Diagnosis and management of tropomyosin receptor kinase (TRK) fusion sarcomas: expert recommendations from the World Sarcoma Network.

Sarcomas are a heterogeneous group of malignancies with mesenchymal lineage differentiation. The discovery of neurotrophic tyrosine receptor kinase (NTRK) gene fusions as tissue-agnostic oncogenic drivers has led to new personalized therapies for a subset of patients with sarcoma in the form of tropomyosin receptor kinase (TRK) inhibitors. NTRK gene rearrangements and fusion transcripts can be detected with different molecular pathology techniques, while TRK protein expression can be demonstrated with immunohistochemistry. The rarity and diagnostic complexity of NTRK gene fusions raise a number of questions and challenges for clinicians. To address these challenges, the World Sarcoma Network convened two meetings of expert adult oncologists and pathologists and subsequently developed this article to provide practical guidance on the management of patients with sarcoma harboring NTRK gene fusions. We propose a diagnostic strategy that considers disease stage and histologic and molecular subtypes to facilitate routine testing for TRK expression and subsequent testing for NTRK gene fusions.

Efficacy and tolerability of trabectedin in elderly patients with sarcoma: subgroup analysis from a phase III, randomized controlled study of trabectedin or dacarbazine in patients with advanced liposarcoma or leiomyosarcoma.

Background: Treatment options for soft tissue sarcoma (STS) patients aged ≥65 years (elderly) can be limited by concerns regarding the increased risk of toxicity associated with standard systemic therapies. Trabectedin has demonstrated improved disease control in a phase III trial (ET743-SAR-3007) of patients with advanced liposarcoma or leiomyosarcoma after failure of anthracycline-based chemotherapy. Since previous retrospective analyses have suggested that trabectedin has similar safety and efficacy outcomes regardless of patient age, we carried out a subgroup analysis of the safety and efficacy observed in elderly patients enrolled in this trial. Patients and methods: Patients were randomized 2 : 1 to trabectedin (n = 384) or dacarbazine (n = 193) administered intravenously every-3-weeks. The primary end point was overall survival (OS); secondary end points were progression-free survival (PFS), time-to-progression, objective response rate (ORR), duration of response, symptom severity, and safety. A post hoc analysis was conducted in the elderly patient subgroup. Results: Among 131 (trabectedin = 94; dacarbazine = 37) elderly patients, disease characteristics were well-balanced and consistent with those of the total study population. Treatment exposure was longer in patients treated with trabectedin versus dacarbazine (median four versus two cycles, respectively), with a significantly higher proportion receiving prolonged therapy (≥6 cycles) in the trabectedin arm (43% versus 23%, respectively; P = 0.04). Elderly patients treated with trabectedin showed significantly improved PFS [4.9 versus 1.5 months, respectively; hazard ratio (HR)=0.40; P = 0.0002] but no statistically significant improvement in OS (15.1 versus 8.0 months, respectively; HR = 0.72; P = 0.18) or ORR (9% versus 3%, respectively; P = 0.43). The safety profile for elderly trabectedin-treated patients was comparable to that of the overall trabectedin-treated study population. Conclusions: This subgroup analysis of the elderly population of ET743-SAR-3007 suggests that elderly patients with STS and good performance status can expect clinical benefit from trabectedin similar to that observed in younger patients. Trial registration: www.clinicaltrials.gov, NCT01343277.

Long-term follow-up results of the multicenter phase II trial of regorafenib in patients with metastatic and/or unresectable GI stromal tumor after failure of standard tyrosine kinase inhibitor therapy.

