Page 67 - Read Online

Ni et al. Hepatoma Res 2020;6:25 I http://dx.doi.org/10.20517/2394-5079.2020.14 Page 7 of 12

based CAR-T cells were designed and prepared. NKG2D-CAR-T cells had an efficient killing effect in vitro
on HCC cell lines SMMC-7721 and MHCC97H, which express high levels of NKG2DLs. However, they
were less efficient in eradicating NKG2DL-silenced SMMC-7721 cells or NKG2DL-negative Hep3B cells.
The overexpression of NKG2DL (MICA or ULBP2) in Hep3B resulted in enhanced killing capacity of
NKG2D-CAR-T cells. Importantly, T cells expressing the NKG2D-BBz CAR effectively killed SMMC-7721
HCC xenografts. Taken together, these findings imply that NKG2D-CAR-T cells might hold great promise
[41]
for future therapeutic intervention of NKG2DL-positive HCC .
[42]
Zhang et al. prepared CD147-CAR-T cells that were inducible. Since CD147 is expressed at a low level on
non-tumor cells, the Tet-On 3G system was introduced to induce CD147CAR expression to minimize the
on-target, off-tumor toxicity. Specifically, Tet-On-CD147-CAR lentiviral plasmid (LV-Tet-CD147CAR) was
constructed, of which CD147-CAR was controlled by the Tet-On 3G system. The presence of doxycycline
(Dox) resulted in enhanced proliferation, cytotoxicity, and cytokine secretion of Tet-CD147-CAR-T cells.
+
Notably, (Dox ) Tet-CD147-CAR-T cells significantly suppressed tumor growth in nude mice through
multiple intra-tumoral administrations. Collectively, these findings suggest that CD147-CAR expression
and activity were inducible, which reduced the toxicity of CAR-T cell therapy. Furthermore, the study
offered evidence to support the potential benefits and translation of CD147-CAR-T cells for the treatment
of HCC patients.

Cytokine-induced killer
Adjuvant cytokine-induced killer (CIK) cell-based immunotherapy is a promising therapeutic approach
[43]
that increases overall survival and decreases relapses in HCC patients. Yoon et al. performed a trial to
investigate the efficacy of adjuvant immunotherapy with activated CIK cells for treating HCC patients.
59 patients with stage I or II HCC who had undergone surgery or radiofrequency ablation, followed by
adjuvant CIK cell immunotherapy at two large-volume centers in Korea were paired with 59 matched
control subjects. They found that adjuvant immunotherapy with autologous CIK cells after curative
treatment prolonged relapse free survival (RFS) of patients with HCC. In a follow-up study of 226 patients
9
with 114 in the immunotherapy group (treated with 6.4 × 10 CIK cells) and 112 controls (no treatment)
after potentially curative treatment for HCC, the immunotherapy group was observed to have a significantly
lower risk of relapse or death. The RFS rate was 44.8% in the immunotherapy group compared to 33.1% in
the control group at 5 years. The risk of all-cause death was also decreased in the immunotherapy group vs.
the control group. Furthermore, the significant increase in RFS and OS in the immunotherapy group lasted
[44]
over 5 years .

[45]
Yu et al. performed a systematic review and meta-analysis of published studies in order to evaluate the
safety and efficacy of CIK cell-based immunotherapy as adjuvant therapy. This included eight randomized
controlled trials (RCTs), six prospective studies, and three retrospective studies. The overall analysis
indicated that CIK cell therapy resulted in an increased survival rate. CIK cells in non-RCTs resulted in
improved progression-free survival, but in RCTs, had similar progression-free survival rates as those of
controls. CIK cell-treatment also led to lower rates of relapse in RCTs and similar results were observed
when non-RCTs and RCTs were combined. Collectively, these findings suggest that adjuvant CIK cell-based
immunotherapy can enhance OS and decrease relapses in HCC patients.

PD-L1 expression may imply the presence of endogenous host immune responses to tumor. In one
retrospective study including 448 HCC patients, 217 cases underwent hepatectomy and 231 were treated
with both hepatectomy and post-operative CIK cell transfusion. CIK treatment led to a significantly
improved prognosis compared to surgery alone. Higher expression levels of PD-L1 were observed in
patients with long-term survival benefit in the CIK treatment group. Patients with more than 5% PD-L1
expression also had better OS and RFS than those with < 5% PD-L1 expression, particularly in the