A phase II, open-label study of ispinesib (SB-715992) in patients with platinum/taxane refractory or resistant relapsed ovarian cancer

5562

Background: Kinesin spindle protein (KSP) is required for mitotic spindle bipolarity and cell cycle progression. Ispinesib (ISP), a selective KSP inhibitor, blocks assembly of the mitotic spindle leading to cell cycle arrest and cell death. Methods: This was a phase II study to determine the effectiveness of ISP in patients (pts) with platinum/taxane resistant or refractory ovarian cancer. Pts with progression during, or recurrence < 6 months after prior platinum/taxane therapy, ECOG status 0–2, and CA-125 > 40 U/ml were eligible. ISP was given as a 1 hr IV infusion of 18 mg/m2 Q 21 days. A 2-stage Green-Dahlberg design was employed. In Stage I, 20 evaluable pts were enrolled. If there were no CA-125 responses (Rustin criteria), the study was to be stopped. If > 1 CA-125 responses were seen, 15 more pts were to be enrolled in Stage 2. Overall response was defined by pts who achieved both CA-125 and RECIST criteria. Results: 22 pts with carboplatin/taxane resistant (9) or refractory disease (13) were enrolled: median age = 63 (43–80); 21 were Caucasian; median no. of cycles = 2 (1 - >16). All pts were evaluable for CA-125 assessment. The best CA-125 response was SD in 10 pts (45%); 12 pts had PD (55%). The best radiographic response was a confirmed PR lasting > 30 weeks in one pt who also met CA-125 progression criteria (5%); 5 pts (26%) had SD; and 13 pts (68%) had PD. The most common AEs, in decreasing order, were neutropenia, fatigue, anemia, leukopenia, thrombocytopenia, diarrhea, nausea, vomiting, and decreased appetite. The most frequent Gr 3/4 AE was neutropenia. Conclusions: This study was terminated after Stage I as the CA-125 response criterion to progress to Stage II was not met. One confirmed radiographic partial response was observed. ISP was well tolerated with an acceptable safety profile.

No significant financial relationships to disclose.

Phase I/II study of arsenic trioxide (ATO) in combination with cytosine arabinoside (ARA-C) in patients with myelodysplastic syndromes (MDS)

16525

Background: MDS is a group of myeloid disorders characterized by ineffective erythropoeisis with peripheral pancytopenia. We studied the efficacy and safety of ATO with/without ARA-C. Methods: We enrolled 10 patients with biopsy proven MDS per original FAB classification. See table for treatment design. Response was as follows: for CR the blast count in the BM should be <5% with normal maturation of all cell lines without evidence of dysplasia and PB values of Hemoglobin >11 g/dL, Neutrophils ≥1500/mm3, Platelets ≥100,000/mm3 lasting 2 months without transfusion support. PR was all of CR criteria except blasts decreased by > 50% over pretreatment or a less advanced MDS FAB classification than pretreatment. SD was failure to achieve at least a PR but without evidence of progression for at least 2 months. Results: 3 of 10 patients completed the study. 7 did not complete due to: 1 death from unrelated causes, 1 death from PD, 2 subjects withdrew, 2 were withdrawn at physician’s discretion, 1 withdrawal from toxicity. Of the 3 patients who completed study, 2 had SD and 1 had PR. 1 SD patient is alive 2 years later with transfusion support and another patient lasted 6 months before requiring transfusion. PR patient succumbed to acute myelogenous leukemia 12 months post-treatment. Conclusions: ATO with ARA-C appears to be an active regimen for patients with high risk MDS. Additional studies are warranted to confirm these findings.

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Variations in circulating catecholamines fail to alter human platelet alpha-2-adrenergic receptor number or affinity for [3H]yohimbine or [3H]dihydroergocryptine

A series of studies were performed to determine the relationship between physiologic levels of circulating plasma norepinephrine and epinephrine and human platelet alpha-2 binding site number and the affinity (KD) of these sites for antagonist radioligands. In one study, alpha-2-adrenergic binding site number and affinity were compared using both [3H]yohimbine and [3H]dihydroergocryptine as radioligands. There was good absolute and relative comparison for binding site number, but only a relative relationship for KD. In 46 normal subjects, there was no significant relationship between site number or KD and age, plasma epinephrine, or plasma norepinephrine concentration. Even after plasma epinephrine was raised nearly 20-fold by means of an intravenous infusion for 4 h in seven normal subjects, neither sites (608 +/- 68 vs. 567 +/- 120 sites/platelet) nor KD (2.01 +/- 0.94 vs. 2.14 +/- 1.15 nM) were significantly changed. Similarly, neither sites (445 +/- 55 vs. 421 +/- 53 sites/platelet) nor KD (1.44 +/- 0.29 vs. 2.10 +/- 0.75 nM) were significantly changed in six normal subjects when plasma norepinephrine levels increased during oral administration of prazosin for 1 wk. Thus, in a cross-sectional analysis and after a change in plasma catecholamine concentrations, there was no relationship in normal subjects between platelet alpha-2 binding site number or affinity of these sites for antagonist radioligands and the circulating catecholamine levels to which the platelets were exposed. In a group (n = 7) of patients who lack epinephrine-induced platelet aggregation due to abnormal thrombopoiesis, binding site number was decreased (304 +/- 36 vs. 572 +/- 29 sites/platelet, P less than 0.001) and KD tended to be greater (8.69 +/- 2.44 vs. 5.40 +/- 0.31 nM, P = NS) than in normal subjects (n = 46), despite having similar plasma catecholamine levels. There was no difference in binding site number (491 +/- 116 sites/platelet) and KD (5.61 +/- 0.84 nM) in patients (n = 5) with autonomic insufficiency and low levels of upright plasma norepinephrine when compared with the normal subjects. Two patients were examined before and after the removal of a pheochromocytoma. Their binding site number and KD were normal before the operation and essentially unchanged after the tumor removal and fall of plasma catecholamines. Thus, this study demonstrates that within the physiologic and pathophysiologic range of plasma catecholamines (in men), there is no relationship between the circulating catecholamine concentration and either platelet alpha-2 adrenergic binding site number or the affinity of these sites for antagonist radioligands.