Zejula win primes Glaxo’s Parp for a larger market

For Glaxosmithkline’s $5bn takeout of Tesaro to make sense a couple of pivotal trials of the US biotech’s Parp inhibitor, Zejula, had to succeed. The first can now be ticked off the list: Prima hit its primary endpoint, Glaxo said today, significantly extending progression-free survival in patients with ovarian cancer, regardless of their biomarker status. This is important because Lynparza, Astrazeneca and Merck & Co’s leading Parp inhibitor, is only indicated to treat BRCA-positive patients in this maintenance setting. Solo-1, the trial that won Lynparza approval here, generated a very impressive result but was started before researchers fully appreciated that Parp inhibitors had utility beyond BRCA-positive patients. Only 15% of newly-diagnosed ovarian cancers carry this particular tumour biomarker, and while these patients respond most strongly to Parp inhibition, others can also benefit. In later treatment lines Parp inhibitors are approved regardless of BRCA status but at Esmo last year, when Solo-1 was presented, doctors expressed caution about translating this to the front line setting without clear evidence (Esmo 2018 – Lynparza delivers a huge result in first-line ovarian cancer, October 21, 2018). Prima could provide this, though the full readout remains crucial. The Esmo cancer conference, which will be held in September, looks a likely venue.

Outlook for the Parp space
    Annual Sales WW ($m)
Product Company 2019e 2021e 2023e
Lynparza Astrazeneca/Merck 1,094 1,786 2,491
Zejula Glaxosmithkline 313 690 990
Rubraca Clovis Oncology 149 339 634
Talzenna Pfizer 55 243 389
  Total incl. others 1,632 3,156 4,822
Source: EvaluatePharma. 

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