Immunogenicity and disease control induced by a multineoantigen vaccine (ADXS-503) in patients with metastatic non–small cell lung cancer who have progressed on pembrolizumab

9042

Background: The administration of a lung cancer-specific immunotherapy with 22 tumor-associated antigens (ADXS-503, A503), has been evaluated as an add-on therapy for patients (pts) with metastatic non-small-cell lung cancer (NSCLC) who have progressed on pembrolizumab (pembro) as last therapy [Haigentz M et al. ASCO 2021]. The present study explores the immunogenicity and potential reversal of immune resistance with A503 when added-on to pembro at the time of progressive disease (PD). Methods: A phase 2 study of A503 + pembro is being conducted in pts with metastatic squamous or non-squamous NSCLC. In Part B of the study, A503 was added-on to pembro within 12 weeks after the first scan showing disease progression following pembro therapy (per RECIST criteria v1.1). Both A503 (1x108 CFU) and pembro (200 mg) were infused by IV every 3 weeks until disease progression or dose-limiting toxicity. Immunogenicity assays included serum cytokine and chemokine levels; flow cytometry; and in-vitro stimulation FluoroSpot assay with 4 different antigen-pools represented in A503 [i.e., hot spot mutations, heteroclitic/wild-type tumor-associated antigens and other antigens not included in the A503 construct (antigen spreading)]. Results: A total of 14 pts have been treated in Part B, of which 13 are clinically evaluable and up to 11 have immune assessments. Combination therapy was well tolerated with transient increased secretion of cytokines for several hours after infusion of A503 consistent with the expected immune activation and transient ‘flu-like’ syndrome. The objective response rate (16%) and disease control rate (46%) were encouraging with 2 partial responses (PR), 4 stable diseases (SD) and 7 pts with PD. Pts with disease control, in particular, generated CD8+ T cells reactive to neoantigens in 1 or more of the 4 antigen pools tested in FluoroSpot. Also, activation of NK cells and of cytotoxic- and memory-CD8+ T cells was mainly observed in pts with PR or SD, but not in those with PD, as shown in the table. Conclusions: Adding A503 to pembro after PD appears to induce innate and adaptive immune responses that may restore or enhance sensitivity to checkpoint inhibitors in pts with clinical benefit. Clinical trial information: NCT03847519. [Table: see text]

A phase 2 study of an off-the-shelf, multi-neoantigen vector (ADXS-503) in patients with metastatic non–small cell lung cancer either progressing on prior pembrolizumab or in the first-line setting

9038

Background: ADXS-503 (A503) is an off-the-shelf, attenuated Listeria monocytogenes (Lm)-based immunotherapy bioengineered to elicit potent T-cell responses against 22 tumor antigens commonly found in non-small-cell lung cancer (NSCLC, i.e. 11 hotspot mutations and 11 tumor-associated antigens, TAAs). Pembrolizumab (pembro) is a programmed death receptor-1 (PD-1)-blocking antibody approved for the treatment of advanced lung cancer. A503 and pembro have complementary mechanisms of immune activation and reversal of immune tolerance. Methods: A phase 2 study of A503 ± pembro is being conducted in patients with metastatic squamous or non-squamous NSCLC. In Part B of the study, A503 was added-on to pembro within 12 weeks of the first scan showing disease progression following pembro (per RECIST criteria v1.1). In Part C of the study, A503 and pembro were administered to previously untreated patients. Both A503 (1x108 CFU) and pembro (200 mg) were infused by IV every 3 weeks until disease progression or limiting toxicity. Results: A total of 17 patients have been treated/evaluated from Part B (n = 14/13) and Part C (n = 3/3). Pembro + A503 was well tolerated in both parts of the study, with mostly grade 1–2, transient and reversible treatment-related adverse events, the most common being fever (47%), chills (35%), fatigue (29%) and nausea (21%). There have been no added immune-related toxicities associated with the combination. Of the 13 evaluable patients in Part B, 2 achieved partial response (PR) and 4 achieved stable disease (SD), yielding an objective response rate (ORR) of 15.4% and a disease control rate (DCR) of 46.2%. Two patients from Part C also achieved SD (DCR 67%). The 2 PRs in Part B have been durable (i.e. 710 and 189 days) as were 5 of the SDs: 3 in Part B (i.e. 448, 175, 117 days) and 2 in Part C (i.e. 322 and 175 days). Both patients with PR in Part B are still undergoing therapy in addition to the other patients who achieved SD. Patients who seem to achieve clinical benefit in both parts of the study include those with PD-L1 expression ≥ 50% and those who show proliferation and/or activation of NK and CD8+ T cells within the first weeks of therapy. In addition, patients with prior pembro exposure ≥ 6 months and DCR > 6 months seem to have clinical benefit when A503 is added to pembro (Part B). Conclusions: The addition of A503 to pembro after disease progression on pembro appears to be well tolerated and induced antigen-specific T-cell responses and durable disease control in 46% of patients in Part B and 67% of patients in Part C. Additional patients are currently being enrolled into both parts of the study to further explore the potential of A503 to restore or enhance sensitivity to checkpoint inhibitors. Clinical trial information: NCT03847519.

