Safety and efficacy of the tumor-selective adenovirus enadenotucirev, in combination with nivolumab, in patients with advanced/metastatic epithelial cancer: a phase I clinical trial (SPICE)

BACKGROUND

Novel combination therapies to overcome anti-PD-1 resistance are required. Enadenotucirev, a tumor-selective blood stable adenoviral vector, has demonstrated a manageable safety profile and ability to increase tumor immune-cell infiltration in phase I studies in solid tumors.

METHODS

We conducted a phase I multicenter study of intravenous enadenotucirev plus nivolumab in patients with advanced/metastatic epithelial cancer not responding to standard therapy. Co-primary objectives were safety/tolerability and maximum tolerated dose and/or maximum feasible dose (MTD/MFD) of enadenotucirev plus nivolumab. Additional endpoints included response rate, cytokine responses, and anti-tumor immune responses.

RESULTS

Overall, 51 heavily pre-treated patients were treated, 45/51 (88%) of whom had colorectal cancer (35/35 patients with information available were microsatellite instability-low/microsatellite stable) and 6/51 (12%) had squamous cell carcinoma of the head and neck. The MTD/MFD of enadenotucirev plus nivolumab was not reached, with the highest dose level tested (1×10¹² vp day 1; 6×10¹² vp days 3 and 5) shown to be tolerable. Overall, 31/51 (61%) patients experienced a grade 3-4 treatment-emergent adverse event (TEAE), most frequently anemia (12%), infusion-related reaction (8%), hyponatremia (6%), and large intestinal obstruction (6%). Seven (14%) patients experienced serious TEAEs related to enadenotucirev; the only serious TEAE related to enadenotucirev occurring in >1 patient was infusion-related reaction (n=2). Among the 47 patients included in efficacy analyses, median progression-free survival was 1.6 months, objective response rate was 2% (one partial response for 10 months), and 45% of patients achieved stable disease. Median overall survival was 16.0 months; 69% of patients were alive at 12 months. Persistent increases in Th1 and related cytokines (IFNγ, IL-12p70, IL-17A) were seen from ~day 15 in two patients, one of whom had a partial response. Among the 14 patients with matching pre-tumor and post-tumor biopsies, 12 had an increase in intra-tumoral CD8⁺ T-cell infiltration and 7 had increased markers of CD8 T-cell cytolytic activity.

CONCLUSIONS

Intravenously dosed enadenotucirev plus nivolumab demonstrated manageable tolerability, an encouraging overall survival and induced immune cell infiltration and activation in patients with advanced/metastatic epithelial cancer. Studies of next-generation variants of enadenotucirev (T-SIGn vectors) designed to further re-program the tumor microenvironment by expressing immune-enhancer transgenes are ongoing.

TRIAL REGISTRATION NUMBER

NCT02636036.

Abstract CT213: A multicenter phase 1a/b study of NG-350A, a tumor-selective anti-CD40-antibody expressing adenoviral vector, and pembrolizumab in patients with metastatic or advanced epithelial tumors (FORTIFY)

Background: The efficacy of immune checkpoint inhibitors is often limited by immunosuppressive tumor microenvironments (TME) and novel combination therapies are required to overcome resistance. NG-350A is a novel T-SIGn (Tumor-Specific Immuno Gene) adenoviral vector that expresses a fully human agonistic IgG anti-CD40 antibody to promote innate and adaptive immune responses. Additionally, NG-350A selectively replicates in tumor cells, allowing IV dosing to be coupled with local transgene expression in the TME, thereby targeting all tumor lesions while limiting systemic exposure. Through these immunostimulatory effects the vector is designed to re-program ‘cold’ TMEs to allow functional anti-cancer immune responses. Data from an ongoing study with IV NG-350A monotherapy have shown promising tolerability, as well as prominent and sustained elevations in inflammatory cytokines (IL-2, IFNγ, IL-17A, IL-2 and IFNα2) consistent with the mechanism of action of anti-CD40 in stimulating TME re-programming [Naing 2021]. Based on these promising initial data, we designed a study to further assess the safety, tolerability and preliminary efficacy of NG-350A + pembrolizumab.

Methods: FORTIFY (NCT05165433) is an open-label, dose-escalating, phase 1a/b study of NG-350A + pembrolizumab. Eligible patients have advanced/metastatic epithelial tumors that have progressed after ≥1 line of systemic therapy and are incurable by local therapy. Patients eligible for phase 1a must have experienced failure of prior PD-1/PD-L1 inhibition as part of any prior line of therapy; patients eligible for phase 1b must have primary resistance to PD-1/PD-L1 inhibition. During phase 1a, up to 30 patients will receive escalating doses of IV NG-350A (Bayesian Optimal Interval design) to a maximum of 1 × 1012 viral particles (vp) on Day 1 and 1 × 1013 vp on Days 3 and 5 (1 cycle). Patients will receive a fixed-dose of pembrolizumab (200 mg IV) on Day 15 and then every 3 weeks thereafter for up to 35 cycles. Phase 1b will further investigate the efficacy/safety of the selected regimen in up to 3 tumor-specific cohorts using a Simon 2-stage design. Co-primary objectives are to characterize the safety and tolerability of NG-350A + pembrolizumab and to identify a recommended dose. Preliminary efficacy and immunogenicity are secondary endpoints. Pharmacodynamic outcomes will be assessed using tumor tissues and blood. Analyses of tumor tissue (serial biopsies at baseline and Day 15 of cycles 1-3 [cycles 1-2 only in Phase 1b]) will explore virus replication, transgene expression and immune/inflammatory responses. Analyses of serial blood samples will explore cytokine production and changes in peripheral immune cell subsets. Recruitment is expected to begin in Q1 2022.

Citation Format: Tom Lillie, Mark O'Hara, Christian Ottensmeier, Eileen Parkes, Lee Rosen, David Krige, Marya Chaney, Jo Carter, Vladimir Evilevitch, Matthew Thomas, Aung Naing. A multicenter phase 1a/b study of NG-350A, a tumor-selective anti-CD40-antibody expressing adenoviral vector, and pembrolizumab in patients with metastatic or advanced epithelial tumors (FORTIFY) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT213.