BACKGROUND: This investigator-initiated trial provided the justification for the phase III GRID study resulting in worldwide regulatory approval of regorafenib as a third-line therapy for patients with metastatic gastrointestinal stromal tumors (GIST). We report the genotype analyses, long-term safety, and activity results from this initial trial of regorafenib in GIST. PATIENTS AND METHODS: The trial was conducted between February 2010 and January 2014, among adult patients with metastatic GIST, after failure of at least imatinib and sunitinib. Patients received regorafenib orally, 160 mg once daily, days 1-21 of a 28-day cycle. Clinical benefit rate (CBR), defined as complete or partial response (PR), or stable disease lasting ≥16 weeks per RECIST 1.1, progression-free survival (PFS), overall survival (OS), long-term safety data, and metabolic response by functional imaging were assessed. RESULTS: Thirty-three patients received at least one dose of regorafenib. The median follow-up was 41 months. CBR was documented in 25 of 33 patients [76%; 95% confidence interval (CI) 58% to 89%], including six PRs. The median PFS was 13.2 months (95% CI 9.2-18.3 months) including four patients who remained progression-free at study closure, each achieving clinical benefit for more than 3 years (range 36.8-43.5 months). The median OS was 25 months (95% CI 13.2-39.1 months). Patients whose tumors harbored a KIT exon 11 mutation demonstrated the longest median PFS (13.4 months), whereas patients with KIT/PDGFRA wild-type, non-SDH-deficient tumors experienced a median 1.6 months PFS (P < 0.0001). Long-term safety profile is consistent with previous reports; hand-foot skin reaction and hypertension were the most common reasons for dose reduction. Notably, regorafenib induced objective responses and durable benefit in SDH-deficient GIST. CONCLUSIONS: Long-term follow-up of patients with metastatic GIST treated with regorafenib suggests particular benefit among patients with primary KIT exon 11 mutations and those with SDH-deficient GIST. Dose modifications are frequently required to manage treatment-related toxicities. CLINICAL TRIAL NUMBER: NCT01068769.

A multicenter phase II study of pazopanib in patients with advanced gastrointestinal stromal tumors (GIST) following failure of at least imatinib and sunitinib.

BACKGROUND: Advanced GISTs are incurable, but often treatable for years with tyrosine kinase inhibitors (TKIs). The majority of GISTs harbor an oncogenic activating mutation in KIT or PDGFRA. Inhibition of this activating mutation with TKIs most often leads to durable disease control for many patients. However, almost all patients develop resistance to these TKIs, typically due to the development of secondary mutations, heralding the need for new therapeutic options. We conducted a phase II study evaluating the efficacy and toxicity of pazopanib, a broad spectrum TKI inhibiting KIT, VEGFRs (-1, -2, and -3), and PDGFR (-α and-ß) in patients with advanced GIST following failure of at least imatinib and sunitinib. METHODS: Patients received pazopanib 800 mg orally once daily. All patients were assessed for efficacy with CT scans every 8 weeks (two cycles). Patients continued pazopanib until progression or unacceptable toxicity. The primary end point was the 24-week nonprogression [complete response+partial response+stable disease (SD)] rate (NPR) per RECIST 1.1. Secondary end points included PFS, OS, and toxicity. RESULTS: Between August 2011 and September 2012, a total of 25 patients were treated at two institutions. Median number of prior therapy was 3 (range 2-7). A total of 90 cycles of pazopanib were administered, with a median of two cycles (range 1 to 17+) per patient. Best response of SD at any time was observed in 12 (48%) patients. The NPR was 17% [95% confidence interval (CI) 4.5-37]. All but one patient discontinued protocol either due to PD (n = 19) or intolerance (n = 4). One patient with succinate dehydrogenase (SDH)-deficient GIST exhibited continuing disease control after 17 cycles. The median PFS for the entire cohort was 1.9 months (95% CI 1.6-5.2), and the median OS was 10.7 months (95% CI 3.9-NR). CONCLUSIONS: Pazopanib was reasonably well tolerated with no unexpected toxicities. Pazopanib as a single agent has marginal activity in unselected heavily pretreated patients with advanced GIST.

Trabectedin is a feasible treatment for soft tissue sarcoma patients regardless of patient age: a retrospective pooled analysis of five phase II trials.