A phase I study of ADXS-504, a cancer type specific immunotherapy, for patients with biochemically recurrent prostate cancer

TPS5115

Background: Roughly 20%-30% of prostate cancer patients experience biochemical recurrence (BCR), rising prostate-specific antigen (PSA) levels, after definitive therapy with radical prostatectomy (RP) or radiation therapy (RT). The optimal therapy and timing of treatment for BCR is unknown, however, for patients who are not eligible for salvage radiation, androgen deprivation therapy (ADT) is the standard first-line treatment. ADT is an effective therapy but has many acute and long-term toxicities. Novel strategies to reduce ADT exposure and prolong disease control are needed. ADXS-504 is a live attenuated Listeria monocytogenes (Lm)-based immunotherapy consisting of a truncated nonhemolytic fragment of listeriolysin O (tLLO) fused to a total of 24 tumor associated antigens (TAA). ADXS-504 was designed so that nearly 20% of patients with BCR cancer will express at least one of the targeted hotspot mutation peptide antigens and that >90% will express at least one of the TAAs targeted by the sequence-optimized TAA peptide antigens. By combining these shared, commonly expressed antigen targets into a single Lm-based immunotherapy, ADXS-504 provides the potential for a potent, disease-specific approach to treating patients with prostate cancer. In addition to the generation of antigen-specific T cell responses, treatment with Lm-based immunotherapies has been shown to reprogram the tumor microenvironment (TME), by reducing the frequencies and function of immunosuppressive regulatory T cells and myeloid-derived suppressor cells within the TME. A pre-clinical murine model showed that a proto-type Lm-construct could reduce the number of metastases after removal of the primary tumor by eliminating residual tumor cells. We hypothesize that ADXS-504 is safe and promotes anti-tumor immune responses that may delay or prevent the use of ADT in castration sensitive prostate cancer. Methods: This is an open-label dose-escalation phase I trial of ADXS-504 in patients with BCR of prostate cancer previously treated with RP or RT. The study will enroll up to 18 subjects with BCR with a PSA ≥ 0.3 and a PSADT ≥ 4 months without evidence of metastatic disease on traditional CT imaging and bone scans. ADXS-504 will be given by IV every 4 weeks level for 6 study treatments, followed by maintenance therapy given every 12 weeks for 4 doses for overall total of 10 doses of study treatment. DLTs will be evaluated over the first 28 days of treatment. PSA response, PSADT, and adverse events will be summarized. The Kaplan- Meier method will be used to estimate time to PSA progression and rPFS. Immunologic activity will be evaluated by ELISpot analysis, flow cytometry, and multiplex assays and blood samples will be collected for gene sequencing analysis. The study is currently open to enrollment. Clinical trial information: NCT05077098.

