Clovis takes PARP prostate cancer pole position with fast FDA review of Rubraca

The FDA has granted a fast review for Clovis Oncology’s Rubraca PARP drug in certain patients with prostate cancer, the first drug in this class to target the indication.

The FDA’s six-month priority review sets up a decision date for Rubraca on 15th May, although rivals from AstraZeneca/Merck & Co and Johnson & Johnson are in close pursuit.

Clovis’ TRITON trials could open the door for treatment early in the disease: TRITON 3 tested Rubraca in BRCA-mutated metastatic castration-resistant prostate cancer (mCRPC) after treatment with androgen therapy – think J&J’s Zytiga or Pfizer/Astellas Xtandi – but before chemotherapy.

TRITON 2 covers the post-chemotherapy indication that Janssen is targeting with Zejula – the FDA granted Breakthrough Therapy designation to this in BRCA-mutated mCRPC cancer patients after androgen receptor therapy and chemo.

AZ and Merck & Co are also developing their PARP drug Lynparza in mCRPC in an indication that covers cancers with mutated homologous recombination repair genes, including BRCA1/2 and ATM.

Results of the large PROfound trial came out in October, showing a statistically significant improvement in the primary endpoint of radiographic progress-free survival compared with Zytiga or Xtandi.

Importantly, it seems that Lynparza performs in the ATM mutation accounting for 5-7% of prostate cancer patients, where Rubraca did not show much activity.

Subsequent trial results from the phase 2 TOPARP-B study published in The Lancet at the beginning of this month suggest that Lynparza is more active in BRCA mutations, but still has a more limited effect in ATM.

Whether the data will translate into a wider indication remains to be seen and for now the advantage lies with Clovis in prostate cancer after a bruising 2019 when Rubraca struggled to gain traction in sales despite its FDA approvals in ovarian cancer, as maintenance therapy and in advanced disease.

The FDA grants priority reviews to medicines that could significantly improve safety or effectiveness for a serious condition if approved.

It shortens the review period from the standard 10 months to six months.

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