The distinct role of CD4+ and CD8+ T-cells during the anti-tumour effects of targeted superantigens

To target T-cells to the tumour area we created a recombinant protein of the bacterial superantigen (SAg) Staphylococcal enterotoxin A (SEA) and the Fab-fragment of a tumour-reactive antibody. This antibody-targeted SAg immunotherapy therapy has been shown to be highly efficient, eliminating > 95% of the pulmonary metastasis in mice carrying established melanoma micrometastases. Earlier studies demonstrated that elimination of the C215-expressing B16-melanoma lung metastasis was dependent on interferon (IFN)-γ release and expression of perforin. In the present study, therapeutic effector functions were analysed both locally at the tumour site and systemically in the spleen. In order to elucidate the role of each T-cell subset during Fab–SEA therapy, CD4 knock-out (KO) and CD8 KO mice were used. Tumour size reduction was statistically significant in Fab–SEA-based tumour therapy in both types of T-cell-deficient mice compared to wild-type mice. CD4 KO mice displayed a drastic reduction in the number of tumour-infiltrating macrophages and CD8+ T-cells. Therapy-induced accumulation of perforin-containing cells at the tumour site was significantly impaired in CD8 KO mice, and marginally in CD4 KO mice. Moreover, CD4 KO mice failed to produce substantial amounts of the tumour suppressive cytokine IFN-γ. This is in sharp contrast to normal mice where a massive local release was recorded. CD8 KO mice displayed a spontaneous production of interleukin (IL)-4 and IL-10 locally in the tumour. Neither normal nor CD4 KO mice produced detectable levels of these Th-2-associated cytokines. The high level of IL-10 was demonstrated to inhibit Fab–SEA tumour therapy, since the therapeutic efficacy was significantly higher in IL-10 KO mice. These results illustrate the importance of a finely tuned cellular collaboration to regulate the various phases of an efficient anti-tumour immune response. © 1999 Cancer Research Campaig

Therapy of human non-small-cell lung carcinoma using antibody targeting of a modified superantigen

Superantigens activate T-cells by linking the T-cell receptor to MHC class II on antigen-presenting cells, and novel reactivity can be introduced by fusing the superantigen to a targeting molecule. Thus, an antibody-targeted superantigen, which activates T cells to destroy tumour cells, might be used as cancer therapy. A suitable target is the 5T4 oncofetal antigen, which is expressed on many carcinomas. We constructed a fusion protein from a Fab of a monoclonal antibody recognizing the 5T4 antigen, and an engineered superantigen. The recombinant product 5T4FabV13-SEAD227A bound the 5T4 antigen expressed on the human non-small-cell lung cancer cell line Calu-1 with a Kd of 1.2 nM while the substitution of Asp227 to Ala in the superantigen moiety reduced binding activity to MHC class II. 5T4FabV13-SEAD227A tumour reactivity was demonstrated in 7/7 NSCLC samples by immunohistochemistry, while normal tissue reactivity was low to moderate. 5T4FabV13-SEAD227A induced significant T-cell-dependent in vitro killing of sensitive 5T4 bearing Calu-1 cells, with maximum lysis at 10−10M, while the capacity to lyse MHC class II expressing cells was approximately 1000 times less effective. Immunotherapy of 5T4FabV13-SEAD227A against human NSCLC was investigated in SCID mice reconstituted with human peripheral blood mononuclear cells. Mice carrying intreperitoneally growing Calu-1 cells showed significant reduction in tumour mass and number after intravenous therapy with 5T4FabV13-SEAD227A. Thus, 5T4FabV13-SEAD227A has highly attractive properties for therapy of human NSCLC. © 2001 Cancer Research Campaign http://www.bjcancer.co

A phase II study of a 5T4 oncofoetal antigen tumour-targeted superantigen (ABR-214936) therapy in patients with advanced renal cell carcinoma

In a phase II study, 43 renal cell carcinoma patients were treated with individualised doses of ABR-214936; a fusion of a Fab recognising the antigen 5T4, and Staphylococcal enterotoxin A. Drug was given intravenously on 4 consecutive days, treatment was repeated 1 month later. Treatment was associated with moderate fever and nausea, but well tolerated. Of 40 evaluable patients, 28 had disease control at 2 months, and at 4 months, one patient showed partial response (PR) and 16 patients stable disease. Median survival, with minimum follow-up of 26 months was 19.7 months with 13 patients alive to date. Stratification by the Motzer's prognostic criteria highlights prolonged survival compared to published expectation. Patients receiving higher drug exposure had greater disease control and lived almost twice as long as expected, whereas the low-exposure patients survived as expected. Sustained interleukin-2 (IL-2) production after a repeated injection appears to be a biomarker for clinical effect, as the induced-IL-2 level on the day 2 of treatment correlated with survival. The high degree of disease control and the prolonged survival suggest that this treatment can be effective. These findings will be used in the trial design for the next generation of drug, with reduced antigenicity and toxicity

