Strong vaccine responses during chemotherapy are associated with prolonged cancer survival

Therapeutic cancer vaccines have effectively induced durable regressions of premalignant oncogenic human papilloma virus type 16 (HPV16)-induced anogenital lesions. However, the treatment of HPV16-induced cancers requires appropriate countermeasures to overcome cancer-induced immune suppression. We previously showed that standard-of-care carboplatin/paclitaxel chemotherapy can reduce abnormally high numbers of immunosuppressive myeloid cells in patients, allowing the development of much stronger therapeutic HPV16 vaccine (ISA101)-induced tumor immunity. We now show the clinical effects of ISA101 vaccination during chemotherapy in 77 patients with advanced, recurrent, or metastatic cervical cancer in a dose assessment study of ISA101. Tumor regressions were observed in 43% of 72 evaluable patients. The depletion of myeloid suppressive cells by carboplatin/paclitaxel was associated with detection of low frequency of spontaneous HPV16-specific immunity in 21 of 62 tested patients. Patients mounted type 1 T cell responses to the vaccine across all doses. The group of patients with higher than median vaccine-induced immune responses lived longer, with a flat tail on the survival curve. This demonstrates that chemoimmunotherapy can be exploited to the benefit of patients with advanced cancer based on a defined mode of action.

Evaluation of pharmacodynamic (PD) and biologic activity in a preoperative window-of-opportunity (WOO) study of giredestrant (GDC-9545) in postmenopausal patients (pts) with estrogen receptor-positive, HER2-negative (ER+/HER2–) operable breast cancer (BC)

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Background: Modulation of ER activity and/or estrogen synthesis is the mainstay therapeutic strategy in ER+ BC treatment. Giredestrant is a highly potent, nonsteroidal oral selective ER degrader (SERD) that achieves robust ER occupancy and is effective regardless of ESR1 mutation status. The first short-term preoperative WOO study (NCT03916744) of giredestrant in ER+/HER2– operable BC was designed for dose selection, while providing an early readout of PD as measured by traditional immunohistochemistry (IHC) and transcriptional profiling by assessing treatment effects in paired tumor tissue pre/posttreatment. We present an interim analysis. Methods: Pts were assigned to 14 days’ preoperative treatment with 10, 30, or 100 mg PO giredestrant QD. Pts had newly diagnosed, stage I–III operable, ER+/HER2– untreated BC ≥1.5 cm in diameter (by ultrasound). Modulation of ER signaling and cell proliferation were assessed using paired formalin-fixed paraffin-embedded tumor specimens collected before and after ̃14 days of study treatment. ER, progesterone receptor (PR), and Ki67 protein levels were analyzed by IHC. Change from baseline in tumor cell proliferation by Ki67 was the primary endpoint. Gene expression analysis was performed using the Illumina TruSeq RNA Access method. Results: From Jul 26, 2019 to Oct 15, 2020, 46/75 biomarker-evaluable pts were enrolled across three dose cohorts (10 mg: n = 15; 30 mg: n = 18; 100 mg: n = 13). Pt demographics and tumor characteristics were similar across cohorts. Baseline PAM50 analysis classified tumors as Luminal A (77%) or B (23%). Giredestrant treatment resulted in robust and indistinguishable PD and biologic activity at all doses. Geometric mean posttreatment proportional reduction of Ki67 was 79% (95% CI: 69–89; 10 mg: 80%; 30 mg: 76%; 100 mg: 80%), and 51% of tumors exhibited complete cell cycle arrest, defined as Ki67 ≤2.7%. Mean posttreatment proportional reductions of ER and PR H-scores were 71% (95% CI: 67–75) and 60% (95% CI: 51–70), respectively. An analysis of a predefined, experimentally derived set of 38 ER target genes (the ‘ER activity signature’), was completed for 42 paired tumor specimens. Forty-one of 42 pts (98%) showed a posttreatment reduction in ER activity with a mean proportional decrease of 79% (95% CI: 70–88). A wide range of baseline ER activity was observed with no correlation to baseline ER or PR H-score, or Ki67. There were no discontinuations due to adverse events (AEs). A single grade 3 serious AE was reported in each cohort (all assessed as unrelated to giredestrant). No grade 4 or 5 AEs were reported. Conclusions: Giredestrant was well tolerated in the preoperative setting in ER+/HER2– operable BC, and PDs were consistent with the 30 mg dose achieving maximal ER inhibition. Clinical trial information: NCT03916744.

Abstract CT002: A strong HPV-specific T-cell response after chemo-immunotherapy for advanced cervical cancer is associated with prolonged survival

The therapeutic synthetic long peptide (SLP) vaccine ISA101 selectively enlarges the pool of tumor-specific T cells recognizing the human papillomavirus type 16 (HPV16) antigens E6 and E7. Vaccine monotherapy for HPV16-induced pre-malignant anogenital lesions is effective, inducing durable complete regressions in approximately 50% of treated patients. However, cancer treatment requires appropriate countermeasures to overcome the suppression of T-cell activation, expansion and effector function imposed by suppressive myeloid cell populations, regulatory T cells and co-inhibitory molecule expression. We recently showed that carboplatin/paclitaxel chemotherapy can normalize the abnormally high levels of immune suppressive myeloid cells, allowing the development of much stronger therapeutic ISA101-induced tumor immunity1. Here we show the effects of ISA101 vaccination during chemotherapy in 77 patients with advanced, recurrent or metastatic cervical cancer in a dose assessment study. Study design involved a single arm dose escalation study with four different ISA101 doses (20, 40, 100 and 300 µg per peptide) with or without immunomodulator pegylated interferon alpha (Pegitron), given concomitantly with standard of care chemotherapy (carboplatin, AUC 6; paclitaxel, 175 mg/m2). Objective regressions were observed in 43% of 72 evaluable patients. The depletion of myeloid suppressive cells by carboplatin/paclitaxel was associated with detection of low level spontaneous HPV16-specific immunity in 26 of the 61 tested patients. Patients mounted type 1 T-cell responses to the vaccine across all doses. No significant differences were observed between the different doses and strength of vaccine-induced T cell responses; the results were therefore combined. Patients with an above median HPV16-specific T cell immune response to ISA101, measured by a validated IFNγ-Elispot, displayed a significantly prolonged median overall survival (OS) of 16.8 months compared to those with a lower HPV-specific immune response (OS 11.2 months, logrank p=0.012). Importantly, this effect was not due to differences in general immune status, as measured by T-cell reactivity to unrelated common microbial recall

antigens. In conclusion, our study demonstrates that chemo-immunotherapy can be exploited to the benefit of patients with cervical cancer and warrants confirmation of the benefit of this type of chemo-immunotherapy in a randomized controlled study in HPV16-induced cancer patients.

1Welters, M. J. et al. Vaccination during myeloid cell depletion by cancer chemotherapy fosters robust T cell responses. Sci Transl Med 8, 334ra352, doi:10.1126/scitranslmed.aad8307 (2016).

