Ploidy, proliferative activity, cluster differentiation antigen expression and clinical remission in high-grade non-Hodgkin's lymphoma

The Bs20x22 anti-CD20-CD22 bispecific antibody has more lymphomacidal activity than do the parent antibodies alone

Previous studies have shown that bispecific antibodies that target both CD20 and CD22 have in vivo lymphomacidal properties. We developed a CD20-CD22 bispecific antibody (Bs20x22) from anti-CD20 and the anti-CD22 monoclonal antibodies (mAb), rituximab and HB22.7, respectively. Bs20x22 was constructed using standard methods and was shown to specifically bind CD20 and CD22. In vitro cytotoxicity assays showed that Bs20x22 was three times more effective than either parent mAb alone and twice as effective as a combination of both parent mAb used at equimolar concentrations. Bs20x22 was also nearly four times more effective at inducing apoptosis than either mAb alone. Examination of the MAPK and SAPK signaling cascades revealed that Bs20x22 induced significantly more p38 phosphorylation than either mAb alone. In an in vivo human NHL xenograft model, treatment with Bs20x22 resulted in significantly greater tumor shrinkage and improved overall survival when compared to either mAb alone or treatment with a combination of HB22.7 and rituximab. The effect of the initial tumor volume was assessed by comparing the efficacy of Bs20x22 administered before xenografts grew versus treatment of established tumors; significantly, greater efficacy was found when treatment was initiated before tumors could become established.

Dose, timing, schedule, and the choice of targeted epitope alter the efficacy of anti-CD22 immunotherapy in mice bearing human lymphoma xenografts

CD22 is a cell-surface adhesion molecule on most B-cell NHL, so it is a promising target for immunotherapy. HB22.7 is an anti-CD22 mAb that binds the two NH₂-terminal immunoglobulin domains and specifically blocks the interaction of CD22 with its ligand. CD22-blocking mAbs induce apoptosis in neoplastic B-cells and are functionally distinguishable from other anti-CD22 mAbs. This study assessed the optimal dose, route, schedule, and the targeted CD22 epitope. Raji NHL-bearing nude mice were studied. A non-blocking anti-CD22 mAb (HB22.27) was used as a control. HB22.27 had minimal effect, whereas HB22.7 improved survival and shrank tumors substantially. HB22.7 doses greater than 1.4 mg/week did not further increase efficacy (or toxicity). Tumors less than 200 mm³ had a higher response rate than did larger tumors. Various schedules of HB22.7 administration were tested; one dose every other week was more effective than more or less frequent dosing. Pharmacokinetic studies revealed that the half-life of HB22.7 was 28 days; this correlated with the time needed to re-populate cell-surface CD22 after treatment with HB22.7. Immuno-PET showed that NHL was rapidly and specifically targeted by copper-64-labeled-HB22.7. This study provided data as to an optimal dose, route, schedule and interval between doses of HB22.7.

Tumor proliferative activity and response to first-line chemotherapy in advanced breast carcinoma

