NE Oncology Issue – September 2011
Ribas A, et al. ASCO 2011: Abstract 8509
Most agents tested in large phase II trials in patients with metastatic melanoma have response rates of 10–20%. Approximately 50% of melanomas harbour a V600E-activating mutation in the BRAF gene, which can now be targeted with investigational inhibitors. In a previous phase I study, treatment with vemurafenib led to a high incidence of tumour regressions in BRAFmutant melanoma.1
At ASCO 2011, Ribas and colleagues presented results of the BRIM-2 study — a pivotal phase II trial of vemurafenib in previously treated patients with BRAFmutant metastatic melanoma.2 The goal of the study was to confirm the best overall response rate (ORR) of vemurafenib in previously treated patients with BRAF V600-mutated melanomas.
- The trial was a single-arm, multicentre, open-label phase II trial in patients with stage IV disease who had received one or greater prior systemic therapy.
- Patients had brain metastases controlled for at least three months following local therapy.
- The primary endpoint was ORR as assessed by an independent review committee (IRC).
- Secondary endpoints were duration of response, progressionfree survival (PFS), overall survival (OS), and safety.
- BRAF mutation status was determined using a PCR-based investigational, companion diagnostic assay (cobas 4800 BRAF V600 Mutation Test, Roche Molecular Systems).
- Patients received oral vemurafenib at a dose of 960 mg twice daily until progressive disease (PD), unacceptable toxicity, or death.
- The trial included 132 patients with a median age of 51.5 years, who were enrolled between October 2009 and March 2010 for a median follow up of 10 months (range: 0.6–14.7 months).
- 54% of patients had an ECOG performance status of 1, and 61% had M1c stage disease; 49% of patients had elevated lactate dehydrogenase (LDH); and 49% had received more than one line of prior therapy (i.e., poor prognostic factors.)
- The ORR was 53% as assessed by independent review committee (IRC).
- 29% of patients had stable disease (SD).
- 14% of patients had PD. (Figure 1)
- There were no differences in response rates according to age, gender, performance status, disease stage, number of prior therapies or prior therapy with high-dose interleukin- 2 (IL-2).
- There was a difference in response rates based on baseline LDH levels with higher response rates in patients with a normal LDH and a lower response rate in patients with a baseline LDH of greater than 1.5 times the upper limit of normal (ULN).
- The median duration of response was 6.8 months (95% CI: 5.6–not reached).
- The median PFS by intent-to-treat-analysis was 6.7 months (95% CI: 5.5–7.8 months) and the PFS at six months was 54%. (Figure 2)
- The median OS has not yet been reached after a median follow-up of 10 months. (Figure 3)
- The OS at six months was 77% (95% CI: 70–85) and at 12 months was 58% (95% CI: 49–67).
- Adverse events (AEs) were generally reversible (with dose modification or interruption).
- The most common AEs (all grades) were arthralgia (seen in 59% of patients), rash (52%), and photosensitivity reaction (52%).
- The most common grade 3 AE was cutaneous squamous cell carcinoma (seen in 26% of patients), the majority of which were centrally reviewed as keratoacanthoma-type.
- 45% of patients required dose reductions, most commonly for rash, arthralgia, and liver function test abnormalities.
- 64% of patients had dose interruptions due to AEs.
- The median daily dose was 91% of the intended total dose.
- Only four patients discontinued therapy due to drug-related AEs.
- Based on positive results as assessed by the primary endpoint of ORR, the BRIM-2 trial confirms that vemurafenib is an active agent in patients with BRAF mutation-positive melanoma who have completed prior systemic therapy.
- The trial met its primary endpoint, with an ORR of 53% and a 95% CI that excludes an ORR of 20%.
- The toxicity profile of vemurafenib at 960 mg twice daily is manageable, with most AEs being reversible with dose modification or interruption.
- The longer follow up of this study is complementary to the benefits in OS seen in the BRIM-3 trial: together, these trials provide evidence that vemurafenib is an effective agent for the treatment of patients with BRAF V600 mutation–positive melanoma.
References: 1. Flaherty KT, Puzanov I, Kim KB, et al. Inhibition of mutated, activated BRAF in metastatic melanoma. N Engl J Med 2010;363:809–819. 2. Ribas A, Kim KB, Schuchter LM, et al. BRIM-2: An open-label, multicenter phase II study of RG7204 (PLX4032) in previously treated patients with BRAF V600E mutation-positive metastatic melanoma. J Clin Oncol (ASCO Annual Meeting Abstracts) 2011;29:8509.
Silvy Lachance, MD, FRCPC, CSPQ
Dr. Silvy Lachance is currently a hematologist, clinical researcher, and Director of the Stem Cell Transplant Program at the MaisonneuveRosement Hospital in Montreal, Quebec, and Professor of Medicine and Director of the Fellowship Program in Stem Cell Transplantation at the University of Montreal. In 1995, Dr. Lachance established the first Stem Cell Transplant Unit at the University Health Centre (CUSE) in Sherbrooke, Quebec. She joined the Hematology and Oncology Division of the Montreal General Hospital as a transplant physician in 1997 and became an Associate Professor of Medicine at McGill University in 2005, holding both positions until 2006. Dr. Lachance has served as chair of the Continuing Medical Education Committee of the Quebec Association of Hematologists and Oncologists, and is currently treasurer of the executive committee. She has also served as chair of the jury for the hematology specialty exam board of the Collège des Médecins du Québec (CMQ). Her research interests include stem cell transplant, graft-versus-host-disease, and lymphoproliferative disorders.
Teresa Petrella, BSc, MD, MSc, FRCPC
Teresa Petrella is a Medical Oncologist at the Odette Cancer Centre (OCC) in Toronto, Canada and an Assistant Professor at the University of Toronto. Dr. Petrella has a BSc in Molecular Biology from the University of Western Ontario and she completed her MD at Queen’s University. Her Internal Medicine and Medical Oncology training was at McMaster University. She subsequently completed a fellowship in Melanoma and Breast Cancer at the Toronto Sunnybrook Regional Cancer Centre along with a Masters degree in Health Research Methodology at McMaster University. She was the recipient of a CIHR/CAMO award for her research in vaccine therapy in combination with interferon for melanoma patients. Dr. Petrella joined the staff at OCC in 2002 and became the head of the Melanoma Site Group. She also chairs the Provincial Guidelines Melanoma Disease Site Group Program in Evidence Based Care the National Cancer Institute of Canada (NCIC) Melanoma Clinical Trials Group. Her research interests are in melanoma and breast cancer and she is currently the Principal Investigator for several multicentre trials investigating novel therapies in melanoma.