PARP1 encompasses a broad scope of DNA repair responses which makes it an attractive candidate for therapeutic inhibition, either alone or in combination with cancer chemotherapy or radiotherapy. Inhibition of PARP1 has potential for use in cancer treatment particularly by increasing tumor sensitivity to chemotherapeutic agents that damage DNA and by inducing synthetic lethality in tumor cells that are highly dependent on PARP1 due to deficiencies in DNA repair proteins (e.g., BRCA1/2).