Abstract CT214: A multicenter phase 1a/b study of NG-641, a tumor-selective transgene-expressing adenoviral vector, and nivolumab in patients with metastatic or advanced epithelial tumors (NEBULA)

Background: T-SIGn (Tumor-Specific Immuno Gene Therapy) vectors are transgene-expressing variants of the blood-stable adenovirus enadenotucirev. Through a novel multimodal combination of immunostimulatory effects the vectors are designed to re-program ‘cold’ tumor microenvironments (TME) to allow functional anti-cancer immune responses. T-SIGn vectors selectively replicate in tumor cells, allowing IV delivery to be coupled with local transgene expression in the TME, thereby targeting all tumor lesions while limiting systemic exposure. NG-641 is a T-SIGn vector that expresses a fibroblast activation protein-directed bi-specific T-cell activator antibody to target cancer-associated fibroblasts (CAFs) and an immune-enhancer module (CXCL9/CXCL10/IFNα2) to recruit and activate immune cells. In an ongoing study (NCT04053283), NG-641 monotherapy has been successfully dose-escalated to 1 × 1012 viral particles (vp) on Day 1 and 3 × 1012 vp on Days 3 and 5; initial results from this study have shown a manageable tolerability profile and elevations in serum cytokines indicative of T-cell activation. Based on these promising initial data with NG-641 monotherapy, we designed a new study to assess NG-641 + nivolumab.

Methods: NEBULA (NCT05043714) is an open-label, dose-escalating, phase 1a/b study of NG-641 + nivolumab. Eligible patients (pts) have advanced/metastatic epithelial tumors that have progressed after ≥1 line of systemic therapy and are incurable by local therapy. Pts eligible for phase 1a must have received prior PD-1/PD-L1 inhibition as part of any line of therapy; pts eligible for phase 1b must have primary resistance to PD-1/PD-L1 inhibition. During phase 1a, up to 30 pts will receive escalating doses of IV NG-641 (Bayesian Optimal Interval design) to a maximum dose of 1 × 1012 viral particles (vp) on Day 1 and 1 × 1013 vp on Days 3 and 5 (1 cycle). Pts will receive a fixed-dose of nivolumab (480 mg IV) on Day 15 and then every 4 weeks thereafter for up to 8 cycles. Phase 1b will further investigate the selected dose regimen in up to 3 tumor-specific cohorts (Cohorts A, B and C) using a Simon 2-stage design. Co-primary objectives are to characterize the safety and tolerability of NG-641 + nivolumab and to identify a recommended dose. Preliminary efficacy and immunogenicity are secondary endpoints. Pharmacodynamic outcomes will be assessed using tumor tissues and blood. Analyses of tumor tissue (serial biopsies at baseline and Day 15 of cycles 1-3 [cycles 1-2 only in Phase 1b]) will explore virus replication, transgene expression, immune/inflammatory responses and effects on CAFs by immunohistochemistry and gene expression analysis. Analyses of serial blood samples will explore cytokine production and changes in peripheral immune cell subsets. Enrollment to the first dose-escalation cohort is ongoing.

Citation Format: Tom Lillie, Eileen Parkes, Christian Ottensmeier, David Krige, Behnaz Ravanfar, Vladimir Evilevitch, Matthew Thomas, Lee Rosen. A multicenter phase 1a/b study of NG-641, a tumor-selective transgene-expressing adenoviral vector, and nivolumab in patients with metastatic or advanced epithelial tumors (NEBULA) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT214.

NEBULA: A multicenter phase 1a/b study of a tumor-selective transgene-expressing adenoviral vector, NG-641, and nivolumab in patients with metastatic or advanced epithelial tumors

TPS2682

Background: Tumor-Specific Immuno Gene Therapy (T-SIGn) vectors are next-generation transgene-armed variants of the adenoviral vector enadenotucirev that selectively replicate in epithelial tumor cells. T-SIGn vectors are blood-stable, allowing IV delivery to be coupled with local transgene expression in the tumor microenvironment (TME), thereby targeting all lesions while limiting systemic exposure. The T-SIGn vector NG-641 encodes four immunostimulatory transgenes: fibroblast activation protein-directed bi-specific T-cell activator antibody to target cancer-associated fibroblasts (CAFs), IFNα2 to promote innate and adaptive immune responses, and CXCL9/10 to induce T-cell infiltration. Through this novel multimodal combination of immunostimulatory effects NG-641 is designed to re-program the TME to allow functional anti-cancer immune responses. In the ongoing STAR study (NCT04053283), NG-641 has been successfully dose-escalated to 1 × 1012 viral particles (vp) on Day 1 and 3 × 1012 vp on Days 3 and 5, with promising preliminary safety/tolerability and pharmacodynamic results. Based on these encouraging preliminary data with NG-641 monotherapy, we designed a new study to assess NG-641 + nivolumab. Methods: NEBULA (NCT05043714) is an open-label, dose-escalating, phase 1a/b study of NG-641 + nivolumab in patients (pts) with advanced/metastatic epithelial tumors that have progressed after ≥1 line of systemic therapy and are incurable by local therapy. Pts are eligible for phase 1a if they have received prior PD-1/PD-L1 inhibition as part of any line of therapy. During phase 1a, up to 30 pts will receive escalating doses of IV NG-641 to a maximum dose of 1 × 1012 viral particles (vp) on Day 1 and 1 × 1013 vp on Days 3 and 5 (1 cycle; Bayesian Optimal Interval design). Pts will receive a fixed-dose of nivolumab (480 mg IV) on Day 15 and then every 4 weeks thereafter for up to 8 cycles. In phase 1b, the recommended dose regimen will be further studied in patients with primary resistance to PD-1/PD-L1 inhibition; patients will be enrolled in up to 3 tumor-specific cohorts (Cohorts A-C; Simon 2-stage design). Co-primary objectives are to characterize the safety and tolerability of NG-641 + nivolumab and to identify a recommended dose. Preliminary efficacy and immunogenicity are secondary endpoints. Pharmacodynamic outcomes will also be assessed. Viral replication, transgene expression, immune/inflammatory responses and effects on CAFs by IHC and gene expression analysis will be analyzed using tumor tissue from serial biopsies (taken at baseline and Day 15 of cycles 1-3 [cycles 1-2 only in Phase 1b]). Serial blood samples will be analyzed to study cytokine production and changes in peripheral immune cell subsets. Enrollment to the first dose-escalation cohort is ongoing. Clinical trial information: NCT05043714.

