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Robert G Maki

Publications and source records attributed to Robert G Maki.

At least 19 recordsLinked to original sources
PubMed2007

Pathologic and molecular heterogeneity in imatinib-stable or imatinib-responsive gastrointestinal stromal tumors.

PURPOSE: Gastrointestinal stromal tumor (GIST) is the most common sarcoma of the intestinal tract. Nearly all tumors express KIT protein, and most have an activating mutation in either KIT or PDGFRA. Therapy with selective tyrosine kinase inhibitors achieves a partial response or stable disease in approximately 80% of patients with advanced GIST. However, after an initial clinical response, some patients develop imatinib resistance. Our goal was to investigate the spectrum of pathologic response and molecular alterations in a group of GIST patients, clinically defined as having imatinib-stable/imatinib-responsive lesions, who underwent surgical resection. EXPERIMENTAL DESIGN: Forty-three tumor nodules from 28 patients were available for pathologic and molecular analysis, which included genotyping for primary and secondary KIT/PDGFRA-mutations, cell cycle alterations, and biochemical activation status of KIT and downstream targets. The transcriptional changes of a subset of these tumors were compared with a group of imatinib-naive GISTs on a U133A Affymetrix expression platform. RESULTS: The histologic response did not correlate with imatinib therapy duration or with proliferative activity. Second-site KIT mutation was identified in only one tumor nodule. Activation of KIT and downstream targets was consistent in all tumors analyzed. Ultrastructurally, a subset of tumors showed a smooth muscle phenotype, which correlated with overexpression of genes involved in muscle differentiation and function. CONCLUSIONS: The histologic response to imatinib is heterogeneous and does not correlate well with clinical response. Second-site KIT mutations are rare in imatinib-responsive GISTs compared with imatinib-resistant tumors. The gene signature of imatinib-response in GISTs showed alterations of cell cycle control as well as up-regulation of genes involved in muscle differentiation and function.

Benzamides↗
PubMed2006

Outcome of metastatic GIST in the era before tyrosine kinase inhibitors.

BACKGROUND: Treatment of metastatic GIST with imatinib mesylate results in a 2-year survival of approximately 72%. The outcome of patients with metastatic GIST not treated with tyrosine kinase inhibitors is not well defined. METHODS: One hundred nineteen patients with metastatic GIST diagnosed prior to July 1, 1998 (approximately 2 years prior to the use of imatinib for GIST) were identified from an institutional database of patients with pathologically confirmed GIST. Mutational analysis was performed in cases with available tissue. The log rank test and Cox regression models were used to assess prognostic factors. RESULTS: Median survival was 19 months with a 41% 2-year survival and a 25% 5-year survival. Resection of metastatic GIST was performed in 81 patients (68%), while 50 (42%) received conventional chemotherapy. Twelve patients (10%) were eventually started on imatinib. Primary tumor size <10 cm, <5 mitoses/50 HPF in the primary tumor, epithelioid morphology, longer disease-free interval, and surgical resection were independent predictors of improved survival on multivariate analysis. Mutational status did not predict outcome. In patients who underwent resection, the 2 year survival was 53%, and negative microscopic margins also independently predicted improved survival. CONCLUSIONS: Treatment with imatinib appears to improve 2-year survival of metastatic GIST by approximately 20% when compared to surgery alone. The combination of imatinib and surgery for the treatment of metastatic GIST therefore warrants investigation.

Adult↗
PubMed2006

Altered bone and mineral metabolism in patients receiving imatinib mesylate.

BACKGROUND: Imatinib mesylate inhibits several tyrosine kinases, including BCR-ABL, the C-KIT receptor, and the platelet-derived growth factor receptors alpha and beta, all of which are associated with disease. We observed that hypophosphatemia developed in some patients with either chronic myelogenous leukemia or gastrointestinal stromal tumors who were receiving imatinib. METHODS: We identified 16 patients who had low serum phosphate levels and 8 patients who had normal serum phosphate levels, all of whom were receiving imatinib. We performed the following biochemical measurements: whole-blood levels of ionized calcium, plasma levels of intact parathyroid hormone, and serum levels of total calcium, phosphate, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, magnesium, and markers of bone formation (bone alkaline phosphatase and osteocalcin) and bone resorption (N-telopeptide of collagen cross-links); urinalysis; and phosphate, calcium, and creatinine levels in "spot" urine specimens. RESULTS: Patients in the low-phosphate group (median serum phosphate level, 2.0 mg per deciliter [0.6 mmol per liter]; normal level, >2.5 mg per deciliter [0.8 mmol per liter]) had elevated parathyroid hormone levels and low-to-normal serum calcium levels, were younger, and were receiving a higher dose of imatinib than patients in the normal-phosphate group (median level, 3.2 mg per deciliter [1.0 mmol per liter]). Both groups had high levels of phosphate excreted in the urine and markedly decreased serum levels of osteocalcin and N-telopeptide of collagen cross-links. CONCLUSIONS: Hypophosphatemia, with associated changes in bone and mineral metabolism, develops in a proportion of patients taking imatinib for either chronic myelogenous leukemia or gastrointestinal stromal tumors. The drug may inhibit bone remodeling (formation and resorption), even in patients with normal serum phosphate levels.

