Table 2

Antitumor activity of SS1(dsFv)PE38 against human gynecologic tumors grown in organotypic culture

TumorPathological diagnosisMesothelin expressionaImmunotoxin concentrations (ng/ml)bTotal no. of cells/sectioncPercentage of apoptotic cells (TUNEL)d
O2Papillary serous ovarian cancerPositive0 (media)50919
1066655
10041078
100020692
O3Hemorrhagic ovarian follicular cystNegative0 (media)32520
1033022
10030518
100030018
BL22-10031514
O4Ovarian endometrioid carcinomaPositive0 (media)42Too few cells to quantitate apoptosis
1016
1008
10002
BL22-10038
O10Cervical squamous cell carcinomaPositive0 (media)12104
1124854
1093658
10089772
100028874
BL22-100107238
O12Papillary serous ovarian carcinomaPositive0 (media)5255
149812
1047810
10020026
100017832
BL22-1005043
O15Ovarian endometrioid carcinomaNegative0 (media)9250
196614
1089016
1008758
10008158
BL22-10097412
  • a Mesothelin expression was quantitated by immunohistochemistry using MabK1. Negative = <30% of cells express mesothelin; positive = ≥30% of cells express mesothelin.

  • b All the organotypic cultures except O2 were treated with different concentrations of SS1 (dsFv)PE38. O2 was treated with SS(dsFv)PE38. Except O2, the organotypic cultures were also treated with 100 ng/ml BL22 as a control immunotoxin because it targets CD22 antigen not present on gynecologic tumors.

  • c Five-μm sections of paraffin-enbedded organotypic cultures were stained for H&E and evaluated by a pathologist for the number of tumor cells per section.

  • d The percentage of apopotic cells in the different treatment groups was evaluated by using a TUNEL assay.