# Spear Bio

> Spear Bio is a Woburn, Massachusetts biotechnology company commercializing SPEAR (Successive Proximity Extension Amplification Reaction), an ultra-sensitive, wash-free immunoassay platform licensed from Harvard's Wyss Institute. SPEAR measures protein biomarkers at attomolar levels from sub-microliter samples using a two-factor authentication mechanism and standard qPCR instruments, delivering more than a 5-log improvement over conventional ELISA. The company sells assay kits - initially for neurodegeneration biomarkers such as pTau217, pTau231, GFAP and neurofilament light - to academic, pharmaceutical and clinical researchers.

- **Founded:** 2021
- **Headquarters:** Woburn, Massachusetts, United States
- **Founders:** Feng Xuan (Co-Founder & CEO (formerly CTO)), Peng Yin (Co-Founder & Lead Inventor; Professor of Systems Biology, Harvard Medical School / Wyss Institute)
- **Team size:** ~54 employees
- **Products:** SPEAR Technology, SPEAR UltraDetect, pTau217 Assay, pTau231 Assay, Neurofilament Light (NfL) Assay
- **Notable:** Raised an oversubscribed $45M Series A in July 2024, Total funding of roughly $53.4M since founding, Exclusively licensed SPEAR technology from Harvard's Wyss Institute

## Products & services

- **SPEAR Technology** — Successive Proximity Extension Amplification Reaction - a homogeneous, wash-free immunoassay platform that quantifies protein biomarkers at attomolar levels from 1 microliter of diluted sample using a two-factor authentication mechanism and standard qPCR readout.
- **SPEAR UltraDetect** — Next-generation ultra-sensitive immunoassay product line for neurodegenerative disease research, launched with four assays: pTau231, pTau217, GFAP and neurofilament light (NfL).
- **pTau217 Assay** — Ultra-sensitive assay for phosphorylated tau 217, a leading blood biomarker for Alzheimer's disease research.
- **pTau231 Assay** — Ultra-sensitive assay for phosphorylated tau 231, an early Alzheimer's research biomarker.
- **Neurofilament Light (NfL) Assay** — Assay for neurofilament light chain, a marker of neuronal damage used across neurology research.
- **NAB-Sure** — Assay for detecting neutralizing antibodies, applicable to immunology and infectious disease research.

## Achievements

- Raised an oversubscribed $45M Series A in July 2024
- Total funding of roughly $53.4M since founding
- Exclusively licensed SPEAR technology from Harvard's Wyss Institute
- Achieved attomolar sensitivity - over 5-log improvement versus conventional ELISA
- Secured strategic investment and global distribution from Bio-Techne
- Launched SPEAR UltraDetect with four neurology biomarker assays in 2025
- Manufactures in an ISO 13485:2016-certified facility

## Latest updates

- **2025-07** — Launched SPEAR UltraDetect, a next-generation ultra-sensitive immunoassay line for neurodegenerative disease research with pTau231, pTau217, GFAP and NfL assays.
- **2024-07** — Closed an oversubscribed $45M Series A led by Foresite Capital and Bio-Techne to accelerate product launch and scale manufacturing.
- **2024-07** — Announced a strategic partnership and investment with Bio-Techne for global distribution of its immunoassays.

## Links

- Website: https://spear.bio
- LinkedIn: https://www.linkedin.com/company/spearbio
- Twitter/X: https://twitter.com/spearbio

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Last updated: 2026-07-18