FORTITUDE: Results of a phase 1a study of the novel transgene-armed and tumor-selective vector NG-350A with and without pembrolizumab (pembro)

2559

Background: Stimulating CD40 may support anti-cancer immune responses; however, on-target toxicity limits systemic dosing. NG-350A is a tumor-selective and blood stable adenoviral T-SIGn vector expressing a potent fully human IgG agonistic anti-CD40 antibody (mAb). NG-350A was designed to selectively deliver anti-CD40 to multiple tumor sites via IV delivery, driving immunological tumor re-engineering while avoiding systemic toxicity. We report results from a first-in-human trial after completion of enrollment. Methods: FORTITUDE (NCT03852511) is a phase 1 study of NG-350A ± pembro in patients (pts) with metastatic/advanced epithelial tumors. NG-350A monotherapy (mTx) was dose-escalated in separate intratumoral (IT; increasing numbers of doses) or IV (one cycle; three increasing dose levels) cohorts. IV NG-350A + pembro (200 mg Q3W for ≤8 cycles) was then assessed. Results: As of Jan 2022, 28 heavily pre-treated pts had received NG-350A, either as IT mTx (n=9; two dose levels), IV mTx (n=16; IV dose levels 1, 3 & 4) or IV + pembro (n=3; IV dose level 2). The MTD of NG-350A ± pembro was not reached, with no DLTs at the highest IT and IV dose levels. The safety profile of NG-350A was consistent with acute reactions to viral particles and asymptomatic aPTT prolongations (Table). No systemic CD40 transgene protein was detected at any dose level and the only SAE to occur in >1 pt was pneumonia. No objective responses were observed; however, 3/6 patients treated with NG-350A mTx at IV dose level 4 achieved stable disease (dose not yet tested with pembro). Dose-dependent specific increases in serum IL-12, IFNγ and IL-17a were detected in pts treated with IV NG-350A mTx from ̃Wk 2. Increases were sustained at ≥5x baseline levels 7 wks after dosing in the majority of evaluable pts treated at higher IV dose levels. These responses did not occur with IT dosing (or in prior studies with an unarmed vector); further follow-up is ongoing for NG-350A + pembro. IV NG-350A also led to the expansion of T cell clones in blood; most of these were newly detected. Conclusions: NG-350A ± pembro was well-tolerated, with no evidence of CD40-related toxicity. NG-350A IV mTx led to specific and sustained cytokine responses consistent with the MoA of the encoded anti-CD40 Ab. Peak cytokine elevations were typically higher than reported with systemic anti-CD40 Abs, suggesting NG-350A can drive local immunological tumor changes while avoiding systemic toxicity. A further trial (FORTIFY, NCT05165433) will continue dose-escalation of NG-350A + pembro to identify a dose level for efficacy assessments. Clinical trial information: NCT03852511. [Table: see text]

Safety and tolerability of T-SIGn vectors when administered using “flat” versus “low-high-high” (LHH) dosing regimens

2572

Background: Tumor-selective viruses, particularly those dosed systemically to deliver transgenes, are potentially powerful cancer therapies. However, acute cytokine reactions to viral particle (vp) infusion may affect vector tolerability [Small 2006], thereby limiting the maximum tolerated dose (MTD) and subsequent transgene delivery. T-SIGn vectors (e.g. NG-641 and NG-350A) are transgene-armed variants of the epithelial tumor-selective adenovirus enadenotucirev (EnAd). Acute serum cytokine increases post-dosing have been seen at the MTD of EnAd (“flat” dosing of 3 x 1012 vp on Days [D] 1, 3 and 5) [Machiels 2019]. Following supportive preclinical data [McElwaine-Johnn 2019], we explored if a LHH dosing regimen, in which a lower dose is given on D1 prior to two higher doses on D3 and 5, may improve vector safety/tolerability thereby allowing higher cumulative doses to be given. Methods: Data were pooled from three Phase 1 dose-escalation studies in advanced/metastatic epithelial cancer: SPICE (EnAd + pembrolizumab/nivolumab; NCT02636036), FORTITUDE (NG-350A ± pembrolizumab; NCT03852511) and STAR (NG-641; NCT04053283). Serum cytokines were measured using a 17-analyte Luminex assay. IL-6/MCP-1 data for D1, 3 and 5 (pre- and 6-10 hrs post-dose) were analyzed to examine acute cytokine changes. TNFα/IFNγ were examined due to their association with cytokine release syndrome (CRS). Samples analyzed from SPICE/FORTITUDE were taken before PD-1 inhibitor administration. Results: 84 patients (SPICE n=51; FORTITUDE n=18; STAR n=15) were included in these analyses; 79 had cytokine data. AEs and Gr≥3 AEs within 1 wk of first dose, and DLTs at any time, were less frequent with a LHH vs flat dosing regimen (Tbl). Importantly, a LHH dose of 1-6-6 (1 x 1012 vp on D1; 6 x 1012 vp on D3 and 5; greater than the previous flat MTD) was tolerated. Acute increases in TNFα/IFNγ were limited and no severe CRS was seen. Increases in IL-6/MCP-1 with 1 x 1011 or 1 x 1012 vp flat dosing were negligible, whereas acute increases in IL-6/MCP-1 were seen after the first dose of 3 x 1012 vp when given as a flat dose (negligible increases on D3/5). Notably, cytokine responses with 1-3-3 dosing (1 x 1012 vp on D1; 3 x 1012 vp on D3 and 5), including after the first 3 x 1012 vp dose on D3, were negligible. Cytokine responses after the first dose of 6 x 1012 vp in the 1-6-6 regimen were similar to those seen with the first dose of the flat 3 x 1012 vp regimen. Conclusions: LHH dosing appears to induce a desensitization mechanism allowing higher cumulative doses of T-SIGn vectors to be given without the associated acute reactions to viral infusions. This finding may have implications for optimizing safety-efficacy profiles of viral vectors in cancer. Clinical trial information: NCT02636036, NCT03852511 and NCT04053283. [Table: see text]

Safety and efficacy of the tumor-selective adenovirus enadenotucirev with or without paclitaxel in platinum-resistant ovarian cancer: a phase 1 clinical trial

BACKGROUND

Treatment outcomes remain poor in recurrent platinum-resistant ovarian cancer. Enadenotucirev, a tumor-selective and blood stable adenoviral vector, has demonstrated a manageable safety profile in phase 1 studies in epithelial solid tumors.

METHODS

We conducted a multicenter, open-label, phase 1 dose-escalation and dose-expansion study (OCTAVE) to assess enadenotucirev plus paclitaxel in patients with platinum-resistant epithelial ovarian cancer. During phase 1a, the maximum tolerated dose of intraperitoneally administered enadenotucirev monotherapy (three doses; days 1, 8 and 15) was assessed using a 3+3 dose-escalation model. Phase 1b included a dose-escalation and an intravenous dosing dose-expansion phase assessing enadenotucirev plus paclitaxel. For phase 1a/b, the primary objective was to determine the maximum tolerated dose of enadenotucirev (with paclitaxel in phase 1b). In the dose-expansion phase, the primary endpoint was progression-free survival (PFS). Additional endpoints included response rate and T-cell infiltration.

