Targeting of small-cell lung cancer using the anti-GD2 ganglioside monoclonal antibody 3F8: a pilot trial.

The present study evaluated the ability of the anti-GD2 ganglioside monoclonal antibody 3F8 to target tumor sites in patients with small-cell lung cancer (SCLC). Of 12 patients entered into the trial, ten received intravenous 3F8 labeled with 2 or 10 mCi iodine-131. The first five patients had recurrent or progressive disease after chemotherapy. Subsequent patients were studied before starting chemotherapy. Radionuclide scans were performed on days 1, 2, and 3 post-infusion and once between day 5 and day 7. Four patients underwent single-photon emission tomography (SPET) imaging. Radionuclide scans demonstrated localization to all known sites of disease, other than small brain metastases in one patient. SPET/CT scan fusion images confirmed precise localization. No significant toxicity was observed. Mean serum half-life was 64.2 h. Analysis of specimens from one patient who died of unrelated causes 6 days post-infusion confirmed the scan results. The present study demonstrates that 3F8 targets SCLC sites in patients. Further studies of anti-GD2 antibodies with higher doses of antibody and radionuclide are warranted to evaluate their role in SCLC.

Analysis of the antibody response to immunization with purified O-acetyl GD3 gangliosides in patients with malignant melanoma.

Gangliosides expressed in malignant melanoma are potential targets for immunotherapy. Immunization of melanoma patients with vaccines containing purified GM2 ganglioside has resulted in induction of GM2 antibodies, and high titers of GM2 antibodies have correlated with increased survival. Melanoma ganglioside 9-O-acetyl GD3 is another candidate for ganglioside vaccine construction because of its limited expression in normal human tissues. As purification of 9-O-acetyl GD3 from human melanoma (9-O-acetylated on the terminal sialic acid) is not practical for broad application, we investigated the antibody response of melanoma patients to O-acetyl GD3 from several additional sources: hamster melanoma (7-O-acetyl GD3), bovine buttermilk (mixture of 7-O-acetyl GD3, 9-O-acetyl GD3 and 7,9-di-O-acetyl GD3) and chemically modified GD3 from bovine brain (9-O-acetylated on the subterminal sialic acid). Only immunization with the buttermilk-derived O-acetyl GD3 preparation resulted in consistent production of IgM antibodies. However, the induced antibodies reacted with the immunogen and with 7-O-acetyl GD3 derived from hamster melanoma but not with 9-O-acetyl GD3 or human melanoma cells expressing 9-O-acetyl GD3 on their cell surface. In contrast, all O-acetyl GD3 derivatives used for immunization were recognized by murine MAbs that reacted with 9-O-acetyl GD3, and immunization of mice with buttermilk-derived O-acetyl GD3 resulted in the production of antibodies that reacted with human melanoma cells expressing 9-O-acetyl GD3. Apparently, the human and murine immune systems preferentially recognize different epitopes on these molecules.

GM2-KLH conjugate vaccine: increased immunogenicity in melanoma patients after administration with immunological adjuvant QS-21.

The cell surface gangliosides GM2, GD2, and GD3 are often overexpressed in malignant melanoma. We have shown previously that immunization of melanoma patients with GM2 and Bacillus Calmette-Guérin induced an IgM antibody response in most patients and that patients with high titer GM2 antibodies showed increased survival. As is commonly seen with carbohydrate antigens (which are T independent), the IgM response was short lived, and an IgG response was rarely observed. To increase immunogenicity, we conjugated GM2 covalently with keyhole limpet hemocyanin (KLH). GM2-KLH vaccine was given to melanoma patients alone or with one of the three adjuvants: Bacillus Calmette-Guérin, DETOX, or QS-21. The most effective vaccine was GM2-KLH with QS-21. It induced a much higher titer, a longer-lasting IgM GM2 antibody response, and a consistent IgG response (isotype IgG1 and IgG3). It also induced the highest titer anti-KLH response. The results suggest that the conjugate GM2-KLH plus QS-21 vaccine elicited significant T-cell help. Because there was no serious toxicity, this vaccine approach is attractive for augmenting the immunogenicity of other gangliosides, such as GD2 and GD3, and to determine the effects of ganglioside antibodies on the course of melanoma. In addition, the finding that QS-21 significantly increased the immunogenicity of GM2-KLH suggests that it may do the same for other conjugate vaccines, many of which are currently used without adjuvant.