Benzamides↗
PubMed2006

Management dilemmas due to a paratracheal follicular dendritic cell tumor.

Follicular dendritic cell tumors are rare cancers of the lymph nodes of the head and neck. Despite a relatively high rate of recurrence, these neoplasms have a limited impact on the airways because they can be potentially cured by surgical resection. We present the case of a young woman with an unresectable follicular dendritic cell tumor involving the paratracheal region causing upper airway obstruction and respiratory failure. This malignant tumor created numerous management dilemmas and therapeutic challenges related to the unstable airway and the need for tracheal stenting to bypass the airway obstruction.

Adult↗
PubMed2006

Future directions for immunotherapeutic intervention against sarcomas.

PURPOSE OF REVIEW: To discuss advances in immunotherapy as pertaining to systemic therapy for sarcomas. RECENT FINDINGS: Developments in immunology will have direct relevance to studies in sarcomas and other cancers in the near future. Vaccines employing peptides are the backbone of many studies today due to issues of cost and ease of production, but intact or transfected whole tumor cells or antigen-pulsed or transfected dendritic cells are now being investigated as the immunogenic principle in sarcomas and other cancers. The importance of dendritic cells in generating immune responses is better appreciated than ever, as is the role of CD4+ CD25+ regulatory T cells in mediating immune responses. Enhancing costimulatory signals to T cells using anti-CD152 (CTLA4) and other antibodies or expanding anti-tumor cytotoxic T lymphocytes ex vivo are other means to enhance immunity to sarcoma-specific antigens. SUMMARY: As of 2006, few studies are examining the utility of immunotherapy in sarcomas. However, a detailed understanding of the remarkable mechanics of how an immune response is mounted and how T cell activation and/or proliferation can be halted by the tumor will be central to properly design new studies of immunological agents against sarcomas and other cancers.

Allergy and Immunology↗
PubMed2005

Phase II study of doxorubicin and bevacizumab for patients with metastatic soft-tissue sarcomas.

PURPOSE: To evaluate the antitumor activity and tolerability of bevacizumab and doxorubicin in patients with metastatic soft-tissue sarcoma (STS). PATIENTS AND METHODS: Patients may have had up to one nonanthracycline line of therapy. Seventeen patients with metastatic STS were treated with doxorubicin at 75 mg/m2 intravenous (IV) push followed by bevacizumab 15 mg/kg IV every 3 weeks. Dexrazoxane was started for total doxorubicin dose exceeding 300 mg/m2. RESULTS: A total of 85 cycles of doxorubicin/bevacizumab were administered, median four cycles (range, one to 11), with three patients receiving one to four cycles of bevacizumab maintenance after reaching 600 mg/m2 doxorubicin. All 17 patients were assessable for response. Two partial responses (12%, 95% CI = 1% to 36%) were observed, lasting seven and 12 cycles of therapy. Eleven patients (65%) had stable disease for four cycles or more. Six patients developed cardiac toxicity grade 2 or greater, with four patients grade 2 (cumulative doxorubicin 75, 150, 300, 300 mg/m2, respectively), one grade 3 (total doxorubicin 591 mg/m2), and one grade 4 (total doxorubicin 420 mg/m2). One patient with extensive lung disease died of recurrent bilateral pneumothoraces, possibly treatment-related. CONCLUSION: The 12% response rate for these patients was no greater than that observed for single-agent doxorubicin. However, the 65% of patients with stable disease lasting four cycles or longer suggests further study is warranted in STSs. The observed cardiac toxicity, despite close monitoring and standard use of dexrazoxane, obliges a change in the dose and/or schedule in future studies of this combination.

Adult↗
PubMed2005

Acquired resistance to imatinib in gastrointestinal stromal tumor occurs through secondary gene mutation.

