A recent phase 3 clinical trial looked at women with advanced or recurrent endometrial cancer. The study compared two treatments. One group received standard chemotherapy plus a placebo. The other group received chemotherapy plus two drugs: dostarlimab and niraparib. After chemo, the first group continued with placebo, while the second group continued with dostarlimab and niraparib as maintenance therapy.
The trial enrolled 291 patients. After about 22 months of follow-up, the group receiving dostarlimab plus niraparib had a 40% lower risk of their cancer progressing or dying compared to the placebo group. This benefit was also seen in patients whose tumors were mismatch repair proficient, a common subtype, where the risk was reduced by 37%.
However, after a longer follow-up of about 36 months, there was no difference in overall survival between the two groups. This means that while the combination helped delay cancer growth, it did not help patients live longer overall.
Safety was a concern. More patients in the treatment group experienced severe side effects (70.7% vs 37.5%) and serious side effects (24.6% vs 9.4%). Also, more patients stopped treatment due to side effects (38.7% vs 11.5%).
In summary, adding niraparib to dostarlimab maintenance improved progression-free survival but did not improve overall survival. Patients and doctors should weigh the potential benefit of delayed progression against the higher risk of side effects.
