medwireNews: The Meet-URO12 trial of maintenance niraparib in advanced urothelial cancer patients without progression after first-line chemotherapy has failed to meet its primary endpoint of improvement in progression-free survival (PFS).
In the intention-to-treat population, median PFS was 2.1 months for the 39 participants who were randomly assigned to receive niraparib alongside best supportive care (BSC) and 2.4 months for their 19 counterparts who received BSC alone, study author Francesca Vignani (Ordine Mauriziano Hospital, Turin, Italy) reported at the 2022 ASCO Genitourinary Cancers Symposium in San Francisco, California, USA.
The 6-month PFS rate was 28.2% in the niraparib group and 26.3% in the control group.
Thus, “clinical selection based on platinum sensitivity did not succeed in selecting patients who may benefit from niraparib,” said Vignani.
The phase 2 study enrolled individuals with unresectable, locally advanced or metastatic urothelial carcinoma who had either a complete or partial response or stable disease after four to six cycles of first-line platinum-based chemotherapy. Participants received BSC either with or without the PARP inhibitor niraparib 300 or 200 mg/day depending on bodyweight and baseline platelet counts.
Vignani noted that trial accrual was stopped prematurely “due to the availability of avelumab in the same setting and the protocol was amended to perform analysis with a minimum of 40 PFS events” instead of the planned 65 events.
Of the 31 patients in the niraparib group and the 16 in the placebo group with available molecular data, a respective 11 (35.5%) and 10 (62.5%) were positive for homologous recombination repair (HRR) gene mutations.
There was no difference in PFS between niraparib plus BSC and BSC alone in these patients either, with an identical median PFS duration of 2.0 months.
But the presenter noted that the analysis of the predictive role of HRR deficiency for niraparib efficacy was “limited by the small number of patients.”
She added that the “safety profile of niraparib was consistent with that observed in other solid tumors.”
Treatment-emergent adverse events (TEAEs) of grade 3 or 4 were observed in 65.8% of participants given niraparib plus BSC and 15.8% of those receiving BSC alone. The most common events of this severity in the niraparib arm were thrombocytopenia and fatigue, each occurring in 15.8% of patients, followed by anemia, in 10.5%. There were no grade 5 TEAEs in either study arm and no cases of myelodysplastic syndrome or acute myeloid leukemia.
“Future studies could evaluate potential synergy of PARP inhibitors in combination with other therapies, such as immune checkpoint inhibitors,” concluded Vignani.
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This independent news story was supported by an educational grant from Pfizer and Merck Healthcare KGaA, Darmstadt, Germany