Citation Format: Cornelis J M Melief, Marij J. Welters, Ignace Vergote, Judith R. Kroep, Gemma G. Kenter, Nelleke Ottevanger, Wiebren A. Tjalma, Hannelore Denys, Mariette van Poelgeest, Hans W. Nijman, Anna K. Reyners, Thierry Velu, Frederic Goffin, Roy Lalisang, Willem-Jan Krebber, Leon Hooftman, Sonja Visscher, Brent A. Blumenstein, Richard B. Stead, Winald Gerritsen, Sjoerd van der Burg. A strong HPV-specific T-cell response after chemo-immunotherapy for advanced cervical cancer is associated with prolonged survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT002.

Efficient Early and Sustained Transduction of Human Fetal Mesencephalon Using Adeno-Associated Virus Type 2 Vectors

The success of transplantation of human fetal mesencephalic tissue into the putamen of patients with Parkinson's disease (PD) is still limited by the poor survival of the graft. In animal models of fetal transplantation for PD, antiapoptotic agents, such as growth factors or caspase inhibitors, or agents counteracting oxidative stress enhance the survival and reinnervation potential of the graft. Genetic modification of the transplant could allow a local and continuous delivery of these factors at physiologically relevant doses. The major challenge remains the development of strategies to achieve both early and sustained gene delivery in the absence of vector-mediated toxicity. We recently reported that E14 rat fetal mesencephalon could be efficiently tranduced by adeno-associated virus type 2 (AAV2) vectors and that gene expression was maintained until at least 3 months after transplantation in the adult rat striatum. Here we report that an AAV2 vector can mediate the expression of the EGFP reporter gene under the control of a CMV promoter in organotypic cultures of freshly explanted solid fragments of human fetal mesencephalic tissue as early as 3 days to at least 6 weeks postinfection. These results suggest that AAV2 vectors could be used to genetically modify the human fetal tissue prior to transplantation to Parkinson's patients to promote graft survival and integration.

Abstract P4-22-22: Cobimetinib (C) combined with paclitaxel (P) as a first-line treatment in patients (pts) with advanced triple-negative breast cancer (COLET study): Updated clinical and biomarker results

Resistance to standard taxane-based chemotherapy is common in triple-negative breast cancer (TNBC). Mutations and gene amplifications in the MAPK pathway that upregulate MAPK signaling are present in many TNBC tumors. Upregulation of the MAPK signaling pathway can result in degradation of the pro-apoptotic protein BIM and upregulation of anti-apoptotic proteins, including BCL-2, BCL-XL, and MCL-1, thus promoting cell survival and desensitizing tumor cells to the pro-apoptotic effects of taxane chemotherapy. Updated data on clinical safety and efficacy are presented along with biomarker data evaluating the effects of treatment on induction of apoptosis.The COLET study (ClinicalTrials.gov ID, NCT02322814; EudraCT number, 2014-002230-32) consisted of a safety run-in (n∼12) followed by a blinded 1:1 randomized expansion stage (n∼90) to C + P or placebo (PBO) + P. The safety stage is complete and the randomized stage is enrolling pts. Two additional cohorts investigating the effect of adding atezolizumab will be recruiting and are out of scope of this submission. Pts in cohort I were treated with P 80 mg/m2 on days 1, 8, and 15 and C/PBO 60 mg/day on days 3–23 of each 28-day cycle until disease progression or unacceptable toxicity. Gene expression and apoptotic index were measured by RNA-Seq and TUNEL staining, respectively, to assess the biologic activity of C + P.Sixteen women (median age, 55.5 years) were enrolled in the safety run-in stage. At data snapshot (April 22, 2016), all 16 pts had received ≥1 dose of study treatment. Median time on treatment was 116 days (range, 7-336) for C and 84 days (range, 0-351) for P. Fifteen (94%) pts had ≥1 adverse event (AE); 5 (31%) pts had grade 1/2 AEs and 10 (63%) pts had grade 3 AEs (Table). No pts experienced grade 4–5 AEs. Among the 16 safety run-in patients, responses to date include partial response (PR; n = 8 [50.0%]), stable disease (SD, n = 4 [25.0%]), and progressive disease (n = 2 [12.5%]), as well as 2 pts with no post-baseline tumor assessment. Six pts maintained a PR at ∼20 weeks and three maintained a PR at ≥40 weeks. To date, matched pre- and on-treatment biopsies were evaluable for 2 pts, 1 with a PR and 1 with SD. In the patient who attained a PR, increased expression of pro-apoptosis genes, including BIM, was observed; but this was not seen in the patient experiencing SD. The PR patient also had an increase in apoptotic index. Updated biomarker data will be reported.This is the first study to evaluate C + P in TNBC. The safety profile of C + P is consistent with that of known safety profiles. Efficacy and safety will be further evaluated in the ongoing randomized stage.

Most common (any grade ≥20%) AEsTreatment-emergent AEs, n (%)C + P (safety run-in stage), N = 16 All gradesGrade 3Diarrhea10 (63)1 (6)Rash8 (50)0Nausea7 (44)0Alopecia5 (31)0Blood CPK level increase5 (31)1 (6)Stomatitis4 (25)2 (13)Asthenia4 (25)1 (6)Constipation4 (25)0Dyspnea4 (25)0Edema peripheral4 (25)0Pyrexia4 (25)0Vomiting4 (25)0AEs, adverse events; C, cobimetinib; CPK, creatinine phosphokinase; P, paclitaxel.

Citation Format: Brufsky A, Kim S-B, Velu T, García-Saenz JA, Tan-Chiu E, Sohn JH, Dirix L, Borms MV, Liu M-C, Moezi MM, Kozloff MF, Sparano JA, Xu N, Wongchenko M, Simmons B, McNally V, Miles D. Cobimetinib (C) combined with paclitaxel (P) as a first-line treatment in patients (pts) with advanced triple-negative breast cancer (COLET study): Updated clinical and biomarker results [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-22-22.

Survival benefit of adding Hyperthermic IntraPEritoneal Chemotherapy (HIPEC) at the different time-points of treatment of ovarian cancer: review of evidence

The standard treatment for advanced ovarian cancer consists in complete cytoreductive surgery (CRS) and intravenous combination chemotherapy with a platinum compound and a taxane. Although response rates to initial therapy are high, many patients will recur and die of peritoneal carcinomatosis. The addition of Hyperthermic IntraPEritoneal Chemotherapy (HIPEC) to the standard therapy aims at increasing survival by reducing peritoneal recurrence. This review describes the survival results of HIPEC at the different time-points of the treatment of ovarian cancer: at upfront CRS, at interval CRS, at consolidation CRS after complete response to initial therapy, at secondary CRS after incomplete response, at salvage CRS for recurrence and as palliative treatment without CRS for unresectable ovarian cancer with chemotherapy resistant ascites. The available evidence suggests that a potential survival benefit of adding HIPEC may be largest in the settings of secondary CRS for stage III ovarian cancer and salvage CRS for recurrent ovarian cancer, two time-points representing failure of initial standard therapy. There is much less evidence for a potential benefit of HIPEC for less advanced stages (I-II) and for earlier time-points in the treatment of ovarian cancer (upfront, interval and consolidation). Postoperative mortality is not higher after CRS and HIPEC (0.7%) than after CRS only (1.4%). Four randomised trials are ongoing and their results are eagerly awaited. Palliative HIPEC without CRS might be used more in patients with incapacitating ascites due to recurrent ovarian cancer which has become resistant to systemic chemotherapy.