Most gastrointestinal stromal tumors (GIST) have an activating mutation in either KIT or PDGFRA. Imatinib is a selective tyrosine kinase inhibitor and achieves a partial response or stable disease in about 80% of patients with metastatic GIST. It is now clear that some patients with GIST develop resistance to imatinib during chronic therapy. To identify the mechanism of resistance, we studied 31 patients with GIST who were treated with imatinib and then underwent surgical resection. There were 13 patients who were nonresistant to imatinib, 3 with primary resistance, and 15 with acquired resistance after initial benefit from the drug. There were no secondary mutations in KIT or PDGFRA in the nonresistant or primary resistance groups. In contrast, secondary mutations were found in 7 of 15 (46%) patients with acquired resistance, each of whom had a primary mutation in KIT exon 11. Most secondary mutations were located in KIT exon 17. KIT phosphorylation was heterogeneous and did not correlate with clinical response to imatinib or mutation status. That acquired resistance to imatinib in GIST commonly occurs via secondary gene mutation in the KIT kinase domain has implications for strategies to delay or prevent imatinib resistance and to employ newer targeted therapies.

Adult↗
PubMed2005

A multicenter Phase II study of bortezomib in recurrent or metastatic sarcomas.

BACKGROUND: Based on evidence of activity in preclinical and Phase I studies, the authors undertook a study of bortezomib, a reversible proteasome inhibitor, for patients with metastatic sarcomas. METHODS: Two arms were opened, each using a Simon two-stage design. Arm A included patients with osteogenic sarcoma, Ewing sarcoma, and rhabdomyosarcoma. Arm B accrued patients with other types of soft tissue sarcomas. Patients were not allowed to have received previous chemotherapy for metastatic disease. The initial dose of bortezomib was a 1.5 mg/m2 intravenous push twice weekly followed by a rest week. The dose was escalated to 1.7 mg/m2 if patients tolerated Cycle 1 well. The dose escalation was eliminated due to toxicity observed in the first six patients. RESULTS: Painful neuropathy, myalgias, and asthenia were the most significant observed toxicities. The most frequent toxicities included fatigue, diarrhea, constipation, and nausea. Pharmacodynamic data from 18 patients with complete data collection did not show consistent differences between patients with or without Grade 2 or Grade 3 neuropathy (toxicity graded according the National Cancer Institute Common Toxicity Criteria). Arm A had low accrual and was closed. One confirmed partial response among 21 evaluable patients was observed on Arm B in a patient with leiomyosarcoma. Due to the inactivity of this agent, the study was closed after the first stage of accrual. CONCLUSIONS: Bortezomib has minimal activity in soft tissue sarcoma as a single agent. If studied further in sarcomas, bortezomib should be investigated in combination with agents with demonstrated preclinical synergy.

Adult↗
PubMed2005

Phase I trial of the cyclin-dependent kinase inhibitor and protein kinase C inhibitor 7-hydroxystaurosporine in combination with Fluorouracil in patients with advanced solid tumors.

PURPOSE: Preclinical studies indicate that the cyclin-dependent kinase and protein kinase C inhibitor 7-hydroxystaurosporine (UCN-01) potentiates the cytotoxic effects of fluorouracil (FU). We designed a phase I clinical trial of FU in combination with UCN-01. PATIENTS AND METHODS: FU was administered as a weekly 24-hour infusion. Doses were escalated in successive cohorts according to a modified Fibonacci design. UCN-01 was administered once every 4 weeks, immediately after disconnection from FU, at a dose of 135 mg/m(2) over 72 hours in cycle 1 and 67.5 mg/m(2) over 36 hours in subsequent cycles. FU and UCN-01 pharmacokinetics were obtained on all patients, and thymidylate synthetase (TS) activity was measured in peripheral-blood mononuclear cells by reverse-transcriptase polymerase chain reaction. RESULTS: We escalated the weekly FU dose to 2,600 mg/m(2) in combination with once a month infusions of UCN-01. Dose-limiting toxicity included arrhythmia and syncope. Other toxicities included hyperglycemia, headache, and nausea and vomiting. The mean maximal plasma concentration of UCN-01 was 33.5 micromol/L. There was significant interpatient variability, which correlated with plasma concentrations of alpha-1 acid glycoprotein. FU was rapidly cleared and the dose had no effect on the area under the curve of UCN-01. Changes in TS expression were detectable in peripheral-blood mononuclear cells after administration of UCN-01 but did not correlate with toxicity or activity. We observed no objective response, although seven patients had stable disease, six of whom had received prior fluoropyrimidines. CONCLUSION: The combination of weekly infusions of FU and monthly UCN-01 can be administered safely and warrants further study in phase II trials. The recommended phase II dose of FU in combination with monthly UCN-01 is 2,600 mg/m(2).

