Rival pharmaceuticals firms AstraZeneca PLC (LON:AZN) and GlaxoSmithKline PLC (LON:GSK) jostled for position as separate trial results revealed the “unprecedented efficacy” of PARP inhibitor drugs on advanced ovarian cancer.
AstraZeneca and GSK revealed results separately at last weekend’s European Society for Medical Oncology symposium in Barcelona, showing their drugs both staved off the return of metastasized ovarian cancer in women who had responded to initial treatment.
AstraZeneca’s drug Lynparza, developed with Merck, edged slightly ahead of its rival as it reduced the risk of disease progression or death by 40%, and gave a median progression-free survival (PFS) of 22 months when used in combination with standard treatment Avastin.
Meanwhile, Glaxo’s drug Zejula reduced the risk of disease progression or death by 38% and only gave a median PFS of 13.8 months.
Both drugs belong to a class known as PARP inhibitors, which work by blocking the DNA repair mechanism to stop cancer cells from replicating.
Analysts at Shore Capital said results were difficult to compare since Lynparza was tested in combination with Avastin, whereas Glaxo studied Zejula as a monotherapy.
However, the British broker was impressed by the Lynparza/Avastin combo’s “unprecedented” 22 months PFS and said that the median PFS results were “a more relevant metric” for weighing up the drugs since the two drugs’ difference in disease progression was only small.
Shore Capital analysts pointed out that results may be skewed more by Avastin’s benefit as both an initial and maintenance therapy, rather than a difference between the new drugs being tested.
AstraZeneca estimated £2.4bn sales of Lynparza by the end of 2024, whereas Glaxo predicted a more conservative £874mln for Zejula by 2023, which Shore Capital suggests might be nudged up by Zejula’s being easier for doctors to prescribe, owing to its success across patients who tested positive and negative for HRD gene mutation.
Glaxo did better in early morning trading, rising 1% while AstraZeneca dipped 2%.