A phase 1 trial of imatinib, bevacizumab, and metronomic cyclophosphamide in advanced colorectal cancer

Background:

This phase 1 clinical trial was conducted to determine the safety, maximum-tolerated dose (MTD), and pharmacokinetics of imatinib, bevacizumab, and metronomic cyclophosphamide in patients with advanced colorectal cancer (CRC).

Methods:

Patients with refractory stage IV CRC were treated with bevacizumab 5 mg kg⁻¹ i.v. every 2 weeks (fixed dose) plus oral cyclophosphamide q.d. and imatinib q.d. or b.i.d. in 28-day cycles with 3+3 dose escalation. Response was assessed every two cycles. Pharmacokinetics of imatinib and cyclophosphamide and circulating tumour, endothelial, and immune cell subsets were measured.

Results:

Thirty-five patients were enrolled. Maximum-tolerated doses were cyclophosphamide 50 mg q.d., imatinib 400 mg q.d., and bevacizumab 5 mg kg⁻¹ i.v. every 2 weeks. Dose-limiting toxicities (DLTs) included nausea/vomiting, neutropaenia, hyponatraemia, fistula, and haematuria. The DLT window required expansion to 42 days (1.5 cycles) to capture delayed toxicities. Imatinib exposure increased insignificantly after adding cyclophosphamide. Seven patients (20%) experienced stable disease for >6 months. Circulating tumour, endothelial, or immune cells were not associated with progression-free survival.

Conclusion:

The combination of metronomic cyclophosphamide, imatinib, and bevacizumab is safe and tolerable without significant drug interactions. A subset of patients experienced prolonged stable disease independent of dose level.

A multinational phase 2 study of nanoliposomal irinotecan sucrosofate (PEP02, MM-398) for patients with gemcitabine-refractory metastatic pancreatic cancer

BACKGROUND

PEP02, also known as MM-398, is a novel nanoliposomal irinotecan that has improved pharmacokinetics and tumour bio-distribution of the free drug. This phase 2 study evaluated PEP02 monotherapy as second-line treatment for pancreatic cancer.

METHODS

Patients who had metastatic pancreatic adenocarcinoma, Karnofsky performance status ≥70, and had progressed following gemcitabine-based therapy were eligible. Intravenous injection of PEP02 120 mg m(-2) was given every 3 weeks. Simon 2-stage design was used. The primary objective was 3-month survival rate (OS(3-month)).

RESULTS

A total of 40 patients were enrolled. The most common severe adverse events included neutropenia, abdominal pain, asthenia, and diarrhoea. Three patients (7.5%) achieved an objective response, with an additional 17 (42.5%) demonstrating stable disease for a minimum of two cycles. Ten (31.3%) of 32 patients with an elevated baseline CA19-9 had a >50% biomarker decline. The study met its primary end point with an OS(3-month) of 75%, with median progression-free survival and overall survival of 2.4 and 5.2 months, respectively.

CONCLUSION

PEP02 demonstrates moderate antitumour activity with a manageable side effect profile for metastatic, gemcitabine-refractory pancreatic cancer patients. Given the limited treatment options available to this patient population, a phase 3 trial of PEP02 (MM-398), referred to as NAPOLI-1, is currently underway.

A multinational phase II study of liposome irinotecan (PEP02) for patients with gemcitabine-refractory metastatic pancreatic cancer

237

Background: PEP02 is a novel nanoparticle liposome formulation of irinotecan (CPT-11) that has improved pharmacokinetics and tumor biodistribution of both CPT-11 and its active metabolite-SN38 compared to the free form drug. PEP02 has showed encouraging safety and efficacy in various tumor types, including significant antitumor activity in a human pancreatic cancer L3.6pl orthotopic nude mouse xenograft model. In previous phase I studies, PEP02 either alone or in combination with 5-FU/LV demonstrated prolonged disease control in 5 of 7 (71%) patients (pts) with gemcitabine (GEM)-refractory advanced pancreatic cancer (PC). This phase II study aims to evaluate PEP02 monotherapy as 2nd-line treatment in pts with metastatic, GEM-refractory PC.

Methods: Pts were eligible if they had metastatic pancreatic adenocarcinoma, KPS ≥ 70, and progressed following one line of GEM-based therapy. Treatment consisted of PEP02 120 mg/m2 administered as a 90-minute infusion every 3 weeks. A Simon's 2-stage design was used with 16 pts in the first stage and 39 pts in total; primary objective was 3-month survival rate (OS3-month).

Results: Between March 2009 and August 2010, 37 pts were enrolled at 3 centers in the U.S. and Taiwan. Characteristics for the first 31 evaluable pts: 13 M/18 F; age 39-82 yrs; 19 Asian/12 Caucasian, KPS 100/90/80/70: 5/14/4/8. Mean number of treatment cycles is 5 (range, 1-22). Disease control rate (minor response + stable disease >2 cycles) is 52%. 8 of 24 pts (33%) with elevated baseline CA19-9 have had >50% biomarker decline. To date, 23/31 pts (74%) have survived > 3 months, with 4 pts still alive after 1 year. Reasons for study discontinuation: 74% progressive disease, 9% drug-related toxicity, 17% other. Preliminary safety data is available for the first stage. Most common G3/4 adverse events included: fatigue (31%), neutropenia (25%), nausea/vomiting (19%), and diarrhea (13%).

Conclusions: This study has already met its primary endpoint (predicted OS3-month >65%). PEP02 appears to have both activity and tolerable side effects for pts with metastatic, GEM-refractory PC, and represents a promising option for this pt population with few standard options.

[Table: see text]

Pancreatic cancer treatment and research: an international expert panel discussion

BACKGROUND

Pancreatic cancer has proven extremely challenging to treat. A collaborative effort is needed to advance research and improve treatment. An expert conference was conducted to elicit perspectives regarding the current treatment and future research of pancreatic cancer.

METHODS

The conference comprised an international panel of experts representing five European countries and the United States.

RESULTS

Adjuvant radiotherapy is used more frequently in the United States than in Europe. In locally advanced disease, there is now more emphasis on early chemotherapy in both Europe and the United States. In metastatic disease, combination chemotherapy is commonly used in Europe and the United States. This varies by country. Advancing pancreatic research will require improving biorepositories and developing a roadmap to prioritize therapeutic targets in different models. Small randomized phase II trials of both non-selected and enriched patient populations will help identify activity of new agents. Phase III trials should only be initiated in appropriate patients based on strong clinical and biological signals. Developing drugs in the adjuvant setting may be preferable to eliminate some of the challenges of drug development in the advanced disease setting.