Interleukin-10: actions and therapeutic potential

Interleukin-10 (IL-10) is a potent anti-inflammatory and immunosuppressive cytokine secreted by several cell types. Most anti-inflammatory effects of IL-10 are caused by its ability to deactivate macrophages and monocytes, whereas its immunosuppressive properties are due to functional inhibition of both antigen-presenting cells and T cells. On the other hand, IL-10 also exerts immunostimulatory effects, especially on B cells, CD8+ cytotoxic T cells and natural killer cells. In vivo administration of recombinant IL-10 (rIL-10) efficiently prevents experimental septic shock induced by endotoxin, staphylococcal superantigen or cecal ligation and puncture, as well as experimental autoimmune diseases mediated by T helper type 1 (T(H)1) cells and other inflammatory disorders. rIL-10 exerts paradoxical effects in cancer models, where it promotes tumour rejection, probably due to its stimulatory properties on cytotoxic cells. On the other hand, rIL-10 increases the severity of experimental infections caused by fungi or bacteria, and enhances systemic autoimmune features in mice with spontaneous lupus syndrome. Although the therapeutic potential of rIL-10 in human diseases seems promising, the multiple facets of rIL-10 in experimental immunopathology indicate that the success of clinical trials with rIL-10 will depend both on the appropriate selection of the patient populations to be treated and on the early detection of possible adverse effects.

A phase II study of the cancer vaccine TG4010 alone and in combination with cytokines in patients with metastatic renal clear-cell carcinoma: clinical and immunological findings

MUC1 over-expression in renal clear-cell carcinoma (RCC) is associated with poor prognosis. This phase II study determined the efficacy and tolerability of TG4010, a cancer vaccine based on a modified vaccinia virus expressing MUC1 and interleukin-2, in combination with cytokines, as first-line therapy in metastatic RCC. Thirty-seven patients with progressive, MUC1-positive RCC received TG4010 10(8) pfu/inj weekly for 6 weeks, then every 3 weeks until progression, when TG4010 was continued in combination with interferon-α2a and interleukin-2. Assessments included clinical response (primary endpoint), safety, time to treatment failure (TTF), overall survival (OS), and immune response. No objective clinical responses occurred. Five of the 27 evaluable patients (18%) had stable disease for >6 months with TG4010 alone and six of 20 patients (30%) had stable disease for >6 months with TG4010 plus cytokines. Median TTF was 4.1, 3.6, and 9.3 months for monotherapy, combination therapy, and overall, respectively. Median OS was 19.3 months for all patients and 22.4 months combination therapy recipients. The most frequent TG4010-related adverse events were minor-to-moderate injection-site reactions, fatigue, and flu-like symptoms. Six of 28 patients showed a MUC1 CD4+ T cell proliferative response during therapy. Anti-MUC1 CD8+ T cells were detected before and after therapy in 3 and 4 patients, respectively. MUC1-specific CD8+ T cell responses were associated with longer survival. Therapy with TG4010 plus cytokines appears to be feasible and well tolerated in patients with metastatic RCC. However, these data should be interpreted with caution, as additional prospective studies are necessary to clarify the clinical efficacy of this therapy.

Development of a successful antitumor therapeutic model combining in vivo dendritic cell vaccination with tumor irradiation and intratumoral GM-CSF delivery

Vaccination of dendritic cells (DC) combined with GM-CSF secreting tumor cells has shown good therapeutic efficacy in several tumor models. Nevertheless, the engineering of GM-CSF secreting tumor cell line could represent a tedious step limiting its application for treatment in patients. We therefore developed in rats, an "all in vivo" strategy of combined vaccination using an in vivo local irradiation of the tumor as a source of tumor antigens for DC vaccines and an exogenous source of GM-CSF. We report here that supplying recombinant mGM-CSF by local injections or surgical implantation of osmotic pumps did not allow reproducing the therapeutic efficacy observed with in vitro prepared combined vaccines. To bypass this limitation possibly due to the short half-life of recombinant GM-CSF, we have generated adeno-associated virus coding for mGM-CSF and tested their efficacy to transduce tumor cells in vitro and in vivo. The in vivo vaccines combining local irradiation and AAV2/1-mGM-CSF vectors showed high therapeutic efficacy allowing to cure 60% of the rats with pre-implanted tumors, as previously observed with in vitro prepared vaccines. Same efficacy has been observed with a second generation of vaccines combining DC, local tumor irradiation, and the controlled supply of recombinant mGM-CSF in poloxamer 407, a biocompatible thermoreversible hydrogel. By generating a successful "all in vivo" vaccination protocol combining tumor radiotherapy with DC vaccines and a straightforward supply of GM-CSF, we have developed a therapeutic strategy easily translatable to clinic that could become accessible to a much bigger number of cancer patients.

Generation of immature autologous clinical grade dendritic cells for vaccination of cancer patients

BACKGROUND

Dendritic cell (DC)-based vaccine is a promising approach for cancer therapy. Pioneer trials have been conducted using DC generated in research conditions. There is now a need for generating DC in clinical grade conditions, including the use of closed systems, avoidance of FCS and respect of good manufacturing practices (GMP).

METHODS

DC were generated from 84 leukapheresis products of 27 cancer patients enrolled in two Phase I/II trials of vaccination of either MAGE+tumors (n = 24) or prostate cancer (n = 3). Monocytes were seeded in culture bags in a serum-free medium supplemented with IL-4 and GM-CSF. After a 7 day culture, DC were collected and most were pulsed with various MAGE-derived peptides.

RESULTS

After a short leukapheresis (mean time: 66 min; mean processed blood: 5 L), a mean of 6 x 10(9) WBC were collected, from which 2.25 x 10(9) were seeded. The culture procedure yielded a large number of DC (mean: 62 x 10(6) DC) harboring the expected phenotype of immature DC (CD1a(+) CD14(-) HLA-DR(+) CD80(+) CD86(+) CD83(-)). This phenotype was not altered by peptide loading. These DC, either fresh or thawed, were functionally effective invitro. Their s.c. and i.v. injections were devoid of any short-term side effect and associated with the induction of immune responses in the patients.

DISCUSSION

Large numbers of functional immature clinical grade DC can be generated in a closed system from leukapheresis products in cancer patients. These results provide the basis for large-scale studies of cancer immunotherapy under improved safety conditions.

Therapeutic efficacy of antitumor dendritic cell vaccinations correlates with persistent Th1 responses, high intratumor CD8+ T cell recruitment and low relative regulatory T cell infiltration

Despite the increasing number of immunotherapeutic strategies for the treatment of cancer, most approaches have failed to correlate the induction of an anti-tumor immune response with therapeutic efficacy. We therefore took advantage of a successful vaccination strategy-combining dendritic cells and irradiated GM-CSF secreting tumor cells-to compare the immune response induced against 9L gliosarcoma tumors in cured rats versus those with progressively growing tumors. At the systemic level, the tumor specific cytotoxic responses were quite heterogeneous in uncured vaccinated rats, and were surprisingly often high in animals with rapidly-growing tumors. IFN-gamma secretion by activated splenic T cells was more discriminative as the CD4+ T cell-mediated production was weak in uncured rats whereas high in cured ones. At the tumor level, regressing tumors were strongly infiltrated by CD8+ T cells, which demonstrated lytic capacities as high as their splenic counterparts. In contrast, progressing tumors were weakly infiltrated by T cells showing impaired cytotoxic activities. Proportionately to the T cell infiltrate, the expression of Foxp3 was increased in progressive tumors suggesting inhibition by regulatory T cells. In conclusion, the main difference between cured and uncured vaccinated animals does not depend directly upon the induction of systemic cytotoxic responses. Rather the persistence of higher CD4+ Th1 responses, a high intratumoral recruitment of functional CD8+ T cells, and a low proportion of regulatory T cells correlate with tumor rejection.

