[Effect of electroacupuncture at "Weizhong" (BL40) on expression of muscular PDGF-CC, PDGFR-α and MMP-1 in rats with lumbar multifidus muscle injury].

OBJECTIVE: To observe the effect of electroacupuncture (EA) of "Weizhong" (BL40) on the expression of platelet-derived growth factor (PDGF)-CC, PDGF receptor (PDGFR)α and matrix metalloproteinase-1 (MMP-1) in rats with lumbar multifidus muscle injury (LMMI) so as to study its mechanisms underlying improvement of skeletal muscle injury. METHODS: Fifty-four male SD rats were randomly divided into normal group (n=6), model group (n=24) and EA group (n=24), and the latter two groups were further divided into four subgroups (1, 3, 5 and 7 days), with 6 rats in each group. The LMMI model was established by injection of 0.5% bupivacaine (BPVC, 100 µL×4) into the multifidus along the L4 and L5 spinous process. EA (2 Hz/50 Hz, 1 mA) was applied to bilateral "Weizhong"(BL40) for 20 min, once daily for 1, 3, 5 and 7 days respectively, from the first day on after modeling. Histopathological changes of the left multifidus muscle were observed after H.E. staining, and the expression of PDGF-CC, PDGFR-α and MMP-1 proteins in the right multifidus was observed by Western blot. RESULTS: Compared with the normal group, the expression levels of PDGF-CC protein in the model subgroup 1 d, 3 d and 7 d were significantly decreased (P<0.05), and those of PDGFR-α and MMP-1 proteins in the model subgroup 5 d and 7 d, and PDGF-CC protein in the model subgroup 5 d significantly increased (P<0.05). In comparison with the model subgroups, the expression levels of PDGF-CC in the EA subgroup 3 d, 5 d and 7 d, PDGFR-α in the EA subgroup 5 d, and MMP-1 in the EA group 3 d and 5 d were significantly increased or significantly further increased (P<0.05). H.E. staining showed different shapes and uneven sizes, with large area of damage, enlarged muscle space and inflammatory cell infiltration in the model group, which was relatively milder in the EA subgroups particularly in subgroup 5 d and 7 d. CONCLUSION: EA stimulation of BL40 for about 5 days has a positive effect in promoting the repair of the injured multifidus muscle in LMMI rats, which may be related to its function in up-regulating the expression of muscular PDGF-CC, PDGFR-α and MMP-1 proteins.

Financial Implications of Avapritinib for Treatment of Unresectable Gastrointestinal Stromal Tumors in Patients With a PDGFRA Exon 18 Variant or After 3 Previous Therapies in a Hypothetical US Health Plan.

Importance: With the approval of avapritinib for adults with unresectable or metastatic gastrointestinal stromal tumors (GISTs) harboring a platelet-derived growth factor receptor alpha (PDGFRA) exon 18 variant, including PDGFRA D842V variants, and National Comprehensive Cancer Network guideline recommendations as an option for patients with GIST after third-line treatment, it is important to estimate the potential financial implications of avapritinib on a payer's budget. Objective: To estimate the budget impact associated with the introduction of avapritinib to a formulary for metastatic or unresectable GISTs in patients with a PDGFRA exon 18 variant or after 3 or more previous treatments from the perspective of a US health plan. Design, Setting, and Participants: For this economic evaluation, a 3-year budget impact model was developed in March 2020, incorporating costs for drug acquisition, testing, monitoring, adverse events, and postprogression treatment. The model assumed that avapritinib introduction would be associated with increased PDGFRA testing rates from the current 49% to 69%. The health plan population was assumed to be mixed 69% commercial, 22% Medicare, and 9% Medicaid. Base case assumptions included a GIST incidence rate of 9.6 diagnoses per million people, a metastatic PDGFRA exon 18 mutation rate of 1.9%, and progression rate from first-line to fourth-line treatment of 17%. Exposures: The model compared scenarios with and without avapritinib in a formulary. Main Outcomes and Measures: Annual, total, and per member per month (PMPM) budget impact. Results: In a hypothetical 1-million member plan, fewer than 0.1 new patients with a PDGFRA exon 18 variant per year and 1.2 patients receiving fourth-line therapy per year were eligible for treatment. With avapritinib available, the total increase in costs in year 3 for all eligible adult patients with a PDGFRA exon 18 variant was $46 875, or $0.004 PMPM. For patients undergoing fourth-line treatment, the total increase in costs in year 3 was $69 182, or $0.006 PMPM. The combined total budget impact in year 3 was $115 604, or $0.010 PMPM, including an offset of $3607 in postprogression costs avoided or delayed. The higher rates of molecular testing resulted in a minimal incremental testing cost of $453 in year 3. Conclusions and Relevance: These results suggest that adoption of avapritinib as a treatment option would have a minimal budget impact to a hypothetical US health plan. This would be primarily attributable to the small eligible patient population and cost offsets from reduced or delayed postprogression costs.