RESULTS

Overall, 38 heavily pretreated patients were enrolled and treated. No dose-limiting toxicities were observed at any doses. However, frequent catheter complications led to the discontinuation of intraperitoneal dosing during phase 1b. Intravenous enadenotucirev (1×10¹² viral particles; days 1, 3 and 5 every 28-days for two cycles) plus paclitaxel (80 mg/m²; days 9, 16 and 23 of each cycle) was thus selected for dose-expansion. Overall, 24/38 (63%) patients experienced at least 1 Grade ≥3 treatment-emergent adverse event (TEAE); most frequently neutropenia (21%). Six patients discontinued treatment due to TEAEs, including one patient due to a grade 2 treatment-emergent serious AE of catheter site infection (intraperitoneal enadenotucirev monotherapy). Among the 20 patients who received intravenous enadenotucirev plus paclitaxel, 4-month PFS rate was 64% (median 6.2 months), objective response rate was 10%, 35% of patients achieved stable disease and 65% of patients had a reduction in target lesion burden at ≥1 time point. Five out of six patients with matched pre-treatment and post-treatment biopsies treated with intravenous enadenotucirev plus paclitaxel had increased (mean 3.1-fold) infiltration of CD8 +T cells in post-treatment biopsies.

CONCLUSIONS

Intravenously dosed enadenotucirev plus paclitaxel demonstrated manageable tolerability, an encouraging median PFS and increased tumor immune-cell infiltration in platinum-resistant ovarian cancer.

TRIAL REGISTRATION NUMBER

NCT02028117.

342 Combining enadenotucirev and nivolumab increased tumour immune cell infiltration/activation in patients with microsatellite-stable/instability-low metastatic colorectal cancer in a phase 1 study

Background

Microsatellite-stable (MSS) and instability-low (MSI-L) metastatic colorectal cancer (mCRC) are typically characterised as ”immune-excluded/desert” tumour microenvironments lacking T-cell infiltration. Anti-PD-1 monotherapy has little clinical benefit in MSS/MSI-L mCRC1 and knowledge of the effects of PD-1 inhibition on T-cell activation/infiltration in this population is limited. Novel combination therapies to overcome anti-PD-1 resistance are required. SPICE is a multicentre, open-label, phase 1 study of the tumour-selective chimeric Ad11/Ad3 group B oncolytic adenovirus enadenotucirev plus nivolumab in patients with metastatic/advanced epithelial tumours refractory to standard therapy. Preliminary data from patients with MSS/MSI-L mCRC demonstrated a median overall survival of 14 months, manageable tolerability and intratumoural T-cell infiltration.2 Here we characterise the immunological effects of tumour re-engineering with enadenotucirev in combination with nivolumab in patients with MSS/MSI-L mCRC.

Methods

Patients received increasing doses and/or cycles of intravenous enadenotucirev followed by up to 8 cycles of nivolumab as previously described.2 Wherever possible, pre- and post-treatment (~5 weeks post-first enadenotucirev) biopsies were collected; samples were analysed using immunohistochemistry and automated image analysis. Peripheral blood mononuclear cell immunophenotyping (multiparameter flow cytometry) and serum cytokines were assessed at multiple times.

Results

43 patients with mCRC were treated (86% MSS/MSI-L; 14% unknown). Among the 13 patients (12/13 MSS/MSI-L; 1/13 unknown) with matched biopsies, 11 had increased intratumoural and stromal CD8+ T-cell infiltration in post-treatment biopsies (median [Q1-Q3] fold changes 6.5× [1.5–25.4] and 1.9× [1.5–3.9], respectively; figure 1). CD4+ T-cell density increased in 10/13 patients and 8/13 patients had increased proportions of PD-L1+ immune cells. Increases in CD8 T-cell proliferation (Ki67; 7/9 patients) and cytolytic activity (Granzyme B; 7/13 patients) markers were seen. 4/13 patients converted from a ”desert” to an ”inflamed” immune phenotype (pathologist scored CD8/pan-cytokeratin staining). Immunophenotyping showed trends towards increased T-cell activation (CD38+ and HLA-DR+ CD8+ T cell populations) post-treatment (9/10 patients), including in one patient who had only received enadenotucirev prior to sampling. Persistent increases in inflammatory cytokines (IFNγ, IL-12p70, IL-17a) were seen in two patients from ~Day 15, including one who achieved a sustained objective response.

Abstract 342 Figure 1

Tumour immune cell infiltration following treatment with enadenotucirev plus nivolumab

Conclusions

These data show that intravenous enadenotucirev plus nivolumab can induce immune infiltration/activation within MSS/MSI-L mCRC. These encouraging findings suggest that immune activation can be achieved even in ”immune-excluded/desert” tumours. SPICE has been closed following completion of dose-escalation. Efforts are now focused on the development of next-generation variants of enadenotucirev designed to further re-programme the tumour microenvironment by expressing immune-enhancer transgenes (T-SIGn vectors); these studies are ongoing (NCT04830592, NCT04053283, NCT03852511).

Acknowledgements

This study was funded by PsiOxus Therapeutics Limited and Bristol Myers Squibb. Medical writing support: Lola Parfitt, MRes, of PsiOxus Therapeutics Limited.

Trial Registration

EudraCT number

2017-001231-39NCT number: NCT02636036

References

Kawazoe A, Kuboki Y, Shinozaki E, et al. Multicenter phase I/II trial of napabucasin and pembrolizumab in patients with metastatic colorectal cancer (EPOC1503/SCOOP trial). Clin Cancer Res 2020;26:5887–5894.

Fakih M, Wang D, Harb W, et al. SPICE: a phase I multicenter study of enadenotucirev in combination with nivolumab in tumors of epithelial origin: an analysis of the metastatic colorectal cancer patients in the dose escalation phase. Ann Oncol 2019:30(suppl_5):v252.

Ethics Approval

The study was approved by the WCG Institutional Review Board (study approval number 20152656), UCLA Institutional Review Board (study approval number IRB#15-002010), Vanderbilt Institutional Review Board (study approval number IRB #171453) and Henry Ford Institutional Review Board (study approval number IRB #10349).

