Inter- And intra-patient heterogeneity of response and progression to targeted therapy in metastatic melanoma

Alexander M. Menzies, Lauren E. Haydu, Matteo S. Carlino, Mary W F Azer, Peter J A Carr, Richard F. Kefford, Georgina V. Long

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55 Citations (Scopus)
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Abstract

Background: MAPK inhibitors (MAPKi) are active in BRAF-mutant metastatic melanoma patients, but the extent of response and progression-free survival (PFS) is variable, and complete responses are rare. We sought to examine the patterns of response and progression in patients treated with targeted therapy. Methods: MAPKi-naïve patients treated with combined dabrafenib and trametinib had all metastases ≥5 mm (lymph nodes ≥15 mm in short axis) visible on computed tomography measured at baseline and throughout treatment. Results: 24 patients had 135 measured metastases (median 4.5/patient, median diameter 16 mm). Time to best response (median 5.5 mo, range 1.7-20.1 mo), and the degree of best response (median -70%, range +9 to -100%) varied amongst patients. 17% of patients achieved complete response (CR), whereas 53% of metastases underwent CR, including 42% ≥10 mm. Metastases that underwent CR were smaller than non-CR metastases (median 11 vs 20 mm, P<0.001). PFS was variable among patients (median 8.2 mo, range 2.6-18.3 mo), and 50% of patients had disease progression in new metastases only. Only 1% (1/71) of CR-metastases subsequently progressed. Twelve-month overall survival was poorer in those with a more heterogeneous initial response to therapy than less heterogeneous (67% vs 93%, P = 0.009). Conclusion: Melanoma response and progression with MAPKi displays marked inter- and intra-patient heterogeneity. Most metastases undergo complete response, yet only a small proportion of patients achieve an overall complete response. Similarly, disease progression often occurs only in a subset of the tumor burden, and often in new metastases alone. Clinical heterogeneity, likely reflecting molecular heterogeneity, remains a barrier to the effective treatment of melanoma patients. Copyright:

Original languageEnglish
Article numbere85004
Pages (from-to)1-9
Number of pages9
JournalPLoS ONE
Volume9
Issue number1
DOIs
Publication statusPublished - 6 Jan 2014
Externally publishedYes

Bibliographical note

Copyright the Author(s) 2014. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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