Quantum-Si Incorporated (NASDAQ:QSI) ("Quantum-Si," "QSI" or the "Company"), a proteomics company redefining protein analysis through single-molecule protein sequencing, today announced that there will be two customer posters presented at the American Association of Cancer Research (AACR) annual meeting on April 17-22, 2026 in San Diego, California.

Poster 2421; April 20, 2026

Primary Author: Nigel O'Neil, PhD

Poster Title: Combining deep mutational scanning and next-generation protein sequencing to harness dominant protein variants to develop DNA repair inhibitors

In the first poster, the researchers describe a complementary genetic (high throughput screens) and proteomic (benchtop protein sequencing) approach to find and model the behavior of therapeutics targeting DNA repair enzymes.

Poster 7650; April 22, 2026

Primary Author: Gloria Sheynkman, PhD

Poster Title: High-resolution detection of post-translational modifications using single-molecule protein sequencing

In the second poster, the researchers demonstrated the ability to resolve and quantify multiple PTMs using Quantum-Si's single-molecule protein sequencing technology. The authors suggested that the technology could be used to add proteoform characterization to biomarker studies, providing additional resolution not readily available in broad biomarker screening panels. The authors further concluded that they expect this technology could democratize advanced protein characterization, making the high-resolution detection of PTMs available to a broader scientific community.

"We are excited to see new customer data being presented at key industry conferences like AACR, that continue to demonstrate the power of our proprietary single-molecule protein sequencing technology," said Jeff Hawkins, President and Chief Executive Officer of Quantum-Si. "We invested significant effort during 2025 to build a pipeline of studies that would demonstrate the power of our technology, and we are very pleased to have a steady flow of customer pre-prints, publications and posters being released this year as we work to expand awareness and build momentum towards the launch of Proteus™."

About Quantum-Si Incorporated

Quantum-Si is transforming proteomics with a benchtop platform that brings single-molecule protein analysis to every lab, everywhere. The Company's platform enables real-time kinetic-based detection and allows researchers to move beyond traditional, multistep workflows and directly access dynamic, functional protein insights with unparalleled resolution. By making protein analysis simpler, faster, and more informative, Quantum-Si is accelerating proteomic discoveries to improve the way we live. Learn more at quantum-si.com or follow us on LinkedIn or X.

Forward Looking Statements

This press release includes "forward-looking statements" within the meaning of the "safe harbor" provisions of the United States Private Securities Litigation Reform Act of 1995. The actual results of the Company may differ from its expectations, estimates, and projections and, consequently, you should not rely on these forward-looking statements as predictions of future events. Words such as "expect," "estimate," "project," "budget," "forecast," "anticipate," "intend," "plan," "may," "will," "could," "should," "believes," "predicts," "potential," "continue," and similar expressions (or the negative versions of such words or expressions) are intended to identify such forward-looking statements. These forward-looking statements include, without limitation, the Company's expectations with respect to future performance and development and commercialization of products, services and applications, its anticipated cash runway, the anticipated timing of product launches and product capabilities (including Proteus), investor confidence in Quantum-Si and our strategic roadmap, and any financial guidance. These forward-looking statements involve significant risks and uncertainties that could cause the actual results to differ materially from those discussed in the forward-looking statements. Many of these factors are outside the Company's control and are difficult to predict. Factors that may cause such differences include, but are not limited to: the inability to maintain the listing of the Company's Class A common stock on The Nasdaq Stock Market; the ability of the Company to grow and manage growth and retain its key employees; the Company's ongoing leadership transitions and succession planning; changes in applicable laws or regulations; the ability of the Company to raise financing in the future; the success, cost and timing of the Company's product development and commercialization activities, including the use and benefit of artificial intelligence in these and other activities; the commercialization and adoption of the Company's existing products and the success of any product the Company may offer in the future, including Proteus; the potential attributes and benefits of the Company's commercialized Platinum protein sequencing instruments and kits and the Company's other products (including Proteus) once commercialized; the Company's ability to obtain and maintain regulatory approval for its products, and any related restrictions and limitations of any approved product; the Company's ability to identify, in-license or acquire additional technology; the Company's ability to maintain its existing lease, license, manufacture and supply agreements; the Company's ability to compete with other companies currently marketing or engaged in the development or commercialization of products and services that serve customers engaged in proteomic analysis, many of which have greater financial and marketing resources than the Company; the size and growth potential of the markets for the Company's products and services, and its ability to serve those markets once commercialized, either alone or in partnership with others; the Company's estimates regarding future expenses, future revenue, capital requirements and needs for additional financing; the Company's financial performance; the Company's defense and initiation of litigation matters; and other risks and uncertainties described under "Risk Factors" in the Company's most recent Annual Report on Form 10-K and Quarterly Reports on Form 10-Q and in the Company's other filings with the SEC. The Company cautions that the foregoing list of factors is not exclusive. The Company cautions readers not to place undue reliance upon any forward-looking statements, which speak only as of the date made. The Company does not undertake or accept any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements to reflect any change in its expectations or any change in events, conditions, or circumstances on which any such statement is based.

View source version on businesswire.com: https://www.businesswire.com/news/home/20260414060888/en/

Investor and Media

Jeff Keyes

Chief Financial Officer

ir@quantum-si.com

Quantum-Si Announces Two Customer Posters to be Presented at the American Association of Cancer Research Annual Meeting