Prolonged response to sorafenib in a patient with refractory metastatic osteosarcoma and a somatic PDGFRA D846V mutation.

Outcome for patients with metastatic or recurrent/refractory osteosarcoma remains poor. Responses to sorafenib, a multikinase inhibitor, have been seen in recurrent/refractory osteosarcoma, although specific biomarkers of response have not been described. We report a partial response in a 7-year-old with refractory osteosarcoma treated with sorafenib 200 mg twice daily. Toxicities included Common Terminology Criteria for Adverse Events Grade 2 skin toxicities and growth suppression. After 51 months of therapy, he suffered a recurrence. Tumor sequencing later revealed a PDGFRA D846V mutation that was not identified in the relapse specimen. This case demonstrates prolonged partial response to sorafenib and provides a potential biomarker for response.

Downregulation of miR­146a promotes proliferation and migration of AOB­treated embryoid body via PDGFRA induction.

Antioxidant of bamboo leaves (AOB) has been proven to have antioxidant activity and an inhibitory effect on free radicals that induce deterioration of macromolecules. The multi­target regulation of microRNAs (miRs) in the complicated process of vasculogenesis and angiogenesis lead to the use of miRNA therapy in vascular development. In the present study, the role of miRNAs on early embryo vascular development upon AOB stimulation was investigated. For this purpose, mouse embryonic stem cells were spontaneously differentiated as embryoid bodies (EBs) and were examined by phase contrast microscopy. miR­146a mimic and scramble control were transfected into EBs and potential targets of miR­146a were predicted. Cell proliferation and migration were detected by cell viability and wound­healing and migration assays, respectively. Angiogenesis was determined by the Spheroid sprouting assay. It was demonstrated that EBs transfected with miR­146a mimic had an increased growth rate compared with the control cells. miR­146a­transfected cells were very susceptible to AOB treatment. Furthermore, among the predicted miR­146a targets, platelet­derived growth factor receptor alpha (PDGFRA) was identified as a bona fide target of miR­146a. In conclusion, PDGFRA was demonstrated to participate in the modulation of cell migration and proliferation of mouse EBs. The present study expanded the current understanding of AOB biology and elucidated the mechanisms underlying early embryo vascular development upon AOB stimulation.

Curcuma longa Is Able to Induce Apoptotic Cell Death of Pterygium-Derived Human Keratinocytes.

