Recombinant NY‐ESO‐1 Cancer Antigen: Production and Purification under cGMP Conditions

The cancer-testis antigen, NY-ESO-1, has been engineered into a bacterial expression plasmid which incorporates a His6-tag. The plasmid was transfected into E. coli strain BL21 and Master and Working cell banks generated from this expression system. Three 15-litre fermentations were performed under cGMP (code of Good Manufacturing Practice) conditions and the crude NY-ESO-1 tagged protein isolated as solubilised inclusion bodies. A three-step cGMP chromatography process (immobilised metal affinity, anion exchange, and hydrophobic interaction) was utilised to purify the protein. The purified NY-ESO-1 is being used in early stage human cancer vaccine trials in Australia and the U.S.A.

Phase I trial of huA33 antibody plus 5-fluorouracil (5FU), leucovorin, and oxaliplatin in patients with metastatic colorectal cancer [LUD2003–005]

3022

Background: The selective targeting of tumors with monoclonal antibodies (mAb) has emerged as a new therapeutic approach in cancer therapy with the A33 glycoprotein being a promising target in colorectal cancer. Specific tumor localization and low toxicity of a humanised A33 specific mAb (huA33) has previously been demonstrated in patients with colorectal carcinoma. In the present study, we determined the safety and efficacy of the combination of huA33 and 5FU plus leucovorin and oxaliplatin (FOLFOX-4) in patients with metastatic colorectal cancer. Methods: Patients had to present with metastatic colorectal cancer with an expected survival of at least 4 months and no more than 2 different pre-treatment regimens. Patients were excluded if they had previously received oxaliplatin or huA33 mAb. Eligible patients received huA33 (10 mg/m2) by iv infusion weekly for 12 weeks (cycle 1). On study day 15, standard FOLFOX-4 chemotherapy was administered every 2 weeks for 10 weeks. Responding patients received a second cycle of weekly huA33 (10 mg/m2) and biweekly FOLFOX-4 chemotherapy. Results: A total of 19 patients (11 female, 8 male) with a median age of 60 years entered the study. 5 patients had received prior chemotherapy, 2 radiation therapy and 18 surgery. Toxicities observed were as expected for FOLFOX-4 treatment alone with hematological side effects to be most prominent and included (only G3 and G4) 1 anemia and 10 neutropenias. The addition of huA33 to FOLFOX-4 did not change the pattern of known non-hematological toxicities with a low rate (14%) of huA33 mAb associated allergic reactions. One sudden death occurred at cycle five that was neither therapy nor disease related. Within the 16 patients currently available for response assessment, the overall response rate was 38% with 1 CR, 5 PR and 5 disease stabilizations. Conclusion: The combination of FOLFOX-4 as standard chemotherapy for this cohort of patients in combination with the humanized A33 antibody did not increase toxicities and was well tolerated. The overall response rate of 38% is in the response range published so far for the FOLFOX-4 regimen in this setting and warrants further analysis in a larger cohort of patients.

[Table: see text]

Booster vaccination of non-small cell lung cancer (NSCLC) patients with MAGEA3 protein and AS02B adjuvant

3015

Background: We have previously reported results of a phase II trial of recombinant ProtD/MAGE-3/His (MAGEA3) protein 300μg administered IM every three weeks for 4 doses with or without adjuvant AS02B to NSCLC patients following resection of MAGEA3 positive disease (JI, 172:3289, 2004). We found that the presence of adjuvant was essential for the development of strong humoral and cellular responses against selected MAGEA3 epitopes. Methods: 14 of the original 18 patients received booster vaccinations. Patients who still had no evidence of disease for up to two years after receiving their original MAGEA3 protein regimen (7 in cohort 1 without adjuvant, 7 in cohort 2 with adjuvant), received 4 additional doses of MAGEA3 protein with adjuvant. T cell immunomonitoring was extended to encompass any MAGEA3 epitope using full length antigen, and the scope of analysis of humoral responses was widened. Results: After just one boost injection, 6 of the 7 patients originally vaccinated with MAGEA3 protein plus adjuvant reached the peak of antibody titers to MAGEA3 attained during the first vaccination and went on to develop a stronger response than during the first cycle. In addition, the spectrum of CD4+ and CD8+ T cells against various new and known epitopes widened with booster vaccination. In contrast, only 3/7 patients originally vaccinated with MAGEA3 protein alone seroconverted to low-titered MAGEA3 responses and showed very limited CD4+ and no CD8+ T cell reactivity, despite now receiving antigen in the presence of adjuvant. Conclusions: These results underscore the importance of proper antigen priming using an adjuvant for generating persistent B and T cell memory, allowing for typical booster responses with re-immunization. In contrast, absence of adjuvant at priming may compromise further immunization attempts. These data provide immunological rationale for vaccine design in light of recently reported favorable clinical findings in NSCLC patients following vaccination with MAGEA3 protein plus adjuvant AS02B (GSK, ASCO 2005).