BACKGROUND: This retrospective pooled analysis assessed the effect of age on the efficacy and safety of trabectedin in young and elderly patients with recurrent advanced soft tissue sarcoma (STS). METHODS: Data from 350 adults with STS treated in five phase II trials with trabectedin were divided in the younger (<60 years; n=267) and the older cohort (≥60 years; n=83). RESULTS: The response rate did not differ with age (younger: 10.1% vs elderly 9.6%). No significant differences were found in median progression-free survival (PFS) in younger (2.5 months) and older (3.7 months) cohort with a comparable PFS rates at 3 (45.1% vs 55.1%) and 6 months (29.5% vs 36.4%). Similar median overall survival was observed in both cohorts (13.0 vs 14.0 months). Reversible neutropenia and aspartate aminotransferase/alanine aminotransferase elevation were the most common abnormalities. A higher incidence of grade 3/4 neutropenia (43.6% vs 60.2%) and fatigue (6.3% vs 14.4%) was observed in older patients. In 24 patients aged ≥70 years, no significant differences in efficacy or safety outcomes were found. CONCLUSION: This analysis demonstrated that trabectedin is a feasible treatment in young and elderly patients with STS, with meaningful clinical benefits and an acceptable safety profile, essential in palliative treatment of elderly patients.

Clinical outcomes and safety with trabectedin therapy in patients with advanced soft tissue sarcomas following failure of prior chemotherapy: results of a worldwide expanded access program study.

BACKGROUND: This expanded access program (EAP) was designed to provide trabectedin access for patients with incurable soft tissue sarcoma (STS) following progression of disease with standard therapy. The outcomes of trial participants accrued over approximately 5 years are reported. PATIENTS AND METHODS: Adult patients with advanced STS of multiple histologies, including leiomyosarcoma and liposarcoma (L-sarcomas), following relapse or disease progression following standard-of-care chemotherapy, were enrolled. Trabectedin treatment cycles (1.5 mg/m(2), intravenously over 24 h) were repeated q21 days. Objective response, overall survival (OS), and safety were evaluated. RESULTS: Of 1895 patients enrolled, 807 (43%) had evaluable objective response data, with stable disease reported in 343 (43%) as best response. L-sarcoma patients exhibited longer, OS compared with other histologies [16.2 months (95% confidence interval (CI) 14.1-19.5) versus 8.4 months (95% CI 7.1-10.7)], and a slightly higher objective response rate [6.9% (95% CI 4.8-9.6) versus 4.0% (95% CI 2.1-6.8)]. The median treatment duration was 70 days representing a median of three treatment cycles; 30% of patients received ≥ 6 cycles. Safety and tolerability in this EAP were consistent with prior clinical trial data. CONCLUSION: Results of this EAP are consistent with previous reports of trabectedin, demonstrating disease control despite a low incidence of objective responses in advanced STS patients after failure of standard chemotherapy. CLINICALTRIALS.GOV: NCT00210665.

Growth modulation index as metric of clinical benefit assessment among advanced soft tissue sarcoma patients receiving trabectedin as a salvage therapy.

BACKGROUND: The growth modulation index (GMI) is the ratio of time to progression with the nth line (TTP(n)) of therapy to the TTP(n)(-1) with the n-1th line. GMI >1.33 is considered as a sign of activity in phase II trials. PATIENTS AND METHODS: This retrospective analysis evaluated the concordance between the GMI and the efficacy outcomes in 279 patients with advanced soft tissue sarcoma (ASTS) treated with trabectedin 1.5 mg/m² (24-h infusion every 3 weeks) in four phase II trials. RESULTS: One hundred and forty-two (51%) patients received one prior line and 137 ≥ 2 lines. The median TTP(n) was 2.8 months (range 0.2-26.8), whereas the median TTP(n)(-1) was 4.0 months (0.3-79.5). The median GMI was 0.6 (0.0-14.4). Overall, 177 patients (63%) had a GMI <1; 21 (8%) a GMI equal to 1-1.33 and 81 (29%) a GMI >1.33, which correlated with the median overall survival in those patients (9.1, 13.9 and 23.8 months, respectively, P = 0.0005). A high concordance rate between the GMI and response rate (P < 0.0001) and progression-free survival (PFS, P < 0.0001) was observed. Good performance status (PS) was the only factor associated with GMI >1.33 (PS = 0; P < 0.04). CONCLUSIONS: A high GMI was associated with favorable efficacy outcomes in patients treated with trabectedin. Further research is needed to assess GMI as an indicator in this setting.

