The a-emitter 211 At labeled to a monoclonal antibody has proven safe and effective in treating microscopic ovarian cancer in the abdominal cavity of mice. Women in complete clinical remission after second-line chemotherapy for recurrent ovarian carcinoma were enrolled in a phase I study. The aim was to determine the pharmacokinetics for assessing absorbed dose to normal tissues and investigating toxicity. Methods: Nine patients underwent laparoscopy 2-5 d before the therapy; a peritoneal catheter was inserted, and the abdominal cavity was inspected to exclude the presence of macroscopic tumor growth or major adhesions. 211 At was labeled to MX35 F(ab9) 2 using the reagent N-succinimidyl-3-(trimethylstannyl)-benzoate. Patients were infused with 211 At-MX35 F(ab9) 2 (22.4-101 MBq/L) in dialysis solution via the peritoneal catheter. g-camera scans were acquired on 3-5 occasions after infusion, and a SPECT scan was acquired at 6 h. Samples of blood, urine, and peritoneal fluid were collected at 1-48 h. Hematology and renal and thyroid function were followed for a median of 23 mo. Results: Pharmacokinetics and dosimetric results were related to the initial activity concentration (IC) of the infused solution. The decay-corrected activity concentration decreased with time in the peritoneal fluid to 50% IC at 24 h, increased in serum to 6% IC at 45 h, and increased in the thyroid to 127% 6 63% IC at 20 h without blocking and less than 20% IC with blocking. No other organ uptakes could be detected. The cumulative urinary excretion was 40 kBq/(MBq/L) at 24 h. The estimated absorbed dose to the peritoneum was 15.6 6 1.0 mGy/(MBq/L), to red bone marrow it was 0.14 6 0.04 mGy/(MBq/L), to the urinary bladder wall it was 0.77 6 0.19 mGy/(MBq/L), to the unblocked thyroid it was 24.7 6 11.1 mGy/(MBq/L), and to the blocked thyroid it was 1.4 6 1.6 mGy/(MBq/L) (mean 6 SD). No adverse effects were observed either subjectively or in laboratory parameters. Conclusion: This study indicates that by intraperitoneal administration of 211 At-MX35 F(ab9) 2 it is possible to achieve therapeutic absorbed doses in microscopic tumor clusters without significant toxicity. The lifetime risk of ovarian cancer is 1%22% in European and U.S. women. Despite seemingly successful cytoreductive surgery, followed by systemic chemotherapy, most patients will relapse and succumb. The relapse is most frequently localized in the abdominal cavity. New systemic chemotherapy regimens have not improved the outcome over the past decade, which prompted experimental intraperitoneal treatments, including radioimmunotherapy.Radioimmunotherapy with b-emitters has displayed promising results, although an international randomized phase III study of 90 Y-HMFG1 showed no improvement in survival or time to relapse (1). This disappointing result could be partly explained by the choice of radionuclide. The long range of this b-emitter results in poor irradiation of small tumor clusters, likely insufficient to eradicate peritoneal micrometastases. Furthermore, the relativel...

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Purpose: P-glycoprotein, encoded by the mdr-1 gene, confers multidrug resistance to a variety of antineoplastic agents, e.g., paclitaxel. Recently, different polymorphisms in the mdr-1 gene have been identified and their consequences for the function of P-glycoprotein, as well as for the treatment response to P-glycoprotein substrates, are being clarified. We analyzed the allelic frequencies at polymorphic sites G2677T/A and C3435T in ovarian cancer patients with good or poor response to treatment with paclitaxel in combination with carboplatin in order to evaluate their predictive values. Experimental Design: Fifty-three patients were included in the study; 28 of them had been relapse-free for at least 1 year and 25 had progressive disease or relapsed within 12 months. A reference material consisting of 200 individuals was also analyzed. The genotypes of each single nucleotide polymorphism (SNP) were determined using Pyrosequencing. Results:The G2677T/A SNP was found to significantly correlate with treatment outcome. The probability of responding to paclitaxel treatment was higher in homozygously mutated patients (T/T or T/A; Fisher's exact test; P < 0.05). The frequency of the T or A alleles was also higher in the group of patients who had a good response (P < 0.05). There was also a dose-dependent influence of the number of mutated alleles on the response to paclitaxel treatment (m 2 test for linear-by-linear association; P = 0.03). However, the C3435T SNP was not found to correlate to treatment outcome. Conclusions: The mdr-1 polymorphism G2677T/A in exon 21 correlates with the paclitaxel response in ovarian cancer and may be important for the function of P-glycoprotein and resistance to paclitaxel and provide useful information for individualized therapy.

The CD19-CD21-CD81 complex regulates signal transduction events critical for B lymphocyte development and humoral immunity. CD81, a molecule with 4 transmembrane domains, member of the tetraspan superfamily, is engaged, together with other tetraspans such as CD9, CD53, CD63, and CD82, in multimolecular complexes containing ␤ 1 integrins and major histocompatibility complex antigens. Here we demonstrate that two other tetraspans, CD82 and the early B cell marker CD9, are coimmunoprecipitated with CD19 from Brij97 lysates of B cell lines. Moreover, CD9 was coprecipitated from lysates of purified CD10؉ early B cells. These associations were confirmed by the cocapping of CD19 with CD9 or CD82. The CD9/CD19 association was disrupted in the presence of digitonin, contrary to the CD81/CD19 association, indicating that CD9 and CD81 interact with CD19 in different ways. The CD9/CD81 association is also disrupted in the presence of digitonin, suggesting that CD9 associates with CD19 only through CD81. To characterize the regions involved in the CD81/CD19 association, two reciprocal CD9/CD81 chimeric molecules were tested for the association with CD19, but none of them could be coprecipitated with CD19 in digitonin, indicating that the domain of CD81 responsible for its association with CD19 is complex. Finally, engagement of CD9 could induce the tyrosine phosphorylation of different proteins, including CD19 itself, suggesting that the CD9/CD19 association is functionally relevant. Thus, a physical and functional link is formed between the CD19-CD21-CD81 complex and the integrin-tetraspan complexes, which is dynamically modulated in the process of B cell differentiation.CD19, the earliest cell surface molecule related to B lineage differentiation, has been shown to provide a costimulatory signal for activation through the B cell receptor. Co-ligation of CD19 with the B cell receptor decreases the threshold for antigen-dependent stimulation by at least 2 orders of magnitude (1). The important role of CD19 in B lymphoid lineage is further supported by transgenic experiments. CD19-deficient mice have an important reduction in serum immunoglobulins levels and an impaired response to T cell-dependent antigens (2, 3). Because the ability of CD19-deficient B cells to undergo differentiation, secrete antibodies, and switch isotype in vitro is not overtly impaired, it has been suggested that the hypogammaglobulinemia could result from defects at earlier stages of B cell activation (3, 4). Conversely, mice overexpressing CD19 have a dramatic alteration in B cell development in bone marrow, whereas mature B cells demonstrate higher in vitro proliferative response (2-4). From these data, CD19 has been suggested to be a general regulator of signaling thresholds in B cells (3). One way of CD19 cross-linking to the B cell receptor is through its association with CR2 (complement receptor 2/CD21) after preimmune recognition of an immunogen by the complement system (5). The presence of at least 2 other molecules in the CD19-CD21 complex (6 ...