Intravesical bacillus Calmette-Guérin therapy prevents tumor progression and death from superficial bladder cancer: ten-year follow-up of a prospective randomized trial.

PURPOSE: Superficial bladder tumors (stage Ta, T1, and Tis) may progress to invade the bladder muscle and cause death from metastatic cancer. Transurethral tumor resection (TURB) is the standard therapy for such tumors, but surgery alone may not prevent tumor progression. Intravesical therapy is widely used as an adjunct to TURB. Bacillus Calmette-Guérin (BCG) is the most active intravesical agent, but whether BCG prevents tumor progression and death from bladder cancer is unknown. PATIENTS AND METHODS: Between 1978 and 1981, 86 high-risk patients with superficial bladder cancer were randomly assigned to receive either TURB (n = 43) or TURB plus BCG (n = 43). Adverse tumor features for progression were equally distributed between the two groups. BCG was administered weekly for 6 weeks. Patients were evaluated every 3 to 6 months thereafter for progression to muscle invasion or metastasis. Control (TURB) patients with recurrent superficial tumors were eligible for crossover to the BCG arm. All patients have been monitored until event or for a minimum of 10 years (range, 10 to 14). RESULTS: The 10-year progression-free rate was 61.9% (95% confidence interval [CI], 47.2% to 76.7%) for patients treated with BCG and 37% (95% CI, 22.9% to 53.1%) for control patients. The median progression-free interval was not reached for the BCG group and was 46 months for the control group (P = .0063). Of 18 control patients crossed over to BCG (median, 29 months), 15 did not show tumor progression. TURB plus BCG resulted in a 10-year disease-specific survival rate of 75%, compared with 55% with TURB alone (P = .03). CONCLUSION: This study shows that intravesical therapy with BCG delays tumor progression and death from tumor in patients who present with superficial bladder cancer.

Serological response patterns of melanoma patients immunized with a GM2 ganglioside conjugate vaccine.

Gangliosides, such as GM2, GD2, GD3, and 9-O-acetyl GD3, are receiving attention as targets for antibody-based and vaccine-based therapies of melanoma. GM2 appears to be a particularly immunogenic ganglioside in humans, as indicated by the presence of naturally occurring IgM anti-GM2 antibodies in approximately 5% of humans and the fact that immunization with irradiated GM2-expressing melanoma cells or purified GM2 adherent to bacillus Calmette-Guérin elicits GM2 antibodies of low to moderate titers in a high proportion of vaccinated patients. To develop vaccines that consistently induce high titers of IgM as well as IgG anti-GM2 antibodies, vaccines containing GM2 conjugated to keyhole limpet hemocyanin as the carrier protein and QS-21 as the adjuvant have been constructed. The serological response of vaccinated patients was monitored by ELISA using purified GM2 ganglioside for IgM and IgG anti-GM2 antibodies and for GM2 cell surface-reactive antibodies by immune adherence assays and cytotoxic tests (IgM antibodies) and mixed hemadsorption assays (IgG antibodies). The majority of vaccinated patients developed IgM and IgG antibodies detectable by ELISA. In most cases, the results of IgM ELISA correlated with assays for cell surface-reactive IgM antibodies. This was not true for IgG anti-GM2 antibodies, where strong discrepancies were seen between high titers in ELISA and little or no reactivity in mixed hemadsorption tests for cell surface-reactive antibodies. These IgG antibodies (and the less frequent IgM antibodies that show similar discrepancies) may be directed against GM2 determinants that are buried, hidden, or not present on GM2-expressing target cells. With regard to a major objective of ganglioside vaccines--i.e., generation of cytotoxic antibodies--the GM2-keyhole limpet hemocyanin/QS-21 vaccine is clearly superior to the previously tested GM2/bacillus Calmette-Guérin vaccine. However, variability in patient response and lack of persistence of high-titered IgM cytotoxic antibodies in many patients are problems that remain to be solved.

Phase I/II study of iodine 131-labeled monoclonal antibody A33 in patients with advanced colon cancer.

