Annual Meeting Proceedings Part 1 - American Society of Clinical ...

550s Melanoma/Skin Cancers
8540 General Poster Session (Board #31F), Sun, 8:00 AM-12:00 PM
Prognostic value of BRAFV600 mutations in melanoma patients after
resection of metastatic lymph nodes. Presenting Author: Philippe Saiag,
Hospital Ambroise Pare, APHP, University Versailles-SQY, Boulogne-
Billancourt, France
Background: Prognosis of AJCC stage III melanoma is heterogeneous.
BRAF V600 mutations are frequent in melanomas. BRAFV600-targeted therapy
has dramatic, but often transitory, efficacy in stage IV patients (pts). We
aimed to determine for the first time the prognostic value of BRAFV600 mutations and other known prognostic criteria in stage III pts with
sufficient nodal invasion. Methods: We searched all pts with cutaneous
melanoma who had radical lymphadenectomy in our institution between
1/1/00 and 15/6/10 and included those with a nodal deposit �2 mm.
BRAFV600 mutations were detected by DNA sequencing and pyrosequencing
in formalin-fixed nodal samples containing �60% melanoma cells.
Samples were considered mutated when �15% of DNA was positive.
Endpoints were overall survival (OS) and distant metastasis free survival
(DMFS). 92 patients had to be included to demonstrate a doubling of OS in
patients without (40 months (m)) and with BRAFV600 mutation (20 m).
Log-rank test and multivariate Cox proportional hazards regression model
were used. Results: 105 consecutive pts were included, with 72% prospectively
followed-up pts. BRAFV600 mutations (E: 83%; K: 14% of pts) were
detected in 40% of pts. Median follow-up was 19 m (range: 3-139). Death
occurred in 83% and 60% of pts with and without BRAF mutations,
respectively, with median OS of 1.4 and 2.8 years. Pts’ age, primary
melanoma ulceration, number of invaded nodes, AJCC staging, and BRAF
status influenced OS and DMFS in the univariate analysis. The multivariate
analysis showed the major prognostic role of BRAF status and of the
number of invaded nodes (table). Conclusions: Provided our findings are
independently replicated, BRAFV600 status should be used to stage
melanoma pts with nodal metastasis. Our results also help to plan adjuvant
trials with BRAFV600-targeted therapy in such patients, for whom the low
tumor load may induce longer efficacy of BRAF-targeted therapies.
OS DMFS
P HR[IC95%] P HR[IC95%]
N invaded nodes (1,2-3,4) 0.005 2.2 [1.3-3.9] 0.005 2.4 [1.3-4.3)
BRAF mutated (Y/N) 0.005 1.9 [1.2-3.1] 0.002 2·1 [1·3-3·4]
Ulceration of primary (Y/N) NS - 0.04 1.7 [1.0-2.8]
AJCC staging, extracapsular spread, macro/micrometastasis, Breslow index: NS.
8542 General Poster Session (Board #31H), Sun, 8:00 AM-12:00 PM
Role of cytokine-induced plasticity in melanoma on invasive, therapyresistant
cells that express EMT-related genes and pathways. Presenting
Author: Jonathan S. Cebon, Ludwig Institute for Cancer Research, Melbourne,
Australia
Background: The acquisition of new mutations can explain resistance to
targeted therapies; however resistance also develops without demonstrable
new mutations. To better understand potential mechanisms for treatment
failure we studied subpopulations of chemo-resistant cells that can be
identified in early passage cell lines and the cellular plasticity that yields
these. Methods: Melanoma subpopulations were identified and sorted on
the basis of functional assays. Gene expression was evaluated with Illumina
HT12 arrays and qPCR to identify potential mechanisms and targets.
Sorted cells were evaluated in vitro for the induction of phenotype
switching and effects of target inhibition. Results: A subset of slow
proliferating label-retaining cells (LRC) was identified using a membrane
dye. Direct isolation of LRC from a pt showed these were not an in vitro
artefact. LRC isolated from multiple cell lines comprised the majority of
cells that resisted cytotoxic drugs and could invade through an artificial
extracellular membrane. Gene expression profiling identified a network of
over-expressed genes related to epithelial-to-mesenchymal transition (EMT)
notable for the expression of Thrombospondin-1 (TSP-1), Transforming-
Growth Factor, Beta Induced, (TGFBI) and other extracellular matrix
molecules. Initial studies show that LRC shared gene expression characteristics
with PLX4032-resistant cells. Although interrogating LRC by qPCR
showed up-regulation of the putative melanoma stem cell marker ABCB5
and the lysine specific demethylase Jarid1B, cell sorting and serial
re-labelling experiments revealed a dynamic and interchangeable phenotype
for these cells, challenging the hierarchical stem cell model for
melanoma. The observed slow-cycling and chemo-resistant phenotype
could be induced in vitro through TGF beta-mediated phenotype switching
and cellular invasion was blocked using an antibody against TSP-1.
