CORRECTING and REPLACING Biocept’s CNSide Cerebrospinal Fluid Assay Aids in Monitoring Treatment Response and Detects Actionable Biomarkers in Patients with Metastatic Breast Cancer

Case series poster to be presented at the Society for Neuro-Oncology Annual Meeting

Third paragraph, sixth sentence of release should read: CNSide detected CSF tumor cells in all eleven measurements taken, compared to six of eleven using cytology. (instead of CNSide detected CSF tumor cells in all nine measurements taken, compared to five of nine using cytology.)

The updated release reads:

BIOCEPT’S CNSIDE CEREBROSPINAL FLUID ASSAY AIDS IN MONITORING TREATMENT RESPONSE AND DETECTS ACTIONABLE BIOMARKERS IN PATIENTS WITH METASTATIC BREAST CANCER

Case series poster to be presented at the Society for Neuro-Oncology Annual Meeting

Biocept, Inc. (Nasdaq: BIOC), a leading provider of molecular diagnostic assays, products and services, today announced the presentation of a multi-institutional case series showing that its CNSide™ cerebrospinal fluid assay helps physicians monitor treatment response and detects actionable mutations in patients with metastatic breast cancer and leptomeningeal disease (LMD). The poster will be presented virtually at the Society for Neuro-Oncology Annual Meeting in Boston, Nov. 19, 2021, from 7:30-9:30 p.m. ET, and Biocept will be exhibiting at booth #303.

Breast cancer is one of the most common cancers associated with LMD, a devastating complication in which cancer spreads to the membrane surrounding the brain and spinal cord. The current standard of care for diagnosing LMD is through clinical evaluation, imaging and cytology, which have limited sensitivity. Median survival after a diagnosis of LMD is just two to three months.

The case series included four breast cancer patients, ages 32 to 57, with suspected LMD who were treated at four different institutions. CNSide and cytology were used in parallel to detect tumor cells in the cerebrospinal fluid at diagnosis and throughout treatment. CNSide was also used to determine tumor cell counts and the presence of HER2 amplification to help guide therapy. At diagnosis, CNSide detected cancer cells in three of three patients, compared with two of three patients for cytology. (The fourth patient was diagnosed before CNSide was available.) CNSide detected CSF tumor cells in all eleven measurements taken, compared to six of eleven using cytology. Throughout treatment, CNSide showed a decrease in CSF tumor cells in all four patients, ranging from 99.7% to 100%, corresponding with an improved clinical response.

“Having a quantitative assay that provides tumor cell counts, rather than just a positive or negative result, is a major advance in the management of patients with leptomeningeal disease,” said Priya Kumthekar, M.D., Neuro-Oncologist and Associate Professor of Neurology at Northwestern Medicine’s Feinberg School of Medicine, who will present the case series poster. “A positive cytology result may suggest that the patient is not responding to treatment, which could lead to therapy being stopped or changed. As this case series shows, CNSide’s quantitative results may show that, in fact, the tumor cell count has dropped dramatically, indicating that the patient is responding, and therapy should be continued.”

“These cases illustrate the value of CNSide in treatment response monitoring and identification of targets for therapy that can produce a sustained response in leptomeningeal disease,” said Michael Dugan, M.D., Chief Medical Officer and Medical Director of Biocept. “CNSide has the potential to allow clinicians to have more confidence in their treatment decisions, improving the clinical management of leptomeningeal disease in a way that may help patients see improvement in symptoms and live significantly longer lives.”

The case series was completed by neuro-oncologists from Smilow Cancer Hospital at Yale New Haven Health, Lou and Jean Malnati Brain Tumor Institute at Northwestern Medicine, UT Southwestern Medical Center and Barrow Neurological Institute. The abstract (#BIOM-05), titled “Case Series of Multi-Institutional Utility of CNSide™ to Manage Leptomeningeal Disease in Patients with Metastatic Breast Cancer,” can be accessed here.

About Biocept

Biocept, Inc., develops and commercializes molecular diagnostic assays that provide physicians with clinically actionable information to aid in the diagnosis, treatment and monitoring of patients with cancer. In addition to its broad portfolio of blood-based liquid biopsy tests, the company has developed the CNSide™ cerebrospinal fluid assay, designed to diagnose cancer that has metastasized to the central nervous system. Biocept also is leveraging its molecular diagnostic capabilities to offer nationwide RT-PCR-based COVID-19 testing and services to support public health efforts during this unprecedented pandemic. For more information, visit www.biocept.com. Follow Biocept on Facebook, LinkedIn and Twitter.

Forward-Looking Statements Disclaimer

This release contains forward-looking statements that are based upon current expectations or beliefs, as well as a number of assumptions about future events. Although Biocept believes that the expectations reflected in the forward-looking statements and the assumptions upon which they are based are reasonable, Biocept can give no assurance that such expectations and assumptions will prove to have been correct. Forward-looking statements are generally identifiable by the use of words like "may," "will," "could," "expect," or "believe" or the negative of these words or other variations on these words or comparable terminology. To the extent that statements in this release are not strictly historical, including without limitation statements regarding the capabilities and potential benefits of Biocept’s CNSide assay and the ability of Biocept’s assays to provide physicians with clinically actional information, such statements are forward-looking, and are made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. The reader is cautioned not to put undue reliance on these forward-looking statements, as these statements are subject to numerous risks and uncertainties, including the risk that Biocept’s products and services may not perform as expected. These and other risks are described in greater detail under the "Risk Factors" heading of Biocept’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2021, filed with the Securities and Exchange Commission (SEC) on November 15, 2021. The effects of such risks and uncertainties could cause Biocept’s actual results to differ materially from the forward-looking statements contained in this release. Biocept does not plan to update any such forward-looking statements and expressly disclaims any duty to update the information contained in this press release except as required by law. Readers are advised to review Biocept’s filings with the SEC, which can be accessed over the Internet at the SEC's website located at www.sec.gov.

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