PURPOSE: A phase I/II study was designed to determine the maximum-tolerated dose (MTD) of iodine 131-labeled monoclonal antibody (mAb) A33 (131I-mAb A33) administered intravenously, its limiting organ toxicity, and its radioisotope retention in tumors, and to develop preliminary evidence of antitumor activity. PATIENTS AND METHODS: Patients (N = 23) with colorectal cancer who had failed to respond to conventional chemotherapy but had not received prior radiotherapy were treated with escalating doses of 131I-mAb A33. Three or more patients were entered at each dose level, starting at 30 mCi/m2, with increments of 15 mCi/m2 to a maximal dose of 90 mCi/m2. Radiolabeling was performed to maintain a specific activity of 30 mCi/m2/4 mg mAb A33 (projected maximum, 15 mCi/mg). Patients were under strict isolation precautions until whole-body radiation levels decreased to less than 5 mrem/h at 1 m. Serial radioimmunoscintigrams were performed in some cases for up to 3 weeks after 131I-mAb A33 administration. RESULTS: All 20 patients with radiologic evidence of disease showed localization of radioisotope to sites of disease. Two patients with elevated carcinoembryonic antigen (CEA) levels and negative radiologic tests did not have positive antibody scans. One patient with a small-bowel cancer also had a negative antibody scan. The major toxicity was hematologic and was more pronounced in patients with compromised bone marrow due to prior chemotherapy. Of five patients who received 78 to 84 mCi/m2 131I-mAb A33, one had grade 3 and one grade 4 toxicity; of six patients treated with 86 to 94 mCi/m2 131I-mAb A33, two had grade 4 and one grade 1 toxicity. The MTD was determined to be 75 mCi/m2 in these heavily pretreated patients. Although the isotope showed variable uptake in the normal bowel, gastrointestinal symptoms were mild (n = 8) or absent. No major responses were observed; however, three patients had evidence of mixed responses, and CEA levels decreased in two patients without clinical or radiologic measurable disease. Immunoreactivity of radiolabeled mAb A33 decreased at the highest dose levels in preparations in which specific activity exceeded 18 mCi/mg. CONCLUSION: The A33 antigen appears to be a promising target for radioimmunotherapy of colon cancer. The modest antitumor activity of 131I-mAb A33 in heavily pretreated patients is encouraging because of its lack of toxicity in the bowel, the only antigen-positive normal tissue.

GD3 vaccines for melanoma: superior immunogenicity of keyhole limpet hemocyanin conjugate vaccines.

Cell surface gangliosides show altered patterns of expression as a consequence of malignant transformation and have therefore been of interest as potential targets for immunotherapy, including vaccine construction. One obstacle has been that some of the gangliosides that are overexpressed in human cancers are poorly immunogenic in humans. A case in point is GD3, a prominent ganglioside of human malignant melanoma. Using an approach that has been effective in the construction of bacterial carbohydrate vaccines, we have succeeded in increasing the immunogenicity of GD3 in the mouse by conjugating the ganglioside with immunogenic carriers. Several conjugation methods were used. The optimal procedure involved ozone cleavage of the double bond of GD3 in the ceramide backbone, introducing an aldehyde group, and coupling to aminolysyl groups of proteins by reductive amination. Conjugates were constructed with a synthetic multiple antigenic peptide expressing repeats of a malarial T-cell epitope, outer membrane proteins of Neisseria meningitidis, cationized bovine serum albumin, keyhole limpet hemocyanin, and polylysine. Mice immunized with these conjugates showed a stronger antibody response to GD3 than mice immunized with unconjugated GD3. The strongest response was observed in mice immunized with the keyhole limpet hemocyanin conjugate of the GD3 aldehyde derivative and the adjuvant QS-21. These mice showed not only a long-lasting high-titer IgM response but also a consistent high-titer IgG response (predominantly IgG1), indicating recruitment of T-cell help, although the titers of IgM and IgG antibodies following booster immunizations were not as high as they are in the response to classical T-cell-dependent antigens. This method is applicable to other gangliosides, and it may be useful in the construction of immunogenic ganglioside vaccines for the immunotherapy of human cancers expressing gangliosides on their cell surface.

Treatment with high dose mouse monoclonal (anti-GD3) antibody R24 in patients with metastatic melanoma.