437 A multicentre phase 1b study of NG-641, a novel transgene-armed and tumour-selective adenoviral vector, and pembrolizumab as neoadjuvant treatment for squamous cell carcinoma of the head and neck

Background

Despite multimodal management strategies, outcomes for patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN) remain poor. Immune checkpoint inhibitors have demonstrated promise as a neoadjuvant strategy to reduce relapse rates1 ; however, the immunosuppressive SCCHN tumour microenvironment (TME) has limited the efficacy of immunotherapy to date. This ‘cold’ TME is characterised by an absence of T-cell activation/inflammation2 and high levels of stromal fibroblast activating protein (FAP),3 indicative of immunosuppressive cancer-associated fibroblasts (CAFs). Novel approaches to ameliorate this immunosuppressive TME are required to realise the full benefit of immunotherapy in SCCHN.NG-641 is a next-generation blood-stable and transgene-armed Tumour-Specific Immuno Gene Therapy (T-SIGn) adenoviral vector that selectively replicates in epithelial tumour cells. NG-641 encodes four immunostimulatory transgenes: a FAP-directed bi-specific T-cell activator antibody to target CAFs, interferon alpha 2 to promote innate and adaptive immune responses, and C-X-C motif chemokine ligands 9 and 10 to induce T cell infiltration.4 Together, these transgenes are designed to locally re-programme the immunosuppressive TME and promote functional anti-cancer immune responses while minimising systemic immune-related toxicities. This mechanism of action is particularly suited to SCCHN and should complement anti–PD-1 inhibitors. We, therefore, designed a study to assess neoadjuvant treatment with NG-641 and pembrolizumab in locally advanced SCCHN.

Methods

The mode-of-action transgene (MOAT) study is a multicentre, open-label, dose-escalating, phase 1b study of NG-641 as monotherapy or with pembrolizumab. Patients are eligible if they have newly diagnosed or recurrent locally advanced SCCHN and have definitive surgery planned within 8 weeks of screening. In Part A, patients will receive three doses of intravenous NG-641 monotherapy prior to surgery (figure 1). Once NG-641 transgene expression is confirmed in excised tumour tissues, Part A will close and NG-641 dose-escalation can continue in Part B. Patients will then also receive a single dose of pembrolizumab given ~5 days after NG-641 to minimize toxicity and take advantage of the mechanism of NG-641 prior to PD-1 blockade. The primary objective is to characterise the safety and tolerability of NG-641 ± pembrolizumab in SCCHN; secondary objectives are to identify a recommended dose of NG-641 plus pembrolizumab and to assess treatment outcomes, including pathological tumour responses and overall survival. Pharmacodynamic outcomes will be assessed following NG-641 ± pembrolizumab, including characterising immune/inflammatory biomarkers in both tumour and blood. The study is to be conducted at 4 sites in the UK; up to 36 patients will be enrolled.

Abstract 437 Figure 1

MOAT study schematic

Acknowledgements

This study was funded by PsiOxus Therapeutics Ltd.

Trial Registration

This trial is registered as NCT04830592 on clinicaltrials.gov.

References

Uppaluri R, Campbell KM, Egloff AM, et al. Neoadjuvant and Adjuvant Pembrolizumab in Resectable Locally Advanced, Human Papillomavirus-Unrelated Head and Neck Cancer: A Multicenter, Phase II Trial. Clin Cancer Res 2020;26:5140–52.

Cristescu R, Mogg R, Ayers M, et al. Pan-tumor genomic biomarkers for PD-1 checkpoint blockade-based immunotherapy. Science 2018;362:eaar3593.

Dolznig H, Schweifer N, Puri C, et al. Characterization of cancer stroma markers: In silico analysis of an mRNA expression database for fibroblast activation protein and endosialin Cancer Immun 2005;5:10.

Champion BR, Besneux M, Patsalidou M, et al. NG-641: An oncolytic T-SIGn virus targeting cancer-associated fibroblasts in the stromal microenvironment of human carcinomas. Cancer Res 2019;79:5013.

Ethics Approval

This study was approved by a central United Kingdom Research Ethics Committee (South Central - Oxford A Research Ethics Committee); approval reference 20/SC/0425, Integrated Research Application System ID 290504. All participants must provide informed consent prior to enrolment.

A multicenter, open label, first-in-human study of an oncolytic viral vector expressing an agonistic anti-CD40 antibody (NG-350A) in patients with epithelial tumors (FORTITUDE)

TPS2668

Background: NG-350A is a transgene modified variant of the oncolytic platform virus enadenotucirev (EnAd) which expresses a fully human agonist anti-cluster of differentiation 40 (anti-CD40) antibody. The principal advantage of encoding anti-CD40 within an oncolytic virus is the ability to potentially achieve very high levels within the tumor coupled with direct cytotoxicity due to viral lysis and stimulation of the immune-system. NG-350A infects and selectively replicates in tumor cells. The anti-CD40 antibodies are expected to activate the patient’s own dendritic cells, macrophages and B-cells to drive CD4+ and CD8+ T-cell immuno-inflammatory responses and immune mediated tumor cell killing. EnAd is a tumor-selective chimeric Ad11/Ad3 group B oncolytic adenovirus developed using directed evolution. Phase I clinical studies have identified a well-tolerated systemic dose and regimen for EnAd monotherapy. EnAd shows a high level of selective replication and cell killing for a broad range of carcinoma cell lines (of epithelial origin) with little replication in normal and non-carcinoma cells. Methods: This first in human study will evaluate the safety, tolerability and preliminary efficacy of NG-350A together with virus kinetics, immunogenicity and other pharmacodynamic effects to elucidate the mechanism of action of NG-350A in patients with advanced or metastatic epithelial tumours. In the dose escalation phase up to 33 patients evaluable for dose-limiting toxicity will receive NG-350A by IV infusion on Day 1, 3 and 5 at 6 US sites. The first IV cohort in the dose-escalation phase will utilize the conventional ‘3+3’ design; thereafter dose recommendations will be based on a continual reassessment method. Following determination of the recommended phase 2 dose up to 20 patients will be treated in a dose-expansion cohort. In a parallel cohort, up to 12 patients will receive a single dose of NG-350A by intratumoural (IT) injection on Day 1 for direct delivery of high viral titres to tumor. Up to six patients are planned to undergo surgical resection of a tumor lesion to optimize translational research. Clinical conduct of the study was initiated in February 2019.