OUP accepted manuscript

Background

ADXS31-142 is an attenuated Listeria monocytogenes-based immunotherapy targeting prostate-specific antigen (PSA), being evaluated as monotherapy and combined with pembrolizumab for metastatic castration-resistant prostate cancer (mCRPC).

Patients and Methods

The 2-part phase I/II KEYNOTE-046 study enrolled men with mCRPC who have progressed after 2 or fewer prior systemic treatment regimens in the metastatic setting. In Part A, intravenous ADXS31-142 monotherapy was given every 3 weeks (q3w) to 3 dose-escalation cohorts. In Part B, ADXS31-142 (1 × 10⁹ colony-forming units) plus pembrolizumab (200 mg) was administered intravenously q3w for 3 doses with a fourth pembrolizumab dose 3 weeks later (12-week cycles) for up to 24 months or until progression/toxicity. Endpoints included safety, overall response rate, progression-free survival (PFS), overall survival (OS), and immunogenicity.

Results

Fifty patients received ADXS31-142 alone (n = 13) or with pembrolizumab (n = 37). Among the 37 RECIST-evaluable patients (n = 8 Part A; n = 29 Part B), there were no objective responses. Median PFS was 2.2 months (95% CI: 0.8-7.4) with monotherapy and 5.4 months (95% CI: 2.3-7.9) with the combination; median OS was 7.8 months (95% CI: 4.4-18.5) and 33.7 months (95% CI: 15.4–not evaluable), respectively. Promising OS benefit was observed in combination-treated patients who had received prior docetaxel (16.0 months, 95% CI: 6.4-34.6; n = 20) and those with visceral metastasis (16.4 months, 95% CI 4.0-not evaluable; n = 11). All patients had ≥1 treatment-related adverse event, mostly grade 1/2 manageable events. No additive toxicity was observed with combination treatment.

Conclusions

Combining ADXS31-142 with pembrolizumab was safe and well tolerated. The observed OS in mCRPC warrants further testing of this combination.

Clinical Trial registration

NCT02325557.

Abstract 1671: Evaluation of total PD-1 expression using multi-color flow cytometry in metastatic non-small Cell lung cancer patients treated with multi-neoantigen vector (ADXS-503) alone and in combination of pembrolizumab to assess T-cell & T-cell memory subsets

Precision for Medicine (Precision) developed and qualified two 17 color flow immunophenotyping assays to be used as pharmacodynamic biomarkers for Advaxis clinical studies in patients with Metastatic Non-Small Cell Lung Cancer treated with ADXS-503 alone and in combination with Pembrolizumab (Pembro). ADXS-503 (A503) is an off-the-shelf, attenuated Listeria monocytogenes (Lm)-based immunotherapy bioengineered to elicit potent T-cell responses against 22 tumor antigens commonly found in NSCLC. Pembrolizumab (Pembro) is a programmed death receptor-1 (PD-1)-blocking antibody approved for the treatment of advanced lung cancer. A503 and Pembro have complementary mechanisms of immune activation and reversal of immune tolerance. Here, we qualified two multi-color flow cytometry assays to quantify total PD-1 expression in cryopreserved peripheral blood mononuclear cells (PBMCs) from individuals that were treated either with A503 only or with A503 in combination with Pembro. The detection of free PD-1 and Pembro-bound PD-1 was achieved by co-staining a partially competing αPD-1 antibody (clone PD1.3.1.3) with a biotinylated αHu-IgG4 antibody. The robustness of the assay was demonstrated using a nine-point half-log serial dilution of Pembro, where the highest concentration was 10µg/mL and the lowest concentration was 0.001µg/mL, including a no drug control. The assay conditions were optimized for sensitivity, optimal signal:noise ratio, detection of free and drug bound receptor by titrating and testing various commercial αPD-1 antibody clones and tertiary reagents to detect biotinylated αHu-IgG4. The Pembro bound receptor was detected using a biotinylated αHu-IgG4 antibody, while the free receptors were quantified using a commercial αPD-1 antibody. The assay was able to quantify free and drug bound PD-1 in the intended immune cell types without compromising the staining of other cell surface and intra-nuclear markers. Majority of the evaluable patients, 6 out of 8, had increased counts of NK, CD4+ and CD8+ T-cells, including TCM, TEM and memory stem cells after the administration of ADXS-503 ± Pembro. PD1 expression on circulating CD4+, CD8+ and NK T-cells was also increased while PD-L1 expression was elevated in on-therapy tumor biopsies in some of these patients. Measuring total PD-1 in T-cells can be more challenging in patients on Pembrolizumab therapy as no known commercial non-competing αPD-1 antibody clones are available. This novel assay will facilitate the evaluation of total PD-1 expression as a pharmacodynamic biomarker in T-cells when PD-1 blockade is being used. These results also support that combination of ADXS-503 with PD-1 blockade could lead to enhancement of efficacy of anti-tumor immunotherapy.