Apoptosis-related mitochondrial dysfunction defines human monocyte-derived dendritic cells with impaired immuno-stimulatory capacities

The death of dendritic cells (DCs) can potentially influence immune responses by affecting the duration of DC stimulation of lymphocytes. Here, we report that cultured mature monocyte-derived DCs manifest early mitochondrial damage (i.e. within 24 hrs), characterized by mitochondrial membrane potential (ψΔm) disruption and mitochondrial release of pro-apoptotic factors, followed by reactive oxygen species (ROS) production and activation of caspases. Afterwards, DCs with mitochondrial alterations are condemned to undergo apoptosis and necrosis. Macroarray analysis results (validated by real time quantitative-PCR (QRT-PCR) and immunoblotting), showed up-regulation of the pro-apoptotic member of the Bcl-2 family, Bim, while expression of several anti-apoptotic molecules was down-regulated. Importantly, pre-apoptotic DCs (characterized by a low Δψm) showed a modified phenotype, with down-regulation.of HLA-DR and of the co-stimulatory molecules CD80 and CD86. Moreover, sorted viable low ψΔm DCs were unable to activate allogeneic T cells, indicating that pre-apoptotic DCs have already lost some of their immuno-stimulatory capabilities long before any detectable signs of death occur. Perturbations to mitochondrial respiration with rotenone identified the same modifications to DC immune functions. These data indicate a strong requirement for mitochondrial integrity for the immuno-stimulatory capacities of DC. Determining ΔΨm could be a useful parameter to select ‘fully’ functional DCs for anti-tumour vaccines.

Overexpression of mouse IsK protein fused to green fluorescent protein induces apoptosis of human astroglioma cells

Intracellular K(+) plays an important role in controlling ion homeostasis for maintaining cell volume and inhibiting activity of pro-apoptotic enzymes. Cytoplasmic K(+) concentration is regulated by K(+) uptake via Na(+) -K(+) -ATPase and K(+) efflux through K(+) channels in the plasma membrane. The IsK (KCNE1) protein is known to co-assemble with KCNQ1 (KvLQT1) protein to form a K(+) channel underlying the slowly activating delayed rectifier K(+) outward current which delays voltage activation. In order to further study the activity and cellular localization of IsK protein, we constructed a C-terminal fusion of IsK with EGFP (enhanced green fluorescent protein). Expression of the fusion protein appeared as clusters located in the plasma membrane and induced degeneration of both transiently or stably transfected cells.

Skin biopsies in DC vaccines for stage III-IV melanoma patients: role of neutrophils?

Dendritic cell (DC) vaccines are used for the induction of anti-tumor T cell reaction in melanoma patients. DC are generated in vitro, pulsed with antigen and matured prior to injection. They are supposed to migrate to lymph nodes and to present the processed antigen to naive T cells allowing activation of tumor-specific lymphocytes. It has been suggested that intradermal injection allows a superior migration to the lymph node. Eight HLA-A2 positive patients with stage III or IV melanomas expressing NA 17 antigen were collected. They were included in a pilot trial of vaccination in which they received IL3/INFb DC presenting the NA17 A2 antigen. In each patient, a skin biopsy was performed at the injection site, 24 h after inoculation. The striking features of the biopsies were the presence of a perivascular CD3+/CD8+ T cell infiltrate with a slight population of CD4+ cells and the presence of a massive neutrophilic infiltrate associated with the injected DC still present, realizing a suppurative granuloma. The persistence of DC 24 h after the injection suggests that migration in the lymph node is not necessary for the induction of the immune response. The skin itself could be the location of a reaction starting with a massive recruitment of neutrophils.

Comparing immunogenicities of tumor-specific antigens administered as therapeutic vaccines in metastatic melanoma patients

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Background: Therapeutic vaccination of metastatic melanoma patients with detectable disease is followed by some tumor regression in only about 10% of the patients, with no clear difference observed between studies carried out with various tumor-specific antigens and vaccination modalities. For antigenic peptide MAGE-A3168–176, presented by HLA-A1 molecules and administered as peptide alone or recombinant ALVAC poxvirus, anti-vaccine T lymphocyte (CTL) responses have been observed in no progressor patient and in only half of the regressors, suggesting a poor immunogenicity of these vaccines. Methods and Results: We compiled anti-vaccine CTL responses measured in the blood of 202 metastatic melanoma patients vaccinated with various associations of 10 different tumor antigens administered as peptides, alone or with adjuvant, recombinant ALVAC poxvirus, or peptide-pulsed dendritic cells. Blood lymphocytes collected before and after vaccination were all analyzed with the same method involving in vitro restimulation in limiting dilution condition followed by labeling with tetramers for each antigen. A CTL response was deemed to have occurred if the CTL frequency increased by at least 10 times, and if the pre-vaccination frequency was lower than 2 x 10-6 of the CD8 cells. No responses were detected against peptides MAGE- A4230–239 (0/26) and MAGE-C2336–344 (0/22). Some were observed against MAGE-A3168–176 (11/81), MAGE-A1278–286 (2/22), MAGE-A3112–120 (2/55), and MAGE-A10254–262 (2/35). Responses were frequently found against NY-ESO-1157–165 (10/19), GnTVVLPDVFIRC (18/73), gp100209–217 (21/33), or Tyrosinase369–377 (11/59). For the latter four antigens, there was no correlation between the occurrence of CTL responses and that of tumor regressions. Neither did we find a correlation between the CTL responses and the expression of the antigen-encoding genes in pre- vaccination tumor samples. Conclusions: These results suggest that some of the antigenic peptides that are commonly used in melanoma vaccines are more immunogenic than others but do not induce more tumor regressions. Therefore, inducing strong CTL responses against these immunogenic peptides is probably not the most appropriate endpoint of future vaccine trials.

No significant financial relationships to disclose.