Hypertension as a potential biomarker of efficacy in patients with gastrointestinal stromal tumor treated with sunitinib.

BACKGROUND: Reliable biomarkers of sunitinib response in gastrointestinal stromal tumor (GIST) are lacking. Hypertension (HTN), an on-target class effect of vascular endothelial growth factor signaling-pathway inhibitors, has been shown to correlate with clinical outcome in advanced renal cell carcinoma treated with sunitinib. PATIENTS AND METHODS: This retrospective analysis examined correlations between sunitinib-associated HTN and antitumor efficacy (N = 319) and safety (N = 1565) across three advanced GIST studies. Blood pressure (BP) was measured on days 1 and 28 of each treatment cycle at a minimum. Time-to-event endpoints were estimated using Kaplan-Meier methods, and patient subgroups with and without HTN (maximum systolic BP ≥ 140 mmHg and/or diastolic BP ≥ 90 mmHg) were compared using Cox proportional hazards models. Landmark analyses evaluated associations between early HTN and efficacy endpoints. Adverse events (AEs) were compared between groups. RESULTS: Sunitinib-associated HTN correlated with improved objective response rates, time to tumor progression, progression-free survival, and overall survival. Almost all benefits remained significant in multivariate and landmark analyses. Overall incidences of HTN-related AEs were low and similar between groups; incidences of cardiovascular AEs were somewhat higher in patients with HTN. CONCLUSION: Sunitinib-associated HTN appeared to correlate with improved clinical outcomes in GIST, while incidences of HTN-associated AEs were generally low and manageable.

Phase III study of nilotinib versus best supportive care with or without a TKI in patients with gastrointestinal stromal tumors resistant to or intolerant of imatinib and sunitinib.

BACKGROUND: This phase III open-label trial investigated the efficacy of nilotinib in patients with advanced gastrointestinal stromal tumors following prior imatinib and sunitinib failure. PATIENTS AND METHODS: Patients were randomized 2:1 to nilotinib 400 mg b.i.d. or best supportive care (BSC; BSC without tyrosine kinase inhibitor, BSC+imatinib, or BSC+sunitinib). Primary efficacy end point was progression-free survival (PFS) based on blinded central radiology review (CRR). Patients progressing on BSC could cross over to nilotinib. RESULTS: Two hundred and forty-eight patients enrolled. Median PFS was similar between arms (nilotinib 109 days, BSC 111 days; P=0.56). Local investigator-based intent-to-treat (ITT) analysis showed a significantly longer median PFS with nilotinib (119 versus 70 days; P=0.0007). A trend in longer median overall survival (OS) was noted with nilotinib (332 versus 280 days; P=0.29). Post hoc subset analyses in patients with progression and only one prior regimen each of imatinib and sunitinib revealed a significant difference in median OS of >4 months in favor of nilotinib (405 versus 280 days; P=0.02). Nilotinib was well tolerated. CONCLUSION: In the ITT analysis, no significant difference in PFS was observed between treatment arms based on CRR. In the post hoc subset analyses, nilotinib provided significantly longer median OS.

Phase II clinical trial of neoadjuvant trabectedin in patients with advanced localized myxoid liposarcoma.

