Prospective Clinical Study of Precision Oncology in Solid Tumors

Systematic studies evaluating clinical benefit of tumor genomic profiling are lacking. We conducted a prospective study in 250 patients with select solid tumors at the Cleveland Clinic. Eligibility required histopathologic diagnosis, age of 18 years or older, Eastern Cooperative Oncology Group performance status 0-2, and written informed consent. Tumors were sequenced using FoundationOne (Cambridge, MA). Results were reviewed at the Cleveland Clinic Genomics Tumor Board. Outcomes included feasibility and clinical impact. Colorectal (25%), breast (18%), lung (13%), and pancreatobiliary (13%) cancers were the most common diagnoses. Median time from consent to result was 25 days (range = 3-140). Of 223 evaluable samples, 49% (n = 109) of patients were recommended a specific therapy, but only 11% (n = 24) received such therapy: 12 on clinical trials, nine off-label, three on-label. Lack of clinical trial access (n = 49) and clinical deterioration (n = 29) were the most common reasons for nonrecommendation/nonreceipt of genomics-driven therapy.

Complementary use of resection and radiofrequency ablation for the treatment of colorectal liver metastases: an analysis of 395 patients

BACKGROUND

Liver resection and radiofrequency ablation (RFA) are two surgical options in the treatment of patients with colorectal liver metastases (CLM). The aim of this study was to analyze patient characteristics and outcomes after resection and RFA for CLM from a single center.

METHODS

Between 2000 and 2010, 395 patients with CLM undergoing RFA (n = 295), liver resection (n = 94) or both (n = 6) were identified from a prospective IRB-approved database. Demographic, clinical and survival data were analyzed using univariate and multivariate analyses.

RESULTS

RFA patients had more comorbidities, number of liver tumors and a higher incidence of extrahepatic disease compared to the Resection patients. The 5-year overall actual survival was 17 % in the RFA, 58 % in the Resection group (p = 0.001). On multivariate analysis, multiple liver tumors, dominant lesion >3 cm, and CEA >10 ng/ml were independent predictors of overall survival. Patients were followed for a median of 20 ± 1 months. Liver and extrahepatic recurrences were seen in 69 %, and 29 % of the patients in the RFA, and 40 %, and 19 % of the patients in the Resection group, respectively.

CONCLUSIONS

In this large surgical series, we described the characteristics and oncologic outcomes of patients undergoing resection or RFA for CLM. By having both options available, we were able to surgically treat a large number of patients presenting with different degrees of liver tumor burden and co-morbidities, and also manage liver recurrences in follow-up.

Safety and efficacy of sorafenib for the treatment of recurrent hepatocellular carcinoma after liver transplantation

INTRODUCTION

Recurrent hepatocellular carcinoma (HCC) following liver transplantation (LT) carries a poor prognosis. The aim of our study was to assess the safety and efficacy of sorafenib in patients with recurrent HCC following LT.

METHODS

A prospectively maintained LT database was retrospectively analyzed for patients with recurrent HCC following LT between 2001 and 2011-34 patients. Patients were divided into two groups based on whether they were prescribed sorafenib (n = 17) or not prescribed sorafenib (n = 17). The primary endpoint was overall survival.

RESULTS

There were no significant differences between the two groups analyzed. Seventeen patients were on sorafenib for recurrent HCC, with a mean daily dose of ~444 mg. Mean duration of treatment was ~10 months. Side effects included: thrombocytopenia, diarrhea, rising transaminases, fatigue, hand-foot skin reaction, and nausea. Survival in the sorafenib vs. non-sorafenib group was greater at three-, six-, nine-, and 12-month intervals and overall survival.

CONCLUSION

Sorafenib can be well tolerated and safe in patients with recurrent HCC following LT and may be associated with a modest survival benefit. To our knowledge, this is the largest single-center retrospective analysis of patients prescribed sorafenib for recurrent HCC after LT.

