Investigating in vitro and in vivo αvβ6 integrin receptor-targeting liposomal alendronate for combinatory γδ T cell immunotherapy

Abstract

The αvβ6 integrin receptor has been shown to be overexpressed on many types of cancer cells, resulting in a more pro-invasive and aggressive phenotype, this makes it an attractive target for selective drug delivery. In tumours that over-express the αvβ6 receptor, cellular uptake of liposomes can be enhanced using ligand-targeted liposomes. It has previously been shown in both in vitro and in vivo studies that liposomal alendronate (L-ALD) can sensitise cancer cells to destruction by Vγ9Vδ2 T cells. It is hypothesised that by using the αvβ6-specific peptide A20FMDV2 as a targeting moiety for L-ALD, the therapeutic efficacy of this therapy can be increased in αvβ6 positive tumours. Targeted liposomes (t-L) were formulated and the targeting efficacy of targeted liposomes (t-L) was assessed by cell uptake and cytotoxicity studies in the αvβ6 positive cells line A375Pβ6. Bio-distribution of both L and t-L were carried out in αvβ6 positive (A375Pβ6 and PANC0403) and αvβ6 negative (A375Ppuro and PANC-1) subcutaneous tumour mouse models. Immuno-compromised mice bearing A375Pβ6 experimental metastatic lung tumours were treated with L-ALD or t-L-ALD as monotherapies or in combination with ex vivo-expanded Vγ9Vδ2 T cells. In vitro, αvβ6-dependant uptake of t-L was observed, with t-L-ALD being more effective than L-ALD at sensitising A375Pβ6 to γδ T cells. Interestingly, t-L-ALD led to slightly higher but not significant reduction in tumour growth compared to L-ALD, when used as monotherapy in vivo. Moreover, both L-ALD and t-L-ALD led to significant reductions in tumour growth when used in combination with γδ T cells in vivo but t-L-ALD offered no added advantage compared to L-ALD.

Vγ9Vδ2 T Cells: Can We Re-Purpose a Potent Anti-Infection Mechanism for Cancer Therapy?

“…zoledronate, alendronate or pamidronate) or 20.1 mAb [121] generally promoted Vγ9Vδ2 T cell mediated tumor killing, there appears to be some variability in the requirement for additional external stimuli. The majority of reports involving solid tumors suggest a stronger dependence on BTN3A agonism [50,147,[149][150][151][153][154][155] than hematologic tumors [156][157][158][159].…”

Organ Biodistribution of Radiolabelled γδ T Cells Following Liposomal Alendronate Administration in Different Mouse Tumour Models

“…Using an ovarian tumour model established by intraperitoneal (IP) inoculation, liposomal alendronate (L-ALD) has been shown to be more effective at slowing tumour growth than ALD when administered intravenously in combination with Vγ9Vδ2 T cells that were injected into the peritoneal cavity of mice [9]. Additionally, we have recently reported that only the combinatory treatment of L-ALD and γδ T cells led to a significant reduction in tumour growth in the experimental metastatic lung melanoma model, after 3 successive intravenous injections [20,21].…”

“…Lipid stock solutions were prepared in chloroform/methanol (4:1 v/v) at concentrations of 20-40 mg/ml and were stored under nitrogen at -20°C to avoid degradation. Alendronic acid liposomes (L-ALD) were prepared by the thin film hydration (TFH) method as previously described [20,21,25]. DSPC, cholesterol and DSPE-PEG2000 (55:40:5 molar volume) were added to a 25 ml round-bottom flask and 2 ml chloroform/ methanol (4:1 v/v) was added.…”

“…The γδ T cells were isolated and expanded as previously described [20,21]. Blood samples of 20-30 ml were obtained from healthy volunteers in an ethically approved protocol ("Use of Donor Blood Samples for Pre-Clinical Development of Active and Passive Immunotherapy for Cancer"; Ref.09/H0804/ 92).…”

Targeting Integrins in Cancer Nanomedicine: Applications in Cancer Diagnosis and Therapy

“…Another non-RGD pentapeptide derived from the synergy domain of fibronectin is Ac-PHSCN-NH 2 , which was clinically developed under the trade name ATN-161 for the treatment of several solid tumors [36,108] due to its high affinity for α5β1-integrin and relatively lower affinity for αvβ3and αvβ5-integrins [109]. Other integrin-targeted peptidomimetics, including SCH221153 (αvβ3-and αvβ5-integrin specific), BCH-15046 (αvβ3-, αvβ5-, and α5β1-integrin specific), SJ749 (α5β1-integrin specific), JSM6427 (α5β1-integrin specific), and A20FMDV2 (αvβ6-integrin specific), have been developed, and these have shown anticancer activities in preclinical models and when used on NPs [110,111].…”