Pterygium is a relatively common eye disease that can display an aggressive clinical behaviour. To evaluate the in vitro effects of Curcuma longa on human pterygium-derived keratinocytes, specimens of pterygium from 20 patients undergoing pterygium surgical excision were collected. Pterygium explants were put into culture and derived keratinocytes were treated with an alcoholic extract of 1.3% Curcuma longa in 0.001% Benzalkonium Chloride for 3, 6, and 24 h. Cultured cells were examined for CAM5.2 (anti-cytokeratin antibody) and CD140 (anti-fibroblast transmembrane glycoprotein antibody) expression between 3th and 16th passage to assess cell homogeneity. TUNEL technique and Annexin-V/PI staining in flow cytometry were used to detect keratinocyte apoptosis. We showed that Curcuma longa exerts a proapoptotic effect on pterygium-derived keratinocytes already after 3 h treatment. Moreover, after 24 h treatment, Curcuma longa induces a significant increase in TUNEL as well as Annexin-V/PI positive cells in comparison to untreated samples. Our study confirms previous observations highlighting the expression, in pterygium keratinocytes, of nuclear VEGF and gives evidence for the first time to the expression of nuclear and cytoplasmic VEGF-R1. All in all, these findings suggest that Curcuma longa could have some therapeutic potential in the treatment and prevention of human pterygium.

Molecular cytology genotyping of primary and metastatic GI stromal tumors by using a custom two-gene targeted next-generation sequencing panel with therapeutic intent.

BACKGROUND AND AIMS: In an era of precision medicine, customized genotyping of GI stromal tumors by screening for driver mutations will become the standard of care. The fidelity of genotype concordance between paired cytology smears and surgical pathology specimens is unknown. In patients with either primary or metastatic sporadic disease, we sought to determine the frequency of KIT and PDGFRA pathogenic alterations within such specimens, imatinib sensitivity, and the concordance of pathogenic alterations between paired specimens. METHODS: DNA obtained from cytology smears from 36 patients, 24 of whom had paired surgical pathology specimens, underwent targeted next-generation sequencing by using a custom panel to evaluate somatic mutations within KIT (exon 2, 9, 10, 11, 13, 14, 15, 17, 18) and PDGFRA (exon 12, 14, 15, 18) genes. Patients with KIT and PDGRFA wild-type genes completed the Qiagen Human Comprehensive Cancer GeneRead DNAseq Targeted Array V2. RESULTS: Genotyping revealed KIT and PDGFRA mutations in 68% and 15% of patients. The wild-type population did not harbor mutations in BRAF, RAS family, SDHB, SETD2, or NF1. Imatinib sensitivity based on the oncogenic kinase mutation prevalence was estimated to be 68%. Mutational concordance between paired cytology and surgical pathology specimens was 96%. CONCLUSIONS: Our data have demonstrated the ability to stratify either primary or metastatic gastrointestinal stromal tumors by mutational subtype using a targeted next-generation sequencing 2 gene mutation panel. We highlight the ability to use cytology specimens obtained via minimally invasive techniques as a surrogate to surgical specimens given the high mutational landscape concordance between paired specimens.

Pilot Study of a Next-Generation Sequencing-Based Targeted Anticancer Therapy in Refractory Solid Tumors at a Korean Institution.

We evaluated the preliminary efficacy and feasibility of a next-generation sequencing (NGS)-based targeted anticancer therapy in refractory solid tumors at a Korean institution. Thirty-six patients with advanced cancer underwent molecular profiling with NGS with the intent of clinical application of available matched targeted agents. Formalin-fixed paraffin-embedded (FFPE) tumors were sequenced using the Comprehensive Cancer Panel (CCP) or FoundationOne in the Clinical Laboratory Improvement Amendments-certified laboratory in the USA. Response evaluations were performed according to RECIST v1.1. Four specimens did not pass the DNA quality test and 32 specimens were successfully sequenced with CCP (n = 31) and FoundationOne (n = 1). Of the 32 sequenced patients, 10 (31.3%) were ≤40 years. Twelve patients (37.5%) had received ≥3 types of prior systemic therapies. Of 24 patients with actionable mutations, five were given genotype-matched drugs corresponding to actionable mutations: everolimus to PIK3CA mutation in parotid carcinosarcoma (partial response) and tracheal squamous cell carcinoma (stable disease; 21% reduction), sorafenib to PDGFRA mutation in auditory canal adenocarcinoma (partial response), sorafenib to BRAF mutation in microcytic adnexal carcinoma (progressive disease), and afatinib to ERBB2 mutation in esophageal adenocarcinoma (progressive disease). Nineteen of 24 patients with actionable mutations could not undergo targeted therapy based on genomic testing because of declining performance status (10/24, 41.7%), stable disease with previous treatment (5/24, 20.8%), and lack of access to targeted medication (4/24, 16.7%). NGS-based targeted therapy may be a good option in selected patients with refractory solid tumors. To pursue this strategy in Korea, lack of access to clinical-grade NGS assays and a limited number of genotype-matched targeted medications needs to be addressed and resolved.