Abstract 2372: Capture and molecular characterization of CTC in metastatic breast, prostate, colorectal, and renal cancer

The most important determinant of prognosis and management of cancer is the incidence of metastasis. As a result, circulating tumor cell (CTC) detection and enumeration has been demonstrated to be a useful tool in assessing prognosis and monitoring therapeutic response. Current approaches to CTC detection largely depend on the antibody-mediated magnetic capture of the CTC using antibodies against the epithelial cell adhesion molecule (EpCAM), a feature which can be exploited in only a select few malignancies, and even in these cases, CTC capture is directly impacted by the variable expression of EpCAM. Responding to these issues, we have developed a novel parylene-based microfilter device for the capture, enumeration, and molecular characterization of CTC by exploiting size differences between larger epithelial tumor cells and smaller non-tumor blood cells. Our size-based approach, in contrast to immunoaffinity-based platforms, is ‘antigen expression-agnostic’; allowing analysis of diverse CTC populations and CTC from tumor types lacking target capture antigens. In the present study, the prospective collection of 500 blood samples from patients being treated at the Cleveland Clinic-Taussig Cancer Institute in Cleveland, OH is currently underway: 450 with advanced breast (BC), prostate (PC), and colorectal cancer (CRC) (150 from each disease site), and 50 with advanced renal cell carcinoma (RCC) and melanoma (25 from each disease site). To date, we have analyzed 28 patient blood samples by the microfilter device, of which 26 (92.8%) where positive for CTC (total at primary disease site, % samples positive, range of CTC detected) - BC: 1, 100%, 48; PC: 13, 84.6%, 1 to 144; CRC: 7, 100%, 18 to >500; RCC: 7, 100%, 1-128.* Further analysis demonstrates a number of interesting molecular characteristics on CTC, including heterogeneity in intensity of cytokeratin (CK) expression, differential patterns of CK staining on CTC (filamentous vs granular), and the occurrence of CTC as individual events or in clusters. Further, our data in blood samples from RCC demonstrate an ability to analyze CTC from non-EpCAM expressing tumor types, an area of study where many platforms have limited utility. With the ability to perform multiple, repeated sample analyses to detect recurrent disease early and enable drug response surveillance, we believe our technology has the potential to provide a faster, more efficient alternative to currently available methods for CTC analysis. The molecular characteristics on CTC we have identified herein could have critical biological relevance and implications for predicting aggressiveness of CTC and improving therapeutic monitoring. In ongoing studies, we are investigating the correlation of CTC enumeration, morphology, and clustering, with tumor type and treatment efficacy. *Data to be updated prior to presentation

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2372. doi:1538-7445.AM2012-2372

Predictors of clinical outcomes of resected ampullary adenocarcinoma: a single-institution experience

BACKGROUND

In the absence of prospective data, the use of adjuvant therapy in ampullary adenocarcinoma is contingent upon the clinicopathological features which can correlate to 5-year post-operative survival and disease relapse.

METHODS

We investigated the factors associated with clinical outcomes among 72 patients who underwent pancreatoduodenectomy at the Cleveland Clinic from 1995 to 2007 for histologically confirmed adenocarcinoma of the ampulla of Vater.

RESULTS

R0 resection was achieved in 96% of patients (median age, 72 years; 58% males, 89% Caucasians). Nineteen patients experienced disease relapse after surgery and 61% were alive within 5 years of follow up. Thirty five percent of patients received some form of adjuvant therapy. Perineural tumor invasion (p < 0.01) and presence of ulcerated tumor on histopathology (p < 0.01) were associated with higher rates of tumor relapse and poor 5-year overall survival in multivariable analysis. Lymph node involvement (p = 0.02) also portended poor overall survival after adjustment for other covariates. Although adjuvant therapy was associated with poor clinical outcomes in univariate analysis, it demonstrated a favorable albeit non-significant trend in multivariable analysis.

CONCLUSIONS

Factors associated with poor clinical outcomes in this contemporary single-institution study, included perineural invasion, tumor ulceration, and lymph node involvement. No definite conclusion could be made in regards to adjuvant treatment.

A phase I study of EKB-569 in combination with capecitabine in patients with advanced colorectal cancer

PURPOSE

To determine the maximum tolerated dose (MTD), characterize the principal toxicities, and assess the pharmacokinetics of EKB-569, an oral selective irreversible inhibitor of the epidermal growth factor receptor tyrosine kinase, in combination with capecitabine in patients with advanced colorectal cancer.