Citation Format: Venkat Mohanram, Natalya Belkina, Angelina R. Bisconte, Jonathan W. Goldman, Gregory J. Gerstner, Missak Haigentz, Thomas Stinchcombe, Balazs Halmos, Surya Vangala, Victor Kabala, Dinesh Simkhada, Cristiane Metran, Darren Davis, Megan Parsi, Andres A. Gutierrez, Deborah Phippard, Suresh S. Ramalingam. Evaluation of total PD-1 expression using multi-color flow cytometry in metastatic non-small Cell lung cancer patients treated with multi-neoantigen vector (ADXS-503) alone and in combination of pembrolizumab to assess T-cell & T-cell memory subsets [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1671.

A phase I study of ADXS-503 alone and in combination with pembrolizumab in subjects with metastatic squamous or non-squamous non-small cell lung cancer (NSCLC)

e21682

Background: ADXS-503 (A503) is an off-the-shelf, attenuated Listeria monocytogenes (Lm)-based immunotherapy bioengineered to elicit potent T cell responses against 22 tumor antigens commonly found in NSCLC (i.e., 11 hotspot mutations and 11 tumor-associated antigens, TAAs). Pembrolizumab (Pembro) is a programed death receptor-1 (PD-1)- blocking antibody with proven efficacy in NSCLC. A503 and Pembro have complementary mechanisms of immune activation and reversal of immune tolerance. Methods: This is a phase I study of A503 ± Pembro in patients (pts) with metastatic squamous or non-squamous NSCLC. Dose escalation with A503 alone has been tested at two dose levels (i.e., 1 and 5 x108 CFU) in Part A in pts refractory or intolerant to prior systemic therapy. In dose escalation Part B, A503 is being evaluated at the same dose levels (DLs) in combination with Pembro in pts with disease progression on Pembro. Part C will be a dose expansion cohort with A503 + Pembro as first-line treatment in the metastatic setting. A503 ± Pembro (200 mg) will be infused intravenously every 3 weeks until disease progression or limiting toxicity. Main endpoints include safety, tolerability and immune-correlative data. Results: Nine patients have been treated: 7 with A503-alone in Part A and two pts with A503+ Pembro in Part B-DL1. No pts in Part A experienced dose-limiting toxicities at the 2 DLs tested. Two Grade 3 adverse events occurred in one pt related to the infusion: hypertension and flu-like syndrome. A transient and manageable SAE (Grade 2 acute kidney injury) was possibly related to A503 alone at 5 x108 CFU. A503+ Pembro have been well tolerated in 2 pts in Part B-DL1. Four pts achieved a best overall response of stable disease, three in Part A and one in Part B. A503 alone induced immune responses in pts so far evaluated in Part A. Conclusions: ADXS-503 alone has demonstrated a manageable safety profile and immune responses in Part A. The 1x108 CFU was identified as the recommended phase II dose. Dose escalation with A503+ Pembro is ongoing and dose expansion in first line treatment is due to start shortly. Clinical trial information: NCT03847519.

