1
Institute of Biological Medicine, Milan, Italy
Corresponding author details:
Paolo Lissoni
Institute of Biological Medicine Milan
Milan,Italy
Copyright:
© 2018 Lissoni P, et al. This is
an open-access article distributed under the
terms of the Creative Commons Attribution 4.0
international License, which permits unrestricted
use, distribution, and reproduction in any
medium, provided the original author and source
are credited
Background: Despite the negative prognostic significance of lymphocytopenia is known for many years no clinical cancer study has been proposed up to now in an attempt to specifically correct the evidence of an abnormally low lymphocyte count. At present it is known that IL-2 is the main growth factor for T lymphocytes. Lymphocyte proliferation is also stimulated by the pineal indole hormone melatonin (MLT), which is provided by an anticancer activity, whereas it is inhibited by cortisol.
Objective: On this basis a preliminary study was carried out to evaluate which may be the optimal therapeutic schedule of cancer- related lymphocytopenia.
Methods: The study included 40 advanced solid tumor patients who were treated by the best supportive care (BSC) (n=9), high-dose MLT alone (n=12) at 100 mg/day in the night, subcutaneous low-dose IL-2 alone (n=9) at 1.8 MIU/day for 5 days/week for 2 weeks followed by 2 weeks-rest period, or IL-2 plus MLT. The duration of study was 6 weeks.
Results: The results were compared to those found in 10 advanced cancer patients treated by the checkpoint inhibitor Nivolumab (NVB) at 3 mg/kg/b.w. every 15 days. Lymphocyte count rapidly increased in a significant manner on IL-2 therapy, and a greater increase was reached by Il-2 + MLT. Lymphocyte mean count also increased on MLT alone and on NVB, without, however any statistically significant increase. Finally lymphocyte mean count progressively decreased on BSC alone.
Conclusions: This preliminary study shows that S.C. low-dose IL-2 is the only drug able
to rapidly correct cancer-related lymphocytopenia, whose efficacy may be further amplified
by the concomitant endocrine therapy with the pineal hormone MLT. Further studies will
be required to evaluate the impact of the lymphocytopenia correction on the survival of
advanced cancer patients.
Checkpoint inhibitors; Immunotherapy; Neuroimmunomodulation; Melatonin; Pineal
gland
Even though the negative prognostic significance of cancer-related lymphocytopenia
in almost all human neoplasms is known for more than 40 years [1] before the same
knowledgement of the fundamental role of lymphocytes in mediating the antitumor immunity
[2,3], lymphocyte count is not generally taken into consideration by the Oncologists in the
clinical management of cancer patients. This behavior should be considered as a clinical
limit, since the lymphocyte count may predict not only the prognosis of the neoplastic
disease and survival, but also the same efficacy of cancer chemotherapy [4], and of the
various antitumor immunotherapies, including the more recent cancer immunotherapy
with checkpoint inhibitors, namely anti-PD-1 and anti-CTLA-4 monoclonal antibodies
[5,6]. Moreover, in addition to PD1 and CTLA-4 similar results could be obtained with anti
PDL1 or PDL2 antibodies. More in detail, the evidence of an abnormal low lymphocyte
count prior to chemotherapy has been proven to be associated with a reduced efficacy
of chemotherapy itself [7], which may be abrogated by a short-period subcutaneous (SC)
low-dose IL-2 before the onset of chemotherapy [8]. On the same way, an evident decline
in lymphocyte number on chemotherapy may predict a reduced efficacy of the treatment
[7]. On the contrary, an evident lymphocytosis during cancer immunotherapy with IL-2 has appeared to predict tumor regression or at least a stabilization
of the neoplastic diseases [3], whereas the prognostic significance
of pre-treatment lymphocyte number and changes in lymphocyte
count on immunotherapy with checkpoint inhibitors should be still
investigated and defined [5,6]. The negative prognostic significance
of lymphocytopenia is independent from the histotype of tumor,
since lymphocyte play an essential role in cell-destruction of almost
all neoplasms. Cancer-related lymphocytopenia may depend on the
same previous anticancer therapies, namely radiotherapy and in a
