Dhanya Ramachandran

Dr. Dhanya Ramachandran

Hannover Medical School, Hanover, Germany
orcid

Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

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

Representative Publications

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13 October 2021 in Cancers
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Dhanya RamachandranDhanya Ramachandran
Dhanya Ramachandran
TDThilo Dörk
Thilo Dörk
Cervical cancer is the fourth common cancer amongst women worldwide. Infection by high-risk human papilloma virus is necessary in most cases, but not sufficient to develop invasive cervical cancer. Despite a predicted genetic heritability in the range of other gynaecological cancers, only few genomic susceptibility loci have been identified thus far. Various case-control association studies have found corroborative evidence for several independent risk variants at the 6p21.3 locus (HLA), while many reports of associations with variants outside the HLA region remain to be validated in other cohorts. Here, we review cervical cancer susceptibility variants arising from recent genome-wide association studies and meta-analysis in large cohorts and propose 2q14 (PAX8), 17q12 (GSDMB), and 5p15.33 (CLPTM1L) as consistently replicated non-HLA cervical cancer susceptibility loci. We further discuss the available evidence for these loci, knowledge gaps, future perspectives, and the potential impact of these findings on precision medicine strategies to combat cervical cancer.

21 February 2019 in British Journal of Cancer
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NCNbcs Collaborators
Nbcs Collaborators
MEMaria Escala-Garcia
Maria Escala-Garcia
QGQi Guo
Qi Guo
TDThilo Dörk
Thilo Dörk
SCSander Canisius
Sander Canisius
MSMarjanka K. Schmidt
Marjanka K. Schmidt
Background We examined the associations between germline variants and breast cancer mortality using a large meta-analysis of women of European ancestry. Methods Meta-analyses included summary estimates based on Cox models of twelve datasets using ~10.4 million variants for 96,661 women with breast cancer and 7697 events (breast cancer-specific deaths). Oestrogen receptor (ER)-specific analyses were based on 64,171 ER-positive (4116) and 16,172 ER-negative (2125) patients. We evaluated the probability of a signal to be a true positive using the Bayesian false discovery probability (BFDP). Results We did not find any variant associated with breast cancer-specific mortality at P < 5 × 10−8. For ER-positive disease, the most significantly associated variant was chr7:rs4717568 (BFDP = 7%, P = 1.28 × 10−7, hazard ratio [HR] = 0.88, 95% confidence interval [CI] = 0.84–0.92); the closest gene is AUTS2. For ER-negative disease, the most significant variant was chr7:rs67918676 (BFDP = 11%, P = 1.38 × 10−7, HR = 1.27, 95% CI = 1.16–1.39); located within a long intergenic non-coding RNA gene (AC004009.3), close to the HOXA gene cluster. Conclusions We uncovered germline variants on chromosome 7 at BFDP < 15% close to genes for which there is biological evidence related to breast cancer outcome. However, the paucity of variants associated with mortality at genome-wide significance underpins the challenge in providing genetic-based individualised prognostic information for breast cancer patients.

16 January 2020 in Nature Communications
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MEMaria Escala-Garcia
Maria Escala-Garcia
JAJean Abraham
Jean Abraham
IAIrene L Andrulis
Irene L Andrulis
HAHoda Anton-Culver
Hoda Anton-Culver
VAVolker Arndt
Volker Arndt
Marjanka SchmidtMarjanka Schmidt
Marjanka Schmidt
Identifying the underlying genetic drivers of the heritability of breast cancer prognosis remains elusive. We adapt a network-based approach to handle underpowered complex datasets to provide new insights into the potential function of germline variants in breast cancer prognosis. This network-based analysis studies ~7.3 million variants in 84,457 breast cancer patients in relation to breast cancer survival and confirms the results on 12,381 independent patients. Aggregating the prognostic effects of genetic variants across multiple genes, we identify four gene modules associated with survival in estrogen receptor (ER)-negative and one in ER-positive disease. The modules show biological enrichment for cancer-related processes such as G-alpha signaling, circadian clock, angiogenesis, and Rho-GTPases in apoptosis.

