Ari Ristimäki

Prof. Dr. Ari Ristimäki

orcid

Research Focus & Metrics

Academic Career Length

26Years (2001-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 February 2002
Verified
Journal Article
Closed access
ARAri Ristimäki
Ari Ristimäki
ASAnna Sivula
Anna Sivula
JLJohan Lundin
Johan Lundin
MLMikael Lundin
Mikael Lundin
TSTiina Salminen
Tiina Salminen
JIJorma Isola
Jorma Isola

13 September 2011 in Breast Cancer Research
Verified
Journal Article
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Harri SihtoHarri Sihto
Harri Sihto
JLJohan Lundin
Johan Lundin
MLMikael Lundin
Mikael Lundin
TLTiina Lehtimäki
Tiina Lehtimäki
ARAri Ristimäki
Ari Ristimäki
HJHeikki Joensuu
Heikki Joensuu
Introduction: Some molecular subtypes of breast cancer have preferential sites of distant relapse. The protein expression pattern of the primary tumor may influence the first distant metastasis site. Methods: We identified from the files of the Finnish Cancer Registry patients diagnosed with breast cancer in five geographical regions Finland in 1991-1992, reviewed the hospital case records, and collected primary tumor tissue. Out of the 2,032 cases identified, 234 developed distant metastases after a median follow-up time of 2.7 years and had the first metastatic site documented (a total of 321 sites). Primary tumor microarray (TMA) cores were analyzed for 17 proteins using immunohistochemistry and for erbB2 using chromogenic in situ hybridization, and their associations with the first metastasis site were examined. The cancers were classified into luminal A, luminal B, HER2+ enriched, basal-like or non-expressor subtypes. Results: A total of 3,886 TMA cores were analyzed. Luminal A cancers had a propensity to give rise first to bone metastases, HER2-enriched cancers to liver and lung metastases, and basal type cancers to liver and brain metastases. Primary tumors that gave first rise to bone metastases expressed frequently estrogen receptor (ER) and SNAI1 (SNAIL) and rarely COX2 and HER2, tumors with first metastases in the liver expressed infrequently SNAI1, those with lung metastases expressed frequently the epidermal growth factor receptor (EGFR), cytokeratin-5 (CK5) and HER2, and infrequently progesterone receptor (PgR), tumors with early skin metastases expressed infrequently E-cadherin, and breast tumors with first metastases in the brain expressed nestin, prominin-1 and CK5 and infrequently ER and PgR. Conclusions: Breast tumor biological subtypes have a tendency to give rise to first distant metastases at certain body sites. Several primary tumor proteins were associated with homing of breast cancer cells.

15 March 2016 in Journal for ImmunoTherapy of Cancer
Verified
Journal Article
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TRTuuli Ranki
Tuuli Ranki
SPSari Pesonen
Sari Pesonen
AHAkseli Hemminki
Akseli Hemminki
KPKaarina Partanen
Kaarina Partanen
KKKalevi Kairemo
Kalevi Kairemo
TJTimo Joensuu
Timo Joensuu
Background We conducted a phase I study with a granulocyte macrophage colony stimulating factor (GMCSF)-expressing oncolytic adenovirus, ONCOS-102, in patients with solid tumors refractory to available treatments. The objectives of the study were to determine the optimal dose for further use and to assess the safety, tolerability and adverse event (AE) profile of ONCOS-102. Further, the response rate and overall survival were evaluated as well as preliminary evidence of disease control. As an exploratory endpoint, the effect of ONCOS 102 on biological correlates was examined. Methods The study was conducted using a classic 3 + 3 dose escalation study design involving 12 patients. Patients were repeatedly treated intratumorally with ONCOS-102 plus daily low-dose oral cyclophosphamide (CPO). Tumor response was evaluated with diagnostic positron emission tomography (PET) and computed tomography (CT). Tumor biopsies were collected at baseline and after treatment initiation for analysis of immunological correlates. Peripheral blood mononuclear cells (PBMCs) were collected at baseline and during the study to assess antigen specificity of CD8+ T cells by interferon gamma (IFNγ) enzyme linked immunospot assay (ELISPOT). Results No dose limiting toxicity (DLT) or maximum tolerated dose (MTD) was identified for ONCOS-102. Four out of ten (40 %) evaluable patients had disease control based on PET/CT scan at 3 months and median overall survival was 9.3 months. A short-term increase in systemic pro-inflammatory cytokines and a prominent infiltration of TILs to tumors was seen post-treatment in 11 out of 12 patients. Two patients showed marked infiltration of CD8+ T cells to tumors and concomitant systemic induction of tumor-specific CD8+ T cells. Interestingly, high expression levels of genes associated with activated TH1 cells and TH1 type immune profile were observed in the post-treatment biopsies of these two patients. Conclusions ONCOS-102 is safe and well tolerated at the tested doses. All three examined doses may be used in further development. There was evidence of antitumor immunity and signals of clinical efficacy. Importantly, treatment resulted in infiltration of CD8+ T cells to tumors and up-regulation of PD-L1, highlighting the potential of ONCOS-102 as an immunosensitizing agent for combinatory therapies with checkpoint inhibitors. Trial registration NCT01598129. Registered 19/04/2012