R24 is a mouse IgG3 monoclonal antibody that reacts with the ganglioside GD3 expressed by melanoma cells and other cells of neuroectodermal origin (e.g. adrenal medulla). Antitumour activity of R24 was demonstrated in initial phase I and pilot trials, but treatment was limited by urticaria at cumulative doses of 400 mg/m2. A trial exploring intensification of the dose of R24 was conducted in eight patients. Planned doses of R24 antibody were 800 and 1200 mg/m2 over 6-8 days by continuous i.v. infusion. All patients received concomitant therapy with hydroxyzine hydrochloride and cimetidine to minimize urticaria. One patient developed anaphylaxis, after which no further therapy was given. All patients developed peripheral blood lymphopenia and marked decreases in serum complement values during treatment, suggesting depletion of two possible effector mechanisms of the antitumour effects of R24. A vascular leak syndrome, manifested by weight gain, oedema and hypotension, was evident in seven patients during the initial 24-36 h of treatment. Serum sickness syndrome was observed in six of seven evaluable patients between days 5 and 8, coincident with the onset of the human anti-globulin response to R24. One patient given 1200 mg/m2 had a minor response (38% reduction in pelvic nodes) lasting 12 months. There was no detectable increase (by immunohistochemical staining) in deposition of R24 within tumour sites at doses used in this trial compared to that observed at doses of 240 and 400 mg/m2. The maximum tolerated dose was 800 mg/m2. Dose-limiting toxicity was manifest as reversible hypertension with end-organ symptoms (chest pain or visual field defects) in patients treated with a dose of 1200 mg/m2.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunization of colorectal cancer patients with modified ovine submaxillary gland mucin and adjuvants induces IgM and IgG antibodies to sialylated Tn.

Tn and sialylated Tn (sTn) are blood group-related epitopes expressed on mucins of colon carcinoma and other epithelial tumors and are, therefore, potential targets for immunological control. We have immunized 20 colorectal cancer patients at high risk for recurrence with a vaccine consisting of partially desialylated ovine submaxillary gland mucin (modified OSM) which contains both Tn and sTn determinants. Six patients were treated with modified OSM alone (group 1), eight patients were treated with modified OSM and the immunological adjuvant DETOX (group 2), and six patients were treated with modified OSM and Bacillus Calmette-Guérin (group 3). Pre- and postvaccination sera were tested by enzyme-linked immunosorbent assay and dot blot immune stains for antibodies reactive with modified OSM. Antibody titers increased in 4 of 8 patients immunized with modified OSM and DETOX, in 5 of 6 patients immunized with modified OSM and B. Calmette-Guérin, and in 0 of 6 patients receiving modified OSM without adjuvant. The specificity of induced IgM and IgG antibodies was confirmed by demonstrating reactivity with OSM, bovine submaxillary mucin, and synthetic glycoconjugates sTn-human serum albumin (HSA) and Tn-HSA in enzyme-linked immunosorbent assay and immune stains. Median IgM pre-postvaccination reciprocal titers were 20/80 for Tn-HSA and 10/320 for sTn-HSA. Low level IgG antibody titers against sTn-HSA were detected after vaccination in 7 patients. Toxicity was limited to inflammatory skin reactions at the site of vaccination resulting from the adjuvants. No inflammatory infiltrates were seen in the skin when the modified OSM vaccine was administered in the absence of an immunological adjuvant. These results demonstrate that sTn and Tn can be recognized by the human immune system and that vaccines containing these structures can be administered safely with immunological adjuvants. Attempts to augment the immunogenicity of these carbohydrate antigens by covalent attachment to immunogenic carrier proteins and the use of more potent immunological adjuvants are now being pursued.

Bacillus Calmette-Guerin therapy for superficial bladder cancer: a 10-year followup.

We report the outcome of 61 patients with superficial bladder tumors who received bacillus Calmette-Guerin (BCG) therapy and were followed for at least 10 years (range 10 to 13 years). A total of 19 patients (31%) remains free of tumor and progression, 17 (28%) had interval superficial recurrences but no progression and 25 (41%) had progression, first identified as muscle invasion in 12, prostatic involvement in 8 or metastasis in 5. Most tumors recurred or progressed within the first 5 years. Of the 61 patients 33 (54%) are disease-free and with an intact bladder, 13 (21%) are alive after cystectomy, 2 (3%) died of other causes, 1 (2%) is alive with metastasis and 12 (20%) died of metastatic urothelial cancer (11 from the bladder or prostate and 1 from an upper tract tumor).