Influence of heat stress on human monocyte-derived dendritic cell functions with immunotherapeutic potential for antitumor vaccines

Mild heat stress can modulate the activities of immune cells, including dendritic cells (DC) and theoretically, would constitute an innovative approach capable of enhancing the antitumor functions of DC. Therefore, we tested the effects of mild heat stress on the physiology and viability of human monocyte-derived DC, the major type of DC used in tumor immunotherapy trials. We first designed a heat-stress protocol consisting of repetitive, sublethal heat shocks throughout the generation of DC. Using this protocol, we observed that heat stress did not perturb the morphology and the phenotype of immature or mature DC or the capacities of immature DC to uptake antigens efficiently. It is noteworthy that in response to heat stress, mature DC produced higher levels of IL-12p70 and TNF-alpha, which are two cytokines involved in the stimulation of inflammatory reaction, whereas IL-10 production remained low. After heat-stress exposure, mature DC have the full ability to stimulate naive T cells with Th1 response polarization (high IFN-gamma and low IL-4 production) in an allogeneic MLR. It is interesting that heat stress enhanced the migratory capacities of DC in response to MIP-3beta/CCL19. Finally, heat stress partly protected DC from apoptosis induced by cytokine withdrawal. Overall, these findings validate the feasibility of improving immune response by heating human monocyte-derived DC and provide a strong rationale for using mild heat stress in combination with DC vaccination to increase antitumor response.

Controlled delivery of glial cell line-derived neurotrophic factor by a single tetracycline-inducible AAV vector

An autoregulated tetracycline-inducible recombinant adeno-associated viral vector (rAAV-pTet(bidi)ON) utilizing the rtTAM2 reverse tetracycline transactivator (rAAV-rtTAM2) was used to conditionally express the human GDNF cDNA. Doxycycline, a tetracycline analog, induced a time- and dose-dependent release of GDNF in vitro in human glioma cells infected with rAAV-rtTAM2 serotype 2 virus. Introducing the Woodchuck hepatitis virus posttranscriptional regulatory element (WPRE) downstream to the rtTAM2 coding sequence, resulted in a more rapid induction and a higher basal expression level. In vivo, 8 weeks after a single injection of the rAAV-rtTAM2-GDNF vector encapsidated into AAV serotype 1 capsids in the rat striatum, the GDNF protein level was 60 pg/mg tissue in doxycycline-treated animals whereas in untreated animals, it was undistinguishable from the endogenous level ( approximately 4 pg/mg tissue). However, a residual GDNF expression in the uninduced animals was evidenced by a sensitive immunohistochemical staining. As compared to rAAV1-rtTAM2-GDNF, the rAAV1-rtTAM2-WPRE-GDNF vector expressed a similar concentration of GDNF in the induced state (with doxycycline) but a basal level (without doxycycline) approximately 2.5-fold higher than the endogenous striatal level. As a proof for biological activity, for both vectors, downregulation of tyrosine hydroxylase was evidenced in dopaminergic terminals of doxycycline-treated but not untreated animals. In conclusion, the rAAV1-rtTAM2 vector which expressed biologically relevant doses of GDNF in the striatum in response to doxycycline with a basal level undistinguishable from the endogenous striatal level, as measured by quantitative ELISA assay, constitutes an interesting tool for local conditional transgenesis.

Generation of cell hybrids via a fusogenic cell line

BACKGROUND

Hybrids obtained by fusion between tumour cells (TC) and dendritic cells (DC) have been proposed as anti-tumour vaccines because of their potential to combine the expression of tumour-associated antigens with efficient antigen presentation. The classical methods used for fusion, polyethylene glycol (PEG) and electrofusion, are cytotoxic and generate cell debris that can be taken up by DC rendering the identification of true hybrids difficult.

METHODS

We have established a stable cell line expressing a viral fusogenic membrane glycoprotein (FMG) that is not itself susceptible to fusion. This cell line has been used to generate hybrids and to evaluate the relevance of tools used for hybrid detection.

RESULTS

This FMG-expressing cell line promotes fusion between autologous or allogeneic TC and DC in any combination, generating 'tri-parental hybrids'. At least 20% of TC are found to be integrated into hybrids.

CONCLUSIONS

It is speculated that this tri-parental hybrid approach offers new possibilities to further modulate the anti-tumour effect of the DC/TC hybrids since it allows the expression of relevant immunostimulatory molecules by appropriate engineering of the fusogenic cell line.

Vaccination of melanoma patients using dendritic cells loaded with an allogeneic tumor cell lysate

The aim of the present phase I/II study was to evaluate the safety, immune responses and clinical activity of a vaccine based on autologous dendritic cells (DC) loaded with an allogeneic tumor cell lysate in advanced melanoma patients. DC derived from monocytes were generated in serum-free medium containing GM-CSF and IL-13 according to Good Manufacturing Practices. Fifteen patients with metastatic melanoma (stage III or IV) received four subcutaneous, intradermal, and intranodal vaccinations of both DC loaded with tumor cell lysate and DC loaded with hepatitis B surface protein (HBs) and/or tetanus toxoid (TT). No grade 3 or 4 adverse events related to the vaccination were observed. Enhanced immunity to the allogeneic tumor cell lysate and to TAA-derived peptides were documented, as well as immune responses to HBs/TT antigens. Four out of nine patients who received the full treatment survived for more than 20 months. Two patients showed signs of clinical response and received 3 additional doses of vaccine: one patient showed regression of in-transit metastases leading to complete remission. Eighteen months later, the patient was still free of disease. The second patient experienced stabilization of lung metastases for approximately 10 months. Overall, our results show that vaccination with DC loaded with an allogeneic melanoma cell lysate was feasible in large-scale and well-tolerated in this group of advanced melanoma patients. Immune responses to tumor-related antigens documented in some treated patients support further investigations to optimize the vaccine formulation.

A phase II study of the cancer vaccine TG4010 alone and in combination with cytokines in patients with metastatic renal cell carcinoma (RCC)

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Background: MUC1 is a glycoprotein often over-expressed and underglycosylated in renal cell carcinoma (RCC) making it an attractive antigenic target for tumor-specific immunotherapy. TG4010 is a cancer vaccine based on a modified vaccinia virus, strain MVA, expressing both MUC1 and Interleukin 2 (MVA-MUC1-IL2). The objective of this phase II, non-randomized study was to determine the efficacy of TG4010 alone and in combination with cytokines. Methods: Thirty seven patients (pts) with progressive metastatic RCC expressing MUC1 in at least 50% of the tumour cells were treated by subcutaneous injections of TG4010, 108 pfu/inj weekly, for 6 weeks then every three weeks until progression. At progression, TG4010 was continued in combination with Interferon α2a (INF) and Interleukin 2 (IL2). Results: Treatment efficacy and toxicities were previously presented at ASCO 2005 (abstr 4653). No objective responses have been observed, however, 7 pts (19%) remained stable for more than 6 months with TG4010 alone, 3 of them more than 22 months. After progression on TG4010 alone 22 pts received TG4010 in combination with cytokines. Six pts (27%) have been stabilized more than 6 months. The median TTP were 2.6 months (95% CI, 2.4–2.9 months) for TG4010 alone and 3.5 months (95% CI, 0.2–6.7 months) for the combined treatment. There were 24 deaths, with a median OS of 19 months (95% CI, 10–27.9) for the whole population. Seven pts were treated by sorafenib after immunotherapy failure. After censoring pts at the introduction of sorafenib, the median OS was 16 months (95% CI, 6–26), with 41% of pts alive at 2-years. The most frequent adverse effects related to TG4010 were minor to moderate injection site reactions, fatigue and flu-like symptoms. Twelve out of 24 pts evaluable for MUC1 ELISpot show evidence for MUC1-specific CD8+ T cell response while 14 out of 21 evaluable for MUC1 specific T cell proliferation were responsive. Conclusions: The cancer vaccine TG4010 alone and in combination with IL2 and INF induces some disease stabilizations in pts with progressive metastatic RCC and can improve survival in a population selected for MUC1 positivity, which is a factor of poor prognosis.

