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ONCO Regular Faculty

Yap Yoon Sim (Ye Yongxin)

Associate Professor


Education Qualifications: MBBS, FRACP, PhD


Dr. Yap is Senior Consultant in the Division of Medical Oncology at the National Cancer Centre Singapore, and Associate Professor at Duke-National University Singapore. 

A recipient of the Singapore National Medical Research Council (NMRC) Clinician Scientist Award (CSA), her research focuses primarily on clinical and translational research in breast cancer, including liquid biopsies and predictive biomarkers, development of novel therapeutic strategies, and epidemiologic studies on treatment outcomes in breast cancer. She is the principal investigator of several phase 1 to 3 clinical trials for various compounds, including CDK inhibitors, PI3K and mTOR inhibitors, selective estrogen receptor degraders, HER2-targeting agents and immunotherapy, in addition to investigator-initiated studies. 

Professional Appointments and Committee Memberships:

  • 2010-now Senior Consultant in Medical Oncology, NCC Singapore
  • 2007-now Clinical Senior Lecturer, Yong Loo Lin School of Medicine, National University of Singapore 
  • 2014-now Journal of Breast Cancer Editorial Board
  • 2018-now International Steering Committee, Japanese Society of Medical Oncology (JSMO)
  • 2019-now Faculty, European Society of Medical Oncology (ESMO), Breast Cancer Track
  • 2020-now Associate Professor, Duke-NUS Medical School
  • 2021-now Breast Cancer Research and Treatment Editorial Board
  • 2022-now Therapeutic Advances in Medical Oncology Editorial Board
  • Steering committee member in breast cancer clinical trials


  • Elder Prize, 1992 for overall academic performance (University of Adelaide)
  • Golden Key National Honour Society, 1998 for overall scholastic performance (University of Adelaide)
  • Best Trainee Oral Presentation award at Medical Oncology Group of Australia Conference, 2004
  • Medical Oncology Group of Australia/Baxter Trainee Educational Achievement Award, 2005 
  • National Medical Research Council (NMRC) Clinician Scientist Award (CSA), 2019

Leadership positions / roles in Education: 

  • Senior Lecturer, NUS Yong Loo Lin School of Medicine 

Research Interests:

Clinical research in breast cancer, including early phase and phase III trials using novel therapeutic regimens.
Translational research in breast cancer, including prognostic, predictive biomarkers
Observational studies in breast cancer

Selected Publications:

1. HER2 expression, copy number variation and survival outcomes in HER2-low nonmetastatic breast cancer: an international multicentre cohort study and TCGA-METABRIC Analysis. Tan RS, Ong WS, Lee KH, Lim AH, Park S, Park YH, Lin CH, Lu YS, Ono M, Ueno T, Naito Y, Onishi T, Lim GH, Tan SM, Lee HB, Ryu HS, Han W, Tan VKM, Wong FY, Im SA, Tan PH, Chan JY, Yap YS. BMC Medicine 2022; 20: 105

2. Overall Survival with Ribociclib plus Letrozole in Advanced Breast Cancer. Hortobagyi GN, Stemmer SM, Burris HA, Yap YS, Sonke GS, Hart L, Campone M, Petrakova K, Winer EP, Janni W, Conte P, Cameron DA, André F, Arteaga CL, Zarate JP, Chakravartty A, Taran T, Le Gac F, Serra P, O'Shaughnessy J.N Engl J Med. 2022 Mar 10;386(10):942-950. 

3. Jhaveri K, Juric D, Yap YS, Cresta S, Layman RM, Duhoux FP, Terret C, Takahashi S, Huober J, Kundamal N, Sheng Q, Balbin A, Ji Y, He W, Crystal A, De Vita S, Curigliano G. A Phase I Study of LSZ102, an Oral Selective Estrogen Receptor Degrader, with or without Ribociclib or Alpelisib, in Pa-tients with Estrogen Receptor-Positive Breast Cancer. Clin Cancer Res. 2021 Nov 1;27(21):5760-5770.

4. Zhu G, Guo YA, Ho D, Poon P, Poh ZW, Wong PM, Gan A, Chang MM, Kleftogiannis D, Lau YT, Tay B, Lim WJ, Chua C, Tan TJ, Koo SL, Chong DQ, Yap YS, Tan I, Ng S, Skanderup AJ. Tissue-specific cell-free DNA degradation quantifies circulating tumor DNA burden. Nat Commun. 2021 Apr 13;12(1):2229. doi: 10.1038/s41467-021-22463-y.