24 June 2020 in International Journal of Cancer
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Dhanya RamachandranDhanya Ramachandran
Dhanya Ramachandran
PSPeter Schürmann
Peter Schürmann
QMQianqian Mao
Qianqian Mao
YWYingying Wang
Yingying Wang
LBLisa‐Marie Bretschneider
Lisa‐Marie Bretschneider
TDThilo Dörk
Thilo Dörk
The human leukocyte antigen (HLA) locus on chromosome 6 has been reported to be associated with cervical cancer. We investigated two independent single‐nucleotide polymorphisms in a large case‐control series of cervical dysplasia and carcinoma that has been newly established by the German Cervigen Consortium, comprising a total of 2481 cases and 1556 healthy females. We find significant associations for both variants, rs9272117 at HLA‐DQA1 and rs2844511 at MICA and HCP5, with cervical disease. Both variants showed evidence of association with invasive cervical cancer (rs9272117: OR 0.89, 95% CI 0.79‐0.99, P = .036; rs2844511: OR 1.17, 95% CI 1.04‐1.31, P = .008) and with high‐grade dysplasia (rs9272117: OR 0.78, 95% CI 0.70‐0.87, P = 7.1 × 10−6; rs2844511: OR 1.13, 95% CI 1.01‐1.26, P = .035), as well as in a combined analysis of both groups (rs9272117: OR 0.83, 95% CI 0.75‐0.91, P = 6.9 × 10−5; rs2844511: OR 1.14, 95% CI 1.04‐1.26, P = .005). Variant rs2844511, but not rs9272117, also showed modest evidence of association with low‐grade dysplasia (OR 1.26, 95% CI 1.04‐1.54, P = .019). In case‐only analyses, rs2844511 tended to predict HPV status (P = .044) and rs9272117 tended to associate with HPV16 (P = .022). RNA studies in cervical samples showed a significant correlation in the transcript levels of MICA, HCP5 and HLA‐DQA1, suggesting extensive co‐regulation. All three genes were upregulated in HPV16‐positive samples. In stratified analyses, rs9272117 was associated with HLA‐DQA1 levels, specifically in HPV‐positive samples, while rs2844511 was associated with MICA and HCP5 levels. The risk allele of rs2844511 was required for correlations between MICA or HCP5 with HLA‐DQA1. Altogether, our results support 6p21.32‐33 as the first consistent cervical cancer susceptibility locus and provide evidence for a link between genetic risk variants, HPV16 status and transcript levels of HLA‐DQA1, HCP5 and MICA, which may contribute to tumor immune evasion.

26 January 2023 in Genome Medicine
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SMStefanie H. Mueller
Stefanie H. Mueller
ALAlvina G. Lai
Alvina G. Lai
MVMaria Valkovskaya
Maria Valkovskaya
KMKyriaki Michailidou
Kyriaki Michailidou
MBManjeet K. Bolla
Manjeet K. Bolla
KKKaroline B. Kuchenbaecker
Karoline B. Kuchenbaecker
Background: Low-frequency variants play an important role in breast cancer (BC) susceptibility. Gene-based methods can increase power by combining multiple variants in the same gene and help identify target genes. Methods: We evaluated the potential of gene-based aggregation in the Breast Cancer Association Consortium cohorts including 83,471 cases and 59,199 controls. Low-frequency variants were aggregated for individual genes’ coding and regulatory regions. Association results in European ancestry samples were compared to single-marker association results in the same cohort. Gene-based associations were also combined in meta-analysis across individuals with European, Asian, African, and Latin American and Hispanic ancestry. Results: In European ancestry samples, 14 genes were significantly associated (q < 0.05) with BC. Of those, two genes, FMNL3 (P = 6.11 × 10−6) and AC058822.1 (P = 1.47 × 10−4), represent new associations. High FMNL3 expression has previously been linked to poor prognosis in several other cancers. Meta-analysis of samples with diverse ancestry discovered further associations including established candidate genes ESR1 and CBLB. Furthermore, literature review and database query found further support for a biologically plausible link with cancer for genes CBLB, FMNL3, FGFR2, LSP1, MAP3K1, and SRGAP2C. Conclusions: Using extended gene-based aggregation tests including coding and regulatory variation, we report identification of plausible target genes for previously identified single-marker associations with BC as well as the discovery of novel genes implicated in BC development. Including multi ancestral cohorts in this study enabled the identification of otherwise missed disease associations as ESR1 (P = 1.31 × 10−5), demonstrating the importance of diversifying study cohorts.

25 March 2021 in Cancers
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Thorsten DerlinThorsten Derlin
Thorsten Derlin
NBNatalia Bogdanova
Natalia Bogdanova
FOFiona Ohlendorf
Fiona Ohlendorf
Dhanya RamachandranDhanya Ramachandran
Dhanya Ramachandran
RWRudolf A. Werner
Rudolf A. Werner
CHChristoph Henkenberens
Christoph Henkenberens
Background: We aimed to characterize γ-H2AX and 53BP1 foci formation in patients receiving somatostatin receptor-targeted radioligand therapy, and explored its role for predicting treatment-related hematotoxicity, and treatment response. Methods: A prospective analysis of double-strand break (DSB) markers was performed in 21 patients with advanced gastroenteropancreatic neuroendocrine tumors. γ-H2AX and 53BP1 foci formation were evaluated in peripheral blood lymphocytes (PBLs) at baseline, +1 h and +24 h after administration of 7.4 GBq (177Lu)Lu-DOTA-TATE. Hematotoxicity was evaluated using standard hematology. Therapy response was assessed using (68Ga)Ga-DOTA-TATE PET/CT before enrollment and after 2 cycles of PRRT according to the volumetric modification of RECIST 1.1. Results: DSB marker kinetics were heterogeneous among patients. Subclinical hematotoxicity was associated with γ-H2AX and 53BP1 foci formation (e.g., change in platelet count vs change in γ-H2AX+ cells between baseline and +1 h (r = −0.6080; p = 0.0045). Patients showing early development of new metastases had less γ-H2AX (p = 0.0125) and less 53BP1 foci per cell at +1 h (p = 0.0289), and demonstrated a distinct kinetic pattern with an absence of DSB marker decrease at +24 h (γ-H2AX: p = 0.0025; 53BP1: p = 0.0008). Conclusions: Assessment of γ-H2AX and 53BP1 foci formation in PBLs of patients receiving radioligand therapy may hold promise for predicting subclinical hematotoxicity and early treatment response.