EXPERIMENTAL DESIGN

Patients were treated with EKB-569 daily for 21 days and capecitabine twice daily for 14 days of a 21-day cycle. The dose levels of EKB-569 (mg/day) and capecitabine (mg/m(2) twice daily) assessed were 25/750, 50/750, 50/1,000 and 75/1,000. An expanded cohort was enrolled at the MTD to better study toxicity and efficacy. Samples of plasma were collected to characterize the pharmacokinetics of the agents. Treatment efficacy was assessed every other cycle.

RESULTS

A total of 37 patients, the majority of whom had prior chemotherapy, received a total of 163 cycles of treatment. Twenty patients were treated at the MTD, 50 mg EKB-569, daily and 1,000 mg/m(2) capecitabine twice daily. Dose-limiting toxicities were diarrhea and rash. No patients had complete or partial responses but 48% had stable disease. The conversion of capecitabine to 5-fluorouracil was higher for the combination of EKB-569 and capecitabine (321+/-151 ng*h/mL) than for capecitabine alone (176+/-62 ng*hours/mL; P=0.0037).

CONCLUSION

In advanced colorectal cancer, 50 mg EKB-569 daily can be safely combined with 1,000 mg/m(2) capecitabine twice a day. A statistically significant increase in plasma levels of 5-fluorouracil for the combination of EKB-569 and capecitabine may be due to the single-dose versus multiple-dose exposure difference, variability in exposure or a potential drug interaction.

A multi-center phase II study of oxaliplatin, irinotecan, and capecitabine in advanced gastric/gastroesophageal junction carcinoma

BACKGROUND

There is no standard first-line therapy for advanced gastric and gastroesophageal junction (GEJ) adenocarcinoma and the prognosis remains poor. Our institution conducted a phase I study of oxaliplatin, irinotecan, and capecitabine given in a novel, weekly schedule. The regimen was tolerated; pharmacodynamic studies revealed no drug interactions, and there was one confirmed response in a gastric cancer patient. We performed a phase II trial in advanced gastric and GEJ adenocarcinoma to determine response rate and response duration.

METHODS

This was a multi-center single treatment arm study involving six sites. Only prior adjuvant therapy was allowed. Patients had ECOG performance status of 0-2, adequate organ function, and were able to tolerate oral medications. All patients received oxaliplatin 60 mg/m(2) intravenously (IV) and irinotecan 50 mg/m(2) IV weekly times 4 weeks with a 2-week rest period. Capecitabine 450 mg bid orally was received on days 1 through 5 every week for 4 weeks, followed by a 2-week rest. Patients were assessed for response after the first two cycles; response duration, overall survival, and adverse events were also recorded. We estimated an improvement in historical response rate by 30% would have clinical meaning.

RESULTS

A total of 39 patients were accrued and all were assessed for toxicity; 30 patients were evaluable for response. The median age was 57.8 years (31-79 years) and 74% were male. Two patients had a complete response, with nine patients achieving a partial response. The total response rate was 28%, with nine patients not evaluable for response. The median response duration was noted at 5.97 months and median overall survival was 8.98 months. There were no grade 5 treatment related events, with all deaths secondary to disease progression. Only five grade 4 events occurred (neutropenia, hyperkalemia, hypokalemia (2), thrombosis/embolism) without grade 4 diarrhea or sensory neuropathy.

CONCLUSIONS

Oxaliplatin, irinotecan, and capecitabine given in a novel, weekly schedule does induce responses in advanced gastric and GEJ adenocarcinoma. However, the total response rate is modest and not an improvement over other regimens.

Multidisciplinary management of colorectal brain metastases: a retrospective study

BACKGROUND

The incidence of brain metastases (BM) from colorectal cancer (CRC) is increasing, and the management of this previously rare complication at a single institution is reported.

METHODS

The records of all patients with BM from 1994 to 2005 were reviewed, and 49 patients (33 men, 16 women) with 102 BM from CRC were identified. Associations between patient and tumor characteristics, treatment modality, and survival were assessed.