Increased yields of IgG2a- and IgG3-secreting hybridomas after fusion of B cells from mice with autoimmune diseases.

Hybridoma technology has made the production of antigen-specific monoclonal antibodies feasible and almost routine, but the production of certain biologically desirable antibody isotypes has remained difficult. Three strains of autoimmune mice (MRL/l, NZB, and BXSB) were compared to a normal strain (BALB/c), in fusions with a BALB/c myeloma (NS-1) in order to study the rescue of relevant isotypes with the desired antigenic specificities. Mice from these four strains were immunized with colon carcinoma cells, and the hybridoma supernatants from thirty fusions were analyzed for (1) reactivity with cell surface determinants on the immunizing cell line; and (2) Ig class and subclass isotypes. We found that compared to BALB/c mice, MRL/l mice produced greater numbers, and NZB and BXSB mice comparable numbers, of cell surface-reactive hybridoma clones per fusion. MRL/l mice produced the largest number and highest percentage of cell-surface reactive IgG2a (22.4%) and IgG3 (10.6%) producing clones, followed by NZB mice which produced predominantly IgG2a clones (12.3%). BXSB mice, which have latent autoimmune disease, showed no significant difference from normal BALB/c controls (IgG2a:0.7% and IgG3:1.9% vs. IgG2a:4.8% and IgG3:4.8%). The increase in IgG2a and IgG3 clones derived from MRL/l mice was age-dependent, correlating with the age at which abnormal proliferation of T cell and splenic enlargement occurs (2-4 months). We conclude that MRL/l mice are useful for generating monoclonal antibodies of the IgG2a or IgG3 isotype, provided fusions are performed at the time of maximal lymphoproliferation.

Cytokines in clinical cancer therapy.

Cytokines have been of much interest in clinical cancer therapy research over the past decade. One important advance during the past year has been the clear demonstration, in large prospective randomized studies, that granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor reduce the neutropenia-related morbidity of cancer therapy.

A phase II trial of high-dose cisplatin and dacarbazine. Lack of efficacy of high-dose, cisplatin-based therapy for metastatic melanoma.

Cisplatin and dacarbazine are used widely in the treatment of metastatic melanoma. To evaluate high-dose cisplatin and dacarbazine, 32 patients with metastatic melanoma were treated with cisplatin 50 mg/m2 and dacarbazine 350 mg/m2 daily for three days repeated at 28-day intervals. Their median age was 43.5 years (range, 25 to 73 years), and their median Karnofsky performance status was 80% (range, 70% to 100%). Measurable and evaluable disease sites (number of patients) included lymph nodes (22), lung (17), soft tissue (16), liver (13), bone (seven), spleen (four), adrenal gland (three), skin (three), and other sites (five). Patients received a median of two cycles of therapy (range, one to eight cycles). Thirty patients were evaluable for response. No complete responses were observed. Five patients had a partial response (17%; 95% confidence interval, 3% to 30%) for 16+, 12+, 7, 6.5, and 3 months. Responding sites of disease included lymph nodes (five of 22), lung (three of 17), and soft tissue (two of 16). Hematologic toxicity (Grade greater than or equal to 3) included neutropenia (16 of 32 patients, 30 of 90 cycles), thrombocytopenia (eight of 32 patients, 12 of 90 cycles), and anemia (five patients). Nine episodes of neutropenia and fever were seen in four patients; two had bacteremia. Nonhematologic toxicity (Grade greater than or equal to 3) included hypotension (two patients), nausea and vomiting (four), neuropathy (two), ototoxicity (four), and hypomagnesemia (nine). The low objective response rate and severe toxicity of this regimen preclude its standard use in patients with metastatic melanoma. A review of cisplatin-based therapy in metastatic melanoma suggests that there is no dose-response relationship. The use of high-dose cisplatin (greater than 100 mg/m2) in the treatment of metastatic melanoma is not recommended.