1 June 2002 in Gastroenterology
Verified
Journal Article
Open access
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CBChristianne J. Buskens
Christianne J. Buskens
BRBastiaan P. van Rees
Bastiaan P. van Rees
ASAnna Sivula
Anna Sivula
JRJohannes B. Reitsma
Johannes B. Reitsma
CHCaj Haglund
Caj Haglund
ARAri Ristimäki
Ari Ristimäki
Background & Aims: Use of nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with a reduced risk of cancer in the digestive tract. Cyclooxygenase (COX) is the best-known target of NSAIDs, and expression of the COX-2 isoform is elevated in esophageal carcinomas but its clinical significance remains unclear. We examined COX-2 expression in esophageal adenocarcinomas and its relation to clinicopathologic parameters. Methods: Tumor sections from 145 consecutive patients undergoing intentionally curative surgery for an adenocarcinoma arising from a Barrett's esophagus were immunohistochemically stained using a COX-2–specific anti-human monoclonal antibody. The specimens were scored based on the intensity and extent of COX-2 immunopositivity. Results: COX-2 immunoreactivity was negative to weak in 21% (COX-2 low) and moderate to strong in 79% (COX-2 high) of the carcinomas. Patients with high COX-2 expression were more likely to develop distant metastases (P = 0.02) and local recurrences (P = 0.05), and survival was significantly reduced (P = 0.002, log-rank test) among patients with high COX-2 expression when compared with the COX-2 low group. Five-year survival rates were 35% (95% confidence interval [CI], 23–47) and 72% (95% CI, 53–90) in COX-2 high and COX-2 low categories, respectively. Furthermore, expression of COX-2 was recognized as an independent prognostic factor by multivariate analysis (relative risk, 3.5; 95% CI, 1.6–7.9). Conclusions: Elevated expression of COX-2 protein is associated with significantly reduced survival of patients undergoing surgery for esophageal adenocarcinoma. These findings support the effort to initiate clinical studies to investigate the effect of COX-2 inhibitors as a novel (adjuvant) chemotherapeutic modality for the treatment of adenocarcinoma arising from Barrett's esophagus.

1 March 2001 in The American Journal of Pathology
Verified
Journal Article
Closed access
ARAri Ristimäki
Ari Ristimäki
ONOuti Nieminen
Outi Nieminen
KSKirsi Saukkonen
Kirsi Saukkonen
KHKristina Hotakainen
Kristina Hotakainen
SNStig Nordling
Stig Nordling
CHCaj Haglund
Caj Haglund

6 September 2019 in Nature Communications
Verified
Journal Article
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TCTatiana Cajuso
Tatiana Cajuso
PSPäivi Sulo
Päivi Sulo
TTTomas Tanskanen
Tomas Tanskanen
RKRiku Katainen
Riku Katainen
ATAurora Taira
Aurora Taira
LALauri A. Aaltonen
Lauri A. Aaltonen
Genomic instability pathways in colorectal cancer (CRC) have been extensively studied, but the role of retrotransposition in colorectal carcinogenesis remains poorly understood. Although retrotransposons are usually repressed, they become active in several human cancers, in particular those of the gastrointestinal tract. Here we characterize retrotransposon insertions in 202 colorectal tumor whole genomes and investigate their associations with molecular and clinical characteristics. We find highly variable retrotransposon activity among tumors and identify recurrent insertions in 15 known cancer genes. In approximately 1% of the cases we identify insertions in APC, likely to be tumor-initiating events. Insertions are positively associated with the CpG island methylator phenotype and the genomic fraction of allelic imbalance. Clinically, high number of insertions is independently associated with poor disease-specific survival.