BACKGROUND: To evaluate neoadjuvant trabectedin (1.5 mg/m(2) 24-h i.v. infusion every 3 weeks; three to six cycles) in patients with locally advanced myoxid liposarcoma (ML) previously untreated with chemotherapy or radiation. PATIENTS AND METHODS: Primary efficacy end point was pathological complete response (pCR) or tumoral regression rate. Objective response according to RECIST (v.1.0) was a secondary end point. RESULTS: Three of 23 assessable patients had pCR [13%; 95% confidence interval (CI), 3% to 34%]. Furthermore, very good and moderate histological responses were observed in another 2 and 10 patients, respectively. Histological decrement in the cellular and vascular tumor component and maturation of tumor cells to lipoblasts were observed in both myoxid and myoxid/round cell variants. Seven patients had partial response according to RECIST (objective response rate of 24%; 95% CI, 10% to 44%). No disease progression was reported. Neoadjuvant trabectedin was usually well tolerated, with a safety profile similar to that described in patients with soft tissue sarcoma or other tumor types. CONCLUSION: Trabectedin 1.5 mg/m(2) given as a 24-h i.v. infusion every 3 weeks is a therapeutic option in the neoadjuvant setting of ML.

Isolation and chromosomal localization of cDNAs encoding a novel human lymphocyte cell surface molecule, LAM-1. Homology with the mouse lymphocyte homing receptor and other human adhesion proteins.

A cDNA encoding a new human lymphocyte cell surface molecule has been isolated and shown to identify a fourth member of a recently discovered family of adhesion proteins. This lymphocyte-associated molecule (LAM-1) is uniquely composed of multiple distinct domains, one domain homologous with animal lectins, one homologous with epidermal growth factor, and two short consensus repeat units similar to those found in C3/C4 binding proteins. This cDNA clone hybridized with RNAs found in B cell lines and T lymphocytes, but not with RNA from other cell types. The amino acid sequence of LAM-1 is 77% homologous with the sequence of the mouse lymphocyte homing receptor, suggesting that LAM-1 may function in human lymphocyte adhesion. The LAM-1 gene is located on chromosome 1q23-25, as is another member of this adhesion family, suggesting that this new family of proteins may be encoded by a cluster of "adhesion protein" loci.

Recombinant human stem cell factor (kit ligand) promotes human mast cell and melanocyte hyperplasia and functional activation in vivo.

Stem cell factor (SCF), also known as mast cell growth factor, kit ligand, and steel factor, is the ligand for the tyrosine kinase receptor (SCFR) that is encoded by the c-kit proto-oncogene. We analyzed the effects of recombinant human SCF (r-hSCF, 5-50 micrograms/kg/day, injected subcutaneously) on mast cells and melanocytes in a phase I study of 10 patients with advanced breast carcinoma. A wheal and flare reaction developed at each r-hSCF injection site; by electron microscopy, most dermal mast cells at these sites exhibited extensive, anaphylactic-type degranulation. A 14-d course of r-hSCF significantly increased dermal mast cell density at sites distant to those injected with the cytokine and also increased both urinary levels of the major histamine metabolite, methyl-histamine, and serum levels of mast cell alpha-tryptase. Five subjects developed areas of persistent hyperpigmentation at r-hSCF injection sites; by light microscopy, these sites exhibited markedly increased epidermal melanization and increased numbers of melanocytes. The demonstration that r-hSCF can promote both the hyperplasia and the functional activation of human mast cells and melanocytes in vivo has implications for our understanding of the role of endogenous SCF in health and disease. These findings also indicate that the interaction between SCF and its receptor represents a potential therapeutic target for regulating the numbers and functional activity of both mast cells and cutaneous melanocytes.

A phase I-II study of everolimus (RAD001) in combination with imatinib in patients with imatinib-resistant gastrointestinal stromal tumors.