Abstract 3655: Biomarker strategy to guide the clinical development of ImmTACTM molecules, a novel class of bispecific T cell engaging biologic drugs

IMCgp100, a first in class immunotherapy, is a T cell redirecting bispecific biologic comprising an affinity enhanced T-cell receptor specific for gp100 and an anti-CD3 scFV. Phase I/IIa data has provided evidence of a favourable safety profile, and durable responses in both cutaneous and uveal melanoma have been observed. To complement the clinical studies we have developed a comprehensive biomarker strategy to aid our understanding of pharmacodynamics, patient response and potential mechanisms of resistance which includes analysis of markers in both the tumour and periphery. The data obtained to date provide evidence of the pharmacodynamic effects of the molecule including chemokine/cytokine release, in both the tumor and periphery, and lymphocyte infiltration into tumors. In addition, changes in the levels of certain chemokines following the first dose of IMCgp100 were associated with tumor shrinkage. The biomarker strategy we have developed forms the basis for the support of the on-going Ph II development of IMCgp100 in both cutaneous and uveal melanoma and for other ImmTAC molecules, as single agents and in combination, for the treatment of solid tumours.

Citation Format: Cheryl McAlpine, David Krige, Sandra Herrero-Gonzalez, Sarah Franklin, Jacob Hurst, William Shingler, Sanjay Patel, Andy Johnson, Debbie Parker, Christina M. Coughlin, Namir J. Hassan, Bent K. Jakobsen. Biomarker strategy to guide the clinical development of ImmTACTM molecules, a novel class of bispecific T cell engaging biologic drugs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3655. doi:10.1158/1538-7445.AM2017-3655

Multifactorial resistance to aminopeptidase inhibitor prodrug CHR2863 in myeloid leukemia cells: down-regulation of carboxylesterase 1, drug sequestration in lipid droplets and pro-survival activation ERK/Akt/mTOR

Aminopeptidase inhibitors are receiving attention as combination chemotherapeutic agents for the treatment of refractory acute myeloid leukemia. However, the factors determining therapeutic efficacy remain elusive. Here we identified the molecular basis of acquired resistance to CHR2863, an orally available hydrophobic aminopeptidase inhibitor prodrug with an esterase-sensitive motif, in myeloid leukemia cells. CHR2863 enters cells by diffusion and is retained therein upon esterase activity-mediated conversion to its hydrophilic active metabolite drug CHR6768, thereby exerting amino acid depletion. Carboxylesterases (CES) serve as candidate prodrug activating enzymes given CES1 expression in acute myeloid leukemia specimens. We established two novel myeloid leukemia sublines U937/CHR2863(200) and U937/CHR2863(5uM), with low (14-fold) and high level (270-fold) CHR2863 resistance. The latter drug resistant cells displayed: (i) complete loss of CES1-mediated drug activation associated with down-regulation of CES1 mRNA and protein, (ii) marked retention/sequestration of the prodrug, (iii) a substantial increase in intracellular lipid droplets, and (iv) a dominant activation of the pro-survival Akt/mTOR pathway. Remarkably, the latter feature coincided with a gain of sensitivity to the mTOR inhibitor rapamycin. These finding delineate the molecular basis of CHR2863 resistance and offer a novel modality to overcome this drug resistance in myeloid leukemia cells.

The combination of HDAC and aminopeptidase inhibitors is highly synergistic in myeloma and leads to disruption of the NFκB signalling pathway

There is a growing body of evidence supporting the use of epigenetic therapies in the treatment of multiple myeloma. We show the novel HDAC inhibitor CHR-3996 induces apoptosis in myeloma cells at concentrations in the nanomolar range and with apoptosis mediated by p53 and caspase pathways. In addition, HDAC inhibitors are highly synergistic, both in vitro and in vivo, with the aminopeptidase inhibitor tosedostat (CHR-2797). We demonstrate that the basis for this synergy is a consequence of changes in the levels of NFκB regulators BIRC3/cIAP2, A20, CYLD, and IκB, which were markedly affected by the combination. When co-administered the HDAC and aminopeptidase inhibitors caused rapid nuclear translocation of NFκB family members p65 and p52, following activation of both canonical and non-canonical NFκB signalling pathways. The subsequent up-regulation of inhibitors of NFκB activation (most significantly BIRC3/cIAP2) turned off the cytoprotective effects of the NFκB signalling response in a negative feedback loop. These results provide a rationale for combining HDAC and aminopeptidase inhibitors clinically for the treatment of myeloma patients and support the disruption of the NFκB signalling pathway as a therapeutic strategy.

Antitumor activity of a small-molecule inhibitor of the histone kinase Haspin

The approval of histone deacetylase inhibitors for treatment of lymphoma subtypes has positioned histone modifications as potential targets for the development of new classes of anticancer drugs. Histones also undergo phosphorylation events, and Haspin is a protein kinase the only known target of which is phosphorylation of histone H3 at Thr3 residue (H3T3ph), which is necessary for mitosis progression. Mitotic kinases can be blocked by small drugs and several clinical trials are underway with these agents. As occurs with Aurora kinase inhibitors, Haspin might be an optimal candidate for the pharmacological development of these compounds. A high-throughput screening for Haspin inhibitors identified the CHR-6494 compound as being one promising such agent. We demonstrate that CHR-6494 reduces H3T3ph levels in a dose-dependent manner and causes a mitotic catastrophe characterized by metaphase misalignment, spindle abnormalities and centrosome amplification. From the cellular standpoint, the identified small-molecule Haspin inhibitor causes arrest in G2/M and subsequently apoptosis. Importantly, ex vivo assays also demonstrate its anti-angiogenetic features; in vivo, it shows antitumor potential in xenografted nude mice without any observed toxicity. Thus, CHR-6494 is a first-in-class Haspin inhibitor with a wide spectrum of anticancer effects that merits further preclinical research as a new member of the family of mitotic kinase inhibitors.

