627 mg/m2/day, respectively. The overall clinical response rate was 90% with 31% of patients having a complete response and 59% having a partial response. A pathological complete response in the breast was achieved in 10% of patients after four cycles of docetaxel/capecitabine. Conclusions: Docetaxel/capecitabine is a highly active regimen in the neoadjuvant setting. Neoadjuvant therapy with 75 mg/m2 docetaxel and 1600 mg/m2/day days 2–15 is recommended.

18F-labelled fluorodeoxyglucose–positron emission tomography (FDG–PET) heterogeneity of response is prognostic in dabrafenib treated BRAF mutant metastatic melanoma

BACKGROUND Little is known about the prevalence and clinical significance of heterogeneity of positron emission tomography with (18)F-labelled fluorodeoxyglucose-positron emission tomography (FDG-PET) response. We aim to determine the prevalence, and clinicopathologic correlates of intra-patient heterogeneity of FDG-PET response in metastatic melanoma treated with dabrafenib, and to determine whether heterogeneity predicts clinical outcome. METHODS Patients with BRAF mutant metastatic melanoma and ≥ 2 FDG avid lesions treated on the Phase I trial of dabrafenib at a single institution (n=23) were included. FDG-PET response was assessed by comparing baseline PET scans with scans at day 15. A heterogeneous response was defined as responding and new or metabolically progressing lesion(s) in a patient, or >10% of lesions with a stable metabolic response and responding lesions in a patient. RESULTS Six (26%) patients had a heterogeneous PET response. The median time to progression (TTP) was 7.4 months (95% confidence interval (CI): 6.5-8.3) for PET homogeneous responders and 3.0 months (95%CI: 0.6-5.4) for PET heterogeneous responders. There were no homogeneous non-responders. Age, BRAF mutation genotype, dose, and lactate dehydrogenase, did not predict for heterogeneity of PET response. Heterogeneity did not correlate with tumour response. Lung metastases were more likely to respond than other visceral metastatic sites. CONCLUSIONS Heterogeneous FDG-PET responses are common in metastatic melanoma treated with dabrafenib, and heterogeneity is associated with a shorter TTP. FDG-PET heterogeneity may predict molecular heterogeneity, and FDG-PET directed biopsies may facilitate investigation into mechanisms of resistance to signal pathway inhibitors.

Disease Interception: Myths, mountains, and mole hills

Malignant diseases develop slowly over time and are often preceded by identifiable premalignancies. As malignancy progresses, so does genomic complexity and the ability of cancers to evade most therapeutic interventions. Accordingly, with some notable exceptions, a relatively low percentage of advanced cancers are effectively treated and even fewer are cured. Despite this appreciation, much less attention has been paid to intercepting the disease process compared with that of treating well-established and refractory disease. One frequently cited reason is that the pharmaceutical industry is not interested in these pursuits. In this commentary, we attempt to define the true hurdles, the degree of difficulty inherent in each, and some important approaches to be considered. Cancer Prev Res; 9(8); 635–7. ©2016 AACR.

Bortezomib with Concurrent Radiation Therapy in Head and Neck Squamous Cell Carcinoma

Abstract Problem: Head and neck squamous cell carcinomas (HNSCCs) exhibit constitutive activation of nuclear factor-kappa B (NF-kB), a transcription factor which regulates genes important in tumor progression. Bortezomib, a potent proteasome inhibitor shown to inhibit NF-kB activation in vitro, has not been studied in HNSCC patients. Methods: We initiated a phase I trial of bortezomib with concurrent radiation therapy in patients with recurrent/metastatic HNSCC. Patient biopsy specimens were stained for apoptotic cells and serum cytokines were measured pre- and posttreatment. To investigate the possible basis for differences in clinical response, we conducted real-time RT-PCR to examine gene expression in HNSCC cell lines treated with bortezomib. Results: Two of the 6 patients treated with 0.6 mg/m2/dose bortezomib with radiation at 1.8 Gy daily fractions to 60–72 Gy showed tumor reductions of more than 50%. Significant apoptosis was demonstrated by TUNEL in 1 patient who had a 50% tumor reduction by 3 weeks, whereas less apoptosis was observed in another patient clinically less responsive. A second patient, who experienced a 90% tumor reduction, had a greater than 90% decrease in levels of NF-kB-dependent serum cytokines IL-6, IL-8, VEGF, GRO-1. Patients not demonstrating marked tumor reductions did not show a significant decrease. In vitro studies revealed significant cell death and suppressed cyclin D1 and IAP-1 gene expression in UMSCC-11A and -11B lines treated with 10-7M bortezomib. Conclusion: In patients with clinically responsive tumors, bortezomib induces apoptotic effects and reductions in NF-kB-regulated cytokines in serum as early as 24 hours posttreatment. Suppression of IAP-1 and cyclin D1 gene expression in HNSCC cells may contribute to the antiproliferative and apoptotic effects of bortezomib. Significance: Further investigation of antiapoptotic and cell cycle genes in patient tissue with real-time RT-PCR is in progress to study the molecular mechanism of differential sensitivity of tumors in HNSCC patients to bortezomib. Understanding this mechanism may significantly improve the efficacy of this drug in HNSCC patients. Support: Intramural Project DC-00016 and NIH Clinical Research Training Program