 Pre-clinical studies, involving epigenetically reduced or mutated "BRCA"-deficient cells (in culture or injected into mice), show that inhibition of RAD52 is synthetically lethal with "BRCA"-deficiency.Although treatments using synthetic lethality can stop or slow progression of cancers and prolong survival, each of the synthetic lethal treatments has some adverse side effects.For example, more than 20% of patients treated with an inhibitor of PD-1 encounter fatigue, rash, pruritus, cough, diarrhea, decreased appetite, constipation or arthralgia.