Antibody response to immunization with ganglioside GD3 and GD3 congeners (lactones, amide and gangliosidol) in patients with malignant melanoma.

GD3 is the ganglioside most abundantly expressed on the cell surface of human melanoma, and treatment with a murine MAb recognizing GD3 has induced major responses in a small proportion of patients with melanoma. We have therefore attempted to induce production of GD3 antibodies in melanoma patients by active immunization. We found, however, that vaccination with GD3-expressing melanoma cells or purified GD3 does not result in antibody production. We describe here attempts to overcome the poor immunogenicity of GD3 in patients with melanoma by chemical modification. GD3 lactones, GD3 amide and GD3 gangliosidol were synthesized, and the humoral immune response to these derivatives was analyzed. Immunization of melanoma patients with these GD3 derivatives resulted in production of IgM antibodies and, in the case of GD3 amide, also of IgG antibodies. The antibodies to the GD3 derivatives did not cross-react with GD3. This is in contrast to observations in the mouse, where GD3 lactone I induced antibodies that showed cross-reactivity with GD3. Thus, the human immune response was specifically directed toward the modified epitope, rather than to the native structure.

Blood group and blood-group-related antigens in normal pancreas and pancreas cancer: enhanced expression of precursor type 1, Tn and sialyl-Tn in pancreas cancer.

Expression of blood-group antigens A, B, Le(a), sialyl-Le(a) (sLe(a)), Le(b), Le(x), Le(y), precursor type I, Tn and sialyl-Tn (sTn) was examined in non-neoplastic pancreas (n = 37) and pancreas cancer (n = 21) using mouse monoclonal antibodies (MAbs). Immunohistochemical assays were performed on sections of paraffin-embedded tissues using the avidin-biotin complex method. In normal pancreas, antibodies detecting Le(a), sLe(a) and Tn reacted with ductal epithelium, and antibodies detecting A and B reacted with acini and ducts, independently of secretor status. Le(x) was weakly expressed in ducts and acini, and sTn could not be detected in normal pancreas. Expression of Le(b), Le(y) and precursor type I was regulated by secretor status: Le(b) and Le(y) were expressed in ducts of secretor and Le(a-b-) individuals, but not in ducts of non-secretors; precursor type I was weakly expressed in acini and ducts of non-secretors and Le(a-b-) individuals, and was absent in acini and ducts of secretors. The following alterations in the expression of blood-group antigens were observed in pancreas cancer: (1) enhanced expression of Le(x), Tn and sTn; (2) enhanced expression of precursor type I independently of secretor status; (3) loss of regulation of Le(b) by the secretor gene; (4) decreased expression of Le(y). The weak expression of precursor type I. Tn and sTn in non-neoplastic pancreas, and their stronger expression in pancreas cancer, suggests that up-regulation of their expression is associated with malignant transformation of pancreatic duct cells.

Antibody response to immunization with purified GD3 ganglioside and GD3 derivatives (lactones, amide and gangliosidol) in the mouse.

GD3 is the ganglioside most abundantly expressed on the cell surface of human melanoma, and treatment with a monoclonal antibody recognizing GD3 has induced major responses in a small proportion of patients. However, we have been unable to induce production of GD3 antibodies in melanoma patients by active immunization with GD3-expressing melanoma cells or purified GD3. In this report we describe attempts to increase the immunogenicity of GD3 in the mouse by chemical modification. GD3 lactone I and II, GD3 amide and GD3 gangliosidol were synthesized, and the humoral immune response to these derivatives was compared with the response to unmodified GD3. The GD3 derivatives were more immunogenic than GD3. At a low dose all congeners induced an IgM response, with antibody titers higher than those elicited by low-dose GD3. The gangliosidol and amide derivatives also induced an IgG response. IgM antibodies induced by immunization with GD3 lactone I cross-reacted with purified GD3 and GD3-expressing melanoma cells. Titers of GD3 cross-reactive antibodies were slightly higher than after immunization with GD3 itself at the same low dose. IgM and IgG antibodies induced by the other congeners did not cross-react with GD3.

A phase I toxicity, pharmacology, and dosimetry trial of monoclonal antibody OKB7 in patients with non-Hodgkin's lymphoma: effects of tumor burden and antigen expression.

