Vaccines in oncology: background and clinical potential

Intra-tumoral gene delivery of feIL-2, feIFN-gamma and feGM-CSF using magnetofection as a neoadjuvant treatment option for feline fibrosarcomas: a phase-I study

Despite aggressive pre- or postoperative treatment, feline fibrosarcomas have a high relapse rate. In this study, a new treatment option based on immune stimulation by intra-tumoral delivery of three feline cytokine genes was performed. The objective of this phase-I dose-escalation study was to determine a safe dose for further evaluation in a subsequent phase-II trial. Twenty-five client-owned cats with clinical diagnosis of fibrosarcoma - primary tumours as well as recurrences - entered the study. Four increasing doses of plasmids coding for feIL-2, feIFN-gamma or feGM-CSF, respectively, were previously defined. In groups I, II, III and IV these doses were 15, 50, 150 and 450 microg per plasmid and a corresponding amount of magnetic nanoparticles. Two preoperative intra-tumoral injections of the magnetic DNA solution were followed by magnetofection. A group of four control cats received only surgical treatment. Side effects were registered and graded according to the VCOG-CTCAE scale and correlated to treatment. Statistical analyses included one-way anova, post hoc and Kruskal-Wallis tests. ELISA tests detecting plasma feIFN-gamma and plasma feGM-CSF were performed. One cat out of group IV (450 microg per plasmid) showed adverse events probably related to gene delivery. As these side effects were self-limiting and occurred only in one of eight cats in group IV, this dose was determined to be well tolerable. Altogether six cats developed local recurrences during a 1-year observation period. Four of these cats had been treated with dose IV. Regarding these observations, a subsequent phase-II trial including a representative amount of cats should be tested for the efficacy of dose IV as well as dose III.

GM-CSF enhances protective immunity to cottontail rabbit papillomavirus E8 genetic vaccination in rabbits

We have reported previously that cottontail rabbit papillomavirus (CRPV) E8 gene immunization induced strong protection against virus challenge. In this study, we primed E8 gene vaccination with mouse granulocyte-macrophage colony-stimulating factor (mGM-CSF), a cytokine that induces differentiation and local recruitment of professional antigen-presenting cells. EIII/JC inbred rabbits were divided into four groups receiving vaccinations with the following constructs: mGM-CSF plus E8, mGM-CSF only, E8 only and vector only. After three immunizations at intervals of 3 weeks, rabbits were challenged with viral DNA at six scarified sites. Papillomas grew on all vaccinated rabbits 4 weeks after inoculation. At week 5, papillomas on four rabbits of mGM-CSF plus E8 and one of E8 only rabbits began to regress. At week 11, all the papillomas on rabbits in the GM-CSF plus E8 vaccination group regressed (regression rate = 100%); regression rates of the mGM-CSF only and E8 only vaccination groups were 50 and 25%, respectively. All papillomas on the vector immunized rabbits remained persistent until the end of the experiment (0%). Antibodies to mGM-CSF were detected in rabbit serum by Western blot. Rabbits vaccinated with E8 plus mGM-CSF or E8 only group had positive Delayed-type hypersensitivity (DTH) skin test to different E8 peptides. These results demonstrated that mGM-CSF could enhance the effects of E8 immunization in rabbits to CRPV infection through cell-mediated immune responses.

Adjuvant autologous renal tumour cell vaccine and risk of tumour progression in patients with renal-cell carcinoma after radical nephrectomy: phase III, randomised controlled trial

BACKGROUND

Organ-confined renal-cell carcinoma is associated with tumour progression in up to 50% of patients after radical nephrectomy. At present, no effective adjuvant treatment is established. We aimed to investigate the effect of an autologous renal tumour cell vaccine on risk of tumour progression in patients with stage pT2-3b pN0-3 M0 renal-cell carcinoma.

METHODS

Between January, 1997, and September, 1998, 558 patients with a renal tumour scheduled for radical nephrectomy were enrolled at 55 institutions in Germany. Before surgery, all patients were centrally randomised to receive autologous renal tumour cell vaccine (six intradermal applications at 4-week intervals postoperatively; vaccine group) or no adjuvant treatment (control group). The primary endpoint of the trial was to reduce the risk of tumour progression, defined as progression or death. All patients were assessed after standardised diagnostic investigations at 6-month intervals for a minimum of 4.5 years.

FINDINGS

By preoperative and postoperative inclusion criteria, 379 patients were assessable for the intention-to-treat analysis. At 5-year and 70-month follow-up, the hazard ratios for tumour progression were 1.58 (95% CI 1.05-2.37) and 1.59 (1.07-2.36), respectively, in favour of the vaccine group (p=0.0204, log-rank test). 5-year and 70-month progression-free survival rates were 77.4% and 72%, respectively, in the vaccine group and 67.8% and 59.3%, respectively, in the control group. The vaccine was well tolerated, with only 12 adverse events associated with the treatment.

INTERPRETATION

Adjuvant treatment with autologous renal tumour cell vaccine in patients with renal-cell carcinoma after radical nephrectomy seems to be beneficial and can be considered in patients undergoing radical nephrectomy due to organ-confined renal-cell carcinoma of more than 2.5 cm in diameter.

Tumor markers and colorectal cancer: utility in management

Colorectal cancer (CRC) is a leading cause of morbidity and mortality. Although genetic testing can screen for rare hereditary CRC syndromes, there is no ideal means of screening for sporadic forms of CRC. This review will focus on markers that are currently used in the management of sporadic CRC and their limitations, as well as possible future clinical applications.

CEA-based vaccines

Carcinoembryonic antigen (CEA), the first tumor-associated antigen to be described, was cloned in 1987 and is expressed on nearly 50% of all human tumors. The identification of T-cell specific epitopes within the coding region of the CEA protein has led to the development of various vaccine strategies that target CEA and CEA-expressing tumors. These vaccines have shown evidence of therapeutic effectiveness in animal models and are being evaluated in early phase clinical trials. Although trials are not designed to elucidate clinical responses, they have provided important information about the ability of individual vaccines to induce CEA-specific immune responses through the use of newer in vitro monitoring assays. Continued clinical testing in patients with less advanced disease and the administration of vaccines in combination with other standard therapy will help define the role of CEA-based vaccines in the treatment and prevention of human cancer.