A Phase Ⅰ clinical trials in 38 patients with solid tumors (
UGT1A1 *28 allele genotype of
wt/wt and
wt/*28), NK012 was intravenously infused at doses ranging from 9 mg/m
2 to 37 mg/m
2 every three or four weeks [
133]. A higher plasma AUC of NK012 and a longer
t1/2 value of polymer-unbound SN-38 at a dose of 28 mg/m
2 (287 μgh/mL & 282 h) were observed compared to that of CPT-11 at a dose of 250 mg/m
2 (27.86 μg h/mL & 13.9 h). Of 37 evaluable patients, 6 patients had partial responses, 18 patients had stable diseases and 12 patients had disease progression. The recommended Phase Ⅱ does of NK012 was 28 mg/m
2 every four weeks. In Japan, a Phase Ⅰ clinical trials of NK012 determined the recommended dose for Phase Ⅱ trial was 28 mg/m
2 and the DLT was neutropenia, in which patients were not homozygous or heterozygous for
UGT1A1 *28 or UGT1A1 *6 [
134]. Subsequently, a Phase Ⅱ trial of NK012 in unresectable, recurrent or metastatic colorectal cancer patients previously receiving Oxaliplatin-based chemotherapy was conducted [
135]. Group A (53 patients with
UGT1A1 genotype
-/-,
*6/-, or
*28/- for evaluating the primary efficacy) and group B (5 patients with
UGT1A1 genotype
*6/*28 or
*6/*6 for evaluating the reference) were administrated intravenously at the initial doses of 28 and 18 mg/m
2 every three weeks. The disease control rate, the median PFS and overall survival were 56%, 3.30 months and 15.03 months, respectively. The overall response rate was 3.8%, which was similar to the irinotecan (4.2%) reported in the Phase Ⅲ EPIC trial. Based on the incidence and severity of DLT (grade ≥ 3 neutropenia), the initial dose of NK012 (28 mg/m
2) may be excessive for patients. The optimal dose of NK012 needs further study to improve the efficacy and safety. In the USA, two Phase Ⅱ clinical trials of NK012 were underway in patients with relapse small cell lung cancer and triple negative breast cancer.