Experts are cautious about using ADCs as long-term frontline maintenance therapy in ovarian cancer. Unlike oral PARPs, prolonged administration of these potent chemotherapies could cause cumulative toxicities, especially bone marrow suppression, potentially rendering patients unable to tolerate essential treatments upon relapse.

The widespread use of PARP inhibitors has altered tumor biology in platinum-sensitive ovarian cancer. A recent meta-analysis of heavily pretreated patients, 97% of whom had prior PARP inhibitor exposure, revealed an objective response rate to subsequent therapy of only 17%—far lower than historical expectations, highlighting a critical unmet clinical need.

Pivotal trials for PARP inhibitor and ARPI combinations (e.g., PROPEL, MAGNITUDE) enrolled patients who were largely ARPI-naive. However, in modern practice, most patients receive an ARPI earlier in their treatment. This creates significant uncertainty about the benefit of these combinations for the majority of today's patients.

When evaluating data for relapsed/refractory AML, clinicians must look beyond headline response rates. The number of prior therapies a patient has received dramatically impacts outcomes. A trial with a median of one prior treatment will have vastly different results than one with five.

The risk of developing myeloid neoplasms from PARP inhibitors in the frontline ovarian cancer setting is very low, around 1%. However, it is critical to adhere to the recommended 2-3 year treatment duration and then stop the therapy to avoid unnecessary long-term risk.

Though cross-trial comparisons are imperfect, Grade 3+ anemia rates offer a stark contrast between approved PARP+ARPI combinations. The rate was 16% for olaparib+abiraterone (PROPEL) versus a much higher 49% for talazoparib+enzalutamide (TALAPRO-2). This suggests toxicity profiles should be a key factor in treatment selection.

Giving adjuvant olaparib to BRCA-mutated patients who have already achieved a pathologic complete response (pCR) from neoadjuvant platinum-based chemotherapy is discouraged. Their prognosis is already excellent, so adding a PARP inhibitor offers little potential benefit while exposing them to unnecessary risks of toxicity, such as MDS/AML.

Despite theoretical differences in potency or PARP1 specificity, all approved PARP inhibitors demonstrate comparable clinical toxicity profiles. Oncologists should counsel patients on a consistent class effect of myelosuppression, primarily grade 3 anemia requiring transfusion in about 25-33% of patients, regardless of the specific agent.

Unlike lenalidomide, which modulates CK1-alpha and can select for p53-mutated cells leading to a risk of secondary leukemia/MDS, both iberdomide and mezigdemide do not share this off-target effect. This critical safety difference makes them promising candidates for long-term use, such as in maintenance therapy.