less manner chemotherapy itself, which in some conditions could
also enhance lymphocyte count, because of its modulatory effects
on cytokine network [4,7], or on the other hand lymphocytopenia
may be induced by tumor cells themselves when they express FASligand (FAS-L) molecule, since the interaction between lymphocytes
expressing FAS molecule and tumor cells positive for FAS-L may
allow the apoptosis of FAS-positive lymphocytes [8]. Some cytokines,
such as IL-18, have been shown to stimulate tumor cell FAS-L
expression [9]. Moreover, since the antitumor immune response
is mainly mediated by lymphocytes, it has to be remarked that
cancer-related lymphocytopenia is not a simple epiphenomenon,
but it may represent a clinical index provided by both prognostic
and physiopathological significance [1-3]. In fact, the evidence of an
abnormally low lymphocyte count with values less than 1.000/mm3
,
has appeared to be associated with a worse prognosis in most tumor
histotypes [1,3,7]. Obviously, the only simple lymphocyte count is
not sufficient to establish the immune status of cancer patients,
which would require other clinical determinations, consisting of at
least the evaluation of the different T lymphocyte subsets, namely T
helper-1 (TH1) and regulatory T lymphocytes (T reg) [10,11], since
the antitumor immunity is mainly induced by TH1 and inhibited by T
reg cells [12,13], as well as the measurement of blood concentrations
of the main human antitumor cytokines, represented by IL-2 [2] and
IL-12 [14], and the most known pro-tumoral immunosuppressive
cytokines, including the pro-inflammatory cytokines, namely TNFalpha, IL-6, IL-17 and IL-1-beta, and the anti-inflammatory ones, such
as TGF-beta and IL-10 [15]. However, from a clinical point of view,
the evidence of cancer-related lymphocytopenia has been proven to
be mainly due to a decline in TH1 lymphocytes in association with a
concomitant increase in T reg cell count and activity [11]. Then, the
simple lymphocyte count could reflect at least in part the status of the
whole immune functions, including the antitumor immunity. More
defined clinical informations may be achieved by detecting the simple
lymphocyte-to monocyte ratio (LMR), since a progressive decline
in LMR has appeared to predict a poor prognosis in all solid tumor
histotypes [16]. This evidence is not surprising, since the antitumor
immunity is mainly induced by T lymphocytes and inhibited by the
monocyte-macrophage system [17], despite the different functions of
the various lymphocyte and monocyte subsets. At present, it is known
that lymphocyte proliferation and differentiation may be influenced
by both cytokines and immunomodulating neurohormones or
neuropeptides, namely the pineal hormones [18,19], and muopiod agonists [20]. Within the cytokine group, IL-2 constitutes
up to now the only cytokine able to induce a clinically evident
increase in lymphocyte count [2,3], namely in TH1 cell number, by
representing the main T cell growth factor [2]. Moreover, as far as the
neuroimmunomodulation of the antitumor immunity is concerned,
at present it is known that the anticancer immune response is
mainly stimulated by the pineal hormones, the most investigated
of them is melatonin (MLT) [18,19] and inhibited by the mu-opioid
agonists [20]. In fact, it has been shown that T lymphocytes may
express both MLT and opioid receptors [18] and at present, despite
the complexity of the neuroimmunomodulation (NIM), it has been
well demonstrated that MLT may activate the antitumor immunity
by directly stimulating TH1 cells and playing a major inhibitory
effect on T reg cell activity [19], by acting on specific MLT-receptor
expressed by lymphocytes themselves, whereas mu-opioid agents
may suppress the antitumor immunity by inhibiting TH1-dependent
IL-2 secretion and inducing T reg cell generation and activation [21].
On these bases, a preliminary clinical study was planned to establish
which may be the most simple, effective, non-toxic and inexpensive strategy to correct cancer-related lymphocytopenia, in an attempt to
improve the prognosis of the neoplastic disease, which in contrast
is worsened by the evidence of an abnormal low lymphocyte count
[1] and to enhance the efficacy of the same antitumor conventional
treatments.