Abstract CT007: Safety and immunogenicity of a personalized neoantigen-Listeria vaccine in cancer patients

Background. Meaningful anti-tumor immunity in cancer patients (pts) has been associated with the presence of specific T cells directed at neoantigens, a class of unique peptides that arise from tumor-specific mutations. ADXS-NEO, a personalized Listeria monocytogenes (Lm)-based immunotherapy, is a bioengineered Lmthat secretes an antigen-adjuvant fusion protein consisting of ≥ 20 unique (personal) neoantigens and a truncated fragment of listeriolysin O (tLLO), which has adjuvant properties. Preliminary safety and immunogenicity results from an ongoing Phase I trial with ADXS-NEO are herein reported.

Methods. ADXS-NEO-02 is a Phase I dose-escalation study of ADXS-NEO in subjects with metastatic microsatellite stable colon cancer (CRC), metastatic squamous histology head and neck cancer, and metastatic non-small cell lung cancer (NSCLC). Manufacturing of ADXS-NEO starts with whole exome sequencing of each pt-matched normal and tumor samples to detect genetic alterations in the coding regions of the genome followed by its production under GMP specifications. ADXS-NEO is infused intravenously every 3 weeks until disease progression or limiting toxicity. Main endpoints include safety, tolerability and immune-correlative data.

Results. The turnaround time for manufacturing ADXS-NEO has consistently been ≤ 8 weeks from biopsy to first dose. Two pts treated at 1X109 CFU (dose level 1) experienced dose limiting toxicities (i.e., Gr 3 hypoxia ± Gr 3 hypotension) within 4 hours of completing the infusion of the second dose. These acute adverse events correlated with elevation of serum IL-6 and other cytokines, and both cases were manageable and reversible with tocilizumab and/or steroids. A dose de-escalation cohort was initiated at 1X108 CFU, which has been found to be safe and tolerated by one pt. In these pts, ADXS-NEO induced: 1) activation and proliferation of CD4+ / CD8+ T cells; 2) neoantigen-specific T cell responses after 1 week of the initial priming dose and 3) antigen spreading and T cell responses to neoantigens not selected by algorithm.

Conclusions. ADXS-NEO at 1X109 CFU was beyond the maximum tolerated dose but it was effective in eliciting a fast and broad anti-tumor immunity, including T cell responses to neoantigens and antigen spreading. Enrollment continues both in monotherapy and combination therapy arms with anti-PD-1/PD-L1 therapy, to define the recommended Phase II dose.

Citation Format: J. Randolph Hecht, Jonathan W. Goldman, Sandy Hayes, David Balli, Michael F. Princiotta, Justin G. Dennie, John Heyburn, Tammy Sands, Sumitra Sheeri, Robert Petit, Andres A. Gutierrez, Frank Tsai. Safety and immunogenicity of a personalized neoantigen-Listeria vaccine in cancer patients [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 CT007.

Survival, safety, and response duration results of nivolumab (Anti-PD-1; BMS-936558; ONO-4538) in a phase I trial in patients with previously treated metastatic renal cell carcinoma (mRCC): Long-term patient follow-up