BACKGROUND: Imatinib is standard therapy for advanced gastrointestinal stromal tumors (GIST), but most patients develop resistance. This phase I-II study assessed the safety and efficacy of co-administering everolimus with imatinib in imatinib-resistant GIST. PATIENTS AND METHODS: In phase I, patients received imatinib (600/800 mg/day) combined with weekly (20 mg) or daily (2.5/5.0 mg) everolimus to determine the optimal dose. In phase II, patients were divided into two strata (progression on imatinib only; progression after imatinib and sunitinib/other tyrosine kinase inhibitor) and received everolimus 2.5 mg plus imatinib 600 mg/day. Primary end point was 4-month progression-free survival (PFS). RESULTS: Combination treatment was well tolerated. Common adverse events were diarrhea, nausea, fatigue, and anemia. In phase II strata 1 and 2, 4 of 23 (17%) and 13 of 35 (37%) assessable patients, respectively, were progression free at 4 months; median PFS was 1.9 and 3.5 months, and median overall survival was 14.9 and 10.7 months, respectively. In stratum 1, 36% had stable disease (SD) and 54% progressive disease (PD), while in stratum 2, 2% had partial response, 43% SD, and 32% PD. CONCLUSION: Predetermined efficacy criteria were met in both strata. The combination of everolimus and imatinib after failure on imatinib and sunitinib merits further investigation in GIST.

KIT oncoprotein interactions in gastrointestinal stromal tumors: therapeutic relevance.

Most gastrointestinal stromal tumors (GISTs) express oncogenic and constitutively active forms of the KIT or platelet-derived growth factor receptor alpha (PDGFRA) receptor tyrosine kinase proteins, and these kinase oncoproteins serve as targets for effective therapies. Given that mutant KIT oncoproteins serve crucial transforming roles in GISTs, we evaluated interactions with the KIT oncoproteins and determined signaling pathways that are dependent on KIT oncogenic activation in GISTs. Tyrosine-phosphorylated KIT oncoproteins interacted with PDGFRA, PDGFRB, phosphatidylinositol 3-kinase (PI3-K) and PKCtheta in GIST cells, and these interactions were abolished by KIT inhibition with imatinib or PKC412 or KIT RNAi. Notably, tyrosine-phosphorylated PDGFRA was prominent in frozen GIST tumors expressing KIT oncoproteins, suggesting that KIT-mediated PDGFRA phosphorylation is an efficient and biologically consequential mechanism in GISTs. Activated signaling intermediates were identified by immunoaffinity purification of tyrosine-phosphorylated proteins in GIST cells before and after treatment with KIT inhibitors, and these analyses show that GRB2, SHC, CBL and MAPK activation are largely KIT dependent in GISTs, whereas PI3-K, STAT1 and STAT3 activation are partially KIT dependent. In addition, we found that phosphorylation of several tyrosine kinase proteins - including JAK1 and EPHA4 - did not depend on KIT activation. Likewise, paxillin activation was independent of the KIT oncogenic signal. These studies identify signaling pathways that can provide both KIT-dependent and KIT-independent therapeutic synergies in GIST, and thereby highlight clinical strategies that might consolidate GIST therapeutic response to KIT/PDGFRA inhibition.

Expression of ras oncogenes in cultured human cells alters the transcriptional and posttranscriptional regulation of cytokine genes.

Autonomous production of cytokines such as the hematopoietic colony-stimulating factors (CSFs), IL-1, or IL-6 has been demonstrated in numerous human and murine neoplasms, and may be involved in the pathogenesis of several paraneoplastic syndromes such as leukocytosis, fever, and hypercalcemia. Because of the high frequency with which mutations in ras protooncogenes have been detected in human tumors, as well as evidence linking ras gene products to activation of certain cellular functions, we investigated whether ras mutations might influence the regulation of cytokine genes. Normal human fibroblasts transfected with a mutant val12 H-ras oncogene expressed increased levels of mRNA transcripts encoding granulocyte-CSF (G-CSF), granulocyte-macrophage-CSF (GM-CSF), and IL-1 beta compared with controls. Human mesothelioma cells transfected with a mutant asp12 N-ras oncogene exhibited similar alterations in cytokine gene expression. Estimates of transcriptional activity by nuclear run-on analysis revealed a selective increase in transcription only for the IL-1 gene. Analysis of mRNA half-life demonstrated a marked increase in the stability of numerous cytokine transcripts, including G-CSF, GM-CSF, IL-1, and IL-6. The addition of anti-IL-1 neutralizing antibody to cultures of cells expressing ras mutants did not block the expression of any of the cytokines examined, suggesting that the baseline expression of GM-CSF, G-CSF, and IL-6 was not a secondary event due to the increased transcription of IL-1. These results indicate that mutations in ras genes may alter expression of several cytokine genes through both transcriptional and posttranscriptional mechanisms.