RESULTS

The median age at diagnosis of BM from CRC was 66 years. Forty patients (82%) had other systemic disease. The median survival after a diagnosis of BM from CRC was 5.1 months. Fifteen patients (31%) underwent surgery at some point, 14 patients (29%) underwent stereotactic radiosurgery (SRS), and 42 patients (86%) received whole-brain radiotherapy during their management. Seven patients (14%) underwent upfront SRS. On multivariate analysis, a longer interval from diagnosis of CRC to diagnosis of BM was associated significantly with shorter survival (p = .01). Sex, Karnofsky performance status, tumor location, recursive partitioning analysis class, and initial treatment modality did not have an impact on survival.

CONCLUSIONS

Because BM from CRC are a late-stage phenomenon, the majority of patients in the current study had other systemic involvement, and survival after CNS involvement was poor. The results indicated that a high prevalence of systemic disease limits the proportion of patients who are strong candidates for upfront SRS, thereby limiting the impact that this modality has on outcomes in this population as a whole. Late development (>1 year after the primary tumor diagnosis) of CNS involvement may predict for poorer survival after therapy for patients with BM from CRC.

Neoadjuvant therapy for hepatocellular carcinoma: is there an optimal approach?

Hepatocellular carcinoma (HCC) is an aggressive tumor that often occurs in the setting of chronic liver disease and cirrhosis. The incidence of hepatocellular carcinoma is increasing in the United States and worldwide. Orthotopic liver transplantation (OLT) is a viable and potentially curative option for selected patients with HCC. Locoregional therapy has been used to control HCC before transplantation because of the limited number of donor organs, to prevent tumor progression, and to decrease the incidence of dropouts from the transplant waiting list. Traditionally, multiple investigational locoregional modalities such as tumor resection, radiofrequency ablation, transarterial chemoembolization, and systemic chemotherapy have been used as "bridging" therapies. While the investigation of novel neoadjuvant treatments is justified in an effort to prevent tumor progression, the absence of randomized controlled trials leaves uncertainty about the utility of these maneuvers in improving outcome. This review summarizes the current data on the different modalities used worldwide in the neoadjuvant treatment of hepatocellular carcinoma, the rationale for these approaches, efficacy, potential complications, and future prospects.

Response to trans-arterial chemoembolization prior to orthotopic liver transplantation or hepatic resection in patients with hepatocellular carcinoma

15114

Background: Trans-arterial chemoembolization (TACE) is often used as pre-operative therapy for patients with hepatocellular carcinoma (HCC) prior to orthotopic liver transplantation (OLT) or hepatic resection (HR). However, the benefit of response to TACE on overall survival (OS) and progression free survival (PFS) remains unclear. Methods: Complete data was available for 24 patients with HCC who underwent TACE prior to either OLT or HR from 1998–2006. Known prognostic factors including tumor size, histology, number of nodules, Child-Pugh class, Okuda stage, MELD score, CLIP score were recorded. Clinical features before and after TACE were identified and tested by univariate analysis. Results: The mean patient age was age 51 years (range 31–65). Underlying diagnoses included: HBV (17%), HCV (54%), alcohol abuse (63%), cryptogenic (8%), nonalcoholic steotohepatitis (4%). The mean maximum tumor diameter was 6.2 cm (range 1.6–16.1 cm), with 13 tumors (54%) measuring >5 cm. The median number of lesions were 2 (range 1 - 7). The Milan criteria was met in 15 patients (63%). Eighteen subjects underwent OLT, while 6 had HR. Median PFS was 35 months (m) (95% C.I. 17–58 m). One- and three-year OS were 95.8% and 73%, respectively. TACE was performed within a mean time of 2.5 months from diagnosis (range 0.5–9 m). Post-TACE, eleven subjects demonstrated a biologic response, defined as decrease in serum alfa-fetoprotein (AFP) by >50%, or reduction in AFP level to <10 ng/mL. However, biologic response did not predict for improved PFS (p =0.41). Additionally, nine patients had a radiographic response to TACE as measured by RECIST criteria, but this also did not predict for improved PFS (p = 0.79). Only tumor size >5 cm (p = 0.04) and CLIP score (p = 0.01) were found to be independent predictors of improved PFS. Conclusions: Neither radiographic nor biologic responses to TACE appear to serve as selection criteria for OLT or HR. Those patients who fail to demonstrate response to TACE should not necessarily be denied surgical therapy. Larger, prospective trials are needed to better evaluate which patients will benefit most from TACE prior to OLT or HR.