4514

Background: Programmed death-1 (PD-1) is an immune checkpoint receptor that negatively regulates T-cell activation. PD-L1, a PD-1 ligand, has been associated with poor prognosis in mRCC pts. In a phase I study of nivolumab, a PD-1 receptor blocking antibody, in pts with previously treated mRCC and other solid tumors, an MTD was not reached at 10 mg/kg IV Q2WK. Cohorts of mRCC pts were expanded at the 1 and 10 mg/kg dose levels. Methods: Pts received nivolumab for ≤12 cycles (4 doses/cycle) until unacceptable toxicity, progression, or complete response. We report overall survival (OS), updated response data, and long-term safety for the mRCC cohorts from a data analysis in July 2012. Results: 34 pts with mRCC were treated at 1 mg/kg (n=18) or 10 mg/kg (n=16). 44% of pts had received ≥3 prior therapies (74% prior antiangiogenic therapy; 59% prior immunotherapy). Median OS across doses has not yet been reached. Median duration of response was 12.9 months for both doses with 5 of the 10 responses lasting ≥1 year. The incidence of grade 3-4 related adverse events for the RCC cohort was 21% and included hypophosphatemia (6%) and respiratory disorders (6%), with no confirmed-drug related deaths or grade 3 pneumonitis. Treatment discontinuation due to drug-related AEs occurred in 18/304 (6%) of patients in the overall treated population. Conclusions: Nivolumab produced durable survival and responses in a subset of heavily pretreated mRCC pts, with an acceptable safety profile, even after long term continuous dosing. Overall survival appears promising for this population of pts. These findings provide the basis for an ongoing randomized phase III trial of nivolumab in mRCC (NCT01668784). Follow-up data through a February 2013 cutoff is being collected. Clinical trial information: NCT00730639. [Table: see text]

A phase I study of lirilumab (BMS-986015), an anti-KIR monoclonal antibody, administered in combination with ipilimumab, an anti-CTLA4 monoclonal antibody, in patients (Pts) with select advanced solid tumors

TPS3106

Background: Immune checkpoint blockade represents a novel form of cancer immunotherapy. Killer cell immunoglobulin-like receptors (KIR) and cytotoxic T lymphocyte antigen-4 (CTLA-4) are immune receptors that down-regulate NK and T cell activity, respectively. The anti-KIR antibody, lirilumab (BMSE986015), potentiates innate immunity by blocking signaling through inhibitory KIRs and has demonstrated modest side effects in a Phase I trial. The anti-CTLA-4 antibody, ipilimumab, potentiates adaptive immunity and has demonstrated improved overall survival in pts with advanced melanoma and preliminary evidence of clinical activity in Phase I and II trials. We hypothesized that coordinate modulation of innate and adaptive immunity by combining anti-KIR and anti-CTLA4 antibodies could achieve enhanced biologic and clinical activity compared to either agent alone. Here, we describe a Phase I study of lirilumab plus ipilimumab in pts with selected advanced solid tumors. Methods: This study will be performed in two parts and enroll approximately 150 pts. During dose escalation, pts with advanced melanoma, non-small cell lung cancer and castrate resistant prostate cancer, will be enrolled. During cohort expansion, 20 pts with each tumor type will be enrolled at the maximum tolerated dose (MTD), or the maximum administered dose, if no MTD is defined. The primary study objectives are to delineate the safety and tolerability, dose limiting toxicities, and MTD of this combination. Secondary objectives are to assess preliminary anti-tumor activity, pharmacokinetics, and immunogenicity of this combination in all pts, and the pharmacodynamic effects on tumor infiltrating lymphocytes in a cohort of melanoma pts. Exploratory objectives include a thorough assessment of the modulation of innate and adaptive immunity by this combination in peripheral blood and/or tumor specimens, and preliminary evaluation of the association of these changes with clinical outcome. Clinical trial registration number: NCT01750580 Clinical trial information: NCT01750580.