Conclusions: Cytokine-induced plasticity in melanoma yields invasive,
therapy-resistant cells which express EMT-related genes and pathways. We
hypothesize that these cells are a source of treatment resistance in vivo and
blocking their emergence may prevent treatment failure.
8541 General Poster Session (Board #31G), Sun, 8:00 AM-12:00 PM
Characterization of ipilimumab exposure-efficacy/safety response relationships
in subjects with previously treated or untreated advanced melanoma.
Presenting Author: Yan Feng, Bristol-Myers Squibb, Princeton, NJ
Background: Ipilimumab (IPI) is a fully human monoclonal antibody
directed against CTLA-4 that is being developed as a novel immunotherapeutic
agent against melanoma and other solid tumors. The objective of
this analysis was to retrospectively characterize the exposure-response
(E-R) relationships for efficacy (overall survival, OS) in subjects with
previously untreated advanced melanoma (pu-MEL), and safety (immune
related adverse-events, irAEs) in subjects with previously treated advanced
melanoma (pt-MEL) or pu-MEL. Methods: The E-R analysis of OS included
498 pu-MEL from a phase III study (CA184024) of IPI administered at 10
mg/kg � dacarbazine (DTIC) or DTIC � placebo; and the E-R analyses of
irAE included 1036 subjects from a phase I study (CA184078), 4 phase
IIstudies (CA184004/007/008/022) and CA184024 of IPI administered
at doses of 0.3, 3 or 10 mg/kg. The relationship between steady-state IPI
trough concentration (Cminss) and OS was described using a Cox proportional
hazards model, and the relationships between Cminss and incidence
of irAEs were described by ordinal logistic regression models (separate
models for any irAE, as well as skin, liver and GI irAE). Results: The risk of
death decreased with increasing Cminss, and is higher for subjects with
elevated baseline LDH level. The risk of death was higher for subjects with
baseline ECOG status � 0 and was higher with increasing stage of disease
(M1C�M1B�M1A�M0). The hazard ratio for OS corresponding to the
median Cminss of 49.99 �g/mL was 0.745 relative to subjects in DTIC �
placebo group. The probability of Grade 2� or Grade 3� GI, skin, liver and
any irAEs also increases with Cminss. Prior anti-cancer therapy (including
prior DTIC) or concomitant DTIC were the only significant covariates in the
E-R irAE models. Conclusions: These model-based analyses suggest that
higher Cminss of IPI appears to be associated with improved survival in
pu-MEL (based on data from CA184024) and higher Cminss also appears
to be associated with increased probability of irAEs in pu-MEL or pt-MEL.
8543 General Poster Session (Board #32A), Sun, 8:00 AM-12:00 PM
Gene expression profile signature (DecisionDx-Melanoma) to predict visceral
metastatic risk in patients with stage I and stage II cutaneous
melanoma. Presenting Author: Navneet Dhillon, Emory University , Atlanta,
GA
Background: The current AJCC TNM staging system has poor specificity for
predicting visceral metastatic risk in patients diagnosed with stage I or
stage II cutaneous melanoma. We, therefore, developed a gene expression
profile signature (GEP) following in silico investigation of previously
published microarray analyses. Methods: 60 formalin fixed paraffin embedded
primary cutaneous melanoma samples from patients with stage I or II
cutaneous melanoma with at least a follow up period of at least 6 years were
macrodissected and analyzed blindly. RNA was isolated, converted to
cDNA and RT-PCR was performed to assess the expression of the gene set.
Expression data and biostatistical analysis was performed using GeNorm
and JMP Genomics (SAS) Predictive modeling included Radial Basis
Machine (RBM) and Partition Tree Analysis (PTA) Metastasis-free survival
(MFS) was assessed using Kaplan-Meier analysis. The following clinical
data was retrieved from medical records: survival, metastases, types of
metastases. 20 out of 60 patients had developed visceral metastases in the
follow up period. Results: GEP was developed following multiple analytical
approaches.Two types of signatures emerged: Low risk (Class 1) and High
risk (Class 2). Without optimizing for sensitivity, the analyses of the 60
sample cohort by radial basis machine (RBM) resulted in 92% ROC (met.
accuracy � 90%, non-met. accuracy � 85%), while partition tree analysis
(PTA) yielded 99% ROC (met. accuracy � 100%, non-met. accuracy �
95%). RBM classification showed 6-year MFS rates of 97% for Class 1 and
19% for predicted Class 2 of metastasis (median MFS � NR and 5.6 yrs,
resp., P�0.0001 Log-Rank respectively). PTA showed 6-year MFS rates of
100% for predicted Class 1 and 14% for Class 2 of metastasis (median
MFS � NR and 5.4 yrs, resp., P�0.0001 Log-Rank respectively).
Conclusions: This study shows that DecisionDx-Melanoma GEP signature
can provide excellent accuracy in predicting metastatic risk in stage I and II
cutaneous melanoma.To our knowledge, the GEP provides the most
accurate predictor to date for development of visceral metastases in
patients with Stage I and II cutaneous melanoma.
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