Solid Tumor-Targeted Infiltrating Cytotoxic T Lymphocytes Retained by a Superantigen Fusion Protein

Successful immune-mediated regression of solid tumors is difficult because of the small number of cytotoxic T lymphocytes (CTLs) that were traffic to the tumor site. Here, the targeting of tumor-specific infiltrating CTLs was dependent on a fusion protein consisting of human epidermal growth factor (EGF) and staphylococcal enterotoxin A (SEA) with the D227A mutation. EGF-SEA strongly restrained the growth of murine solid sarcoma 180 (S180) tumors (control versus EGF-SEA, mean tumor weight: 1.013 versus 0.197 g, difference  = 0.816 g). In mice treated with EGF-SEA, CD4+, CD8+ and SEA-reactive T lymphocytes were enriched around the EGFR expressing tumor cells. The EGF receptors were potentially phosphorylated by EGF-SEA stimulation and the fusion protein promoted T cells to release the tumoricidal cytokines interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α). Intratumoral CTLs secreted cytolytic pore-forming perforins and granzyme B proteins near the surface of carcinomas, causing the death of many tumor cells. We additionally show that labeled EGF-SEA was directly targeted to the tumor tissue after intravenous (i.v.) injection. The findings demonstrate that antibody-like EGF-SEA plays an important role in arresting CTLs in the solid tumor site and has therapeutic potential as a tumor-targeting agent

Facilitators of co-leadership for quality care.

Olive Cocoman and colleagues argue that national leadership for quality of care requires working in a co-leadership model such that quality and programme units have equal standing and clearly defined individual roles and responsibilitie

Strengthening the policy, implementation, and accountability environment for quality care: experiences from quality of care network countries

Despite global commitment to universal health coverage with quality, poor quality of care (QOC) continues to impact health outcomes for mothers and newborns, especially in low-and-middle income countries. Although there is much experience from small-scale projects, without a long-term perspective it is unclear how to implement quality of care effectively and consistently for impact. In 2017, ten countries together with the WHO and a coalition of partners established the Network for Improving Quality of Care for Maternal, Newborn and Child Health (the Network). The Network agreed to pursue four strategic objectives—Leadership, Action, Learning and Accountability (LALA) for QOC. This paper describes, analyses and reflects on what has worked and some of the challenges faced in implementation of the LALA framework. The implementation of the LALA framework has served as a catalyst to develop an enabling environment for QOC in the Network countries through strengthening the policy, implementation, accountability and community engagement for quality care. Developing an enabling health system environment takes time, but it is possible and shows results. The implementation shows that health systems continue to face persistent challenges such as capacities to quickly scale up changes across subnational levels, limited workforce capability to implement quality improvement consistently and gaps in quality of relevant data. The implementation has also highlighted the need to develop new mechanisms for community engagement and learning systems that inform scaling up of good QOC practices across programmes and levels of care. Moving forward, the Network countries will build on the experiences and lessons learned and continue to strengthen the implementation of LALA strategic objectives for impact. We hope the Network experience will encourage other countries and partners to adopt the Network implementation model to enable delivery of quality care for everyone, everywhere, and actively collaborate and contribute to the QOC global learning network

Exploring and prioritising strategies for improving uptake of postnatal care services in Thyolo, Malawi: A qualitative study.

Although postnatal care services form a critical component of the cascade of care in maternal, newborn, and child health the uptake of these services has remained low worldwide. This study explored and prioritised the strategies for optimising the uptake of postnatal care (PNC) services in Malawi. A qualitative descriptive study followed by nominal group techniques was conducted at three health facilities in Malawi from July to December 2020 and in October 2021. We conducted focus group discussions among postnatal mothers, fathers, healthcare workers, elderly women, and grandmothers. We conducted in-depth interviews with midwives and key health managers. Nominal group techniques were used to prioritise the main strategies for the provision of PNC. The demand strategies include appointment date reminders, provision of free health passport books, community awareness campaigns, and involvement of men in the services. The supply strategies included training health providers, improving clinic operations: task-shifting and hours of operation, having infrastructure for the services, and linkage to other services. Having services delivered near end-user residences was a crosscutting strategy. Refresher training and improvement in the clinic operations especially on hours of operation, appointment date reminders, and linkage to care were the prioritised strategies. There is a need to use acceptable and contextualised strategies to optimise the uptake and delivery of postnatal care services. Educating the healthcare workers and the community on postnatal services is key to increasing the demand and supply of the services