• SRF617 inhibits the enzymatic activity of CD39 on cells.
• By blocking CD39, SRF617 enhances total CD4 cell proliferation and dendritic cell maturation in the presence of exogenous ATP.
• SRF617 inhibits CD39 enzymatic activity in tumors, reduces systemic adenosine levels, inhibits tumor growth and increases tumor associated macrophages in preclinical tumor models.
• Combination of a murine surrogate of SRF617 with anti-PD-1 inhibition significantly increases survival versus anti-PD-1 inhibition alone, in a preclinical mouse tumor model.

Surface Oncology is an immuno-oncology company developing next-generation antibody therapies focused on the tumor microenvironment with lead programs targeting CD73, CD39, IL-27, CD112R and CD47. Surface's novel cancer immunotherapies are designed to achieve a clinically meaningful and sustained anti-tumor response and may be used alone or in combination with other therapies. The Company has a pipeline of six novel immunotherapies and a strategic collaboration with Novartis focused on NZV930 (CD73) and potentially one additional undisclosed program. For more information, please visit www.surfaceoncology.com.

Certain statements set forth in this press release constitute "forward-looking" statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. Forward-looking statements can be identified by terms such as "believes," "expects," "plans," "potential," "would" or similar expressions and the negative of those terms. These forward-looking statements are based on Surface Oncology's management's current beliefs and assumptions about future events and on information currently available to management.

Forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause Surface Oncology's actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. These risks include, but are not limited to, risks and uncertainties related to Surface Oncology's ability to successfully develop SRF388, SRF617, SRF813 and its other product candidates through current and future milestones or regulatory filings on the anticipated timeline, if at all, the therapeutic potential of Surface Oncology's product candidates, the risk that results from preclinical studies or early clinical trials may not be representative of larger clinical trials, the risk that Surface Oncology's product candidates, including SRF388 and SRF617, will not be successfully developed or commercialized and the risks related to Surface Oncology's dependence on third parties in connection with its manufacturing, clinical trials and preclinical studies. Additional risks and uncertainties that could affect Surface Oncology's future results are included in the section titled "Risk Factors" in our Annual Report on Form 10-K for the year ending December 31, 2018, which is available on the Security and Exchange Commission's website at www.sec.gov and Surface Oncology's website at www.surfaceoncology.com.

Additional information on potential risks will be made available in other filings that Surface Oncology makes from time to time with the Securities and Exchange Commission. In addition, any forward-looking statements contained in this press release are based on assumptions that Surface Oncology believes to be reasonable as of this date. Except as required by law, Surface Oncology assumes no obligation to update these forward-looking statements, or to update the reasons if actual results differ materially from those anticipated in the forward-looking statements.

Contacts:
Endurance Advisors
Pete Rahmer
[email protected] 
415-515-9763

Ten Bridge Communications
Tom Donovan
[email protected]
857-559-3397