Drug targeting to monocytes and macrophages using esterase-sensitive chemical motifs

The therapeutic and toxic effects of drugs are often generated through effects on distinct cell types in the body. Selective delivery of drugs to specific cells or cell lineages would, therefore, have major advantages, in particular, the potential to significantly improve the therapeutic window of an agent. Cells of the monocyte-macrophage lineage represent an important target for many therapeutic agents because of their central involvement in a wide range of diseases including inflammation, cancer, atherosclerosis, and diabetes. We have developed a versatile chemistry platform that is designed to enhance the potency and delivery of small-molecule drugs to intracellular molecular targets. One facet of the technology involves the selective delivery of drugs to cells of the monocyte-macrophage lineage, using the intracellular carboxylesterase, human carboxylesterase-1 (hCE-1), which is expressed predominantly in these cells. Here, we demonstrate selective delivery of many types of intracellularly targeted small molecules to monocytes and macrophages by attaching a small esterase-sensitive chemical motif (ESM) that is selectively hydrolyzed within these cells to a charged, pharmacologically active drug. ESM versions of histone deacetylase (HDAC) inhibitors, for example, are extremely potent anticytokine and antiarthritic agents with a wider therapeutic window than conventional HDAC inhibitors. In human blood, effects on monocytes (hCE-1-positive) are seen at concentrations 1000-fold lower than those that affect other cell types (hCE-1-negative). Chemical conjugates of this type, by limiting effects on other cells, could find widespread applicability in the treatment of human diseases where monocyte-macrophages play a key role in disease pathology.

Aminopeptidase inhibition as a targeted treatment strategy in myeloma

Myeloma cells are highly dependent on the unfolded protein response to assemble folded immunoglobulins correctly. Therefore, targeting protein handling within a myeloma cell by inhibiting the aminopeptidase enzyme system, which catalyses the hydrolysis of amino acids from the proteins NH2 terminus, represents a therapeutic approach. CHR-2797, a novel aminopeptidase inhibitor, is able to inhibit proliferation and induce growth arrest and apoptosis in myeloma cells, including cells resistant to conventional chemotherapeutics. It causes minimal inhibition of bone marrow stromal cell (BMSC) proliferation but is able to overcome the microenvironmental protective effects, inhibiting the proliferation of myeloma cells bound to BMSCs and the increase in vascular endothelial growth factor levels seen when myeloma cells and BMSCs are bound together. Additive and synergistic effects are seen with bortezomib, melphalan, and dexamethasone. Apoptosis occurs via both caspase-dependent and non-caspase-dependent pathways with an increase in Noxa, cleavage of Mcl-1, and activation of the unfolded protein response. Autophagy is also seen. CHR-2797 causes an up-regulation of genes involved in the proteasome/ubiquitin pathway, as well as aminopeptidases, and amino acid deprivation response genes. In conclusion, inhibiting protein turnover using the aminopeptidase inhibitor CHR-2797 results in myeloma cell apoptosis and represents a novel therapeutic approach that warrants further investigation in the clinical setting.

CHR-2797: an antiproliferative aminopeptidase inhibitor that leads to amino acid deprivation in human leukemic cells

CHR-2797 is a novel metalloenzyme inhibitor that is converted into a pharmacologically active acid product (CHR-79888) inside cells. CHR-79888 is a potent inhibitor of a number of intracellular aminopeptidases, including leucine aminopeptidase. CHR-2797 exerts antiproliferative effects against a range of tumor cell lines in vitro and in vivo and shows selectivity for transformed over nontransformed cells. Its antiproliferative effects are at least 300 times more potent than the prototypical aminopeptidase inhibitor, bestatin. However, the mechanism by which inhibition of these enzymes leads to proliferative changes is not understood. Gene expression microarrays were used to profile changes in mRNA expression levels in the human promyelocytic leukemia cell line HL-60 treated with CHR-2797. This analysis showed that CHR-2797 treatment induced a transcriptional response indicative of amino acid depletion, the amino acid deprivation response, which involves up-regulation of amino acid synthetic genes, transporters, and tRNA synthetases. These changes were confirmed in other leukemic cell lines sensitive to the antiproliferative effects of CHR-2797. Furthermore, CHR-2797 treatment inhibited phosphorylation of mTOR substrates and reduced protein synthesis in HL-60 cells, both also indicative of amino acid depletion. Treatment with CHR-2797 led to an increase in the concentration of intracellular small peptides, the substrates of aminopeptidases. It is suggested that aminopeptidase inhibitors, such as CHR-2797 and bestatin, deplete sensitive tumor cells of amino acids by blocking protein recycling, and this generates an antiproliferative effect. CHR-2797 is orally bioavailable and currently undergoing phase II clinical investigation in the treatment of myeloid leukemia.

Identification of potential stroke targets by lentiviral vector mediated overexpression of HIF-1 alpha and HIF-2 alpha in a primary neuronal model of hypoxia

The identification of genes differentially regulated by ischemia will lead to an improved understanding of cell death pathways such as those involved in the neuronal loss observed following a stroke. Furthermore, the characterization of such pathways could facilitate the identification of novel targets for stroke therapy. We have used a novel approach to amplify differential gene expression patterns in a primary neuronal model of stroke by employing a lentiviral vector system to specifically bias the transcriptional activation of hypoxically regulated genes. Overexpression of the hypoxia-induced transcription factor subunits HIF-1 alpha and HIF-2 alpha elevated hypoxia-mediated transcription of many known HIF-regulated genes well above control levels. Furthermore, many potentially novel HIF-regulated genes were discovered that were not previously identified as hypoxically regulated. Most of the novel genes identified were activated by a combination of HIF-2 alpha overexpression and hypoxic insult. These included several genes with particular importance in cell survival pathways and of potential therapeutic value. Hypoxic induction of HIF-2 alpha may therefore be a critical factor in mediating protective responses against ischemic injury. Further investigation of the genes identified in this study may provide increased understanding of the neuronal response to hypoxia and may uncover novel therapeutic targets for the treatment of cerebral ischemia.

Sequence variation in the early genes E1E4, E6 and E7 of human papilloma virus type 6

The majority of condylomata acuminata (anogenital warts) are caused by infection with Human Papilloma Virus type 6 (HPV-6). We have sequenced the HPV-6 early genes, E1-E4, E6 and E7 from wart biopsy DNA samples sourced from the UK and USA and derived a consensus sequence for these genes and the proteins they encode. When compared to the prototype HPV-6b sequence, published over 12 years ago, the E1-E4 consensus sequence showed 3/91 (3.3%) amino acid changes, the E6 consensus sequence showed 1/150 (0.7%) changes and the E7 consensus sequence showed 1/98 (1.0%) changes. Since many of the early gene sequences from biopsy material were more similar to the HPV-6a subtype than HPV-6b, this data supports the use of HPV-6a as the HPV-6 prototype.