5. Saura C, Oliveira M, Feng YH, Dai MS, Chen SW, Hurvitz SA, Kim SB, Moy B, Delaloge S, Gradishar W, Masuda N, Palacova M, Trudeau ME, Mattson J, Yap YS, Hou MF, De Laurentiis M, Yeh YM, Chang HT, Yau CCT, Wildiers H, Haley B, Fagnani D, Lu YS, Crown J, Lin J, Takahashi M, Takano T, Yamaguchi M, Fujii T, Yao B, Bebchuk J, Keyvanjah K, Bryce R, Brufsky A. Neratinib + Capecitabine vs Lapatinib + Capecitabine in HER2+ Metastatic Breast Cancer Previously Treated with Two or more HER2-Directed Regimens: Phase III NALA Trial. J Clin Onc. 2020; 38(27):3138-3149. 

6. Yap YS, Chiu J, Ito Y, Ishikawa T, Aruga T, Kim SJ, Toyama T, Saeki T, Saito M, Gounaris I, Su F, Ji Y, Han Y, Gazdoiu M, Masuda N. Ribociclib, a CDK 4/6 inhibitor, plus endocrine therapy in Asian women with advanced breast cancer. Cancer Sci. 2020;111(9):3313-3326.

7. Lee SC, Shimasaki N, Lim JSJ, Wong AL, Yadav K, Yong WP, Tan LK, Koh LP, Poon MLM, Tan SH, Ow SG, Bharwani L, Yap YS, Foo M, Coustan-Smith E, Sundar R, Tan HL, Chong WQ, Kumara-kulasinghe NB, Lieow JLM, Koe PJX, Goh BC, Campana D. Phase I trial of expanded, activated autol-ogous NK cell infusions with trastuzumab in patients with HER2-positive cancers. Clin Cancer Res. 2020 ;26(17):4494-4502. 

8. Yap YS, Lu YS, Tamura K, Lee JE, Ko EY, Park YH, Cao AY, Lin CH, Toi M, Wu J, Lee SC. Insights Into Breast Cancer in the East vs the West: A Review. JAMA Oncol. 2019;5(10):1489-1496.

9. Lin CH, Yap YS, Lee KH, Im SA, Naito Y, Yeo W, Ueno T, Kwong A, Li H, Huang SM, Leung R, Han W, Tan B, Hu FC, Huang CS, Cheng AL, Lu YS. Contrasting Epidemiology and Clinicopathology of Female Breast Cancer in Asians versus the US Population. J Natl Cancer Inst. 2019;111(12):1298-1306. 

10. Saw S, Lim J, Lim SH, Wong M, Lim C, Yap YS. Patterns of relapse after neoadjuvant chemotherapy in breast cancer: implications for surveillance in clinical practice. Breast Cancer Res Treat. 2019 Aug;177(1):197-206. 

11. Frayling IM, Mautner VF, van Minkelen R, Kallionpaa RA, Aktaş S, Baralle D, Ben-Shachar S, Calla-way A, Cox H, Eccles DM, Ferkal S, LaDuca H, Lázaro C, Rogers MT, Stuenkel AJ, Summerour P, Varan A, Yap YS, Zehou O, Peltonen J, Evans GD, Wolkenstein P, Upadhyaya M. Breast cancer risk in neurofibromatosis type 1 is a function of the type of NF1 gene mutation: a new genotype-phenotype correlation. J Med Genet. 2019 Apr;56(4):209-219.

12. Yap YS, Singh AP, Lim JHC, Ahn JH, Jung KH, Kim J, Dent RA, Ng RCH, Kim SB, Chiang DR. Eluci-dating therapeutic molecular targets in premenopausal Asian women with recurrent breast cancers npj Breast Cancer. 2018 volume 4, Article number: 19 

13. Yap YS, Munusamy P, Lim C, Chan CHT, Prawira A, Loke SY, Lim SH, Ong KW, Yong WS, Ng SBH, Tan IBH, Callen DF, Lim JCT, Thike AA, Tan PH, Lee ASG. Breast cancer in women with neurofibro-matosis type 1 (NF1): a comprehensive case series with molecular insights into its aggressive pheno-type. Breast Cancer Res Treat. 2018 Oct;171(3):719-735.

14. Yap YS, Kwok LL, Syn N, Chay WY, Chia JWK, Tham CK, Wong NS, Lo SK, Dent RA, Tan S, Mok ZY, Koh KX, Toh HC, Koo WH, Loh M, Ng RCH, Choo SP, Soong RCT. Predictors of Hand-Foot Syn-drome and Pyridoxine for Prevention of Capecitabine-Induced Hand-Foot Syndrome: A Randomized Clinical Trial. JAMA Oncol. 2017 Nov 1;3(11):1538-1545.

15. Goh JY, Feng M, Wang W, Oguz G, Yatim SMJM, Lee PL, Bao Y, Lim TH, Wang P, Tam WL, Kodahl AR, Lyng MB, Sarma S, Lin SY, Lezhava A, Yap YS, Lim AST, Hoon DSB, Ditzel HJ, Lee SC, Tan EY, Yu Q. Chromosome 1q21.3 amplification is a trackable biomarker and actionable target for breast cancer recurrence. Nat Med. 2017 Nov; 23(11):1319-1330.