Introduction
Vulvar cancer is a malignant tumor that originates from the vulvar, representing around 5% of all gynecological malignancies. The overall incidence and mobility of vulvar cancer has been rising in the past few decades(1). Nearly 90% of vulvar cancer cases are squamous cell carcinoma (SCC), followed by melanoma. So far, only limited treatment options are available for vulvar cancer. Surgery is still the major treatment strategy for vulvar cancer patients, sometimes with additional support of chemotherapy or radiotherapy. For vulvar cancer patients with regional and distant metastasis, the five-year survival rate of traditional therapies is 53% and 19%, respectively(2). Therefore, it is urgent to develop new therapeutic strategies for vulvar cancer patients.
Cancer immunotherapy, as represented by anti-PD1/PDL1 antibodies and CAR-T therapy, has revolutionized the history of cancer treatment and significantly prolonged the survival of cancer patients, especially patients with advanced or metastatic tumors(3, 4). However, only limited randomized clinical trials of immunotherapy have been performed for vulvar cancer patients(5). Immunohistochemistry analysis showed that considerable immune cell infiltration could be found in vulvar tumor(6, 7). Notably, 78% of HPV-induced SCC has shown high intraepithelial T cell infiltration and 40-60% in HPV negative SCC. Moreover, a high intraepithelial infiltration with CD3+ T cells is associated with overall and recurrence-free survival(7), providing a solid evidence to consider developing immunotherapy for vulvar cancer.
TIL therapy is a type of adoptive cellular therapy, which collects infiltrated lymphocytes from the tumor through biopsy or surgery, amplifies them in the laboratory with interleukin-2 (IL-2) and then reinfuses back intravenously to the patient(8). Compared with CAR-T cell therapy, which significantly enhances the treatment of hematological malignancies, TIL therapy holds unique advantages in tackling the solid tumors. TILs collected from the tumor site have multiple TCR clones that can recognize heterogeneous tumor antigens, while CAR-T cells only recognize single antigen epitopes. Having been stimulated by tumor antigens in vivo, TILs usually express chemokine receptors on the surface and show superior homing capacity to tumor site upon adoptive transfer(9, 10). In addition, off-target toxicity is seldomly reported in TIL therapy.
The National Cancer Institute of the United States started to explore TIL therapy to treat patients with metastatic melanoma in 1988, and demonstrated an objective response rate (ORR) of 60%(11). For a long time, however, TIL therapy was only successful in treating melanoma. Currently, TIL preparation is being explored for more cancer types, such as non-small cell lung cancer, ovarian cancer, colorectal cancer, bile duct cancer, breast cancer and cervical cancer, and such TILs have shown promising results in clinical trials(12-14). A recent phase 2 trial of autologous TIL therapy showed an ORR of 44.4% in 27 cervical cancer patients who had received multiple lines of conventional treatment(15).
The relatively high T cell infiltration found in the tumor site indicates the high potential of TIL as a new therapeutic strategy for patients with vulvar cancer, but the feasibility of TIL collection and amplification from vulvar cancer hasn’t been investigated yet. Therefore, we isolated and expanded TILs from vulvar cancer (VC TILs) in comparison with those from cervical cancer (CC TILs) in the present study. The TCR diversity and clonetypes of TIL samples were further compared with PBMC (peripheral blood mononuclear cell) from the same donor. By evaluating and comparing multiple indicators of TILs from these two tumor types, we demonstrated that our manufacturing process can successfully culture and expand VC TILs with good effector functions, and both VC and CC TILs have more enriched TCR clones than PBMC.