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Hypoxic-response elements in the oncolytic parvovirus Minute virus of mice do not allow for increased vector production at low oxygen concentration

Vectors derived from the autonomous parvovirus Minute virus of mice, MVM(p), are promising tools for the gene therapy of cancer. The validation of their in vivo anti-tumour effect is, however, hampered by the difficulty to produce high-titre stocks. In an attempt to increase vector titres, host cells were subjected to low oxygen tension (hypoxia). It has been shown that a number of viruses are produced at higher titres under these conditions. This is the case, among others, for another member of the family Parvoviridae, the erythrovirus B19 virus. Hypoxia stabilizes a hypoxia-inducible transcription factor (HIF-1alpha) that interacts with a 'hypoxia-responsive element' (HRE), the consensus sequence of which ((A)/(G)CGTG) is present in the B19 and MVM promoters. Whilst the native P4 promoter was induced weakly in hypoxia, vector production was reduced dramatically, and adding HRE elements to the P4 promoter of the vector did not alleviate this reduction. Hypoxia has many effects on cell metabolism. Therefore, even if the P4 promoter is activated, the cellular factors that are required for the completion of the parvoviral life cycle may not be expressed.

A new dendritic cell vaccine generated with interleukin-3 and interferon-beta induces CD8+ T cell responses against NA17-A2 tumor peptide in melanoma patients

Dendritic cells derived from monocytes cultured in the presence of type I interferon were found to induce efficient T cell responses against tumor antigens in vitro. We vaccinated eight stage III or IV melanoma patients with dendritic cells generated with interferon-beta and interleukin-3, activated by poly I: C, and pulsed with the tumor-specific antigen NA17.A2. This dendritic cell vaccine was well-tolerated with only minor and transient flu-like symptoms and inflammatory reactions at the injection sites. In most patients, isotopic imaging documented dendritic cells (DC) migration from the intradermal injection site to the draining lymph nodes. Finally, mixed lymphocyte-peptide culture under limiting dilution conditions followed by tetramer labeling indicated that three out of eight patients mounted a CD8 T cell response against the NA17.A2 antigenic peptide. We conclude that DC generated in type I-IFN represent an interesting alternative to DC generated in IL-4 and GM-CSF for cancer immunotherapy.

Dacarbazine, cisplatin, and interferon-alfa-2b with or without interleukin-2 in metastatic melanoma: a randomized phase III trial (18951) of the European Organisation for Research and Treatment of Cancer Melanoma Group

BACKGROUND

Based on phase II trial results, chemoimmunotherapy combinations have become the preferred treatment for patients with metastatic melanoma in many institutions. This study was performed to determine whether interleukin-2 (IL-2) as a component of chemoimmunotherapy influences survival of patients with metastatic melanoma.

PATIENTS AND METHODS

Patients with advanced metastatic melanoma were randomly assigned to receive dacarbazine 250 mg/m2 and cisplatin 30 mg/m2 on days 1 to 3 combined with interferon-alfa-2b 10 x 10(6) U/m2 subcutaneously on days 1 through 5 without (arm A) or with (arm B) a high-dose intravenous decrescendo regimen of IL-2 on days 5 through 10 (18 x 10(6) U/m2/6 hours, 18 x 10(6) U/m2/12 hours, 18 x 10(6) U/m2/24 hours, and 4.5 x 10(6) U/m2 for 3 x 24 hours). Treatment cycles were repeated in the absence of disease progression every 28 days to a maximum of four cycles.

RESULTS

Three hundred sixty-three patients with advanced metastatic melanoma were accrued. The median survival was 9 months in both arms, with a 2-year survival rate of 12.9% and 17.6% in arms A and B, respectively (P = .32; hazard ratio, 0.90; 95% CI, 0.72 to 1.11). There was also no statistically significant difference regarding progression-free survival (median, 3.0 v 3.9 months) and response rate (22.8% v 20.8%).

CONCLUSION

Despite its activity in melanoma as a single agent or in combination with interferon-alfa-2b, the chosen schedule of IL-2 added to the chemoimmunotherapy combination had no clinically relevant activity.

Immune characterization of clinical grade-dendritic cells generated from cancer patients and genetically modified by an ALVAC vector carrying MAGE minigenes

Gene delivery into dendritic cells (DC) is most efficiently achieved by viral vectors. Recombinant canarypox viruses (ALVAC) were validated safe and efficient in humans. We aimed firstly to evaluate DC transduction by ALVAC vectors, then to investigate if such infection induced or not the maturation of the DC, and finally to assess the efficiency of ALVAC-MAGE-transduced DC to activate specific CTL clones. Clinical grade DC from melanoma patients were generated from blood monocytes and infected with a recombinant ALVAC virus encoding either a marker gene (EGFP) or the MAGE-1-MAGE-3 minigenes. According to the patient-donor, 22+/-16% of immature DC were successfully transduced. Flow cytometry analysis of surface markers expressed on DC after ALVAC infection did not reveal a mature phenotype. Moreover, ALVAC transduction did not interfere with the capacity of the DC to further mature under poly:IC stimulation. But most importantly, our results demonstrated that DC from HLA-A1 patient-donors infected with the recombinant ALVAC MAGE-1-MAGE-3 minigenes virus were capable of activating a MAGE 3/A1 CTL clone more efficiently than same DC loaded with MAGE 3/A1 peptide, as shown by increased IFN-gamma secretion. These results could be the basis for the development of a new clinical strategy in melanoma patient's immunotherapy.

High frequency of antitumor T cells in the blood of melanoma patients before and after vaccination with tumor antigens

After vaccination of melanoma patients with MAGE antigens, we observed that even in the few patients showing tumor regression, the frequency of anti-vaccine T cells in the blood was often either undetectable or <10⁻⁵ of CD8 T cells. This frequency being arguably too low for these cells to be sole effectors of rejection, we reexamined the contribution of T cells recognizing other tumor antigens. The presence of such antitumor T cells in melanoma patients has been widely reported. To begin assessing their contribution to vaccine-induced rejection, we evaluated their blood frequency in five vaccinated patients. The antitumor cytotoxic T lymphocyte (CTL) precursors ranged from 10⁻⁴ to 3 × 10⁻³, which is 10–10,000 times higher than the anti-vaccine CTL in the same patient. High frequencies were also observed before vaccination. In a patient showing nearly complete regression after vaccination with a MAGE-3 antigen, we observed a remarkably focused antitumoral response. A majority of CTL precursors (CTLp's) recognized antigens encoded by MAGE-C2, another cancer-germline gene. Others recognized gp100 antigens. CTLp's recognizing MAGE-C2 and gp100 antigens were already present before vaccination, but new clonotypes appeared afterwards. These results suggest that a spontaneous antitumor T cell response, which has become ineffective, can be reawakened by vaccination and contribute to tumor rejection. This notion is reinforced by the frequencies of anti-vaccine and antitumor CTLs observed inside metastases, as presented by Lurquin et al. (Lurquin, C., B. Lethé, V. Corbière, I. Théate, N. van Baren, P.G. Coulie, and T. Boon. 2004. J. Exp. Med. 201:249–257).