The study included 40 lymphocytopenic metastatic cancer
patients (non-small cell lung cancer n=14, colorectal cancer n=13,
gastric cancer n=6, pancreatic adenocarcinoma n= 7), for whom no
other effective standard anticancer therapy was available, because of
lack of response to previous antitumor treatments, or poor clinical
conditions unable to substain a chemotherapeutic approach, then
suitable for the only supportive care. Lymphocytopenia was defined
as lymphocyte count less than 1,000/mm3
. Eligibility criteria were,
as follows: histologically proven solid tumor, metastatic disease,
measurable lesions, progression on previous antitumor treatments,
life expectancy less than 1 year, and persistent lymphocytopenia,
with lymphocyte count less than 1000/mm3
for at least 3 consecutive
months. Because of its immunosuppressive effect on lymphocyte
proliferation, patients under chronic therapy with corticosteroids
were not included in the study. The experimental protocol was
explained to each patient, and written consent was obtained. Patients
were randomly treated with the only best supportive care (BSC),
with high-dose MLT alone, with subcutaneous (SC) low-dose IL-2,
or with IL-2 plus MLT. Moreover, the results were compared to those
observed in a group of 10 consecutive metastatic cancer patients
(lung cancer: 7; melanoma:3) with lymphocytopenia prior to therapy,
who were treated by Nivolumab (NVM), a fully human IgG4 antiPD-1 monoclonal antibody. Lymphocyte count was considered to be
within the normal range when it was greater than 1.500/mm3
(95%
confidence limits). MLT was orally administered at a dose of 100
mg/day once/day during the dark period of the day according to its
circadian secretion, generally 30 minutes prior to sleeping. IL-2 was
SC injected at a dose of 1.8 M IU/day in the afternoon for 5 consecutive
days /week for 2 consecutive weeks, corresponding to one complete
IL-2 cycle, by repeating a second cycle after 2 week-rest period. The
period of IL-2 injection was limited to only 2 consecutive weeks on
the basis of previous clinical studies [8], which have shown no evident
further increase in lymphocyte count after 2 weeks of IL-2 therapy.
Moreover, according to previous studies, in the group of patients who
received IL-2 plus MLT, IL-2 injection was preceded by MLT therapy
alone for at least 1 week prior to IL-2 administration, in an attempt
to make the immune system of patients more responsive to IL-2 itself.
Finally, NVM was intravenously (I.V) injected at a dose of 3 mg/kg
b.w. at 15-day intervals for at least 3 consecutive cycles. Data were
reported as mean +/- SE, and statistically analyzed by the Student’s t
test, the chi-square test, and the analysis of variance, as appropriate.
Lymphocyte mean values observed on study are illustrated in
Figure 1. Lymphocyte mean number decreased and increased on BSC
alone and on high-dose MLT alone, respectively, without, however,
statistically significant differences with respect to the pre-treatment
values. Moreover, no spontaneous normalization of lymphocyte count
was observed on study. On the contrary, a normalization of lymphocyte
count, with values more than 1,500/mm3
was achieved in 2/10
(20%) patients treated by high-dose MLT alone. Lymphocyte mean
values significantly increased on SC low-dose IL-2 administration
within few days of treatment, and they persisted significantly higher
with respect to the number seen prior to therapy during the whole
period of the clinical observation (P<0.01 vs before), and they became
within the normal range in 6/10 (60%) patients. The maximal
lymphocytosis, however, was obtained by SC low-dose IL-2 plus highdose MLT, and lymphocyte mean values observed under IL-2 plus
MLT were significantly higher with respect to both pre-treatment
values (P<0.001) and those observed on IL-2 alone (P<0.05), with a
normalization of lymphocyte count on study in 8/10 (80%) patients.
No side-effect occurred on SC low-dose IL-2, and in particular no
cardiovascular, renal and neurological toxicity was seen. On the same way neither neutropenia, nor thrombocytopenia occurred. Lowgrade asthenia was referred by 7/10 (70%) patients treated by IL-2
alone, and in only 2/10 (20%) patients concomitantly treated with
MLT. This difference was statistically significant (P<0.05). As far as
the immunomodulating effects of NVM are concerned, lymphocyte
mean count increased on therapy, without however statistically
significant differences with respect to the values observed prior to
therapy. Nevertheless, by considering lymphocyte changes in relation
to the clinical response to the treatment, patients with partial tumor
regression (n=2) or disease stabilization (n=4) showed a statistically
significant increase on therapy with respect to the values prior to
treatment (1,275 +/- 87 vs 842 +/- 68/mm3
, P<0.05), whereas no
change was observed in patients who had a progressive disease (n=4)
(893 +/- 86 vs 868 +/- 75/mm3
).
Figure 1: Change in lymphocyte mean count during therapy with best supportive care (BSC) alone, melatonin (MLT) alone,
interleukin-2 (IL-2) alone, IL-2 plus MLT or Nivolumab (NVB).