CONCLUSION

Progress in research combined with encouraging improvements from the past offer hope for the future of pancreatic cancer patients.

A phase II study of gemcitabine (GEM) given at fixed-dose rate (FDR) infusion, low-dose cisplatin (CDDP), and bevacizumab (BEV) for metastatic adenocarcinoma of the pancreas (PanCa): Update with completion of study accrual

4548

Background: The objectives of this study are to determine safety and efficacy in pts with metastatic PanCa treated with a novel combination consisting of FDR GEM, low-dose CDDP, and BEV. We present here updated results on the full 53-pt study cohort. Methods: Chemotherapy-naive pts with histologically confirmed PanCa and documented extrapancreatic metastases received GEM 1,000 mg/m2 at FDR infusion (10 mg/m2/min), CDDP 20 mg/m2, and BEV 10 mg/kg, all administered on dd 1 and 15 of a 28-dd cycle. Pts were monitored by CT scans every 2 cycles and monthly serum CA19–9 measurements. Results: 53 pts (24M,29F; median age 60 y.o. [range 39–85]; ECOG PS 0–1) were enrolled betw 6/2004 and 9/2006 (med f/u, 513 dd; range, 93–885). 16 pts remain alive, with 9 still undergoing study rx. Pts received a median of 4.75 cycles of rx (range, 0.5–20). 29 pts discontinued study rx 2o to progressive dz (med # of cycles, 5; range, 0.5–20); 9 pts 2o to rx-assoc toxicity; 4 pts 2o to plateau in response with cumulative asthenia (after 8–12 cycles); and 2 pts 2o to prolonged rx delay from bowel obstruction. Major events include 2 bowel perforations, one associated with placement of a duodenal stent; 4 major GI bleeds; 7 DVT/PE; 1 stroke-like sxs; and 3 cardiac events (MI x 1, arrhythmias x 2). 4 pts (7.5%) developed grade 3/4 HTN. Gr 3/4 hematologic toxicities inc. neutropenia in 4 pts (7.5%) and thrombocytopenia in 1 pt (2.9%). 16 pts (20%) required dose reduction in gemcitabine during study rx and 4 required holding of cisplatin. There were 3 deaths potentially assoc with rx. 12 pts (22.6%) have had an unconfirmed response (1 CR, 11 PR) and 26 pts (49.1%) have had stable dz for >2 cycles, for an overall dz control rate of 71.7%. 20 of 35 pts (57.1%) with elev baseline CA19–9 levels (>2X ULN) had >50% biomarker decline during rx. Median TTP is 6.2 months. Median overall survival is 8.0 months with an est. 1-yr survival rate of 40%. Conclusions: The addition of BEV to FDR GEM/low-dose CDDP shows promising efficacy, particularly in TTP and 1-yr survival rate, with manageable toxicity. Further efforts are ongoing to identify which pts are most likely to benefit from BEV-based rx.

[Table: see text]

Detection and significance of circulating tumor cells (CTC) in patients with metastatic pancreatic cancer (PC) receiving systemic therapy

4596

Background: Detection of CTC in the peripheral circulation of pts with solid tumors may provide useful prognostic and predictive information. In a previously reported pilot study, we detected CTC in approx 2/3rds of pts with all stages of PC using a flow cytometric-based approach. This study examines the significance of CTC using two separate methods in pts with metastatic PC undergoing systemic rx. Methods: Blood was obtained at baseline and after 2 months of rx from pts with metastatic PC participating in a phase II trial of gemcitabine, cisplatin, and bevacizumab. Two methods for measuring CTC were tested: immunomagnetic capture/flow cytometry (IC/FC) using anti-EpCAM Abs, and the Veridex CellSearch system. Wilcoxon Rank tests were used to test the association of CTC concentration at each time point, and change in concentration over time, with overall survival, time to tumor progression, and CA19–9 response. Results: CTC were measured in 48 indiv pts at baseline (31 using IC/FC, 23 using CellSearch, 6 using both methods) and in 39 indiv pts after 2 months of rx (20 IC/FC, 23 CellSearch, 4 both methods). No correlation was found between CTC concentration at either baseline or at 2 mos and any clinical endpoints (see table ). This was true for both IC/FC and CellSearch methods. 25 pts had serial CTC measurements using consistent methods at both time points (17 IC/FC, 12 CellSearch, 4 both methods). CTC concentration decreased in 9 of 17 pts (52.9%) tested by IC/FC and in 5 of 12 pts (41.7%) tested by CellSearch; however, change in CTC concentration over time was not associated with clinical outcomes. Too few pts have been tested by both methods at a given time point to establish a significant correlation betw the two methods. Conclusions: CTC can be detected in pts with metastatic PC using both methods tested in this study, albeit at low concentrations. The small sample size to date precludes our ability to determine the prognostic and predictive significance of these cells in this disease setting.

[Table: see text]

No significant financial relationships to disclose.

A phase II study of gemcitabine (GEM) given at fixed-dose rate (FDR) infusion, low-dose cisplatin (CDDP), and bevacizumab in metastatic pancreatic cancer (PanCa)

