Recent years have seen a revolution in the treatment of metastatic melanoma, with the introduction of both immunotherapy and targeted agents, but to date, only a limited number of studies have examined how these drugs are used in clinical practice.
A new study that looked at the current "real-world treatment patterns of therapies" in patients with metastatic melanoma in the United States was presented during the poster session at the Society for Melanoma Research 2015 Congress in San Francisco.
Specifically, the researchers focused on the use of two newer drugs — the immunotherapy ipilimumab (Yervoy, Bristol-Myers Squibb) and the BRAF-targeted drug vemurafenib (Zelboraf, Roche/Plexxikon) — and the use of two older chemotherapy products — dacarbazine and temozolomide (Temodar, Merck Sharp & Dohme Corp.) — from January 1, 2011 to August 31, 2013.
"These real-world data are generally consistent with the observations from clinical trials," said researcher Zhongyun Zhao, PhD, director of global health economics at Amgen, Inc., in Los Angeles. "Treatment could be discontinued in the event of toxic effects that could not be tolerated, rapidly progressive disease, or a significant decline in performance status."
"In clinical trials, about 60% of patients completed four doses," he told Medscape Medical News.
Before 2011, systemic treatment options for melanoma were limited, and consisted of older conventional agents such as dacarbazine and temozolomide. However, none of these older drugs were able to demonstrate improvements in overall survival. Survival is better with the newer drugs than with dacarbazine, but even so, the number of patients surviving over the long term remains low, the researchers point out.
Extrapolation to the American Population
Dr Zhao and his colleagues conducted a retrospective cohort analysis of a representative sample of patients in the United States undergoing treatment for metastatic melanoma from the IMS PharMetrics Plus Health Plan Claims Database.
"It is one of the largest health plan claims database in the United States," Dr Zhao said. "It comprises adjudicated claims for more than 150 million unique patients across the country, with approximately 40 million active in the most recent calendar year, with both pharmacy and medical coverage."
Information in the IMS Database dates from 2006, and there is a typical lag related to claims adjudication of 3 to 4 months, Dr Zhao explained. The data are representative of the geography, employers, payers, providers, and therapy areas in the United States, and cover 90% of hospitals, 90% of doctors, and 85% of the Fortune 100 companies.
The majority of patients in this database are commercially or self-insured; only a small percentage are covered by Medicare or Medicaid. However, "the impact of insurance type was not examined in the study," Dr Zhao reported.
Use and Duration Varied
Of the 1043 patients with metastatic melanoma involved in the analysis, 405 were first treated with ipilimumab, 361 with vemurafenib, 74 with dacarbazine, and 203 with temozolomide.
The most common sites for metastasis were the lungs (42%), brain (34%), liver (28%), and bone (24%). Hypertension was the most frequent comorbidity.
For therapies with continuous dosing schedules, the mean duration of treatment was 174 days for vemurafenib, 64 days for dacarbazine, and 100 days for temozolomide, and the median duration of treatment was 148 days for vemurafenib, 52 days for dacarbazine, and 59 days for temozolomide.
For patients treated with ipilimumab, 234 patients (58%) received the full four doses, 79 (20%) received three doses, 57 (14%) received two doses, and 35 (9%) received only one dose. In addition, 10 patients (4%) received one retreatment, but none received a second retreatment.
The use of the specific drugs varied during the study period. There was a steady decline in the use of dacarbazine — from 45.9% in 2011, to 32.4% in 2012, to 21.6% in 2013 — and in the use of temozolomide — from 50.7% in 2011, to 34.5% in 2012, to 18.4% in 2013.
In contrast, the use of ipilimumab rose dramatically — from 5.0% in 2011 to 63.5% in 2012 — but then dropped to 31.6% in 2013. The same pattern was seen for vemurafenib, which rose from 28.3% in 2011 to 48.8% in 2012, but then fell to 23.0% in 2013.
These data raise a number of questions, such as why use of the newer drugs decreased, and why some patients are not receiving the full treatment cycle.
"The current research described what happened, but not the reasons why they happened," Dr Zhao explained. "Further research is needed to address these questions."
The study was funded by Amgen. Dr Zhao and two of his coauthors are associated with Amgen; his other coauthors are, or were, employees of IMS Health.
Society for Melanoma Research (SMR) 2015 Congress.