Neutral super-oxidised solutions are effective in killing P. aeruginosa biofilms

Bacteria growing in biofilms can become up to 1000-fold more resistant to antibiotics and biocides as compared to their planktonic counterparts. As a result of this increased resistance, biofilms and biofilm-related infections cannot be effectively treated with conventional antibiotic therapy. The goal of this study was to determine the efficacy of three neutral pH, super-oxidised solutions (nSOSs, OIS-80, OIS-125, OIS-200, Microcyn Technology) varying in oxychlorine concentration (80, 125 and 200 ppm) against P. aeruginosa grown planktonically and as biofilms. Exposure for 20 s of exponential phase cells to any of the three solutions was sufficient to reduce viability by more than five logs. However, only exposure for 10 min to OIS-125 and OIS-200 for 10 min was sufficient to eradicate stationary phase P. aeruginosa cells. The efficacy of nSOSs on P. aeruginosa biofilms, grown to maturity in continuous flow tube reactors, was determined upon treatment up to 60 min. Viability pre- and post-treatment was determined by CFU counts. The effect of these solutions on P. aeruginosa biofilms and biofilm architecture was further visualised by confocal scanning laser microscopy and quantitatively analysed by COMSTAT. Under these experimental conditions, only OIS-125 and OIS-200 achieved a >3-log reduction and biofilm disaggregation within 30 min of exposure. Because OIS-125 and OIS-200 enhance the disaggregation of biofilms, their use in the treatment of surface-related biofilm infections deserves further investigation.

One-oligonucleotide method for constructing vectors for RNA interference

AIM

To develop an easy, fast, automated, and inexpensive method for constructing short-hairpin-RNA cassettes for RNAi studies.

METHODS

Using single oligonucleotides, a variety of DNA cassettes for RNAi vectors were constructed in only few minutes in an automated manner. The cassettes, targeting the eGFP, were cloned into plasmids driven by RNA polymerase III promoter H1. Then, the plasmids were transfected into HeLa cells that were later infected with a recombinant adenovirus encoding the eGFP gene. The level of eGFP fluorescence was evaluated by confocal imaging and flow cytometry.

RESULTS

The plasmids constructed with the DNA cassettes made by the one-oligonucleotide method inhibited eGFP with different potencies, ranging from 55% to 75%.

CONCLUSION

By using the method reported here, it is possible to simultaneously construct hundreds of different DNA cassettes for RNAi experiments in an inexpensive, automated way. This method will facilitate functional genomics studies on mammalian cells.

Microcyntm: a novel super-oxidized water with neutral pH and disinfectant activity

A new super-oxidized water (SOW) product, Microcyn, was tested for in vitro antimicrobial and antiviral activities. The effectiveness of this neutral-pH SOW at killing Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Candida albicans in pure culture was evaluated. One millilitre (approximately 10(8)colony-forming units/mL) of each micro-organism was subjected to 9 mL Microcyn or sterile water at room temperature for 30s. Under these conditions, a log(10) reduction factor of 8 in the level of all pathogens occurred in the treatment samples. In addition, results of tests with three batches of Microcyn exposed to Bacillus atrophaeus spores for 5 min demonstrated complete inactivation of the spores within 2-3 min (log(10) reduction factor >4). The effectiveness of Microcyn in reducing human immunodeficiency virus-1 (HIV-1) on hard surfaces (glass) was also evaluated in compliance with Environmental Protection Agency requirements for virucidal claims. After exposure of the tested surfaces to Microcyn for 5 min without agitation, there was a log(10) reduction factor >3 in the viral load as measured by both cytopathic effect and antigen p24 of HIV-1 production in MT-2 cultures. Microcyn activity against adenoviral vector type 5 was also analysed under simulated laboratory in-use conditions with viral suspensions. In order to increase the sensitivity of the test, the fluorescent light emitted by AdGFP-infected cells was measured with the use of a flow cytometer. A log(10) reduction factor >3 in the viral load was achieved after a 5-min exposure to Microcyn under these strict conditions. These results show that Microcyn exerts a wide antimicrobial spectrum with major advantages over acidic SOWs, including neutral pH, lower free active chlorine (51-85 ppm) and long shelf life (1 year).