[Topical photodynamic therapy in cutaneous oncology]

Photodynamic therapy (PDT) or photodynamic chemotherapy is a new therapeutic two-step procedure consisting of an administration of a photosensitizer followed by light irradiation. PDT has been used for the treatment of cutaneous malignancies and offers the advantage over surgery of being a selective and non-invasive approach. The authors present a review of Medline-indexed experiences and trials of topical PDT in cutaneous oncology, and, by the way, remind anatomoclinical features of non-melanoma skin cancers. Complete response rates and cosmetic outcome after topical PDT with 5-aminolevulinic acid are encouraging and enable from now to consider this promising procedure as a new effective approach to manage skin cancers, particularily superficial and extensive lesions including actinic keratoses, superficial basocellular carcinomas and Bowen's disease.

Highly Successful Therapeutic Vaccinations Combining Dendritic Cells and Tumor Cells Secreting Granulocyte Macrophage Colony-stimulating Factor

In an attempt to induce potent immune antitumor activities, we investigated, within the rat 9L gliosarcoma model, distal therapeutic vaccinations associating three therapies: dendritic cell vaccination, intratumoral granulocyte macrophage colony-stimulating factor (GM-CSF) gene transfer, and tumor apoptosis induction. Vaccines of dendritic cells coinjected with processed GM-CSF secreting 9L cells induced systemic responses, resulting in the complete regression of distant preimplanted 9L tumor masses in, with the best strategy, 94% of male rats. All of the cured rats developed a long-term resistance to a rechallenge with parental cells. The curative responses were correlated with the detection of elevated specific cytotoxic activities and a CD4+, CD8+ T cell-, and natural killer (NK) cell-mediated IFN-gamma production. The survival rate of the rat seemed more directly linked to the amount of GM-CSF secreted by the transduced tumor cells, which in turn depended on the toxicity of the apoptosis-inducing treatment, than to the level of apoptosis induced. Unexpectedly, alive GM-CSF secreting 9L cells became apoptotic when injected in vivo. Thus we documented the positive role of apoptosis in the induction of therapeutic antitumor responses by comparing, at equal GM-CSF exogenous supply, the effects of dendritic cells coinjected with apoptotic or necrotic 9L cells. The data showed the superior therapeutic efficiency of combined vaccines containing apoptotic tumor cells. In conclusion, vaccinations with dendritic cells associated with apoptotic tumor cells secreting GM-CSF show a very high therapeutic potency that should show promise for the treatment of human cancer.

In vivoanti-tumour activity of recombinant MVM parvoviral vectors carrying the human interleukin-2 cDNA

BACKGROUND

The natural oncotropism and oncotoxicity of vectors derived from the autonomous parvovirus, minute virus of mice (prototype strain) [MVM(p)], combined with the immunotherapeutic properties of cytokine transgenes, make them interesting candidates for cancer gene therapy.

METHODS

The in vivo anti-tumour activity of a recombinant parvoviral vector, MVM-IL2, was evaluated in a syngeneic mouse melanoma model that is relatively resistant in vitro to the intrinsic cytotoxicity of wild-type MVM(p).

RESULTS

In vitro infection of the K1735 melanoma cells prior to their injection resulted in loss of tumorigenicity in 70% of mice (7/10). Tumour-free mice were protected against a challenge with non-infected parental cells. In addition, MVM-IL2-infected tumour cells induced an anti-tumour activity on parental cells injected at a distant location. These non-infected tumour cells were injected either at the same time or 7 days before the injection of MVM-IL2-infected cells. In the latter setting, which mimics a therapeutic model for small tumours, 4/10 mice were still tumour-free after 4 months.

CONCLUSIONS

Our results show that (i) the MVM-IL2 parvoviral vector efficiently transduces tumour cells; and (ii) the low multiplicity of infection (MOI = 1) used in our experiments was sufficient to elicit an anti-tumour effect on distant cells, which supports further studies on this vector as a new tool for cancer gene therapy.

Recombinant AAV-mediated gene delivery to the central nervous system

Various regions of the brain have been successfully transduced by recombinant adeno-associated virus (rAAV) vectors with no detected toxicity. When using the cytomegalovirus immediate early (CMV) promoter, a gradual decline in the number of transduced cells has been described. In contrast, the use of cellular promoters such as the neuron-specific enolase promoter or hybrid promoters such as the chicken beta-actin/CMV promoter resulted in sustained transgene expression. The cellular tropism of rAAV-mediated gene transfer in the central nervous system (CNS) varies depending on the serotype used. Serotype 2 vectors preferentially transduce neurons whereas rAAV5 and rAAV1 transduce both neurons and glial cells. Recombinant AAV4-mediated gene transfer was inefficient in neurons and glial cells of the striatum (the only structure tested so far) but efficient in ependymal cells. No inflammatory response has been described following rAAV2 administration to the brain. In contrast, antibodies to AAV2 capsid and transgene product were elicited but no reduction of transgene expression was observed and readministration of vector without loss of efficiency was possible from 3 months after the first injection. Based on the success of pioneer work performed with marker genes, various strategies for therapeutic gene delivery were designed. These include enzyme replacement in lysosomal storage diseases, Canavan disease and Parkinson's disease; delivery of neuroprotective factors in Parkinson's disease, Huntington disease, Alzheimer's disease, amyotrophic lateral sclerosis, ischemia and spinal cord injury; as well as modulation of neurotransmission in epilepsy and Parkinson's disease. Several of these strategies have demonstrated promising results in relevant animal models. However, their implementation in the clinics will probably require a tight regulation and a specific targeting of therapeutic gene expression which still demands further developments of the vectors.

Autonomous parvovirus vectors: preventing the generation of wild-type or replication-competent virus

The preferential expression of autonomous parvoviruses in tumour cells and their oncolytic activity has attracted attention to the potential use of these viruses as vectors for cancer gene therapy. Moreover, they are non-pathogenic in adult animals and they seem to be associated with low or no immunogenicity. Other interesting features are their episomal replication and high stability. Vectors derived from the autonomous parvoviruses MVM(p) or H1 express proteins that can directly or indirectly interfere with tumour development. They retain cis- and trans-acting sequences required for viral DNA amplification; the transgene replaces part of the capsid coding genes. Their development has been hampered by low titres and contamination with replication-competent virus (RCV) that is generated through homologous recombination with helper plasmids. Several approaches have been used to avoid recombination between vectors and helpers. In most instances, reducing the homology up- or downstream of the transgene in either the vector or the helper did not significantly affect RCV production. However, completely eliminating homology downstream of the transgene, splitting VP genes on different helpers or pseudotyping vectors resulted in the production of RCV-free stocks. Although VP-containing particles could sometimes be identified in these stocks by in situ hybridisation, they did not amplify and are therefore not true RCV. The integration of capsid-coding sequences into packaging cells also reduced contamination by RCV and allowed for the amplification of vectors through serial infections. Great progress has been made recently towards the generation of truly RCV-free stocks of vectors derived from autonomous parvoviruses H1 and MVMp. Combining these new vectors with a new packaging cell line should greatly facilitate their development.