4041

Background: The objectives of this study are to determine safety and efficacy in pts with metastatic PanCa treated with a novel combination consisting of FDR GEM, low-dose CDDP, and BEV. We present here interim results of the first 35 pts. Methods: Chemotherapy-naive pts with histologically confirmed PanCa and documented extrapancreatic metastases received the following: GEM 1000 mg/m2 at FDR infusion (10 mg/m2/min), CDDP 20 mg/m2, and BEV 10 mg/kg, all administered on dd 1 and 15 of a 28-dd cycle. Pts were monitored by CT scans every 2 cycles and monthly serum CA19–9 measurements. Results: 35 pts (15M,20F; median age 60 y.o. [range 39–85]; ECOG PS 0–1) have been enrolled betw 6/2004 and 1/2006 (med f/u, 288 dd; range, 50–542). 18 pts remain alive, with 7 still undergoing study rx. Pts received a median of 4 cycles of rx (range, 0.5–12). Reasons for study discontinuation: 15 pts had progressive dz (med # of cycles, 6; range, 0.5–10); 2 pts completed max # of allowable rx cycles (twelve); 2 pts came off rx 2 o to cumulative asthenia after plateau in response with 8 and 10 cycles of rx. Other major events inc. 2 bowel perforations, one associated with placement of a duodenal stent; 3 major GI bleeds; 1 malignant HTN; and 1 stroke-like sx. 3 pts d/c’ed rx 2o to prolonged rx delays (two persistent bowel obstruction, one grade 3 renal/liver function abnls). Addn grade 3/4 toxicities inc. 7 pts with LFT abnls (20%), 4 with HTN (11.4%), and 3 with thromboembolic events (8.6%). Hematologic toxicities were rare (grade 3/4 neutropenia 5.7%, plts 2.9%). 7 pts (20%) required dose reduction of GEM and 2 required d/c of CDDP. No rx-associated deaths were observed. 7 of 33 evaluable pts (21.2%) have had an unconfirmed response (1 CR, 6 PR) and 15 pts (45.5%) have had stable dz for > 2 cycles, inc. 2 with minor response, for an overall dz control rate of 66.7%. 13 of 21 pts (61.9%) with elev. baseline CA19–9 levels (≥2X ULN) have had ≥50% biomarker decline during rx. Updated efficacy data will be presented at the meeting. Conclusions: The toxicity profile observed in this trial is similar to that previously reported with other BEV-containing regimens. Rates of disease control and CA 19–9 response are encouraging, suggesting this combination is deserving of further study.

[Table: see text]

Serum CA19-9 response as a surrogate for clinical outcome in patients receiving fixed-dose rate gemcitabine for advanced pancreatic cancer

The use of serial serum measurements of the carbohydrate antigen 19-9 (CA19-9) to guide treatment decisions and serve as a surrogate end point in clinical trial design requires further validation. We investigated whether CA19-9 decline represents an accurate surrogate for survival and time to treatment failure (TTF) in a cohort of 76 patients with advanced pancreatic cancer receiving fixed-dose rate gemcitabine in three separate studies. Statistically significant correlations between percentage CA19-9 decline and both overall survival and TTF were found, with median survival ranging from 12.0 months for patients with the greatest degree of biomarker decline (>75%) compared with 4.3 months in those whose CA19-9 did not decline during therapy (P<0.001). Using specific thresholds, patients with ⩾25% decline in CA19-9 during treatment had significantly better outcomes than those who did not (median survival and TTF of 9.6 and 4.6 months vs 4.4 and 1.5 months; P<0.001). Similar results were seen using both 50 and 75% as cutoff points. We conclude that serial CA19-9 measurements correlate well with clinical outcomes in this patient population, and that decline in this biomarker should be entertained for possible use as a surrogate end point in clinical trials for the selection of new treatments in this disease.

Outpatient treatment with (131)I-anti-B1 antibody: radiation exposure to family members

The Nuclear Regulatory Commission (NRC) regulations that govern release of patients administered radioactive material have been revised to include dose-based criteria in addition to the conventional activity-based criteria. A licensee may now release a patient if the total effective dose equivalent to another individual from exposure to the released patient is not likely to exceed 5 mSv (500 mrem). The result of this dose-based release limit is that now many patients given therapeutic amounts of radioactive material no longer require hospitalization. This article presents measured dose data for 26 family members exposed to 22 patients treated for non-Hodgkin's lymphoma with (131)I-anti-B1 antibody after their release according to the new NRC dose-based regulations.

METHODS

The patients received administered activities ranging from 0.94 to 4.77 GBq (25--129 mCi). Family members were provided with radiation monitoring devices (film badges, thermoluminescent or optically stimulated luminescent dosimeters, or electronic digital dosimeters). Radiation safety personnel instructed the family members on the proper wearing and use of the devices. Instruction was also provided on actions recommended to maintain doses to potentially exposed individuals as low as is reasonably achievable.

RESULTS

Family members wore the dosimeters for 2--17 d, with the range of measured dose values extending from 0.17 to 4.09 mSv (17--409 mrem). The average dose for infinite time based on dosimeter readings was 32% of the predicted doses projected to be received by the family members using the NRC method provided in regulatory guide 8.39.

CONCLUSION

Therapy with (131)I-anti-B1 antibody can be conducted on an outpatient basis using the established recommended protocol. The patients can be released immediately with confidence that doses to other individuals will be below the 5-mSv (500 mrem) limit.

AGA technical review on the epidemiology, diagnosis, and treatment of pancreatic ductal adenocarcinoma. American Gastroenterological Association

This literature review and the recommendations therein were prepared for the American Gastroenterological Association Clinical Practice and Practice Economics Committee. The paper was approved by the Committee in March 1999 and by the AGA Governing Board in May 1999.

Pancreatic cancer

Despite the many advances reported during the past year, pancreatic cancer remains a profound therapeutic challenge. Helical CT has become the preferred staging study at many institutions. The role of chemoradiation therapy in a preoperative and postoperative setting is being defined. Gemcitabine has become first-line therapy for patients with advanced pancreatic adenocarcinoma. It is hoped that the increasing knowledge of the molecular biology of pancreatic carcinoma will lead to improvements in diagnosing, staging, and treating pancreatic adenocarcinoma.

Complications and technical limitations of hepatic arterial infusion catheter placement for chemotherapy

PURPOSE

To determine the rate of complications associated with hepatic arterial infusion (HAI) catheter placement, as well as technical success related to liver perfusion.

MATERIALS AND METHODS

The authors reviewed 44 patients who underwent 106 HAI catheter placements, including 15 men and 29 women with an average age of 55 years (range, 32-82 years). One to nine placements were performed per patient with 61 (58%) via the left brachial artery, 40 (38%) via the right femoral artery, and five (4%) via the left femoral artery. Chemoinfusion lasted 4 days, with initial catheter placement assessed on technetium-99m macroaggregated albumin (MAA) perfusion scans, as well as daily abdominal radiographs.

RESULTS

One hundred attempted hepatic arterial catheter placements were completed. Liver perfusion was global in 66 (66%) cases, in the right lobe only in 28 (28%) cases, and in the left lobe only in six (6%) cases. Eight (8%) had gastrointestinal (GI) tract perfusion; this was eliminated in seven cases (7%) after catheter repositioning. Forty-six (43%) placement attempts required embolization of 62 GI vessels to preclude GI chemoinfusion. Complications included one cerebrovascular accident (related to removal of a left brachial catheter), eight brachial artery thromboses (four that required emergent thrombectomy), six hepatic arterial dissections, four hepatic arterial thromboses, and four catheter malfunctions.

