NEW YORK (Reuters Health) Jul 29 - Don't bother with phase III trials of exemestane for hormone-responsive advanced breast cancer in older women, Spanish researchers say.
In a phase II trial, exemestane was no better than anastrozole, they reported online June 29th in Cancer.
Further formal comparisons are not justified, said lead author Dr. Antonio Llombart-Cussac of Arnau de Vilanova University Hospital, Lleida, and his colleagues.
Aromatase inhibitors have varying inhibitory potencies that could lead to differences in clinical outcomes. In particular, the research team notes, exemestane and anastrozole seem to delay recurrence in women with early breast cancer, with steroidal exemestane suppressing estrogen slightly more than nonsteroidal anastrozole.
To explore its possible advantages for advanced postmenopausal breast cancer, the team randomized 103 women, median age 72 years, to receive either oral exemestane 25 mg daily or oral anastrozole 1 mg daily until disease progression.
Both compounds were well tolerated with generally mild adverse events, according to the authors.
But the time to progression was twice as long with the comparator agent: six months with exemestane vs 12 months with anastrozole.
During a median follow-up of nine months, the objective response rates were 36.2% for exemestane and 46% for anastrozole. Clinical benefit rates were 59.6% and 68% for exemestane and anastrozole, respectively.
"The observed results prompted us to discard the planned phase 3 trial," the researchers say.
However, at progression, 28 patients crossed over to the other aromatase inhibitor. Among the 16 patients who switched to exemestane, 7 (43.7%) obtained a clinical benefit as opposed to only 1 of 12 patients who switched to anastrozole after failure on exemestane (8.3%).
This may be worth exploring, the authors observe.
"Although it was not the primary objective of the current study, we observed a dissimilar tumor behavior based in the sequential aromatase inhibitor approach that we used," the research team concluded.
SOURCE: http://bit.ly/pURml2
Cancer 2011.
In a phase II trial, exemestane was no better than anastrozole, they reported online June 29th in Cancer.
Further formal comparisons are not justified, said lead author Dr. Antonio Llombart-Cussac of Arnau de Vilanova University Hospital, Lleida, and his colleagues.
Aromatase inhibitors have varying inhibitory potencies that could lead to differences in clinical outcomes. In particular, the research team notes, exemestane and anastrozole seem to delay recurrence in women with early breast cancer, with steroidal exemestane suppressing estrogen slightly more than nonsteroidal anastrozole.
To explore its possible advantages for advanced postmenopausal breast cancer, the team randomized 103 women, median age 72 years, to receive either oral exemestane 25 mg daily or oral anastrozole 1 mg daily until disease progression.
Both compounds were well tolerated with generally mild adverse events, according to the authors.
But the time to progression was twice as long with the comparator agent: six months with exemestane vs 12 months with anastrozole.
During a median follow-up of nine months, the objective response rates were 36.2% for exemestane and 46% for anastrozole. Clinical benefit rates were 59.6% and 68% for exemestane and anastrozole, respectively.
"The observed results prompted us to discard the planned phase 3 trial," the researchers say.
However, at progression, 28 patients crossed over to the other aromatase inhibitor. Among the 16 patients who switched to exemestane, 7 (43.7%) obtained a clinical benefit as opposed to only 1 of 12 patients who switched to anastrozole after failure on exemestane (8.3%).
This may be worth exploring, the authors observe.
"Although it was not the primary objective of the current study, we observed a dissimilar tumor behavior based in the sequential aromatase inhibitor approach that we used," the research team concluded.
SOURCE: http://bit.ly/pURml2
Cancer 2011.
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