Ecteinascidin-743 (ET-743) for chemotherapy-naive patients with advanced soft tissue sarcomas: multicenter phase II and pharmacokinetic study.

PURPOSE: To evaluate the response rate, toxicity profile, and pharmacokinetics of ecteinascidin-743 (ET-743) as first-line therapy in patients with unresectable advanced soft tissue sarcoma (STS). PATIENTS AND METHODS: Thirty-six patients with STS were enrolled onto the study between September 1999 and August 2000. Patients were treated with 1.5 mg/m2 of ET-743 given as a 24-hour continuous intravenous (IV) infusion every 21 days. Pharmacokinetic sampling was performed in 23 patients. RESULTS: One complete and five partial responses were achieved in 35 assessable patients for an overall response rate of 17.1% (95% CI, 6.6% to 33.6%). In addition, one patient had a minor response, leading to an overall clinical benefit of 20%. Neutropenia and transaminitis were the main grade 3 to 4 toxicities, which occurred in 33% and 36% of the patients. The estimated 1-year progression-free and overall survival rates were 21% (95% CI, 11% to 41%) and 72% (95% CI, 59% to 88%), respectively. Total body clearance (L/h) was not significantly correlated with body-surface area (r = -0.28; P = .21). Mild hepatic impairment or the extent of prior cytotoxic therapy does not seem to contribute significantly to the high interpatient variability (49%) in the clearance of this drug. Severity of treatment-related toxicity was not correlated with pharmacokinetic variables. CONCLUSION: ET-743 demonstrates clinical activity as first-line therapy against STS with acceptable toxicity. Additional studies to establish empirical dosing guidelines may be necessary to improve the safety of the drug in patients with varying degrees of hepatic dysfunction and definitively establish the role of ET-743 for patients with these malignancies.

KIT activation is a ubiquitous feature of gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract, and they are generally resistant to chemotherapy and radiation therapy. Most GISTs express the KIT receptor tyrosine kinase protein, and a subset of GISTs contain activating mutations within the KIT juxtamembrane region. We evaluated 48 GISTs, including 10 benign, 10 borderline, and 28 malignant cases, to determine whether KIT expression and activation are general properties of these tumors. Immunohistochemical KIT expression was demonstrated in each case. Somatic KIT mutations were found in 44 tumors (92%), of which 34 (71%) had juxtamembrane region mutations. Other GISTs had KIT mutations in the extracellular region (n = 6) and in two different regions in the tyrosine kinase domain (n = 4). Contrary to previous reports, KIT mutations were not identified preferentially in higher-grade tumors: indeed, they were found in each of 10 histologically benign GISTs. Notably, mutations in all KIT domains were associated with high-level KIT activation/phosphorylation, and KIT activation was also demonstrated in the four GISTs that lacked detectable KIT genomic and cDNA mutations. These studies underscore the role of KIT activation in GIST pathogenesis, and they suggest that activated KIT might represent a universal therapeutic target in GISTs.

STI571 inactivation of the gastrointestinal stromal tumor c-KIT oncoprotein: biological and clinical implications.