As expected, since it represents the main or at least apparently
the only clinically active lymphocyte growth factor able to clinically
increase lymphocyte count, this study shows that IL-2 is the most
effective treatment of cancer-related lymphocytopenia, even at
non-toxic SC low doses. Moreover, the stimulatory effect of IL-2 on
lymphocyte proliferation has appeared to be further amplified by the
concomitant administration of pharmacological doses of MLT, and
also this evidence is not surprising, since cancer progression has been
proven to be constantly associated with a progressive decline in the
nocturnal production of the pineal indole MLT, and most in general in
the endocrine function of the pineal gland, which constitutes the main
anti-tumor organ in the human body, whose diminished function has
appeared to be associated with a reduced immunobiological activity of
lL-2 itself [8,19]. A clear lymphocyte increase has been observed also
in patients under immunotherapy with checkpoint inhibitors, which,
however, was limited to the only patients, who achieved a tumor regression, or at least a disease control, by further confirming the
fundamental role of lymphocytes in mediating tumor regression and
control. Unfortunately, in the past years IL-2 was clinically used just
as a potentially anticancer agent, without taking into consideration
the immunological nature of the molecule, it was proposed in the
treatment of tumors less responsive to chemotherapy, namely
renal cancer and malignant melanoma, or in patients, who failed to
respond to chemotherapy. In contrast, according to these preliminary
results and the more recent discoveries in the antitumor immunity,
IL-2 could be used either alone, or in a more favourable way in
association with the other most commonly used anticancer therapies,
including chemotherapy, radiotherapy and immunotherapy itself, in
an attempt to increase lymphocyte number, or at least to counteract
the potential chemotherapy and radiotherapy-induced decline in
lymphocyte number, since it has been demonstrated a lower efficacy
of most antitumor therapies, namely chemotherapy itself [4], in
the presence of lymphocytopenia. Because of the fundamental role
of lymphocytes in mediating and realizing an effective anticancer
immune response, it is very probable that the correction of cancerrelated lymphocytopenia by IL-2, the physiological growth factor
for lymphocytes [2], could not represent a simple epiphenomenon,
but a clinical event, which may allow a greater efficacy of the
different anticancer strategies and approaches. Therefore, since
lymphocytopenia has been proven to predict a lower survival in
cancer patients, the treatment of both spontaneous and anticancer
therapy-induced lymphocytopenia would have to be considered
as a fundamental strategy in the medical Oncology for cancer cure,
irrespectively of the type of treatment and tumor histotypes, being
lymphocytopenia one of the main negative prognostic biological
parameters [1]. Obviously, further studies, carried out to evaluate IL-2
effects on the different lymphocyte subsets, will be required to better
monitor and define the influence of IL-2 on the whole anticancer immunity, in particular on T reg lymphocytes, which in contrast may
suppress the anticancer immune reaction [12,13], because of the
possible stimulatory role of IL-2 not only on T helper and cytotoxic
T lymphocytes, which mediate the antitumor immune response, but
also on T reg cells themselves, event though this event is possible only
in the presence of high concentrations of TGF-beta. In any case, the
potential stimulatory role of IL-2 on T reg cell generation could display
potential therapeutic effects in the autoimmune diseases, which in
contrast are characterized by a decline in the functionless of T reg
cell system. In addition, lymphocytopenia has recently appeared to be
associated with a worse prognosis also in the case of both myocardial
and brain infarction, because of the fundamental role of lymphocytes
in tissue damage repairing. Therefore, IL-2 therapy could constitute
in a near future a fundamental strategy to modulate the immunoinflammatory response in the overall human systemic diseases.
Finally, it has to be remarked that recent clinical observations have
demonstrated that a decline in lymphocyte-to-monocyte ratio (LMR)
is associated with a negative prognosis in patients with advanced
cancer, because of its association with an increase percentage of T
reg cell count. Then, the simple evaluation of LMR could represent
an inexpensive synthetic biomarker to evaluate the immunological
status of the single cancer patient [16,22].
In conclusion, SC low-dose IL-2 may be considered as the
most effective and less toxic therapy of advanced cancer-related
lymphocytopenia, whose efficacy may be further amplified by the
pineal immunomodulating hormone melatonin. An increase in
lymphocyte count may be also obtained by the immunotherapy with
checkpoint inhibitors, which however would seem to be limited to
the only patients who obtained a control of tumor progression. Then,
a pretreatment and/or a concomitant therapy with SC low-dose
IL-2 could be successfully associated to checkpoint inhibitors in an
attempt to enhance their antitumor immune effect.
Copyright © 2020 Boffin Access Limited.