Clinical and therapeutic considerations of GIST.

Gastrointestinal stromal tumors (GIST) are rare tumors of the digestive tract, with an incidence of about 1.5 per 100,000/year. Clinical features may vary depending on location, size and aggressiveness. The diagnosis is confirmed by immunohistochemistry tests that identify CD 117 or DOG1 (typical receptors/markers for most GISTs) at the level of biopsy specimen. The treatment of localized GIST is based primarily on the surgery, while for metastatic GIST the targeted therapy with tyrosine kinase inhibitors represents the current standard. The neoadjuvant and adjuvant therapy indications guided and depending on genetic analysis included in the diagnostic and treatment algorithm as well as the strategy for cases surveillance are listed in the journal. All these data obtained from the literature have been integrated in a practical experience of 19 cases of GIST, operated in the clinic in the last 10 years for which we have proposed an adapted diagnostic algorithm.

Sorafenib efficacy in thymic carcinomas seems not to require c-KIT or PDGFR-alpha mutations.

PURPOSE: To retrospectively evaluate sorafenib activity and safety in patients with metastatic thymic carcinoma (TC) and to correlate outcome with c-KIT and PDGFR-alpha mutational status. PATIENTS AND METHODS: Patients with metastatic thymic carcinoma treated with sorafenib after at least one prior line of chemotherapy were included. Objective response rate (ORR) and toxicity were evaluated. Analysis of c-KIT and PDGFR-alpha mutational status was performed retrospectively. RESULTS: From October 2007 to August 2011, 5 patients with metastatic thymic carcinoma were evaluated. A median of 8 cycles of sorafenib (range=3-29) were administered. Two patients (40%) displayed a partial response (PR), two patients presented stable disease (SD), while one patient had progression. The median progression-free (PFS) and overall survival were 28 weeks and 92 weeks, respectively. At mutational analysis, only one patient with PR had c-KIT mutation in exon 17 and was successfully treated with sunitinib for 12 months after progression to sorafenib. No PDGFR-alpha mutations were found. CONCLUSION: Sorafenib activity seems independent from the c-KIT and PDGFR-alpha mutational status. After progression, sequence treatment with a different tyrosine kinase inhibitor can be considered. These results are promising and need further confirmation on larger, possibly prospective, series of patients.

Prognostic value of KIT/PDGFRA mutations in gastrointestinal stromal tumors: a meta-analysis.