Activation of a Ca2+-permeable cation channel by two different inducers of apoptosis in a human prostatic cancer cell line

1. We have combined patch clamp recording with simultaneous [Ca2+]i measurements in single LNCaP cells (a human prostate cancer cell line), to study the activation of Ca2+-permeable channels by two different inducers of apoptosis, ionomycin and serum deprivation. 2. In perforated patch recording, LNCaP cells had a membrane potential of -40 mV and a resting [Ca2+]i of 90 nM. Application of ionomycin at levels that induced apoptosis in these cells (10 microM) produced a biphasic increase in [Ca2+]i. The first rise in [Ca2+]i was due to release of Ca2+ from internal stores and it was associated with a membrane hyperpolarization to -77 mV. The latter was probably due to the activation of high conductance, Ca2+- and voltage-dependent K+ channels (maxi-K). Conversely, the second rise in [Ca2+]i was always preceded by and strictly associated with membrane depolarization and required external Ca2+. Serum deprivation, another inducer of apoptosis, unmasked a voltage-independent Ca2+ permeability as well. 3. A lower concentration of ionomycin (1 microM) did not induce apoptosis, and neither depolarized LNCaP cells nor produced the biphasic increase in [Ca2+]i. However, the first increment in [Ca2+]i due to release from internal Ca2+ stores was evident at this concentration of ionomycin. 4. Simultaneous recordings of [Ca2+]i and ion channel activity in the cell attached configuration of patch clamp revealed a Ca2+-permeable, Ca2+-independent, non-selective cation channel of 23 pS conductance. This channel was activated only during the second increment in [Ca2+]i induced by ionomycin. The absence of serum activated the 23 pS channel as well, albeit at a lower frequency than with ionomycin. 5. Thus, the 23 pS channel can be activated by two unrelated inducers of apoptosis and it could be another Ca2+ influx mechanism in programmed cell death of LNCaP cells.

Gene therapy for cancer using tumour-specific prodrug activation

Current treatments for metastatic malignant disease are often ineffective. One of the most promising of the selective genetic strategies against cancer is VDEPT (virally directed enzyme prodrug therapy). This uses a viral vector to carry a prodrug-activating enzyme gene into both tumour and normal cells. By linking the foreign gene downstream of tumour-specific transcription units, tumour-specific expression of the foreign enzyme gene can be achieved. We have developed a genetic therapy strategy using VDEPT against cancers that overexpress the oncogene ERBB2. This occurs in approximately one-third of breast and pancreatic tumours (and in a smaller proportion of other tumours) and involves transcriptional up-regulation of the ERBB2 gene with or without gene amplification. We have constructed a chimeric minigene consisting of the proximal ERBB2 promoter linked to the gene encoding cytosine deaminase, an enzyme that can deaminate the prodrug 5-fluorocytosine (5-FC) to form cytotoxic 5-fluorouracil (5-FU). We have constructed a double-copy recombinant retrovirus to deliver the enzyme gene under the control of the ERBB2 promoter into a panel of ERBB2 expression-positive (ERBB2+) and -negative (ERBB2-) pancreatic and breast cell lines. Cytosine deaminase activity was high in ERBB2+ transduced cells but was not detected in ERBB2- transduced cells. Significant cell death was observed in ERBB2+ transduced cells treated with 5-FC whereas ERBB2- cells were not affected. Hence we present a novel gene therapy strategy that is potentially tumour-specific and could be used against a range of tumour types that overexpress the ERBB2 oncogene.

Gene therapy for cancer

The molecular basis of cancer is now understood to involve activation of dominant oncogenes and inactivation of tumour suppressor genes, and these genetic events may represent novel targets for cancer therapy. This review focuses on the potential use and ethical implications of gene transfer to alter the behaviour of somatic cells in cancer patients. Antisense nucleic acids and ribozymes represent informational drugs that may be used to modulate the expression of selected genes and suppress malignant behaviour in cancer cells. Genetic immunomodulation by introducing genes for cytokines into cancer cells or lymphocytes can stimulate a cytotoxic immune response against the tumour. Gene transfer techniques can be applied to target prodrug activation specifically to tumour cells and also to protect normal tissues against toxic chemotherapy. Gene replacement therapy could even be used to restore the function of defective tumour suppressor genes.