Adult↗
PubMed2005

Mechanisms of sarcomagenesis.

Sarcomas comprise a heterogeneous group of malignancies that are derived from mesenchymal cells, which under normal circumstances lead to the development of connective tissues such as bone, muscle, fat, and cartilage. During the past decade, insight has been gained regarding the aberrancies that occur during normal development that result in mesenchymal cells transforming into sarcomas. More recently, these insights have led to the development of successful therapies that target the specific mechanisms inherent to individual sarcomas. This overview discusses some of the aberrant molecular mechanisms shared in sarcomas and reviews several sarcoma subtypes in which the most advances have been made. Finally, the ways in which these advances in basic science are translating into and redefining clinical practice are highlighted.

Animals↗
PubMed2005

De novo osteogenic sarcoma in patients older than forty: benefit of multimodality therapy.

UNLABELLED: The treatment of primary osteogenic sarcoma is well established in younger patients; however, controversy surrounds the treatment of this disease in the older population. To confirm multimodality therapy results in longer survival than surgery alone, 58 patients older than 40 years with primary osteogenic sarcoma were assessed retrospectively for the benefits of multimodality treatment versus surgery alone. We then asked whether specific patient and tumor characteristics and treatment modalities affected the rates of survival. Finally, we questioned whether pulmonary metastatectomy increased survival. The 5-year and 10-year overall survival for the group was 58% and 44%, respectively. Multimodality therapy increased survival compared with surgery alone in patients with high-grade disease. On multivariate analysis, considerable prognostic factors for improved overall survival for the entire group were age younger than 60 years, volume less than 100 cm, normal alkaline phosphatase, localized disease, negative surgical margins, and absence of recurrence. Pulmonary metastatectomy improved survival in selected patients. LEVEL OF EVIDENCE: Therapeutic study, Level III-1 (retrospective cohort study). See the Guidelines for Authors for a complete description of levels of evidence.

Adult↗
PubMed2005

Gastrointestinal stromal tumors in children and young adults: a clinicopathologic, molecular, and genomic study of 15 cases and review of the literature.

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the intestinal tract that typically occur in adults over the age of 40 years. GISTs in younger patients are rare and not well characterized. The objective was to define the characteristics of GISTs in children and young adults (<30 years old). Clinicopathologic and molecular features, including KIT/PDGFRA genotype, in GISTs from 5 children and 10 young adults were analyzed. Gene expression analysis was performed on 5 gastric tumor samples from 2 children, 2 gastric tumors from young adults, and 10 gastric GISTs from older adults using an U133A Affymetrix platform (22,000 genes). All five pediatric GISTs occurred in girls, involved the stomach as multiple nodules, showed predominantly an epithelioid morphology, often involved lymph nodes, and lacked KIT or PDGFRA mutations. Although all five patients developed recurrence (four in the liver, three in the peritoneum, and two in both sites), four are still alive with disease. Of the 10 GISTs in young adults, half occurred in the small bowel and had spindle cell morphology, and one case had lymph node metastasis. KIT mutations were identified in seven cases, four in exon 11 and three in exon 9. Seven patients developed recurrence, and at last follow-up two patients had died of disease. Gene expression analysis showed high expression of PHKA1, FZD2, NLGN4, IGF1R, and ANK3 in the pediatric and young adult versus older adult cases. GISTs that occur in children are a separate clinicopathologic and molecular subset with predilection for girls, multifocal gastric tumors, and wild-type KIT/PDGFRA genotype. In contrast, GISTs in young adults are a more heterogeneous group, including cases that resemble either the pediatric or the older adult-type tumors. The distinct gene expression profile suggests avenues for investigation of pathogenesis and potential therapeutic strategies.

Adolescent↗
PubMed2004

Cohort analysis of patients with localized, high-risk, extremity soft tissue sarcoma treated at two cancer centers: chemotherapy-associated outcomes.