CONCLUSIONS

HAI catheter placement via the left brachial artery has increased complications. Nearly one-half of placements required embolization of GI vessels to preclude GI perfusion. Global perfusion is possible in two-thirds of cases.

Patient-specific dosimetry of indium-111- and yttrium-90-labeled monoclonal antibody CC49

The objective of this work was to develop patient-specific dosimetry for patients with metastatic gastrointestinal tract cancers who received 111In-CC49 IgG for imaging before therapy with 90Y-CC49 IgG.

METHODS

Whole-body imaging of 12 patients, who received 111-185 MBq (3-5 mCi) of 111In-CC49, commenced in < 2 hr postinfusion and was continued daily for 4-5 days. SPECT data were acquired at 24 and 72 hr to determine the range of 111In-CC49 activity concentrations in tumors and normal organs. Time-activity curves were generated from the image data and scaled from 111In-CC49 to 90Y-CC49 for dosimetric purposes. Absorbed-dose calculations for 90Y-CC49 included the mean and range in tumor and normal organs. Computed 90Y-CC49 activity concentrations were compared with measurements on 10 needle biopsies of normal liver and four tumor biopsies.

RESULTS

In 9 of 10 normal liver samples, the range of computed 90Y-CC49 activity concentrations bracketed measured values. This was also the case for 3 of 4 tumor biopsies. Absorbed-dose calculations for 90Y-CC49 were based on patients' images and activities in tissue samples and, hence, were patient-specific.

CONCLUSION

For the radiolabeled antibody preparations used in this study, quantitative imaging of 111In-CC49 provided the data required for 90Y-CC49 dosimetry. The range of activities in patients' SPECT images was determined for a meaningful comparison of measured and computed values. Knowledge of activity distributions in tumors and normal organs was essential for computing mean values and ranges of absorbed dose and provided a more complete description of the absorbed dose from 90Y-CC49 than was possible with planar methods.

Unconjugated bilirubin inhibits in vitro cytotoxic T lymphocyte activity of human lymphocytes

Septic complications have been major problems in the management of patients with obstructive jaundice and neonatal jaundice. This study investigates effects bilirubin on human T lymphocyte responses against allogeneic mixed lymphocyte reaction. In vitro exposure of human peripheral blood mononuclear cells (PBMNC) with unconjugated bilirubin at pathological levels (6 to 12 mg/dl) did not alter the subsets of CD3, CD4, CD8, CD14, CD19 and CD56 positive populations, or expression of costimulatory surface molecules CD2, CD3, CD4 and CD8. Further incubation of bilirubin-treated PBMNC with irradiated B lymphoid Raji cells after removal of the extracellular bilirubin resulted in a dose-dependent decrease of cytotoxic T lymphocyte (CTL) activity, DNA synthesis, and expression of Tac antigen (CD25) and transferrin receptor (CD71). However, no significant change of interleukin-2 (IL-2) production was observed after this incubation between bilirubin-treated and -untreated PBMNC. These results suggest that bilirubin inhibits the induction of CTL activity, and this defect may result from the impaired responsiveness against IL-2. These observations may help explain the increased infection observed in hyperbilirubinemic patients.

Intracellular accumulation of unconjugated bilirubin inhibits phytohemagglutin-induced proliferation and interleukin-2 production of human lymphocytes

Decreased immune responses have been documented in hyperbilirubinemic patients. This study investigates the effects of intracellular bilirubin accumulation on lymphoproliferative response to phytohemagglutin A (PHA). Human peripheral blood mononuclear cells (PBMNC) were preincubated with unconjugated bilirubin dissolved in bovine albumin solution at pathological levels seen in clinical hyperbilirubinemia (0-12 mg/dl), washed, and further cultured with PHA. DNA synthesis was measured by [3H]thymidine uptake. Interleukin-2 (IL-2) activity was determined by the CTLL proliferation assay. The amount of intracellular bilirubin and expression of cell surface antigens were analyzed by flow cytometry. In vitro exposure of normal PBMNC to bilirubin resulted in the accumulation of intracellular bilirubin and a decrease in DNA synthesis after PHA stimulation in a time- and dose-dependent manner. Addition of autologous untreated monocytes could not correct the decreased DNA synthesis of bilirubin-treated lymphocytes. IL-2 production by bilirubin-treated PBMNC after PHA stimulation was significantly decreased compared to bilirubin-untreated PBMNC. However, addition of exogenous IL-2 to pretreated PBMNC could not correct the decreased DNA synthesis. Expression of Tac antigen and transferrin receptor on bilirubin-treated lymphocytes after PHA stimulation was not significantly different from bilirubin-untreated cells. These results suggest that decreased PHA-induced T-lymphocyte proliferation following bilirubin-pretreatment may result from impairment of proliferation at a step beyond transferrin receptor expression. These observations may help explain the increased susceptibility to infection often observed in hyperbilirubinemic patients.

Unconjugated bilirubin inhibits in vitro major histocompatibility complex-unrestricted cytotoxicity of human lymphocytes

Septic complications have been major problems in the management of patients with obstructive jaundice and neonatal jaundice. This study investigates effects of unconjugated bilirubin on lymphocyte-mediated cytotoxicity against human tumor target cells. In vitro exposure of human peripheral blood lymphocytes (PBL) with bilirubin IX alpha in bovine albumin solution resulted in a dose-dependent decrease of both natural killer activity and antibody dependent cellular cytotoxicity (ADCC) activity. Inhibition of both activities correlated with the amounts of intracellular bilirubin. Expression of cell surface CD16, CD56 antigen, and IL-2 receptor beta chain was unchanged in bilirubin-treated PBL as compared to bilirubin-untreated PBL. When bilirubin-treated PBL were cultured with interleukin-2 (IL-2), a dose-dependent decrease of lymphokine-activated killing activity, ADCC activity, and DNA synthesis was observed. Expression of CD56 antigen and IL-2 receptor alpha chain was unchanged in bilirubin-treated PBL following IL-2 stimulation as compared to bilirubin free control. These results suggest that bilirubin inhibits major histocompatibility complex-unrestricted cytotoxicity in both unstimulated and IL-2 stimulated lymphocytes. These observations may help explain the increased susceptibility to infection observed in hyperbilirubinemic patients.

