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Allschwil, Switzerland, June 28, 2021

Polyphor provides update on the Phase III FORTRESS study of balixafortide in patients with advanced HER2 negative breast cancer

- Co-primary endpoint of the study objective response rate (ORR) was not met

- The board of directors is undergoing a strategic assessment regarding the future of the company

Polyphor AG (SIX: POLN), a research driven clinical stage, Swiss biopharmaceutical company committed to discovering and developing best-in-class molecules in oncology and antimicrobial resistance today announced that its global Phase III study, FORTRESS, evaluating balixafortide (POL6326) in combination with eribulin for the treatment of patients with HER2 negative, locally recurrent or metastatic breast cancer, did not meet its co-primary endpoint.

At the primary analysis, balixafortide plus eribulin showed no improvement in the objective response rate (ORR) compared with eribulin alone (13.0% versus 13.7%; p=1.00) in the third line and later population (n=330 patients) followed for a minimum of 6 months. The clinical benefit rate, a key secondary endpoint indicating a stable disease or any confirmed response for a duration of at least 6 months as assessed by the IRC (independent radiological committee) was observed in 16.7% of patients in the balixafortide plus eribulin arm and 19.6% in the eribulin alone arm. The study confirmed the positive safety and tolerability profile of balixafortide in line with the previously reported Phase Ib study. Polyphor will continue to analyze the data, review with the experts and will decide about the future of the study in mid-July.

The board of directors is undergoing a strategic assessment and will consider a full range of options regarding the future of the company and will provide an update not later than end of July.

"Given the high unmet medical need for patients with HER2 negative breast cancer in a late stage of the disease, we are disappointed that the FORTRESS study did not meet its coprimary endpoint," says Gökhan Batur, CEO of Polyphor. "We thank all the patients, investigators and healthcare professionals as well as our employees for their active participation in this study."

About the FORTRESS study

The FORTRESS study (POL6326-009) is an international, multicenter, randomized active-controlled, open-label Phase III trial which investigates the efficacy, safety and tolerability of intravenous balixafortide given with eribulin versus eribulin alone in the treatment of HER2 negative, locally recurrent or metastatic breast cancer. The study had randomized 432 patients with HER2 negative MBC with at least 344 patients receiving third or subsequent line and 88 patients receiving second line chemotherapy.

About balixafortide

Balixafortide (POL6326) is a potent, specific, and highly selective antagonist of the chemokine receptor CXCR4, a G-protein coupled receptor (GPCR) that regulates the trafficking and homing of both cancer cells and cells of the patient's immune system.

For further information please contact:

For Investors:

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Bernhard Schmid
LifeSci Advisors
+41 44 447 12 21
bschmid@lifesciadvisors.com

About Polyphor
Polyphor is a research driven clinical-stage, Swiss biopharmaceutical company committed to discovering and developing best-in-class molecules in oncology and antimicrobial resistance leveraging the company's leading macrocyclic peptide technology platform. Polyphor has finished patient enrollment of a Phase III trial of balixafortide (POL6326) in combination with eribulin in patients with advanced breast cancer. In addition, it has discovered and is developing the Outer Membrane Protein Targeting Antibiotics (OMPTA). OMPTA are potentially the first new class of antibiotics in clinical development in the last 50 years against Gram-negative bacteria. The company's lead OMPTA program is an inhaled formulation of murepavadin for the treatment of Pseudomonas aeruginosa infections in patients with cystic fibrosis. Polyphor is based in Allschwil near Basel and is listed on the SIX Swiss Exchange (SIX: POLN). For more information, please visit www.polyphor.com.

Disclaimer
This press release contains forward-looking statements which are based on current assumptions and forecasts of the Polyphor management. Known and unknown risks, uncertainties, and other factors could lead to material differences between the forward-looking statements made here and the actual development, in particular Polyphor's results, financial situation, and performance. Readers are cautioned not to put undue reliance on forward-looking statements, which speak only of the date of this communication. Polyphor disclaims any intention or obligation to update and revise any forward-looking statements, whether as a result of new information, future events or otherwise.