BACKGROUND: The postulated relationship between KIT/PDGFRA mutations and their prognostic value in gastrointestinal stromal tumors (GISTs) has generated intense attention during the past decade, despite the fact that a great deal of studies have been conducted on this subject. To provide a strong quantitative estimate of this postulated relationship, we carried out a meta-analysis which combined, compared, and summarized the results of existing relevant studies. METHODS: Studies were identified by searching databases and reviewing citations in relevant articles. Of 48 potentially relevant studies, we combined individual patient data from 18 studies which involved 1,487 patients with GISTs, by which we made a comparison between the positive KIT mutation subgroup and the negative KIT mutation subgroup (PDGFRA mutation and wild type). We tabulated and analyzed the patient characteristics from each study, including general information such as age and gender, histopathological parameters, and clinical follow-up outcomes. RESULTS: KIT mutations, compared with PDGFRA mutations and wild type, showed a marked increased risk not only for tumor size (>5 cm) but also for higher mitotic activity (>5), suggesting that KIT mutations significantly correlated with the National Comprehensive Cancer Network (NCCN) high risk or National Institutes of Health (NIH) high risk (1.74 (95% CI, 1.20 to 2.53) and 2.00 (95% CI, 1.08 to 3.68), respectively). Moreover, higher recurrence and metastasis was observed in GISTs with KIT mutations, revealing its closer correlation with clinical malignant risk (P<0.001 for each, with odds ratio (OR) of 2.06 (95%, 1.37 to 3.11) and 2.77 (95%, 1.64 to 4.67), respectively). High risk or malignant GISTs with KIT mutations had a significantly poorer prognosis, as measured by 3-year overall survival, compared to those with PDGFRA mutations and wild type (0.47 (95% CI, 0.25 to 0.90)). CONCLUSIONS: KIT mutations, compared with PDGFRA mutations and wild type, represent a poorer prognostic marker in high risk or malignant GISTs.

The alternative lengthening of telomere phenotype is significantly associated with loss of ATRX expression in high-grade pediatric and adult astrocytomas: a multi-institutional study of 214 astrocytomas.

Loss-of-function of alpha thalassemia/mental retardation syndrome X-linked (ATRX) protein leads to a phenotype called alternative lengthening of telomeres (ALT) in some tumors. High-grade astrocytomas comprise a heterogeneous group of central nervous system tumors. We examined a large cohort of adult (91) and pediatric (n=88) high-grade astrocytomas as well as lower grade forms (n=35) for immunohistochemical loss of ATRX protein expression and the presence of ALT using telomere-specific fluorescence in situ hybridization, with further correlation to other known genetic alterations. We found that in pediatric high-grade astrocytomas, 29.6% of tumors were positive for ALT and 24.5% were immunonegative for the ATRX protein, these two alterations being highly associated with one another (P<0.0001). In adult high-grade astrocytomas, 26.4% of tumors were similarly positive for ALT, including 80% of ATRX protein immunonegative cases (P<0.0001). Similar frequencies were found in 11 adult low-grade astrocytomas, whereas all 24 pilocytic astrocytomas were negative for ALT. We did not find any significant correlations between isocitrate dehydrogenase status and either ALT positivity or ATRX protein expression in our adult high-grade astrocytomas. In both cohorts, however, the ALT positive high-grade astrocytomas showed more frequent amplification of the platelet-derived growth factor receptor alpha gene (PDGFRA; 45% and 50%, respectively) than the ALT negative counterparts (18% and 26%; P=0.03 for each). In summary, our data show that the ALT and ATRX protein alterations are common in both pediatric and adult high-grade astrocytomas, often with associated PDGFRA gene amplification.

[Molecular mechanism and therapeutic strategy for resistance to tyrosine kinase inhibitors in targeted treatment of gastrointestinal stromal tumors].

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the GI tract. Aberrant activation of tyrosine kinase through mutated KIT or platelet-derived growth factor receptor (PDGFRA) is the key pathogenic factor in most cases. Tyrosine kinase inhibitors (TKI) such as imatinib and sunitinib can suppress activation of tyrosine kinase receptor and has gained wide recognition as the first-line adjuvant therapy for advanced or high-risk GIST after surgery. It has become the classic model of treatment for solid tumor with molecular targeted therapy. However, the emergence of drug-resistance limits the long-term benefit of these drugs in most patients and has been a challenging clinical concern. Many factors are related to the resistance of TKI, of which KIT/PDGFRA mutation is the most important one. Genetic amplification of KIT, loss of heterozygosity, activation of an alternative downstream signaling pathways, and drug concentration are all possible factors. Therefore, reasonable individual treatment strategy and early resistance evaluation for imatinib- and sunitinib-resistant GISTs are important to patients with drug resistance in order to improve therapeutic efficacy and quality of life.