Radiolabeled iododeoxyuridine: safety evaluation

The emphasis of radiolabeled iododeoxyuridine (*IUdR) research at our institution to date has been to assess its safety as a potential therapeutic agent. Toward this goal, we have performed preclinical and clinical studies, using various routes of administration, to detect adverse changes in normal tissues in both humans and animals. As IUdR is rapidly dehalogenated by the liver, the intravenous route is unlikely to be successful in therapeutic efforts. We have therefore focused our attention on more "protected" routes: intra-arterial and intravesicular administration.

METHODS

Studies were performed in farm pigs after multiple administrations of [125I]IUdR into the aorta, carotid artery and bladder. IUdR and metabolites were measured in venous blood samples at appropriate time intervals after administration, after which histologic examination of tissues was performed. Studies in human have been performed after intra-arterial administration of [123I]IUdR in patients with liver metastases and intravesicular administration in patients with bladder carcinoma, initially using [123I]IUdR and currently using both [123I]IUdR and [125I]IUdR. Blood samples for pharmacokinetics and metabolite analysis and tissue for autoradiography (when feasible) have been obtained.

RESULTS

To date, no evidence of adverse effects on normal tissue or alteration of hematologic or metabolic indices have been seen in pigs or humans. When instilled in the bladder, there is little leakage of IUdR in the circulation.

CONCLUSION

When [125I]IUdR is used as a therapeutic agent, we anticipate little or no effect on normal tissues.

Modulation of tumor-associated antigen expression on human pancreatic and prostate carcinoma cells in vitro by alpha- and gamma-interferons

Interferons (IFNs) are known to have antiviral effects and have been shown to enhance the expression of tumor-associated antigens (TAA) on different target cells. In our current study, we investigated the potential of IFN-alpha or IFN-gamma to enhance the expression of the TAAs recognized by monoclonal antibodies (MAbs) 19-9, B72.3, 17-1A, and BR55-2 on pancreatic cancer cell lines and the potential of IFN-gamma to modulate the expression of a single TAA, BR55-2, on nonpancreatic cancer cell lines. Expression of these TAAs, percentage of positive cells and mean fluorescence intensity, was measured by flow cytometry. In these studies, we provide evidence that one prostate (DU 145) and two pancreatic (HPAF and BxPC-3) cancer cell lines that moderately express BR55-2 can be upregulated by IFN-gamma treatment, with optimal enhancement occurring between 48 and 72 h with 1,000 IU/ml. Cell lines that highly expressed BR55-2 could not be further upregulated by the doses of IFNs tested during the various periods used. IFN-alpha or IFN-gamma treatments did not significantly change the levels of TAA expression on pancreatic cancer cell lines that bound MAbs 17-1A or 19-9. Cell lines that did not bind MAbs 17-1A, 19-9, B72.3, or BR55-2 before IFN treatments could not be induced to express these antigens after treatment. Although antigen expression does not ensure detectable therapeutic benefit, increased antigen expression on tumor tissues may augment the efficacy of MAbs bearing radionuclides, toxins, or effector cells to the tumor site. In each of these situations, the use of IFNs to enhance TAA expression, particularly IFN-gamma, may merit consideration.

Diagnostic use of radiolabeled antibodies for cancer

Antibodies against a variety of tumor-associated antigens have been studied, as well as a number of modifications to the antibodies themselves, including Fab' fragments and chimeric, humanized, and human antibodies. The appropriate use of radioimmunoconjugates in the evaluation of cancer patients has not yet been clearly defined. Only a few studies have assessed their use, primarily through the intravenous route, in initial disease staging. To date, immunolymphoscintigraphy has not proven promising in the staging of cancers. More emphasis has been given to the use of IV radioimmunoconjugates to detect residual and recurrent disease, with generally favorable results. In addition, radioimmunoguided surgery, using small, handheld probes to detect foci of antibody accumulation, appears to be a valuable tool. As better production techniques become available and large clinical trials provide more clearly defined indications for radioimmunoconjugate use, these agents should enter the arena for routine diagnostic use.

Comparison of subcutaneous and intravenous administration of recombinant human granulocyte-macrophage colony-stimulating factor for peripheral blood stem cell mobilization

In an effort to determine whether subcutaneous or continuous intravenous infusion administration of rhGM-CSF results in better hematopoietic progenitor mobilization, the findings of two sequential clinical trials were reviewed. Patients who had received prior chemotherapy for leukemia, lymphoma, multiple myeloma, breast cancer, or other solid tumors and were candidates for high-dose therapy received rhGM-CSF, 250 micrograms/m2/day, either as a continuous intravenous infusion (trial 1) or subcutaneously (trial 2) for stem cell mobilization. At least five apheresis collection procedures were performed to collect a target number of 6.5 x 10(8) mononuclear cells (MNC)/kg. For the 37 patients in trial 1, the collections contained a median of 7.99 x 10(8) MNC/L (range 6.42-21.36) and a median of 5.27 x 10(4) CFU-GM/kg (range 0.28-19.35). In trial 1, 25 patients were autografted with their cells and recovered 0.5 x 10(9) granulocytes/L at a median of 12 days (range 6-16). For the 33 patients in trial 2, the autograft product contained a median of 7.63 x 10(8) MNC/kg (range 6.51-22.66) and 6.31 x 10(4) CFU-GM/kg (range 0.06-60.4). In trial 2, 25 patients were autografted. The median time to reach 0.5 x 10(9) granulocytes/L was 11 days (range 9-26). All patients received rhGM-CSF after peripheral stem cell transplant. No significant differences in the collected products or the time to hematopoietic recovery was found between the two trials (p > 0.05). The mobilization effects of subcutaneous rhGM-CSF in these pretreated patients were similar to those of intravenous rhGM-CSF.

Immunologic effects of levamisole in mice and humans: evidence for augmented antibody response without modulation of cellular cytotoxicity

Selected immunomodulatory effects of levamisole were studied in patients with asymptomatic metastatic colon cancer and in a preclinical model (CF1 female mice treated with methyl-azoxymethanol acetate) for colon tumors. In the patient population studied, there was no augmentation of cellular cytotoxicity or alteration in lymphocyte subpopulations that participate in these functions. An increase in Fc receptor binding on circulating monocytes was apparent at the 4-week timepoint; however, a corresponding increase in antibody-dependent cellular cytotoxicity was observed in only one of the six patients studied. In most patients, cellular cytotoxicity diminished with time. No significant effects on cellular immunity or carcinogenesis were observed in our murine studies. However, treatment with levamisole did increase circulating immunoglobulin levels and IgM response in mice immunized with the T-dependent antigen keyhole limpet hemocyanin. This parameter was not tested in the human trial. Failure to demonstrate antitumor effects on cellular immunity by levamisole in both human and murine studies suggests that these effects, if they do exist, may involve immunological parameters that were not tested using our methods or that may not be apparent in patients with more advanced malignancy.