Mutations in the c-KIT receptor occur somatically in many sporadic Gastrointestinal Stromal Tumors (GIST), and similar mutations have been identified at the germline level in kindreds with multiple GISTs. These mutations activate the tyrosine kinase activity of c-KIT and induce constitutive signaling. To investigate the function of activated c-KIT in GIST, we established a human GIST cell line, GIST882, which expresses an activating KIT mutation (K642E) in the first part of the cytoplasmic split tyrosine kinase domain. Notably, the K642E substitution is encoded by a homozygous exon 13 missense mutation, and, therefore, GIST882 cells do not express native KIT. GIST882 c-KIT protein is constitutively tyrosine phosphorylated, but tyrosine phosphorylation was rapidly and completely abolished after incubating the cells with the selective tyrosine kinase inhibitor STI571. Furthermore, GIST882 cells evidenced decreased proliferation and the onset of apoptotic cell death after prolonged incubation with STI571. Similar results were obtained after administering STI571 to a primary GIST cell culture that expressed a c-KIT exon 11 juxtamembrane mutation (K558NP). These cell-culture-based studies support an important role for c-KIT signaling in GIST and suggest therapeutic potential for STI571 in patients afflicted by this chemoresistant tumor.

Quality-of-life benefit in chemotherapy patients treated with epoetin alfa is independent of disease response or tumor type: results from a prospective community oncology study. Procrit Study Group.

PURPOSE: To evaluate prospectively the effectiveness of epoetin alfa as an adjunct to chemotherapy in patients with cancer based on changes in quality-of-life parameters and hemoglobin levels, and to correlate these changes with antitumor response. PATIENTS AND METHODS: Two thousand three hundred seventy patients with nonmyeloid malignancies who received chemotherapy were enrolled onto this study from 621 US community-based practices. Patients received epoetin alfa 10,000 U three times weekly, which could be increased to 20,000 U three times weekly depending on the hemoglobin response at 4 weeks. Treatment continued for a maximum of 16 weeks in patients who showed evidence of hematologic response. RESULTS: Two thousand two hundred eighty-nine patients (97%) were eligible for efficacy analyses. Epoetin alfa therapy was associated with improved quality-of-life parameters; these improvements correlated significantly with hemoglobin levels and were independent of tumor response. Provider-reported Karnofsky performance scores did not correlate with the improved quality-of-life changes. Epoetin alfa therapy was also associated with a significant increase in hemoglobin levels and decrease in transfusion use. Tumor type, chemotherapy agent/regimen, prior chemotherapy, baseline hemoglobin level, and baseline erythropoietin level were not predictive of a positive response to treatment. Epoetin alfa was well tolerated. CONCLUSION: Epoetin alfa appears to have a beneficial impact on patient-reported functional capacity and quality of life in patients with cancer who received chemotherapy independent of tumor response. Concordantly, epoetin alfa appeared to increase hemoglobin levels and decrease transfusion use. Patients responded across all tumor types. The results suggest that epoetin alfa effectively improves functional outcomes in patients with cancer who receive chemotherapy.

A phase I trial of recombinant human tumor necrosis factor and interferon-gamma: effects of combination cytokine administration in vivo.

The combination of tumor necrosis factor (TNF) and interferon-gamma has synergistic bioactivity in numerous preclinical model systems. We have tested this potential synergism in vivo by administration of both cytokines to patients with advanced cancer using overlapping 24-hour continuous intravenous (IV) infusions in a phase I trial. Thirty-six patients were treated with a fixed dose of interferon-gamma (200 micrograms/m2/d) with interpatient dose escalation of TNF (from 5 to 205 micrograms/m2/d). The dose-limiting toxicity at the maximal-tolerated dose (MTD) of TNF (205 micrograms/m2) with interferon-gamma was hypotension. Other toxicities noted included an influenza-like syndrome, transient decreases in circulating leukocyte and platelet counts, subclinical evidence of disseminated intravascular coagulation, and the sporadic occurrence of acute pulmonary toxicity. The recommended phase II dose for this combination schedule is TNF, 136 micrograms/m2, with interferon-gamma, 200 micrograms/m2. The addition of interferon-gamma to TNF resulted in a greater than three-fold increase in toxicity compared with TNF administered as a single agent, supporting the hypothesis that the combination of these cytokines may induce synergistic effects in vivo.