Tyrosine kinase receptor status in endometrial stromal sarcoma: an immunohistochemical and genetic-molecular analysis.

Endometrial stromal sarcomas (ESS) are rare uterine malignant mesenchymal neoplasms, which are currently treated by surgery, as effective adjuvant therapies have not yet been established. Tyrosine kinase inhibitors have rarely been applied in ESS therapy, with few reports describing imatinib responsivity. The aim of this study was to analyze the status of different tyrosine kinase receptors in an ESS series, in order to evaluate their potential role as molecular targets. Immunohistochemistry was performed for EGFR, c-KIT, PDGFR-α, PDGFR-ß, and ABL on 28 ESS. EGFR, PDGFR-α, and PDGFR-ß gene expression was investigated by real-time polymerase chain reaction (qRT-PCR) on selected cases. "Hot-spot" mutations were screened for on EGFR, c-KIT, PDGFR-α, and PDGFR-ß genes, by sequencing. All analysis was executed from formalin-fixed, paraffin-embedded specimens. Immunohistochemical overexpression of 2 or more tyrosine kinase receptors was observed in 18 of 28 tumors (64%), whereas only 5 tumors were consistently negative. Gene expression profiles were concordant with immunohistochemical overexpression in only 1 tumor, which displayed both high mRNA levels and specific immunoreactivity for PDGFR-α, and PDGFR-ß. No activating mutations were found on the tumors included in the study. This study confirms that TKRs expression is frequently observed in ESS. Considering that the responsiveness to tyrosine kinase inhibitors is known to be related to the presence of specific activating mutations or gene over-expression, which are not detectable in ESS, TKRs immunohistochemical over-expression alone should not be considered as a reliable marker for targeted therapies in ESS. Specific post-translational abnormalities, responsible for activation of TKRs, should be further investigated.

PDGF receptor alpha is an alternative mediator of rapamycin-induced Akt activation: implications for combination targeted therapy of synovial sarcoma.

Akt activation by the IGF-1 receptor (IGF-1R) has been posited to be a mechanism of intrinsic resistance to mTORC1 inhibitors (rapalogues) for sarcomas. Here we show that rapamycin-induced phosphorylation of Akt can occur in an IGF-1R-independent manner. Analysis of synovial sarcoma cell lines showed that either IGF-1R or the PDGF receptor alpha (PDGFRA) can mediate intrinsic resistance to rapamycin. Repressing expression of PDGFRA or inhibiting its kinase activity in synovial sarcoma cells blocked rapamycin-induced phosphorylation of Akt and decreased tumor cell viability. Expression profiling of clinical tumor samples revealed that PDGFRA was the most highly expressed kinase gene among several sarcoma disease subtypes, suggesting that PDGFRA may be uniquely significant for synovial sarcomas. Tumor biopsy analyses from a synovial sarcoma patient treated with the mTORC1 inhibitor everolimus and PDGFRA inhibitor imatinib mesylate confirmed that this drug combination can impact both mTORC1 and Akt signals in vivo. Together, our findings define mechanistic variations in the intrinsic resistance of synovial sarcomas to rapamycin and suggest therapeutic strategies to address them.

Repression of PDGF-R-α after cellular injury involves TNF-α, formation of a c-Fos-YY1 complex, and negative regulation by HDAC.