Hypersensitivity to therapeutic murine monoclonal antibodies

OBJECTIVE

To determine the predictive value of pre-treatment skin tests and in vitro IgE/IgG4 anti-murine monoclonal antibodies in patients treated with murine monoclonal antibodies.

DESIGN

Patients treated at two cancer institutions were evaluated by skin testing and solid phase immunoassays to detect IgE and IgG4 specific anti-murine monoclonal antibodies. Skin testing by scratch and intradermal skin testing was done on patients before treatment with murine monoclonal antibodies. IgE & IgG4 specific anti-murine monoclonal antibodies were determined before treatment in all patients and at 1, 7, 14 and 21 days post-treatment in 1 patient.

SETTING

Cancer patients undergoing murine monoclonal antibody treatment in two university medical centers were recruited for the study.

PARTICIPANTS

Twelve patients, aged 41-75 years with gastrointestinal cancers (colon, stomach, pancreas or liver) with metastatic disease, who had relapses or conventional therapy were enrolled. Some patients had previous exposure to rodents, either as laboratory personnel or had kept them as pets.

INTERVENTION

One patient who experienced an anaphylactic reaction to murine monoclonal antibody infusion was desensitized so therapy could continue.

MAIN OUTCOME MEASURES

Skin tests, immunoassays, and patient history were correlated with adverse reactions to infusions of murine monoclonal antibodies.

MAIN RESULTS

Skin tests (scratch method) and/or in vitro immunoassays may predict allergic outcomes in patients receiving infusions of murine monoclonal antibodies. Intradermal skin testing with murine monoclonal antibodies may result in false positive reactions and have less predictive value. Specific IgE or IgG4 were elevated in the two patients who experienced severe adverse reactions to murine monoclonal antibodies but not in those patients with no reactions and therefore, may have some predictive value. A history of past exposure to mice may also increase the risk of adverse reactions. In one patient, intravenous desensitization enabled treatment to proceed.

CONCLUSION

Scratch skin tests, in vitro IgE and/or IgG4 immunoassays together with a past history of previous exposure to murine antigen(s) may predict potential allergic reaction to therapy with murine monoclonal antibodies.

The effect of garlic extract on human metabolism of acetaminophen

Several studies suggest that the constituents of garlic may inhibit experimentally induced carcinogenesis. To evaluate the chemopreventive properties of garlic in humans, the effects of chronic administration of an aged garlic extract on the disposition of acetaminophen and metabolites were studied. This commonly used drug was chosen because it forms a reactive electrophilic metabolite after oxidative metabolism. Sixteen subjects ingested daily doses of garlic extract (approximately equivalent to six to seven cloves of garlic) for 3 months. Before the course of garlic, at the end of each month and 1 month after termination of garlic administration, a 1-g oral dose of acetaminophen was given to each subject. Plasma and urine were measured for acetaminophen and the glucuronide, sulfate, cysteinyl, mercapturate, and methylthio metabolites. It was found that garlic treatment had no discernible effect on oxidative metabolism but was associated with a slight increase in sulfate conjugation of drug. These findings suggest that garlic extract has limited potential as a chemopreventive agent.

Dose-related comparison of antibody-dependent cellular cytotoxicity with chimeric and native murine monoclonal antibody 17-1A. Improved cytolysis of pancreatic cancer cells with chimeric 17-1A

Chimeric 17-1A antibody (IgG1 kappa) was constructed by linking variable region genes of murine monoclonal antibody 17-1A with genes for human kappa light chain and gamma 1 heavy-chain constant regions. This study was undertaken to compare in vitro antibody-dependent cellular cytotoxicity (ADCC) between the chimeric 17-1A (IgG1 kappa) and native murine 17-1A antibody (IgG2a kappa) with human peripheral blood mononuclear cells (PBMNC) against 7 human tumor (1 colon, 6 pancreas) cell lines. ADCC activity was measured by chromium-release assay. When freshly-isolated PBMNC from healthy donors were used for effector cells, significantly higher ADCC activity of chimeric antibody compared to murine antibody at optimal antibody dose (10 micrograms/mL) and lower doses (to 0.6 micrograms/mL) was observed against tumor cells with relatively high 17-1A expression. This high ADCC activity of the chimeric antibody persisted even when freshly-isolated monocyte-depleted PBMNC was used. When interleukin-2 activated PBMNC were used, comparable increases in ADCC were observed with both chimeric and murine antibody. These results suggest that chimeric 17-1A antibody is a more effective mediator of in vitro ADCC activity with human freshly-isolated PBMNC than the native murine antibody and this may be a better choice for clinical cancer trials evaluating possible immunotherapy with monoclonal antibody.

Purification and analysis of glycoproteins bearing blood group-A determinants from hamster pancreatic ductal adenocarcinomas

Although the hamster pancreas does not express A, B or H blood group antigens, all hamster pancreatic ductal adenocarcinomas induced by treatment with N-nitrosobis(2-oxopropyl)amine express blood group-A antigen. Thus, the acquisition of blood group-A antigen expression in this system is a cancer-associated alteration. We have purified three major blood group-A antigen bearing glycoproteins (gp120, gp135 and gp150) from hamster pancreatic cancer cell membrane preparations using affinity chromatography on DBA (Dolichos biflorus) agglutinin-agarose. When assayed by immunoblotting, gp120 and gp135 showed strong blood group-A reactivity, which was removed by treating membrane samples with peptide-N-glycosidase F. Blood group-A reactivity was unchanged by treatment of the membrane fractions with endoglycosidases F and H. In addition, these two glycoproteins bearing blood group-A antigen also bound L-PHA (Phaseolus vulgaris leucoagglutinin). These results demonstrate that gp120 and gp135 express blood group-A antigen on Asn-linked multi-antennary complex type glycan structures. The gp150 showed weak blood group-A expression. This is the first demonstration of the neoexpression of cancer-associated blood group-A determinants which reside on Asn-linked glycan structures.

