[Efficacy and safety of high dose NK 622 (toremifene citrate) in tamoxifen failed patients with breast cancer].

Efficacy and safety of high dose administration of NK 622 (toremifene citrate) were studied in tamoxifen (TAM)--failed patients with breast cancer. The patients included in the study were the following failure cases in TAM therapy: unresponded cases in TAM therapy (TAM unresponded cases), temporary responded (CR, PR) but progressed cases in TAM therapy (TAM temporary responded cases), and those relapsing during TAM adjuvant therapy or within 6 months after the adjuvant therapy (TAM adjuvant failed cases). NK 622 of a 120 mg/day dose were orally given daily once at least for 8 weeks. The response rates in evaluable cases were 6.3% (1/16) in TAM unresponded cases, 11.1% (1/9) in TAM temporary responded cases, 15.4% (4/26) in TAM adjuvant failed cases, and 11.8% (6/51) in total cases including 1 CR and 5 PR cases. Long NC in which duration of NC maintained for more than 6 months was observed in 18.8% (3/16) of TAM unresponded cases, 22.2% (2/9) of TAM temporary responded cases, 11.5% (3/26) of TAM adjuvant failed cases, and 15.7% (8/51) of total cases. Rates of response and long NC were 14.3 and 19.0% in postmenopausal patients with estrogen receptor positive cancer, respectively. A median value of duration to the onset of response was 34 days (15-137). Median duration of response and long NC were 127 days (39-381) and 238.5 days (178-281), respectively. Adverse effects were experienced in 3 (5.1%) of 59 patients: nausea in 1, vertigo in 1 and increase of GOT, GPT, LDH and gamma-GTP in another 1. The side effects were moderate and reversible. From these results, NK 622 seems to become a safe and effective drug for TAM-failed patients with breast cancer by using a 120 mg/day dose.