No significant financial relationships to disclose.

Phase II trial of vaccination with full length NY-ESO-1/IMX in patients with advanced malignant melanoma

2571

Background: NY-ESO-1 is an immunogenic “cancer-testis” (CT) antigen, expressed in many cancers including melanoma. Iscomatrix adjuvant (IMX), a saponin-based adjuvant, was formulated with NY-ESO-1 (ESO) protein (ESO/IMX). ESO/IMX was highly immunogenic as defined by ESO specific antibody (Ab), delayed type hypersensitivity (DTH) & T-cell responses in patients (pts) with resected ESO+ve cancer. Disease free survival in vaccine recipients with resected melanoma appeared longer than in controls. A prospective evaluation was subsequently undertaken to determine whether ESO/IMX could mediate antitumor responses in pts with advanced NY ESO-1+ve melanoma. Methods: 27 pts were vaccinated in a trial designed to assess objective clinical responses, safety, & immunogenicity. Vaccination consisted of 100 μg ESO/IMX administered q 4 wk × 3; this cycle was repeated in pts without symptomatic progression unless they required other treatment. Pts were then eligible to continue vaccination q12 weeks so long as they were responding or stable. Results: ESO/IMX was well tolerated. 13 pts progressed when evaluated after the first cycle at week 11. No objective clinical responses were seen. Vaccine-induced antibody titers to NY-ESO-1 were comparable to those seen in the earlier minimal residual disease trial (ranging to > 1: 390,000). DTH & T-cell responses were less marked. This occurred despite many pts with advanced measurable disease having pre-existing spontaneous ESO immunity ( Table ). DTH responses were seen in 11 pts; 5 had pre-existing responses (2 were boosted) and 6 were induced. The DTH responses were lost by week 33. Conclusion: No objective responses were seen. Vaccine-induced immunity appeared to be attenuated in the presence of advanced metastatic disease. Ongoing laboratory studies are investigating the role of regulatory T cells in the suppression of ESO-specific immunity in these pts with a view to adopting strategies to counter regulatory responses e.g. low-dose cyclophosphamide prior to vaccination.

[Table: see text]

[Table: see text]

Specific targeting, biodistribution, and lack of immunogenicity of chimeric anti-GD3 monoclonal antibody KM871 in patients with metastatic melanoma: results of a phase I trial

PURPOSE

KM871 is a chimeric monoclonal antibody against the ganglioside antigen GD3, which is highly expressed on melanoma cells. We conducted an open-label, dose escalation phase I trial of KM871 in patients with metastatic melanoma.

PATIENTS AND METHODS

Seventeen patients were entered onto one of five dose levels (1, 5, 10, 20, and 40 mg/m2). Patients received three infusions of KM871 at 2-week intervals, with the first infusion of KM871 trace-labeled with indium-111 (111In) to enable assessment of biodistribution in vivo. Biopsies of metastatic melanoma sites were performed on days 7 to 10.

RESULTS

Fifteen of 17 patients completed a cycle of three infusions of KM871. No dose-limiting toxicity was observed during the trial; the maximum-tolerated dose was therefore not reached. Three patients (at the 1-, 5-, and 40-mg/m2 dose levels) developed pain and/or erythema at tumor sites consistent with an inflammatory response. No normal tissue uptake of 111In-KM871 was observed, and tumor uptake of 111In-KM871 was observed in all lesions greater than 1.5 cm (tumor biopsy 111KM871 uptake results: range, 0.001% to 0.026% injected dose/g). The ratio of maximum tumor to normal tissue was 15:1. Pharmacokinetic analysis revealed a 111In-KM871 terminal half-life of 7.68 +/- 2.94 days. One patient had a clinical partial response that lasted 11 months. There was no serologic evidence of human antichimeric antibody in any patient, including one patient who received 16 infusions over a 12-month period.

