The Tumor Immune Microenvironment in Cutaneous Squamous Cell Carcinoma Arising in Organ Transplant Recipients

Rapid Life-Saving Response to Anti-PD-1 in a Solid Organ Transplant Recipient With Metastatic Cutaneous Squamous Cell Carcinoma: A Case Report and Review

SUMMARY

Anti-programmed cell death protein 1 (PD-1) therapy is considered effective in the treatment of metastatic or locally advanced cutaneous squamous cell carcinoma but the use of these agents in solid organ transplant recipients (SOTRs) is often taken with caution. While anti-tumor effects without graft rejection have been reported, studies have shown high rates of fatal graft rejection with immune checkpoint therapy. In this case report, we present an SOTR patient with life-threatening, acute hypoxic respiratory failure due to rapidly progressive metastatic cutaneous squamous cell carcinoma with lung and pleural involvement. Modification of their immunosuppressive regimen and treatment with front-line anti-PD-1 inhibitor, pembrolizumab, led to rapid clinical response with near complete resolution of metastatic pulmonary disease and no long-term evidence of graft rejection. Our case report shows that front-line treatment with PD-1 inhibitors can be safely administered in SOTR patients with rapid metastatic disease control.

A combined opposite targeting of p110δ PI3K and RhoA abrogates skin cancer

Malignant melanoma is the most aggressive and deadly skin cancer with an increasing incidence worldwide whereas SCC is the second most common non-melanoma human skin cancer with limited treatment options. Here we show that the development and metastasis of melanoma and SCC cancers can be blocked by a combined opposite targeting of RhoA and p110δ PI3K. We found that a targeted induction of RhoA activity into tumours by deletion of p190RhoGAP-a potent inhibitor of RhoA GTPase-in tumour cells together with adoptive macrophages transfer from δD910A/D910A mice in mice bearing tumours with active RhoA abrogated growth progression of melanoma and SCC tumours. Τhe efficacy of this combined treatment is the same in tumours lacking activating mutations in BRAF and in tumours harbouring the most frequent BRAF(V600E) mutation. Furthermore, the efficiency of this combined treatment is associated with decreased ATX expression in tumour cells and tumour stroma bypassing a positive feedback expression of ATX induced by direct ATX pharmacological inactivation. Together, our findings highlight the importance of targeting cancer cells and macrophages for skin cancer therapy, emerge a reverse link between ATX and RhoA and illustrate the benefit of p110δ PI3K inhibition as a combinatorial regimen for the treatment of skin cancers.