Flow cytometric measurement of intracellular bilirubin in human peripheral blood mononuclear cells exposed to unconjugated bilirubin

Human peripheral blood mononuclear cells were incubated at 37 degrees C with bilirubin in bovine albumin solution. Histological analysis of bilirubin-treated cells demonstrated a prominent brown pigment deposited in the cytoplasm. Homogenates of these cells in chloroform-methanol solution showed an identical absorption spectrum with pure bilirubin dissolved in the same solution. When bilirubin-treated cells were excited at 488 nm, a significant autofluorescence was detected by flow cytometry at 585 nm in a dose-dependent manner, which had a significant correlation with the amount of bilirubin chemically extracted from the cells (r = 0.963, n = 34, p less than 0.001). Intraassay and interassay variability of the autofluorescence by flow cytometric analysis was small (both less than 5%). When bilirubin-treated cells were stained with fluorescein-labeled anti-CD14 antibody, the CD14 positive cell population can be fractionated without interference of autofluorescence derived from intracellular bilirubin. These results suggest that flow cytometric analysis of bilirubin-treated cells can quantitate intracellular bilirubin, and that bilirubin does not interfere with analysis of surface antigens.

Quantitation of metastatic tumor burden from human colon tumor xenografts using radiolabelled monoclonal antibody 17-A fragments

In realistic models of human tumor xenograft metastasis, the metastatic foci arise in perivascular sites and rarely grow to sizes which are easily quantifiable by visual inspection. As an alternative approach, we have used monoclonal antibody (MAb) 17-1A F(ab')2 fragments labelled with radioiodine (125I) to study the differential accumulation of label in xenografts and metastatic tumor sites as well as in noninvolved tissues of NIH Swiss nude mice receiving HT-29 human colon tumor cells. Images of the whole-body distribution and sites of localization were determined using a pinhole-collimated Angergamma camera. Radioactivity was determined in tissue samples using a well scintillation system, and pharmacokinetics were assessed during the initial 72 h after injection of antibody fragments. The half-life of 125I-F(ab')2 fragments in the blood, 8.6 h, was similar in nontumor-bearing control and tumor-bearing mice. The half-life in subcutaneous tumor xenografts was 30.1 h. The tumor xenograft to tissue activity ratios per unit weight (radiolocalization indices) at 72 h were: blood 90, lung 65, pancreas 50, muscle 35, spleen 20, liver and mesenteric lymph node 10. All subcutaneous xenografts were successfully imaged, and images of 5 of 9 mice (55%) appeared to demonstrate the presence of metastatic tumor by differential and focal accumulation of MAb fragments after 48 or 72 h in the lung (2 cases) or abdominal cavity (3 cases). Necropsy and subsequent histological and biodistribution studies confirmed the presence of metastatic tumor in these sites and identified tumor in several additional sites. The smallest volume of metastatic tissue in liver or lung determined at necropsy which appeared to have been detected by imaging was about 20 mm3. Generally, for mice with metastatic tumors, the radioactivity per unit weight of metastatic tumor-bearing organs compared to tumor-free organs was 2- to 7-fold greater. The results indicate that a radiolocalization index of > or = 2 is generally necessary for metastatic tumor detection by imaging although this is influenced by the extent of anatomical location of the tumor. It was possible to predict the tissue distribution of the fragments from the planar image for the amounts of radioactivity (approximately 1 mCi/kg body weight) employed in this study. These results demonstrate the utility of this approach to quantitate the metastatic burden arising from human colon tumor xenografts in this experimental model.

Characterization of bilirubin transport system by human peripheral blood mononuclear cells

Decreased immune responses have been observed in hyperbilirubinemic patients. This study investigates bilirubin transport into human peripheral blood mononuclear cells (PBMNCs). In vitro incubation of PBMNCs at 37 degrees C with 0-12 mg/dl bilirubin in solution with a fixed bovine serum albumin (BSA) concentration (3.0 g/dl) resulted in a dose-dependent increase of intracellular bilirubin in both monocytes and lymphocytes. Bilirubin uptake in monocytes was significantly higher (up to 2.7 times) than in lymphocytes under the same culture conditions. When PBMNCs were incubated with varying concentrations of bilirubin (0-16 mg/dl) in fixed BSA (3.0 g/dl) solution or at a fixed bilirubin/albumin molar ratio (0.4), the initial velocity of uptake in both cell fractions was proportional to the free (unbound to albumin) bilirubin concentration rather than the total bilirubin concentration. Bilirubin uptake by both cell fractions was significantly inhibited by treatment with metabolic inhibitors. Bilirubin uptake by monocytes continued to increase in parallel with incubation temperature from 0 degrees C to 40 degrees C, whereas uptake by lymphocytes reached a maximal level at 20 degrees C and remained constant thereafter. These results suggest that monocytes and lymphocytes incorporate bilirubin in proportion to the free bilirubin concentration and this function may rely on different energy-dependent mechanisms.

Progress in chemoprevention of gastrointestinal cancers

Carcinogenesis is a complex and multistep process. Numerous inhibitors (either naturally occurring or synthetic) have been identified that can interfere with various phases of carcinogenesis, including the endogenous formation of carcinogens, the activation or detoxification of carcinogens, or events in tumor promotion. Many of these compounds have survived a complex screening program and are currently in or ready for clinical application. In gastrointestinal malignancies, colon neoplasia has been a popular target for chemoprevention. The identification of preneoplastic events in colon mucosa or in the progression of malignancy from adenomas to adenocarcinomas has permitted the study of numerous compounds such as calcium salts, difluoromethylornithine, and prostaglandin synthesis inhibitors on intermediate biomarkers or on the development of recurrent adenomas or cancers. A variety of other compounds with general efficacy in other tumor models have also been shown to be effective inhibitors of tumorigenesis in preclinical models of esophageal, gastric, pancreatic, and hepatic carcinogenesis. This review provides an overview of carcinogenesis and principles of chemoprevention and highlights certain developments in the past year that exemplify the experience and progress in this area.

Immunotherapy with monoclonal antibody (Mab) in pancreatic adenocarcinoma

Conventional therapy of pancreatic exocrine cancer is disappointing. The poor prognosis of the disease challenges development of novel therapeutic strategies. We report the results of clinical trials of the monoclonal antibody (Mab) 17-1A in patients with histologically verified unresectable pancreatic exocrine cancer. No antitumor response was seen in 18 patients treated with Mab 17-1A (500 mg) admixed with 10(9) autologous mononuclear cells, and 81% of the patients developed antimouse antibody response. Combination of recombinant gamma interferon and Mab 17-1A mixed with autologous mononuclear white cells resulted in complete response of 4-mo duration in 1 out of 25 evaluable patients and unusually stable disease from 4 to 48+ mo in another 6 patients. High intermittent doses of infused Mab 17-1A did not show any objective antitumor response and caused serious anaphylaxis in two of the patients in the trial. Because examination of six pancreatic adenocarcinoma cell lines with different doses of Mab 17-1A and IL-2 failed to augment lytic activity of mononuclear effector cells against all cancer cell lines tested, there seemed to be no rationale for pursuing clinical studies with IL-2 and Mab 17-1A in either the murine or chimeric form. Attractive therapeutic approaches include active immunotherapy with immunization using idiotypic antibodies or targeted toxicity with the use of radioimmunoconjugates, particularly 125I-labeled chimeric Mab 17-1A.

