Our results indicate the long-term activity of imatinib in therapy of inoperable and/or metastatic cases of DFSP, including FS-DFSP. Some DFSP patients initially evaluated as unresectable/metastatic or necessitating mutilating surgery turned resectable after imatinib therapy and this rational approach leading to complete remission maybe potentially curative.
Background
Gastrointestinal stromal tumors (GIST) mutational status is recognized factor related to the results of tyrosine kinase inhibitors therapy such as imatinib (IM) or sunitinib (SU). Arterial hypertension (AH) is common adverse event related to SU, reported as predictive factor in renal cell carcinoma.
The aim
of the study was to analyze the outcomes and factors predicting results of SU therapy in inoperable/metastatic CD117(+) GIST patients after IM failure.
Methods
We identified 137 consecutive patients with advanced inoperable/metastatic GIST treated in one center with SU (2
nd
line treatment). Median follow-up time was 23 months. Additionally, in 39 patients there were analyzed selected constitutive single nucleotide polymorphisms (SNPs) of
VEGFA
and
VEGFR2
genes.
Results
One year progression-free survival (PFS; calculated from the start of SU) rate was 42% and median PFS was 43 weeks. The estimated overall survival (OS, calculated both from start of SU or IM) was 74 weeks and 51 months, respectively. One-year PFS was 65% (median 74 weeks) in 55 patients with AH
vs
. 22% (median 17 weeks) in patients without AH. Patients with primary tumors carrying mutations in
KIT
exon 9 or wild-type had substantially better 1-year PFS (68% and 57%; median 65.5 and 50.5 weeks, respectively) than patients having tumors with
KIT
exon 11 or
PDGFRA
mutations (34% and 15%; median 36.8 and 9 weeks, respectively). We identified two independent factors with significant impact on PFS and OS in univariate and multivariate analysis: primary tumor genotype and presence of AH. The most common adverse events during therapy were: fatigue, AH, hypothyroidism, hand and foot syndrome, mucositis, skin reactions, dyspepsia, and diarrhea. Two deaths were assessed as related to tumor rupture caused by reaction to SU therapy. The presence of C-allele in rs833061 and the T-allele in rs3025039 polymorphism of
VEGFA
were associated with significantly higher risk of hypothyroidism (OR: 10.0 p = 0.041 and OR: 10.5; p = 0.015, respectively).
Conclusions
We confirmed that many advanced GIST patients benefit from SU therapy with OS > 1.5 year. Primary tumor
KIT/PDGFRA
genotype and SU-induced AH, as surrogate of its antiangiogenic activity are two independent factors influencing both PFS and OS.
Note
The preliminary data of this study were presented during Annual Meeting of American Society of Clinical Oncology, 4-8 June 2011 and Connective Tissue Oncology Society Meeting, 26-28 October 2011 in Chicago, IL.
Objective: We assessed the status of the BRAF V600E mutation in cell-free circulating tumor DNA (cfDNA) isolated from the plasma of patients with metastatic melanoma treated with the BRAF inhibitor vemurafenib, collected at different time points during therapy to evaluate the sensitivity and specificity of quantitative polymerase chain reaction and droplet digital polymerase chain reaction (ddPCR) and the correlation between the level of plasma cfDNA p.V600E and the long-term clinical outcome. Methods: cfDNA in patients with BRAF-mutated melanoma ( n = 62) was analyzed at baseline and at 4−8 weeks from the start of vemurafenib therapy. BRAF mutations were assessed using tumor tissue-derived DNA and circulating cfDNA from plasma samples. Quantification of BRAF V600E was performed in cfDNA using ddPCR. Results: cfDNA V600E was detected in the plasma of 48/62 (77%) patients at baseline and in 18/62 (29%) patients after 4–8 weeks of treatment. Patients positive for BRAF mutations in cfDNA at baseline had shorter progression-free survival (PFS) and overall survival (OS) compared with patients with undetectable cfDNA BRAF mutations. Undetectable cfDNA p.V600E at baseline and after 4–8 weeks of therapy was associated with the best prognosis. When treated as a continuous variable, the log-transformed concentration of baseline cfDNA p.V600E was significantly associated with both PFS and OS. This effect was retained in the multivariate OS Cox model adjusted for Eastern Cooperative Oncology Group performance status, the presence of brain metastases, patient age, and previous systemic treatment. Conclusions: Monitoring of plasma BRAF p.V600E cfDNA concentrations in patients with metastatic melanoma on targeted therapy may have prognostic value. Undetectable cfDNA p.V600E before and during treatment was associated with a favorable prognosis.
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