No significant financial relationships to disclose.

Predictors of survival after radiofrequency thermal ablation of colorectal cancer metastases to the liver: a prospective study

PURPOSE

The aim of this study was to determine the predictors of survival at the time of radiofrequency thermal ablation (RFA) in patients with colorectal liver metastasis.

PATIENTS AND METHODS

One hundred thirty-five patients with colorectal liver metastases who were not candidates for resection underwent laparoscopic RFA.

RESULTS

The median Kaplan-Meier survival for all patients was 28.9 months after RFA treatment. Patients with a carcinoembryonic antigen (CEA) less than 200 ng/mL had improved survival compared with those with a CEA more than 200 (34 v 16 months; P = .01). Patients with the dominant lesion less than 3 cm in diameter had a median survival of 38 v 34 months for lesions 3 to 5 cm, and 21 months for lesions greater than 5 cm (P = .03). Survival approached significance for patients with one to three tumors versus more than three tumors (29 v 22 months; P = .09). The presence of extrahepatic disease did not affect survival. Only the largest liver tumor size more than 5 cm was found to be a significant predictor of mortality by Cox proportional hazards model, with a 2.5-fold increased risk of death versus the largest liver tumor size less than 3 cm (P = .05).

CONCLUSION

This study determines which patients do best after RFA. Historical survival with chemotherapy alone is 11 to 14 months, suggesting RFA has a positive impact on overall survival. Limited amounts of extrahepatic disease do not appear to affect survival adversely. RFA is a useful adjunct to chemotherapy in those patients with liver-predominant disease.

Phase I trial of weekly docetaxel and gemcitabine in patients with refractory malignancies

BACKGROUND

A Phase I study using weekly docetaxel and gemcitabine was conducted to investigate toxicity; to determine the maximum tolerated dose (MTD) of each agent; and, in a preliminary fashion, to determine the antitumor activity of the combination.

METHODS

Docetaxel and gemcitabine were administered intravenously on Days 1, 8, and 15 every 28 days. The dose levels of docetaxel and gemcitabine were as follows: Level I, docetaxel 20 mg/m(2)and gemcitabine 400 mg/m(2); Level II, docetaxel 30 mg/m(2)and gemcitabine 400 mg/m(2); Level III, docetaxel 30 mg/m(2)and gemcitabine 600 mg/m(2); Level IV, docetaxel 36 mg/m(2)and gemcitabine 600 mg/m(2); and Level V, docetaxel 36 mg/m(2)and gemcitabine 800 mg/m(2).

RESULTS

Thirty-three eligible patients were entered. The diagnoses were as follows: Eleven patients had nonsmall cell lung carcinoma, 3 patients had carcinoma of the bladder, 3 patients had renal carcinoma, 2 patients had adrenal carcinoma, 5 patients had unknown primary tumors, and 9 patients had miscellaneous malignancies. Fifty-nine percent of patients had received prior chemotherapy. The median age was 62 years (range, 27-77 years), and the median Eastern Cooperative Oncology Group performance status was 1 (range, 0-1). Five patients were treated at Dose Levels I and II, 6 patients were treated at Dose Levels III and V, and 11 patients were treated at Dose Level IV. Grade 3-4 toxicities during Cycle I included neutropenia, thrombocytopenia, mucositis, and diarrhea. Dose-limiting toxicity, consisting of neutropenia and thrombocytopenia, occurred in three of six patients at Dose Level V. The combination of docetaxel 36 mg/m(2) and gemcitabine 600 mg/m(2) (Dose Level IV) was determined as the MTD and was the recommended Phase II dose. Two patients had a partial response: one patient with bladder carcinoma (Dose Level II) and one patient with nonsmall cell lung carcinoma (Dose Level III).