Wound healing is a complex dynamic process involving a variety of cell types, including fibroblasts that express and respond to cytokines and growth factors in the local microenvironment. The mechanisms controlling gene expression after injury at a transcriptional level are poorly understood. Here we show that decreased expression of a key receptor, PDGF-receptor (R)-α, after fibroblast injury is due to the release and paracrine activity of TNF-α. TNF-α inhibits PDGF-R-α expression and this involves formation of a c-Fos-Yin Yang 1 (YY1) complex and histone deacetylase (HDAC) activity. c-Fos, induced by TNF-α, negatively regulates PDGF-R-α transcription. Small interfering RNA (siRNA) targeting c-Fos or the zinc finger transcription factor YY1 inhibits TNF-α suppression of PDGF-R-α expression. Coimmunoprecipitation studies show that TNF-α stimulates the formation of a complex between c-Fos with YY1. Furthermore, chromatin immunoprecipitation (ChIP) analysis reveals the enrichment of c-Fos, YY1, and HDAC-1 at the PDGF-R-α promoter in cells exposed to TNF-α. With suberoylanilide hydroxamic acid (SAHA) and HDAC-1 siRNA, we demonstrate that HDAC mediates TNF-α repression of PDGF-R-α. These findings demonstrate that transcriptional repression of PDGF-R-α after fibroblast injury involves paracrine activity of endogenous TNF-α, the formation of a c-Fos-YY1 complex, and negative regulatory activity by HDAC.

Sorafenib in patients with metastatic gastrointestinal stromal tumors who failed two or more prior tyrosine kinase inhibitors: a phase II study of Korean gastrointestinal stromal tumors study group.

PURPOSE: To evaluated the efficacy and safety of sorafenib in patients with advanced gastrointestinal stromal tumors (GIST) who failed to previous standard treatments. EXPERIMENTAL DESIGN: Thirty-one patients with measurable metastatic GIST who failed both imatinib and sunitinib were accrued. Sorafenib was administered orally at 400 mg twice daily until disease progression or development of intolerance. The primary endpoint was disease control rate (response + stable disease, DCR) at 24 weeks. RESULTS: Sorafenib was well tolerated, with hand-foot skin reaction, fatigue, hypertension, and abdominal pain being the most frequent adverse events. The relative dose intensity of sorafenib during the first 6 months was >80%. Four patients achieved partial response (response rate 13%, 95% CI 1-25%), and 16 (52%) had stable disease. DCR at 24 weeks was measured as 36% (95% CI 19-52%). Median progression-free and overall survivals were 4.9 and 9.7 months, respectively. Progression-free survival of patients with prior use of nilotinib (P = .0085) and with primary genotypes other than KIT exon 11 mutation (P = .0341) was significantly shorter than that of patients without. CONCLUSIONS: Sorafenib showed antitumor activity in this population of imatinib and sunitinib pretreated GIST. With sorafenib, about one third of patients can maintain disease control for more than 24 weeks.

Patterns of care, prognosis, and survival in patients with metastatic gastrointestinal stromal tumors (GIST) refractory to first-line imatinib and second-line sunitinib.

BACKGROUND: Data regarding the management and outcome of patients with metastatic gastrointestinal stromal tumors (GIST) refractory to 1st-line imatinib and 2nd-line sunitinib are limited. METHODS: Medical records of 223 imatinib-resistant and sunitinib-resistant GIST who were treated in 11 major referral centers were reviewed. RESULTS: The three most frequent drugs used in the 3rd-line setting were: nilotinib n = 67 (29.5%), sorafenib n = 55 (24.5%), and imatinib n = 40 (17.5%). There were 18 patients (8%) who received best supportive care (BSC) only. The median progression-free survival (PFS) and overall survival (OS) on 3rd-line treatment were 3.6 months [95% confidence interval (95% CI), 3.1-4.1] and 9.2 months (95% CI, 7.5-10.9), respectively. Multivariate analysis showed that, in the 3rd-line setting, albumin level and KIT/PDGFRA mutational status were significantly associated with PFS, whereas performance status and albumin level were associated with OS. After adjustment for prognostic factors, nilotinib and sorafenib provided the best PFS and OS. Rechallenge with imatinib was also associated with improved OS in comparison with BSC. CONCLUSION: In the 3rd-line setting, rechallenge with imatinib provided limited clinical benefit but was superior to BSC. Sorafenib and nilotinib have significant clinical activity in imatinib-resistant and sunitinib-resistant GIST and may represent an alternative for rechallenge with imatinib.