Eighteen patients with relapsed non-Hodgkin's lymphoma (NHL) were infused with escalating doses of monoclonal antibody (mAb) OKB7, trace-labeled with iodine-131 (131I), in order to study toxicity, pharmacology, antibody localization, and dosimetry of radioiodine. OKB7 is a noncytotoxic mouse immunoglobulin G2b (IgG2b) mAb reactive with B cells and most B-cell NHL. Three patients each were treated at six dose levels ranging from 0.1 mg to 40 mg. All patients had radionuclide imaging and counting daily, had serial blood sampling to study pharmacokinetics, human antimouse antibody (HAMA), and circulating antigen, and had a biopsy of accessible lymphoma to determine delivery of isotope to tumors and assess the effect of tumor antigen expression on mAb delivery. Bone marrow biopsies were also done in the majority of patients. There was no toxicity. Serum clearance showed a median early phase half-life of 1.9 hours and a later phase half-life of 21.7 hours. Median total body clearance half-life was 22 hours. Pharmacokinetics were not dose-related. HAMA was detected in five patients. Circulating blocking antigen was detected in the serum of four patients, but at levels that were of pharmacologic consequence only in one. Biopsied tumor tissue from five patients did not express OKB7 antigen. No significant uptake of antibody was seen in these tumor sites. Mean total uptake of isotope into lymphoma measured in biopsies correlated linearly over the 400-fold increase in injected mAb dose. However, the percent of injected dose found per gram of tumor was unrelated to dose, but correlated inversely with tumor burden. In two patients with minimal tumor burden, 1.0 mg and 5.0 mg doses of OKB7 resulted in tumor to body radioisotope dose ratios of 22 and 7, which would theoretically permit tolerable delivery of 4,400 and 1,400 rads to these tumors, respectively, if OKB7 were conjugated with higher doses of 131I.

Human monoclonal antibody with dual GM2/GD2 specificity derived from an immunized melanoma patient.

GM2 ganglioside is a common cell surface constituent of human melanoma and other tumors of neuroectodermal origin, and vaccination with GM2 ganglioside results in high levels of anti-GM2 antibodies in patients with melanoma. Lymphocytes from a GM2-vaccinated patient (VS) were transformed by Epstein-Barr virus and tested for production of antibodies with reactivity for GM2-positive tumor cells. A high percentage of antibody-producing B cells was detected, but antibody reactivity was generally lost during culture expansion. Two cultures, however, remained stable for antibody productivity and one was used to develop a stable hybrid line with mouse myeloma. The monoclonal antibody (designated 3-207) derived from patient VS has dual specificity for GM2 and GD2, despite the fact that only GM2 antibody could be detected in the patient's serum. Monoclonal antibody 3-207 shows high-titered reactivity with a range of melanoma, astrocytoma, neuroblastoma, and leukemia cell lines, cells with prominent cell surface expression of GM2 and GD2. The cell surface reactivity of monoclonal antibody 3-207 was not abolished by treatment of target cells with neuraminidase, as the enzyme converted GD2 to GM2, which was still detected by monoclonal antibody 3-207.

The response of patients with superficial bladder cancer to a second course of intravesical bacillus Calmette-Guerin.

Of 347 patients who received an initial 6-week course of intravesical bacillus Calmette-Guerin for superficial transitional cell carcinoma of the bladder 28 (8%) were treated with another course. Subsequent progression of disease (muscle infiltration, metastasis or local progression) occurred in 13 patients (46%). Of the 15 patients (54%) without progression 10 (36%) had a complete response and 5 (33%) had new tumors, and they were rendered free of disease after transurethral resection. The median duration of response to course 1 of bacillus Calmette-Guerin was shorter for patients with disease progression after course 2 than for those with no progression (15 and 27 months, respectively, p equals 0.05). The median followup after course 2 was 31.2 months (range 15.6 to 56.4 months). The median interval between courses 1 and 2 of intravesical bacillus Calmette-Guerin was 21.6 months (range 3.6 to 78.8 months). The interval from course 2 of bacillus Calmette-Guerin to progression correlated with the duration of response to course 1 of treatment (p equals 0.01). It appears that a subsequent treatment with bacillus Calmette-Guerin is most likely to be useful in patients who have a sustained response to the initial treatment.