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Scientist/Sr. Scientist - Assay & Screening

Assay and Screening | South San Francisco, CA | Full Time

Job Description

Scientist/Senior Scientist - Assay and Screening

Plexxikon, a member of the Daiichi Sankyo Group, is a leader in the discovery and development of novel, small molecule pharmaceuticals. The company utilizes its proprietary discovery platform to successfully develop a portfolio of competitively differentiated clinical and preclinical stage compounds in a number of therapeutic areas. Our most advanced, Zelboraf™ (vemurafenib) was the first precision medicine to be approved for the treatment of BRAF-mutant metastatic melanoma. Turalio™ (pexidartinib), Plexxikon’s second marketed drug, is the first and only approved therapy for tenosynovial giant cell tumors. Plexxikon's novel discovery approach, combined with experienced management and scientific teams and a broad network of scientific and development partners, have been key drivers of the company's success since it began operations in 2001. Plexxikon is a small business with approximately 70 employees based in South San Francisco, CA.

 The Assay and Screening group supports projects at all stages of the pipeline as part of an integrated and cross-functional drug discovery team. Assay biologists are responsible for creating small molecule screening strategies, developing biochemical and cellular assays, and deciphering mechanisms of actions, including validation of new targets. We are seeking a highly motivated scientist with expertise in cell signalling, epigenetics, immunology or cancer biology to join the team. The scientist will report to the associate director of the Assay and Screening team. This is a unique opportunity to work within a successful biotechnology company and be a key contributor to drug discovery in Plexxikon.  


  • Develop and optimize high throughput biochemical and cell-based assays and perform in vitro compound screens for small molecule hit discovery and lead optimization
  • Understand target and disease biology, elucidate mechanisms of action for hits/leads using biochemical assays and disease-relevant cellular models, and support preclinical biomarker research
  • Research and champion new small molecule drug targets, conduct proof-of-concept and feasibility studies, play a key role in the initiation of projects and remain a main contributor throughout the project lifecycle
  • Contribute to new technology platform evaluation and implementation. 
  • Record, report, and present experimental findings in departmental and company-wide meetings, communicate results to multi-disciplinary teams, generate standard operating procedures, prepare formal technical reports (including regulatory documents and publications) and study summaries, support overall laboratory efforts
  • Work closely and collaboratively with scientists across the organization including assay & screening, protein/structure science, medicinal chemistry, DMPK, translational and clinical science, providing expertise to project teams
  • Maintain a command of relevant scientific literature, identify emerging research trends, evaluate implications for internal projects, and leverage those insights to inform the experimental design and clinical concept development
  • Maintain various lab equipment, reagents, and maintain a safe and productive lab environment
  • Other duties as assigned


  • PhD degree in biochemistry, cell biology, cancer biology, immunology, or related field with a minimum of 2+ years post-doctoral or industrial experience (title commensurate with experience)
  • A proven record of scientific achievements (strong publication record) demonstrating scientific vigour and creativity while carrying out independent research
  • Experience with enzymatic and binding assays using standard biochemical techniques e.g., alphascreen, FP and TR-FRET; Experience with biophysical approaches such as MST and SPR is a plus
  • Extensive research experience with various approaches to studying molecular and cell biology e.g., 3D growth assays, reporter gene assays, stable cell line development, Q-PCR, flow cytometry, HCS and genetic approaches such as siRNA, shRNA, and CRISPR
  • A problem solver, team-oriented, highly motivated, ability to multitask, and adaptable to changing priorities in a fast-paced environment
  • Exemplary communication skills: written, and verbal across cross-functional teams
  • Strong time management and organizational skills
  • Must be authorized to work in the US

We offer a chance to work with talented people in a collaborative environment and provide top-notch benefits including health insurance, generous time off, annual performance bonuses, and long-term incentives. As an equal opportunity employer, Plexxikon is committed to a diverse workforce. Employment decisions regarding recruitment and selection will be made without discrimination based on race, color, religion, national origin, gender, age, sexual orientation, physical or mental disability, genetic information or characteristic, gender identity and expression, veteran status, or other non-job-related characteristics or other prohibited grounds specified in applicable federal, state and local laws.