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.