Assessment of in vivo chemotherapy-induced DNA damage in a p53-mutated rat tumor by micronuclei assay

Production of DNA damage is the basis of cancer treatments such as chemo- and radiotherapy. Such treatments induce mitotic catastrophe, a form of cell death resulting from abnormal mitosis and leading to the formation of interphase cells with multiple micronuclei. In this study, we compared apoptosis induction and micronuclei formation to assess the DNA damage provoked in vivo by cytotoxic agents in established 9L rat gliosarcoma tumors expressing a mutated p53 gene. Results from TUNEL assays revealed the efficiency of local gamma-irradiation at the tumor site to induce apoptosis within 9L tumor mass. However, little or no apoptosis was detected after systemic (ip) injection of cisplatin (1 mg/kg). Interestingly, the micronuclei assays showed that not only gamma-irradiation but also cisplatin treatment led to an increase in the emergence of binucleated cells with micronuclei. Apoptosis induction and micronuclei emergence are thus not absolutely correlated. However, micronuclei assays, rarely performed on solid tumors, appear more sensitive than apoptosis assays in evaluating DNA damage linked to chemotherapy.

[New therapeutic approachs in melanoma]

During the last decade, new insights in cellular and molecular biology have opened new avenues in cancer immunotherapy. Two distinct modalities have been developed: adoptive immunotherapy and anti-tumoral vaccination (active immunotherapy). We will first describe the main strategies of adoptive immunotherapy and then elaborate on the protocols of anti-tumoral vaccination against tumor associated antigens (TAA). In that context, we will pay peculiar attention on the pivotal role of dendritic cells (DC) as natural adjuvant.

IL-2 Production by Virus- and Tumor-Specific Human CD8 T Cells Is Determined by Their Fine Specificity

Memory CD8 T cells mediate rapid and effective immune responses against previously encountered Ags. However, these cells display considerable phenotypic and functional heterogeneity. In an effort to identify parameters that correlate with immune protection, we compared cell surface markers, proliferation, and cytokine production of distinct virus- and tumor-specific human CD8 populations. Phenotypic analysis of epitope-specific CD8 T cells showed that Ag specificity is associated with distinct CCR7/CD45RA expression profiles, suggesting that Ag recognition drives the expression of these molecules on effector/memory T cells. Moreover, the majority of central memory T cells (CD45RAlowCCR7dull) secreting cytokines in response to an EBV epitope produces both IL-2 and IFN-gamma, whereas effector memory CD8 cells (CD45RAdullCCR7-) found in EBV, CMV, or Melan-A memory pools are mostly composed of cells secreting exclusively IFN-gamma. However, these various subsets, including Melan-A-specific effector memory cells differentiated in cancer patients, display similar Ag-driven proliferation in vitro. Our findings show for the first time that human epitope-specific CD8 memory pools differ in IL-2 production after antigenic stimulation, although they display similar intrinsic proliferation capacity. These results provide new insights in the characterization of human virus- and tumor-specific CD8 lymphocytes.

Monoclonal anti-MAGE-3 CTL responses in melanoma patients displaying tumor regression after vaccination with a recombinant canarypox virus

We have analyzed the T cell responses of HLA-A1 metastatic melanoma patients with detectable disease, following vaccination with a recombinant ALVAC virus, which bears short MAGE-1 and MAGE-3 sequences coding for antigenic peptides presented by HLA-A1. To evaluate the anti-MAGE CTL responses, we resorted to antigenic stimulation of blood lymphocytes under limiting dilution conditions, followed by tetramer analysis and cloning of the tetramer-positive cells. The clones were tested for their specific lytic ability and their TCR sequences were obtained. Four patients who showed tumor regression were analyzed, and an anti-MAGE-3.A1 CTL response was observed in three of these patients. Postvaccination frequencies of anti-MAGE-3.A1 CTL were 3 x 10(-6), 3 x 10(-3), and 3 x 10(-7) of the blood CD8 T cells, respectively. These three responses were monoclonal. No anti-MAGE-1.A1 CTL response was observed. These results indicate that, like peptide immunization, ALVAC immunization produces monoclonal responses. They also suggest that low-level antivaccine CTL responses can initiate a tumor regression process. Taken together, our analysis of anti-MAGE-3.A1 T cell responses following peptide or ALVAC vaccination shows a degree of correlation between CTL response and tumor regression, but firm conclusions will require larger numbers.

Minocycline-induced activation of tetracycline-responsive promoter

Minocycline has been suggested to be an anti-apoptotic compound and an anti-inflammatory agent in various models of neurodegeneration. In the present study, using a stable cell line expressing green fluorescent protein under the control of a tetracycline-responsive promoter, we demonstrate that minocycline is able to promote tetracycline-controlled gene expression although it needs longer time and higher concentration to reach the effect obtained with the classical inducer doxycycline. Furthermore, the extinction of the system after antibiotics removal is faster when using minocycline. Interestingly, minocycline displays lower cytotoxicity than doxycycline. It is thus tempting to speculate that combining the intrinsic neuroprotective activity of minocycline with its ability to induce tetracycline-regulatable promoters would be greatly beneficial for neuroprotective/neurorestaurative gene therapy.

IL-10 in vivo gene expression in a cell-induced animal model of proliferative vitreoretinopathy

Due to inhibitory activities on cell-mediated immune responses, interleukin-10 (IL-10) has been proposed as a good candidate to treat inflammatory eye disease and proliferative vitreoretinopathy (PVR). In this study we evaluate the effect of human IL-10 (hIL-10) expression in a cell-induced animal model of PVR. Rabbit dermal fibroblasts were genetically modified by infection with retroviral particles carrying the neomycin resistance gene (neoR) alone or in combination with the hIL-10 gene. PVR was induced in rabbits by intravitreal injections of RDF hIL-10 or RDF neo. Some rabbits received instead injections of soluble recombinant hIL-10 (rhIL-10). PVR was graded by fundoscopy. Eyes were enucleated for histology at day 28. ELISA was performed to measure hIL-10 production in RDF supernatants and in vitreous samples, 24 h after injection. Results showed that in vitro hIL-10 production by RDF was 24,500 pg/10(6) cells/ml/24 h. In vivo IL-10 secretion was detected in all rabbits injected with RDF hIL-10 but was undetectable in control rabbits. Similar clinical grades of PVR were found in rabbits injected with RDF hIL-10 or RDF neo. Histology showed that all eyes injected with RDF hIL-10 had significant inflammatory infiltration whereas only one control eye was clearly inflamed. Rabbits injected with soluble rhIL-10 had normal fundoscopy and normal histology. In conclusion, our results show that in vivo, in a cell-induced model of PVR, hIL-10 has no effect in the clinical progression of PVR. Histology, however, shows that pro-inflammatory effects seem to overcome its suppressive properties.

Micronuclei to detect in vivo chemotherapy damage in a p53 mutated solid tumour

Apoptosis induction and micronuclei formation were compared following cytotoxic treatments in two rat glioma differing in p53 integrity. In vitro, micronuclei emergence but not apoptosis was linked to the p53 mutated status. In vivo, micronuclei assays were more sensitive to evaluate DNA damage induced by chemotherapy in a p53-mutated solid tumour.