CONCLUSION

This study is the first to demonstrate the biodistribution and specific targeting of an anti-GD3 antibody to metastatic melanoma in patients. The long half-life and lack of immunogenicity of KM871 makes this antibody an attractive potential therapy for patients with metastatic melanoma.

Filgrastim in patients with chemotherapy-induced febrile neutropenia. A double-blind, placebo-controlled trial

OBJECTIVE

To determine if filgrastim (recombinant human methionyl granulocyte colony-stimulating factor) used in addition to standard inpatient antibiotic therapy accelerated recovery from infection associated with chemotherapy-induced neutropenia.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

Hematology and oncology wards of four teaching hospitals.

PATIENTS

218 patients with cancer who had fever (temperature > 38.2 degrees C) and neutropenia (neutrophil count < 1.0 x 10(9)/L) after chemotherapy.

INTERVENTION

Patients were randomly assigned to receive filgrastim (12 micrograms/kg of body weight per day) (n = 109) or placebo (n = 107) beginning within 12 hours of empiric therapy with tobramycin and piperacillin. Patients received treatment and remained in the study until the neutrophil count was greater than 0.5 x 10(9)/L and until 4 days without fever (temperature < 37.5 degrees C) had elapsed.

MEASUREMENTS

Days of neutropenia and fever and days in the study (hospitalization); time to resolution of fever and febrile neutropenia; and frequency of the use of alternative antibiotics.

RESULTS

Compared with placebo, filgrastim reduced the median number of days of neutropenia (3.0 compared with 4.0 days of a neutrophil count of < 0.5 x 10(9)/L; P = 0.005) and the time to resolution of febrile neutropenia (5.0 compared with 6.0 days; P = 0.01) but not days of fever (3.0 days for both groups). The frequency of the use of alternative antibiotics was similar in the two groups (46% compared with 41%; P = 0.48). The median number of days patients were hospitalized while on study was the same (8.0 days; P = 0.09); however, filgrastim decreased the risk for prolonged hospitalization (> 11 days, 4th quartile) by half (relative risk, 2.1 [95% CI, 1.1 to 4.1]; P = 0.02). In exploratory subset analyses, filgrastim appeared to provide the greatest benefit in patients with documented infection and in patients presenting with neutrophil counts of less than 0.1 x 10(9)/L.

CONCLUSIONS

Filgrastim treatment used with antibiotics at the onset of febrile neutropenia in patients with cancer who have received chemotherapy accelerated neutrophil recovery and shortened the duration of febrile neutropenia.

A prospective evaluation of therapeutic drug monitoring

Since therapeutic drug monitoring is rapidly becoming a widely used tool in clinical medicine, we prospectively assessed 390 serum drug assays over a 4-week period to determine the appropriateness of serum sample collection. The results of appropriately collected samples were used to evaluate the ability of the physician to interpret and apply this information. Of the 244 samples evaluated in the study, 104 (43%) were inappropriately collected. The physician apparently misapplied the results in 40 of 101 (40%) instances. When combined, this represented a misuse of therapeutic drug monitoring 70% of the time and documented an unjustifiable expense of $3,600 for the 4 weeks. The magnitude of misuse of this tool warrants the implementation of measures to assure appropriate serum sampling and application of therapeutic drug monitoring.

Basics of cardiovascular hemodynamic monitoring

The usefulness of invasive hemodynamic monitoring is being continuously demonstrated and plays a major role in the advances in critical care medicine. Minute-to-minute monitoring generates continuous information to which the clinician must respond, often with potent pharmacologic agents requiring further monitoring and continued reevaluation. By understanding the concepts of hemodynamic monitoring, the clinical pharmacist in the critical care environment can play an important role in the selection and use of these agents. Further discussions on the usefulness of various pharmacologic agents used in critical care medicine may be found in future issues of this column.