CONCLUSIONS

Overall, weekly docetaxel and gemcitabine were well tolerated. Further studies using this combination are planned, including a Phase II trial in patients with advanced nonsmall cell lung carcinoma.

A phase II pharmacodynamic study of pyrazoloacridine in patients with metastatic colorectal cancer

PURPOSE

To perform a phase II trial of pyrazoloacridine (PZA), a novel DNA intercalator, in patients with metastatic colorectal carcinoma and no previous therapy.

METHODS

PZA was administered at a dose of 750 mg/m2 intravenously over 3 h every 21 days. Pharmacokinetic studies to determine PZA plasma concentrations were performed.

RESULTS

No responses were seen in 14 response-evaluable patients. Patients received a median of two cycles of PZA (range 1-6). Toxicity included neutropenia and neurologic side-effects, which were > or = grade III in 73% and 14%, respectively. High plasma concentrations of PZA (Cmax) correlated with low neutrophil counts (P = 0.04).

CONCLUSIONS

PZA is inactive at this dose and schedule in colorectal cancer, and produces moderately severe toxicity.

Phase II trial of liposomal doxorubicin (Doxil) in advanced soft tissue sarcomas

PURPOSE

To assess the objective response rate, toxicity experienced, progression-free survival, and overall survival of patients with previously untreated advanced soft tissue sarcomas treated with a liposomal doxorubicin formulation (Doxil).

METHODS

Patients with metastatic or recurrent soft tissue sarcoma who had received no prior chemotherapy for advanced disease were treated with liposomal doxorubicin (Doxil) according to a two stage accrual design. Doxil was administered at 50 mg/m2 every 4 weeks. A total of 15 patients were treated and are evaluable for response and toxicity.

RESULTS

The male/female ratio was 7/8, the median age was 60 years (34-75) and the ECOG performance status was 0-1 in >90% of patients. Leiomyosarcoma (7/15) and malignant fibrous histiocytoma (2/15) were the most common histologic diagnoses. No objective responses were observed in the 15 evaluable patients. No lethal toxicity occurred. Grade 3-4 leukopenia or neutropenia were reported in 3/15 (20%) patients. Grade 3 mucositis or hand-foot syndrome occurred in 2/15 (13%) and 1/15 (7%) patients respectively and seemed more severe in older patients. The median time to progression was 1.9 months (range 0.9-6.2). Twelve patients have now died. The Kaplan-Meier estimate of median overall survival is 12.3 months. As called for in the study design, accrual was terminated because no responses were obtained in the first 15 patients.

CONCLUSION

Though well-tolerated, Doxil given according to this dose and schedule to patients with advanced soft tissue sarcoma had no significant therapeutic activity. A correlation between older age and skin/mucosal toxicity of Doxil is suggested in this study but needs confirmation. Future investigations of Doxil in soft tissue sarcomas should use a different schedule and dose.

Randomized trial of carboplatin plus amifostine versus carboplatin alone in patients with advanced solid tumors

BACKGROUND

To test the hypothesis that the cytoprotectant amifostine attenuates the thrombocytopenia produced by carboplatin, the authors performed a randomized trial comparing treatment with carboplatin alone versus the combination of amifostine and carboplatin.

METHODS

Patients with refractory or carboplatin-sensitive malignancies were randomized to receive either carboplatin, 500 mg/m2 alone or carboplatin, 500 mg/m2 in conjunction with 2 doses of amifostine of 910 mg/m2 each.

RESULTS

Fifty-five patients with a variety of malignancies were entered on this study. One patient withdrew from each arm prior to the administration of any therapy, leaving 30 evaluable patients treated with carboplatin alone and 23 treated with the combination of amifostine and carboplatin. For 82 cycles of therapy with amifostine plus carboplatin, the median platelet nadir was 127 x 10(9)/L while the median platelet nadir was 88 x 10(9)/L over the 80 courses of therapy with carboplatin alone (P = 0.023). The median platelet nadir after the first cycle of therapy was 144 x 10(9)/L for patients treated with amifostine plus carboplatin and 85 x 10(9)/L for patients treated with carboplatin alone (P = 0.24). The median survival for 9 patients with advanced nonsmall cell lung carcinoma treated with carboplatin alone was 39 weeks whereas the median survival for 12 such patients treated with amifostine plus carboplatin was 52 weeks (P = 0.116).

