A novel strategy involves combining antibody-drug conjugates (ADCs) with PARP inhibitors. This approach could potentially overcome the need for a germline BRCA mutation, significantly broadening the patient population that could benefit from PARP inhibitor therapy in triple-negative breast cancer.

The next innovation for PARP inhibitors will likely involve combinations with other DNA-damaging agents beyond just ARPIs. Promising partners include radioligands like radium (an alpha emitter) and lutetium, or even therapies like superphysiologic testosterone (BAT) that are theorized to work by inducing DNA breaks.

Early data shows that combining PARP inhibitors with radioligand therapy like lutetium-PSMA is surprisingly safe, unlike toxic combinations with chemotherapy. This promising strategy may potentiate the DNA-damaging effect of the beta-emitting radiopharmaceutical, potentially extending its benefit to a broader patient population beyond those with HR-deficient tumors.

A novel strategy for BRCA2-mutant metastatic prostate cancer is to use PARP inhibitors as an induction therapy for 6-10 months rather than continuously. This approach aims to achieve a deep response while preserving bone marrow, which is critical for tolerating future therapies like radioligands and chemotherapy in older patients with a long disease course.

The selection between PARP inhibitors like olaparib and niraparib is not one-size-fits-all. It's a personalized decision based on patient preference for dosing frequency (once vs. twice daily), tolerance for side effects like hypertension, and potential drug-drug interactions.

Eikon's strategy for its PARP inhibitor wasn't just to create a better version of an existing drug class, but one with superior combinability. By selectively targeting PARP1, they minimized the hematologic toxicity that prevented older PARP inhibitors from being used with chemotherapies like taxanes, opening up earlier lines of treatment.

For high-risk, HR+ patients with germline BRCA mutations, data suggest they derive less benefit from CDK4/6 inhibitors. A practical approach is to give one year of the PARP inhibitor olaparib first, followed by a CDK4/6 inhibitor, capitalizing on the delayed initiation allowance in major trials.

Recent trial data shows that patients with somatic BRCA1/2 mutations (found only in the tumor, not inherited) can achieve significant responses to PARP inhibitors. This finding supports routine tumor genomic testing to identify more candidates for this targeted therapy beyond just those with germline mutations.

In high-risk, BRCA-positive patients eligible for both, clinicians favor giving a PARP inhibitor first. The rationale is based on established survival data, shorter one-year duration, and emerging biological evidence suggesting BRCA2-mutated tumors may be resistant to CDK4/6 inhibitors due to concurrent RB gene loss.