Letrozole (CGS 20267). A phase I study of a new potent oral aromatase inhibitor of breast cancer

Allan Lipton, Laurence Demers, Harold Harvey, Kathleen B. Kambic, Howard Grossberg, Carolyn Brady, H. Adlercruetz, Patrick F. Trunet, Richard J. Santen

Research output: Contribution to journalArticle

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Abstract

Background. Letrozole (CGS 20267), a triazole derivative, is a new, once‐daily, oral nonsteroidal inhibitor of aromatase activity. Methods. In this Phase I trial, 23 heavily pretreated postmenopausal patients with metastatic breast cancer received letrozole at doses ranging from 0.1 to 5.0 mg once daily. Results. No hematologic, biochemical, or significant clinical toxicity was encountered. Serial steroid measurements were determined in 19 of these patients. Letrozole at all doses tested produced a marked suppression of plasma estrone, estradiol, estrone sulfate, and urine estrone and estradiol. This was observed within 24 hours of the initial dose of letrozole and resulted in a greater than 90% suppression of plasma and urinary estrogen levels within 2 weeks. Letrozole appears to be highly selective in its action and does not compromise glucocorticoid or mineralocorticoid production or thyroid function. Of the 21 evaluable patients, there were 2 with partial responses and 7 with stable disease. Conclusions. Letrozole is a well tolerated, potent, and specific inhibitor of estrogen biosynthesis in postmenopausal patients with metastatic breast cancer.

Original languageEnglish (US)
Pages (from-to)2132-2138
Number of pages7
JournalCancer
Volume75
Issue number8
DOIs
StatePublished - Jan 1 1995

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letrozole
Aromatase Inhibitors
Breast Neoplasms
Estrone
Estrogens
Mineralocorticoids
Triazoles
Glucocorticoids
Estradiol

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research

Cite this

Lipton, Allan ; Demers, Laurence ; Harvey, Harold ; Kambic, Kathleen B. ; Grossberg, Howard ; Brady, Carolyn ; Adlercruetz, H. ; Trunet, Patrick F. ; Santen, Richard J. / Letrozole (CGS 20267). A phase I study of a new potent oral aromatase inhibitor of breast cancer. In: Cancer. 1995 ; Vol. 75, No. 8. pp. 2132-2138.
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Letrozole (CGS 20267). A phase I study of a new potent oral aromatase inhibitor of breast cancer. / Lipton, Allan; Demers, Laurence; Harvey, Harold; Kambic, Kathleen B.; Grossberg, Howard; Brady, Carolyn; Adlercruetz, H.; Trunet, Patrick F.; Santen, Richard J.

In: Cancer, Vol. 75, No. 8, 01.01.1995, p. 2132-2138.

Research output: Contribution to journalArticle

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T1 - Letrozole (CGS 20267). A phase I study of a new potent oral aromatase inhibitor of breast cancer

AU - Lipton, Allan

AU - Demers, Laurence

AU - Harvey, Harold

AU - Kambic, Kathleen B.

AU - Grossberg, Howard

AU - Brady, Carolyn

AU - Adlercruetz, H.

AU - Trunet, Patrick F.

AU - Santen, Richard J.

PY - 1995/1/1

Y1 - 1995/1/1

N2 - Background. Letrozole (CGS 20267), a triazole derivative, is a new, once‐daily, oral nonsteroidal inhibitor of aromatase activity. Methods. In this Phase I trial, 23 heavily pretreated postmenopausal patients with metastatic breast cancer received letrozole at doses ranging from 0.1 to 5.0 mg once daily. Results. No hematologic, biochemical, or significant clinical toxicity was encountered. Serial steroid measurements were determined in 19 of these patients. Letrozole at all doses tested produced a marked suppression of plasma estrone, estradiol, estrone sulfate, and urine estrone and estradiol. This was observed within 24 hours of the initial dose of letrozole and resulted in a greater than 90% suppression of plasma and urinary estrogen levels within 2 weeks. Letrozole appears to be highly selective in its action and does not compromise glucocorticoid or mineralocorticoid production or thyroid function. Of the 21 evaluable patients, there were 2 with partial responses and 7 with stable disease. Conclusions. Letrozole is a well tolerated, potent, and specific inhibitor of estrogen biosynthesis in postmenopausal patients with metastatic breast cancer.

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