CONCLUSIONS

These data support the hypothesis that amifostine attenuates the myelosuppression of carboplatin. Additional studies of amifostine in combination with carboplatin-containing chemotherapy regimens are warranted.

Amifostine: potential for clinically useful cytoprotection

The ability to target malignant cells for cytotoxicity while sparing normal host tissues has proven to be limited. These limitations have resulted in unacceptable toxicity or insufficiently effective therapy. Continuing investigation of new, potentially useful cytotoxic agents must continue. An alternative approach, also worthy of study, is the selective protection of normal tissues. This approach, used in conjunction with available therapeutic agents, may open the therapeutic window and incrementally enhance the effectiveness of cytotoxic therapy. A variety of methods have been used to protect normal tissues selectively. Regional protection can be used for certain organ systems, such as the oral mucosa. Selective protection on a systemic level is more difficult but agents that seem to protect normal but not malignant tissues selectively are being developed. Among these is amifostine, which was originally selected by the U.S. defense department for study as a radioprotectant. Pre-clinical studies have suggested that amifostine is differentially concentrated in normal tissues but not in malignant tissues. Tissue-specific differences in the activity of alkaline phosphatase, which dephosphorylates amifostine to its active metabolite WR-1065, and in pH are thought to be involved in this relative specificity. Clinical studies indicate that amifostine can reduce the myelosuppression produced by cyclosphosphamide, the combination of cyclophosphamide and cisplatin, and, perhaps, carboplatin. The protective effects of amifostine on nonhematopoietic toxicities are being investigated. Future trials will investigate the integration of amifostine with cytokine-based supportive care in order to define the role of this potentially clinically useful cytoprotectant agent.

Eradication of neuroblastoma cells in vitro by monoclonal antibody and human complement: method for purging autologous bone marrow

We describe an in vitro method which is useful for purging autologous bone marrow of neuroblastoma cells. The method utilizes a single murine monoclonal antibody 3G6 (an immunoglobulin MK) which we have previously developed against the ganglioside GD2; undiluted human complement; and unfractionated whole bone marrow at 1 X 10(7) nucleated cells/ml. Tumor cell clonogenic assays, Hoechst 33342 fluorescent nuclear stain, and trypan blue viability stain methods were used to assay cytotoxicity. This complement-mediated cytotoxicity technique killed 99.9-100% of neuroblastoma cell lines NMB-7, LAN-1, LAN-5, and IMR-6, while normal marrow precursor cells were not detectably damaged. The presence of normal bone marrow did not inhibit the human complement-mediated cytotoxicity. Applying the cytotoxicity method to whole unseparated bone marrow demonstrated killing of seeded neuroblastoma cells, with no gross hemolysis or cell clumping. The method did not require expensive special equipment, use of animal complement sera, or prior fractionation of the bone marrow. The average marrow nucleated cell recovery was 95%. These studies indicate that in vitro purging of autologous marrow infiltrated with neuroblastoma with monoclonal antibody 3G6 and human complement is both technically feasible and effective in eradicating residual tumor while preserving bone marrow stem cells.

Fluorimetric studies of tryptophyl exposure in concanavalin A

Studies of the iodide ion quenching of the intrinsic fluorescence of Concanavalin A indicate that 50% of the tryptophyl fluorescence originates from exposed residues. This agrees with the X-ray crystallographic determination that two of the four tryptophan residues in a Concanavalin A monomer are on the surface. Previous studies have indicated that conformational changes induced by sugar binding alter the environment of aromatic residues. The present investigation finds that neither the specific binding of alpha-methyl-D-mannoside nor alteration of the Concanavalin A quaternary structure changes the number or accessibility of the solvent-exposed tryptophan residues. It therefore appears that the major conformational transitions in Concanavalin A do not affect steric access to the surface tryptophans and the effects previously observed may be ascribed to structurally internal tryptophan residues.