AstraZeneca PLC is ending an agreement to collaborate on cancer research with Seres Therapeutics Inc., effective Apr. 2, 2021.

The U.K. pharmaceutical giant will still pay Seres the remaining $6.7 million installment of the total $20 million in up-front payment milestones required under the agreement.

The collaboration started in March 2019, to study the role of the microbiome in certain cancers and cancer immunotherapy.

The U.K. pharmaceutical giant told Seres that the termination of the agreement was based on budget considerations, according to a SEC filing.

AstraZeneca disclosed in April that its preclinical research activities would be reduced as part of a restructuring that includes the dissolution of its biologics unit MedImmune LLC.

Cambridge, Mass.-based Seres, a developer of biological drugs, said it continues to conduct research on its experimental microbiome therapeutics through ongoing partnerships with Memorial Sloan Kettering Cancer Center, The University of Texas MD Anderson Cancer Center, and the Parker Institute for Cancer Immunotherapy, as well as other means.