A 31P magnetic resonance spectroscopy study of mitochondrial function in skeletal muscle of patients with Parkinson's disease

The activity of complex I of the respiratory chain is decreased in the substantia nigra of patients with Parkinson's disease (PD) but the presence of this defect in skeletal muscle is controversial. Therefore, the mitochondrial function of skeletal muscle in patients with PD was investigated in vivo using 31P magnetic resonance spectroscopy. Results from 7 PD patients, 11 age matched controls and 9 mitochondrial myopathy patients with proven complex I deficiency were obtained from finger flexor muscle at rest, during exercise and in recovery from exercise. In resting muscle, the patients with mitochondrial myopathy showed a low PCr/ATP ratio, a low phosphorylation potential, a high P(i)/PCr ratio and a high calculated free [ADP]. During exercise, stores of high energy phosphate were depleted more rapidly than normal, while in recovery, the concentration of phosphocreatine and free ADP returned to pre-exercise values more slowly than normal. In contrast, the patients with PD were not significantly different from normal for any of these variables, and no abnormality of muscle energetics was detected. Three of the PD patients also had mitochondrial function assessed biochemically in muscle biopsies. No respiratory chain defect was identified in any of these patients by polarography or enzyme analysis when compared with age-matched controls. These results suggest that skeletal muscle is not a suitable tissue for the investigation and identification of the biochemical basis of the nigral complex I deficiency in PD.

Platelet mitochondrial function in Parkinson's disease. The Royal Kings and Queens Parkinson Disease Research Group

There is increasing evidence that defective function of the mitochondrial enzyme NADH CoQ reductase (complex I) is involved not only in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) toxicity, but also in idiopathic Parkinson's disease (PD). Complex I deficiency has been identified in PD substantia nigra and appears to be disease-specific and selective for the substantia nigra within the central nervous system. We describe a method for preparation of an enriched mitochondrial fraction from 60 mL blood. Using this technique, we analyzed respiratory chain function in 25 patients with PD and 15 matched control subjects. We confirm a previous report of a specific complex I deficiency in PD platelet mitochondria. Although there was a statistically significant decrease in complex I activity in the PD group compared with the control group (p = 0.005), the defect was mild (16%); it was not possible to distinguish PD from control values on an individual basis. This deficiency is not detectable in platelet whole-cell homogenates, presumably reflecting the relative insensitivity of this preparation and the limited decrease in complex I activity in PD. The presence of a mild complex I defect in platelets together with a more severe defect in substantia nigra suggests either that the pharmacological characteristics shared by these two tissues render them susceptible to a particular toxin or toxins, or that the defect is widely distributed and other biochemical events enhance the deficiency in substantia nigra.(ABSTRACT TRUNCATED AT 250 WORDS)

Human mitochondrial complex I dysfunction

In humans, complex I dysfunction has been observed in a high percentage of patients with mitochondrial myopathy. Analysis of mitochondria from these patients suggests the function and assembly of complex I is particularly susceptible to abnormalities of mitochondrial DNA, involving either point mutations of tRNA genes or major deletions. The evidence for a complex I defect in Parkinson's disease is accumulating, although the cause of this deficiency or the role it plays in the events that culminate in dopaminergic cell death remains unresolved.

Brain, skeletal muscle and platelet homogenate mitochondrial function in Parkinson's disease

The recent discovery of mitochondrial complex I deficiency in the substantia nigra of patients with idiopathic Parkinson's disease has provided new understanding into the possible mechanisms that may underlie this neurodegenerative disorder. The biochemical defect is identical to that induced in humans, primates and mice exposed to the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. We have studied mitochondrial respiratory chain function in various brain regions, in skeletal muscle and in blood platelets from patients with idiopathic Parkinson's disease and from matched controls. We provide evidence suggesting that the complex I deficiency in Parkinson's disease is limited to the brain and that this defect is specific for the substantia nigra. The tissue specificity of the complex I deficiency in Parkinson's disease and its localization to the substantia nigra support the proposition that complex I deficiency may be directly involved in the cause of dopaminergic cell death in Parkinson's disease. An understanding of the molecular basis of this biochemical defect will provide valuable insight into the cause of Parkinson's disease. Our findings of normal mitochondrial function in platelet homogenates suggests that this tissue cannot be used to develop a 'diagnostic test' for Parkinson's disease.

Mitochondrial function in Parkinson's disease. The Royal Kings and Queens Parkinson's Disease Research Group

There is increasing evidence for a defect of mitochondrial respiratory chain function in Parkinson's disease. Specific NADH CoQ1 reductase (complex I) deficiency has been identified in the substantia nigra. Available evidence suggests that this defect is confined to the substantia nigra and is not present elsewhere in the parkinsonian brain. The absence of a detectable mitochondrial abnormality in the substantia nigra of patients with multiple system atrophy also suggests that the complex I deficiency in Parkinson's disease is not simply due to an artifact of neuronal degeneration. Evidence for abnormal mitochondrial function in skeletal muscle is conflicting; two studies showed multiple respiratory chain defects and one study was unable to demonstrate any deficiency. A severe deficiency of complex I activity has been found in platelet mitochondria from parkinsonian patients. This finding has not as yet been confirmed. Platelet homogenates do not show the complex I deficiency, however, suggesting that such a preparation may be too insensitive to detect the defect. The role of complex I deficiency in the events that culminate in dopaminergic cell death in Parkinson's disease remains unresolved. It is likely that if this mitochondrial defect is confirmed, it will be related to a number of other factors, including environmental agents, oxidative stress, and genetic predisposition.

The use of a geographical information system for hospital catchment area research in Natal/KwaZulu

We use a computerised geographical information system (GIS) to study the population per bed ratios and the implications of open access to the private and the formerly white hospital services in Natal. The advantages of the GIS method over the more usual administrative boundary-based beds per capita ratios are discussed. While the latter method would suggest that hospital bed resources in the province are racially unequal but nevertheless adequate (264 people per general and referral bed for the whole population, 195 for whites and 275 for blacks) the GIS analysis reveals widespread inadequacy, worse for blacks. Of the estimated hospital catchment areas half have more than 275 black people per general and referral bed, and half of these have more than 550 black people per bed. One-third of the catchment areas estimated for whites have ratios above 275 people per bed, and one half of these are also above 550 people per bed. The GIS analysis shows that open access to beds previously reserved for whites will make no difference to rural blacks, and almost none to urban blacks, because there were relatively few such beds, and they were concentrated in the cities. For the same reasons, the opening of private hospital beds to all patients would not significantly alleviate the apparent bed shortages in priority areas. By contrast, people in these priority areas would gain significantly improved access to general hospital care if selected chronic disease and industrial hospitals were upgraded to provide general hospital services.(ABSTRACT TRUNCATED AT 250 WORDS)