PURPOSE: Patients with American Joint Committee on Cancer stage III soft tissue sarcoma (STS) have high risks of distant recurrence and death. The role of chemotherapy for these patients remains controversial despite several randomized trials and a meta-analysis. METHODS: We reviewed the treatments and outcomes of 674 consecutive adult patients presenting with primary stage III extremity STS between 1984 and 1999. Pre- or postoperative doxorubicin-based chemotherapy was used in a nonrandomized fashion in approximately half of this high-risk population. The objective of this review was to evaluate the impact of chemotherapy while accounting for known prognostic variables. RESULTS: Among 674 patients, 338 (50%) were treated with local therapy only, and 336 (50%) were treated with local therapy plus chemotherapy. The median follow-up for survivors was 6.1 years. Five-year local and distant recurrence-free interval probabilities were 83% and 56%, respectively, for the two groups combined. The 5-year disease-specific survival (DSS) rate was 61%. Cox regression analyses showed a time-varying effect associated with chemotherapy. During the first year, the hazard ratio associated with DSS for patients treated with chemotherapy versus no chemotherapy was 0.37 (95% CI, 0.20 to 0.69; P = .002). Thereafter, this hazard ratio was 1.36 (95% CI, 1.02 to 1.81; P = .04). CONCLUSION: It seems that the clinical benefits associated with doxorubicin-based chemotherapy in patients with high-risk extremity STS are not sustained beyond 1 year. These results suggest that caution should be used in the interpretation of randomized clinical trials of adjuvant chemotherapy that seem to demonstrate clinical benefits with relatively short-term follow-up.

Adult↗
PubMed2004

Gene expression in gastrointestinal stromal tumors is distinguished by KIT genotype and anatomic site.

PURPOSE: Gastrointestinal stromal tumors (GISTs) are specific KIT expressing and KIT-signaling driven mesenchymal tumors of the human digestive tract, many of which have KIT-activating mutations. Previous studies have found a relatively homogeneous gene expression profile in GIST, as compared with other histological types of sarcomas. Transcriptional heterogeneity within clinically or molecularly defined subsets of GISTs has not been previously reported. We tested the hypothesis that the gene expression profile in GISTs might be related to KIT genotype and possibly to other clinicopathological factors. EXPERIMENTAL DESIGN: An HG-U133A Affymetrix chip (22,000 genes) platform was used to determine the variability of gene expression in 28 KIT-expressing GIST samples from 24 patients. A control group of six intra-abdominal leiomyosarcomas was also included for comparison. Statistical analyses (t tests) were performed to identify discriminatory gene lists among various GIST subgroups. The levels of expression of various GIST subsets were also linked to a modified version of the growth factor/KIT signaling pathway to analyze differences at various steps in signal transduction. RESULTS: Genes involved in KIT signaling were differentially expressed among wild-type and mutant GISTs. High gene expression of potential drug targets, such as VEGF, MCSF, and BCL2 in the wild-type group, and Mesothelin in exon 9 GISTs were found. There was a striking difference in gene expression between stomach and small bowel GISTs. This finding was validated in four separate tumors, two gastric and two intestinal, from a patient with familial GIST with a germ-line KIT W557R substitution. CONCLUSIONS: GISTs have heterogeneous gene expression depending on KIT genotype and tumor location, which is seen at both the genomic level and the KIT signaling pathway in particular. These findings may explain their variable clinical behavior and response to therapy.

Cell Line, Tumor↗
PubMed2004

Pleomorphic characteristics of a germ-line KIT mutation in a large kindred with gastrointestinal stromal tumors, hyperpigmentation, and dysphagia.

PURPOSE: Somatic mutations that result in the activation of the growth factor receptor KIT are commonly found in gastrointestinal stromal tumors (GISTs). Six families have been reported in which a germ-line mutation in KIT is associated with an autosomal dominant predisposition to the development of GISTs. Hyperpigmentation, urticaria pigmentosa, and dysphagia have been described in some, but not all, families. Preliminary correlations between the site of mutation and the clinical phenotype have been proposed, but the strength of these associations is not defined. DESIGN: A large kindred with multiple GISTs, hyperpigmentation, and dysphagia was identified after the index case presented with multiple GISTs. A germ-line mutation in KIT (W557R) was identified in an affected cousin, after which a large family meeting was held and testing offered. Clinical data were obtained by interview and, whenever possible, medical record documentation. RESULTS: To date, 19 individuals have been tested, and the mutation has been shown to cosegregate with the syndrome. The phenotypic expression, however, is variable. GISTs, often presenting as upper gastrointestinal bleeding, and hyperpigmentation are common, but not diagnosed in all documented or obligate carriers. Dysphagia is a less prevalent complaint. The diagnosis of GISTs appears to be made at a younger age in more recent generations. Metastatic disease is uncommon. CONCLUSIONS: A germ-line mutation in KIT resulting in an amino acid substitution in the juxtamembrane region is associated with a syndrome of GIST, hyperpigmentation, and dysphagia, although the prominence of each component varies.

Age Factors↗