The relationship between tumor proliferative activity and response to first-line chemotherapy and survival was investigated in 76 advanced breast cancer patients. Proliferative activity was determined by means of Ki-67 immunohistologic staining on primary tumors (55 patients) or at the relapse site (21 patients), and was classified as low ( < or = 25% of stained cells) or high ( > 25% of stained cells). The usual WHO response criteria were used. The median duration of follow-up was 18 months (range 3-58). Forty-seven patients (62%) had tumors with low, and 29 (38%) had tumors with a high rate of proliferative activity. The two groups were well balanced in terms of important variables such as disease-free survival, performance status, age, menopausal status, and the type of first-line chemotherapy (anthracycline-based regimens versus cyclophosphamide-methotrexate-5-fluorouracil). The estrogen receptor (ER) content, measured by means of immunohistochemical assay, was markedly different in the two groups, with 27/47 tumors with low proliferative activity (57%) and 6/29 with high-proliferative activity (21%) being ER positive ( > or = 45% of stained cells) (p = 0.003). Moreover, a significant difference in the metastatic pattern was also evident, with a higher incidence of bone and a lower incidence of soft tissue metastases in the group of patients with tumors with low proliferative activity (p = 0.004). Overall, 10/47 responses (21%: PR = 7, and CR = 3) were observed in the group with a low rate of proliferative activity, versus 14/29 (48%: PR = 9, and CR = 5) in the group with highly proliferative tumors, the difference being statistically significant (p = 0.03). When a multivariate analysis was performed, the only factor that retained independent prognostic significance was the predominant site of disease, particularly soft tissues (p = 0.003). Despite the difference in response rate, when survival analysis was performed according to the Kaplan-Meier method, no significant difference was observed in the two groups, but when the analysis was limited to responsive patients, the median survival observed in those with a low and those with a high rate of proliferation was 35 and 19 months respectively (p = 0.02). The same results were obtained when multivariate survival analysis was carried out using Cox's regression model. These data suggest that there is a link between tumor proliferative activity and response to chemotherapy in advanced breast cancer, and may indicate the need to use more intensive treatments in selected patients with highly proliferative tumors.

Quantitative study of KI-67 antibody staining in 46 T-cell malignant lymphomas using image analysis

Image analysis with a SAMBA 2005 (ALCATEL-TITN, Co) was used to quantify the Ki-67 stained area percentage in 46 T-cell malignant lymphomas (T-ML), classified according to the updated Kiel classification. This parameter demonstrated correlation with the number of Ki-67-positive cellular profiles (r = 0.88, P less than 0.001) and was more reproducible than cell counting. A significant difference was found between low and high grade T-ML (mean values +/- SEM respectively of 10.20 +/- 1.82 per cent and 25.63 +/- 3.15 per cent). The most interesting findings were that: (1) AILD-type T-ML showed an intermediate proliferation rate (15.55 +/- 2.72 per cent) between pleomorphic T-ML with medium and with large cells (respectively 12.53 +/- 3.64 per cent and 22.43 +/- 3.46 per cent), both of which belong to the high grade malignancy group. This finding is in accordance with the poor prognosis of this subtype despite its classification in the low grade malignancy group. (2) Subclassification of the pleomorphic MLs according to the predominance of small, medium or large cells, demonstrated significant differences between these three subtypes. However, the great overlap of values between pleomorphic T-ML with medium and with large cells, seems to indicate that the subclassification of these two subtypes is less valid. (3) A wide range of values with overlap was observed in AILD-type ML, in pleomorphic with medium or large cells and in lymphoblastic T-ML: for these T-ML with variable survival courses, the Ki-67 area percentage, one parameter of proliferative activity, appears worth studying as a prognostic factor.

Correlation of morphology, immunophenotype, and flow cytometry with remission induction and survival in high grade non-Hodgkin's lymphoma

A series of cases of high grade non-Hodgkin's lymphomas has been studied by morphology (110 cases), immunocytochemistry (90 cases), using reagents reactive in fixed paraffin-embedded tissue, and flow cytometry (77 cases). B-cell tumours constituted 67.0 per cent of the total, T-cell tumours 22.0 per cent, and unclassified cases 8.8 per cent. Immunocytochemistry revealed two anaplastic carcinomas. Of the 77 cases studied by flow cytometry, 67.5 per cent were diploid and 32.5 per cent DNA aneuploid. T-cell tumours were more likely to be diploid than B-cell tumours, though the difference did not reach statistical significance. T-cell tumours had a significantly lower proliferative index (%S + G2) than B-cell tumours (P = 0.002). The overall remission induction rate was 68 per cent and actuarial 3-year survival 47 per cent. There was a trend for cases with %S + G2 less than 22 per cent to survive longer (P = 0.07). This trend became statistically significant when aneuploid cases were added to the high PI group (P = 0.04). No correlation was seen between morphological or immunophenotypic groups and remission induction rates or survival.