Phase II trial of interferon gamma and monoclonal antibody 17-1A in pancreatic cancer: biologic and clinical effects

Thirty patients with advanced measurable pancreatic adenocarcinoma were entered onto a phase II trial with recombinant interferon gamma (Biogen, Cambridge, MA; 10(6) U/m2 daily for 4 days) and monoclonal antibody (Mab) 17-1A (Centocor, Malvern, PA; 150 mg in autologous leukocytes on days 2, 3, and 4 following interferon infusion). The effect of a single interferon gamma treatment on natural and antibody-dependent cellular cytotoxicity (ADCC), Fc receptor occupancy by antibody, and human leukocyte antigen-DR (HLA-DR) expression on monocytes and lymphocytes was also studied. Toxicity was modest and generally limited to grade I to II fever, nausea and vomiting, and hepatotoxicity. Five patients were considered to be nonassessable for response. Of the 25 assessable patients, one objective response (complete remission for a duration of 4 months) was observed. Stable disease for 2 months or greater was noted in nine patients. The median survival for the group was 5 months. Analysis of cytotoxicity data obtained prior to treatment showed reduced natural cytotoxic activity in these patients compared with normal volunteers. A significant improvement in natural cytotoxic activity to normal levels occurred within 24 hours following the interferon gamma infusion. This was also associated with augmented antibody-dependent cellular cytotoxicity. Although HLA-DR expression was not increased on either monocytes or lymphocytes, an increased capacity of both lymphocytes and monocytes to bind Mab 17-1A was observed. In all in vitro assays of ADCC, the presence of antibody excess was associated with improved cytolytic activity. In spite of the favorable modulation of cytolytic activity and improved ability of effector cells to bind Mab, we failed to demonstrated adequate clinical efficacy in the treatment of patients with pancreatic adenocarcinoma using this dose and schedule of interferon gamma and Mab 17-1A. Future trials will focus on alternate schedules of Mab 17-1A with the hope of improving tumor antigen saturation and circulating levels of infused antibody.

Chemoprevention of mouse colon tumors with difluoromethylornithine during and after carcinogen treatment

alpha-Difluoromethylornithine (DFMO) treatment has been shown to modify carcinogenesis in many experimental tumor models, including skin, breast, and colon. This study was designed to determine whether DFMO treatment can inhibit experimental mouse colon tumors after carcinogen treatment and whether an associated effect of DFMO on cell proliferation in colon mucosa occurs. Male CD1 mice (40 per group) received dimethylhydrazine (30 mg/kg/week x 6 weeks, s.c.) and various schedules of DFMO, 1% in drinking water: Group A, none; Group B, following dimethylhydrazine treatment; Group C, during dimethylhydrazine treatment; and Group D, continuously throughout the study. Measurements of RBC polyamine levels showed that DFMO treatment ablated putrescine levels and confirmed that a systemic biological effect was achieved. Analysis of tumor data showed a significant inhibitory effect of DFMO treatment on colon tumor (adenomas and adenocarcinomas) incidence in Groups B (24%) and D (20%) compared to control Group A (52%, P less than 0.05 A versus B, P less than 0.02 A versus D) and on squamous cell carcinomas of the anus in all groups (P less than 0.001 A versus B, P less than 0.05 A versus C, A versus D). No consistent effect of DFMO treatment on cell proliferation in colon mucosa was identified. This study supports the hypothesis that DFMO treatment alters events in the postinitiation phases of mouse colon tumorigenesis.

Reactivity of CO17-1A and B72.3 in benign and malignant pancreatic diseases

The immunoreactivity of two monoclonal antibodies, CO17-1A (recognizing 17-1A antigen) and B72.3 (recognizing TAG-72), was examined in pancreatic tissues from individuals without pancreatic disease and from those with benign and malignant pancreatic disease. 17-1A antigen was found in all cells in the normal tissue, whereas TAG-72 was present in the duct cells in only one case. Both antigens were present in benign diseases; however, in some cells and in some conditions, TAG-72 was significantly less common (P less than .01 to .001) than 17-1A antigen. In pancreatic cancer, 17-1A antigen was present in 87% of cases and TAG-72 antigen was present in 92% of cases. The results indicate that B72.3 is more specific to pancreatic cancer than C017-1A.

Comparative studies on the expression of tumor-associated glycoprotein (TAG-72), CA 19-9 and DU-PAN-2 in normal, benign and malignant pancreatic tissue

Expression of tumor-associated glycoprotein (TAG-72) was examined by immunohistochemistry in pancreatic specimens from normal donors, and from patients with chronic pancreatitis and pancreatic cancer, and was compared with expression of CA 19-9 and DU-PAN-2. In the normal pancreas, TAG-72 was expressed in fewer ductal and ductular cells than were CA 19-9 (p less than 0.05) and DU-PAN-2 (p less than 0.01 and 0.001 respectively), whereas in chronic pancreatitis all 3 antigens were expressed in ductal cells but only CA 19-9 and DU-PAN-2 in ductular cells (p less than 0.001). In the specimens from normal pancreas and chronic pancreatitis cases, TAG-72 was localized in the Golgi region, whereas CA 19-9 and DU-PAN-2 showed diffuse cytoplasmic and glycocalyx patterns. In pancreatic cancer, although the rate of expression of all 3 antigens was similar, their cellular localization differed significantly: only TAG-72 was expressed in the Golgi region (p less than 0.001), whereas CA 19-9 showed mainly glycocalyx (p less than 0.05) and/or intra-luminal patterns (p less than 0.01) compared with that of the other 2 antigens. We conclude that, due to differences in expression of TAG-72 in benign versus malignant cells, the monoclonal antibody against TAG-72 (B72.3) may be suitable for radio-immunodetection or radio-immunotherapy of pancreatic cancer.