This raises the risk that female patients will have been given unsafe doses, or prescribed the drug with on the basis of false optimism.
The researchers last night called for frontline doctors to pay greater heed to their patient’s gender when weighing up the risks and benefits of prescribing immunotherapy.
They also said future trials should include more women to make the results more relevant to the whole patient population.
“Despite the available evidence on the potential role played by sex in influencing how drugs work, trials testing new therapies rarely take sex into account,” said Dr Fabio Conforti, from the European Institute of Oncology.
“Both sex and gender can potentially affect the strength of the body’s immune response.”
On average, women mount stronger immune responses than do men, which results in more rapid clearance of pathogens, explaining the lower severity and prevalence of many infections in women, and their greater response to vaccination than men.
However, they females also account for roughly 80% of all patients with systemic autoimmune diseases worldwide.
“Therefore, it’s possible that differences in the immune system of women and men could be relevant to the natural course of chronic inflammatory conditions such as cancer, and potentially how they respond to drugs,” said Dr Conforti.