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Guardant Health is a cancer diagnostics company headquartered in Stanford Research Park. It makes blood tests that look for fragments of tumor DNA circulating in the bloodstream, an approach usually called liquid biopsy. Its corporate headquarters is at 3100 Hanover Street, part of the complex that once served as Hewlett-Packard's corporate home.
This page covers the company's founding, its move into Palo Alto and its place among the life science companies on the Peninsula. It is not medical advice. Questions about cancer screening or testing belong with a doctor.
What Guardant Health does
When a tumor grows, it sheds tiny pieces of DNA into the blood. Guardant's tests read those pieces with DNA sequencing and look for the genetic changes that mark a cancer. Doctors can then use the results without always taking a tissue sample by needle or surgery.
The company's annual report for 2025 describes several product lines.
- Guardant360 tests help match people with advanced cancer to targeted treatments. One version, Guardant360 CDx, is approved by the FDA as a companion diagnostic.
- Guardant Reveal looks for cancer that remains or comes back after treatment.
- Shield is a blood test for colorectal cancer screening in adults 45 and older at average risk. The FDA approved it in 2024. Medicare coverage followed in August 2024, according to the company.
- GuardantINFINITY and related services support drug companies running research and clinical trials.
Guardant began selling Guardant360 tests to cancer doctors in 2014. It earns most of its revenue from test fees paid by insurers and from work for drug developers.
The founders and the Stanford link
Helmy Eltoukhy and AmirAli Talasaz met at Stanford University in 2002. Both later worked at Illumina, the DNA sequencing company. Talasaz left Illumina in 2012. The two co-founded Guardant during 2012 and 2013. They now serve together as co-chief executives, an unusual arrangement for a public company.
The company has stayed close to where its founders met. Our page on the Stanford School of Medicine covers the medical campus a few miles away.
The founding was not free of conflict. In 2022 Illumina sued Guardant and its founders over trade secrets and patents. Guardant rejected the claims. The two companies settled in 2023 and signed a long-term supply agreement.
Funding and the public listing
Guardant raised large sums as a private company. Reported rounds include $30 million in 2014, with $10 million from Sequoia Capital. Another $50 million came in 2015, led by Lightspeed Venture Partners. A Series D in January 2017 raised about $100 million. Later that year a SoftBank-led round raised $360 million to fund work on screening and recurrence tests.
The company went public on Nasdaq in 2018 under the ticker GH. Its initial public offering raised $237.5 million. This page does not comment on the stock or the company's finances.
The move to Hanover Street
Before the move, Guardant was based in Redwood City, just north of Palo Alto. Its main clinical laboratory is still there, licensed under federal CLIA rules and accredited by the College of American Pathologists, according to its annual report.
In July 2020 Guardant signed a lease for two levels of the former Hewlett Packard Enterprise headquarters on Hanover Street in Palo Alto. The Mercury News reported the deal in August 2020 and described it as one of the largest office leases in Silicon Valley that year. The company later moved its corporate headquarters into the roughly 250,000 square foot space.
The complex has a long corporate past. Hewlett-Packard used 3000 Hanover Street as its corporate address in the 2000s. Hewlett Packard Enterprise started there in 2015. Tesla later leased part of the site and in 2023 named it its global engineering headquarters. Our Hewlett Packard Enterprise profile covers that history. Guardant's own address on the complex is 3100 Hanover Street.
The annual report also says the Palo Alto site does research and technology development work and holds a CLIA license. Other company labs are in San Diego and Long Island City, New York.
How the product line grew
Guardant did not start with a screening test. It built outward from tests for people already diagnosed with cancer.
- 2014. Guardant360 goes on sale to oncologists for people with advanced solid tumors.
- May 2016. Project Lunar begins, studying people at high risk of several cancers with research partners including UCSF.
- 2017. GuardantOMNI launches for drug company research.
- 2018. Medicare begins covering Guardant360 for some lung cancer patients.
- 2021. Guardant Reveal launches for colorectal cancer patients after surgery.
- 2024. Shield wins FDA approval for colorectal cancer screening.
The company also expanded abroad. A joint venture with SoftBank, Guardant Health AMEA, launched in 2018 to sell tests in Africa, Asia and the Middle East. Guardant bought out the venture in 2022 for about $178 million.
Who has used the Hanover Street complex
| Occupant | Address and era | Notes |
|---|---|---|
| Hewlett-Packard | 3000 Hanover Street, 2000s | Corporate address before the 2015 split. |
| Hewlett Packard Enterprise | 3000 Hanover Street, from November 2015 | Announced a move to Santa Clara in November 2017. |
| Guardant Health | 3100 Hanover Street, lease signed July 2020 | Two levels, about 250,000 square feet. Now corporate headquarters. |
| Tesla | 3000 Hanover Street, lease agreed 2021 | About 325,000 square feet. Global engineering headquarters since February 2023. |
Guardant's place in the local ecosystem
Palo Alto is better known for computers and software than for medicine, but life science has deep roots here. Syntex, Varian and Stanford Medicine all shaped the local economy long before Guardant. Our Varian profile covers one of the earliest research park tenants, which later became a leader in cancer radiation equipment.
Guardant fits a newer pattern: a genomics company built by engineers, funded by Sand Hill Road firms and housed in former computer company offices. Its move into the old HP buildings shows how the research park keeps changing tenants while the buildings stay. Our Stanford Research Park guide explains how the park works.
Visiting notes
Good to know
- The Hanover Street headquarters is a private office. It is not a lab you can visit, a clinic or a blood draw site.
- Guardant tests are ordered by a health care provider. Do not bring samples or paperwork to the office.
- The Hanover Street area is spread out. A car or bike is the easiest way to see it, along with Tesla's engineering headquarters nearby.
- Visiting someone at Stanford Hospital instead? Our hospital visitors guide covers parking and places to stay.
Guardant Health timeline
| Date | Event |
|---|---|
| 2002 | Eltoukhy and Talasaz meet at Stanford. |
| 2012 to 2013 | Guardant Health co-founded. |
| 2014 | Guardant360 tests go on sale to oncologists. |
| 2017 | SoftBank-led $360 million round. |
| 2018 | Initial public offering on Nasdaq as GH. |
| July 2020 | Lease signed at the former HPE headquarters on Hanover Street. |
| 2023 | Settlement and supply deal with Illumina. |
| 2024 | Shield approved by the FDA; Medicare coverage follows in August. |
For more companies with a Palo Alto chapter, see our companies hub.
Frequently asked questions
Where is Guardant Health headquartered?
Guardant Health's corporate headquarters is at 3100 Hanover Street, Palo Alto, CA 94304, in Stanford Research Park. Its website and its annual report for 2025 both list that address. The company's main clinical laboratory is in Redwood City.
Who founded Guardant Health?
Helmy Eltoukhy and AmirAli Talasaz co-founded the company in 2012 and 2013. The two met at Stanford University in 2002 and later both worked at Illumina. They serve together as co-chief executives.
What does Guardant Health make?
Guardant makes blood tests that look for DNA shed by tumors. Its products include Guardant360 for people with advanced cancer, Guardant Reveal for checking for remaining or returning cancer after treatment and Shield, a blood test for colorectal cancer screening.
Can I get a Guardant test at the Palo Alto office?
No. The Hanover Street headquarters is a corporate office, not a patient clinic or blood draw site. Guardant tests are ordered through a health care provider. Samples are processed at the company's laboratories.
Is Guardant Health related to Hewlett-Packard?
Only through real estate. In July 2020 Guardant leased space in the former Hewlett Packard Enterprise headquarters complex on Hanover Street. It later moved its corporate headquarters there.