Lansoprazole as a rescue agent in
chemoresistant tumors: a phase I/II study in companion animals with
spontaneously occurring tumors
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3264547/
"
Abstract
Background
The
treatment of human cancer has been seriously hampered for decades by
resistance to chemotherapeutic drugs. Mechanisms underlying this
resistance are far from being entirely known. A very efficient mechanism
of tumor resistance to drugs is related to the modification of tumour
microenvironment through changes in the extracellular and intracellular
pH. The acidification of tumor microenvironment depends on proton pumps
that actively pump protons outside the cells, mostly to avoid
intracellular acidification. In fact, we have shown in pre-clinical
settings as pre-treatment with proton-pumps inhibitors (PPI) increase
tumor cell and tumor responsiveness to chemotherapeutics. In this study
pet with spontaneously occurring cancer proven refractory to
conventional chemotherapy have been recruited in a compassionate study.
Methods
Thirty-four
companion animals (27 dogs and 7 cats) were treated adding to their
chemotherapy protocols the pump inhibitor lansoprazole at high dose, as
suggested by pre-clinical experiments. Their responses have been
compared to those of seventeen pets (10 dogs and 7 cats) whose owners
did not pursue any other therapy than continuing the currently ongoing
chemotherapy protocols.
Results
The
drug was overall well tolerated, with only four dogs experiencing side
effects due to gastric hypochlorhydria consisting with vomiting and or
diarrhea. In terms of overall response twenty-three pets out of 34 had
partial or complete responses (67.6%) the remaining patients experienced
no response or progressive disease however most owners reported
improved quality of life in most of the non responders. On the other
hand, only three animals in the control group (17%) experienced short
lived partial responses (1-3 months duration) while all the others died
of progressive disease within two months.
Conclusions
high
dose proton pump inhibitors have been shown to induce reversal of tumor
chemoresistance as well as improvement of the quality of life in pets
with down staged cancer and in the majority of the treated animals PPI
were well tolerated. Further studies are warranted to assess the
efficacy of this strategy in patients with advanced cancers in companion
animals as well as in humans.
Keywords: chemotherapy, lansoprazole, mitoxantrone, carboplatin, proton pump
Introduction
Cancer
initiation, progression, and invasion occur in a complex and dynamic
microenvironment which depends on the hosts and sites where tumors
develop. The response to chemotherapy by tumor cells depends on the
concentration of cytostatics accumulated within the cells. The
accumulation of anticancer drugs in tumor cells is dependent on
functional expression of efflux transporters, but also on the pH of
extracellular microenvironment. However, while the role of
chemotransporters in the chemoresistance of malignant tumors has been
very well documented, little is known about the role of tumor acidity
and mechanisms underlying tumor acidification, including proton
exchangers and their impact on the chemosensitivity of cancer cells.
Tumor cells rely on H+ exchangers to relieve themselves from
the dangerous protons byproduct of cancer metabolism that could trigger a
cascade of lytic enzymes that ultimately would lead to self-digestion.
Among these the most prominent are the vacuolar H+-ATPases (V-ATPases). V-ATPases are ATP dependent H+ transporters
that utilize the energy freed by the hydrolysis of ATP with the active
transport of protons from the cytoplasm to the lumen of intracellular
compartments or, if located within the cytoplasmic membrane, the
extracellular compartment [1-4]. Two important physiological mechanisms of regulating V-ATPase activity in vivo are
reversible dissociation of the domain carrying ATP from the proton
exchanger domain and changes in coupling efficiency of proton transport
and ATP hydrolysis [5-12].
Malignant tumor cells overexpress lysosomal proteins on the cell
surface, with abnormal lysosomal activities, possibly involving deranged
V-ATPase function [13,14].
The acidic tumor environment is a consequence of anaerobic glucose
metabolism resulting in accumulation of acid byproducts such as
lactates. This involves the upregulation of hypoxia-inducible factor 1α [15]
or can be dependent on inadequate tumor perfusion, hypoxia secondary to
disordered tumor growth or enhanced transmembrane pH regulation [16].
These pumps, coupled with other ion exchangers, play a paramount role
in the establishment and maintenance of malignant tumor microenvironment
and their action lead to the selection of more aggressive cell
phenotypes able to survive in this highly hostile microenvironment.
V-ATPases
play a critical role in the maintenance of an appropriate relatively
neutral intracellular pH, and an acidic extracellular pH by actively
excreting protons either through ion exchange mechanisms or by
segregating H+ within cytoplasmic organelles that are subsequently expelled [17].
It is hypothesized that the low extracellular pH of tumors might
trigger proteases (MMP-2, MMP-9, cathepsin B, and cathepsin L), leading
to the dissolution of extracellular matrix. Proton exchangers-mediated
acidification of tumor microenvironment significantly contributes to
tumor invasion and dissemination [18,19].
In fact, it has been shown that by inhibiting V-ATPases through RNA
interference, it was possible to prevent cancer metastases in a murine
model [19].
This could be a novel strategy to deal with the process of tumor
dissemination through the increase of the extracellular tumor pH, thus
inhibiting the activation of tumor proteases. From the therapeutic point
of view, the changes in the pH gradient occurring between the
intracellular and the extracellular compartments as well as the pH
gradient between the cytoplasm and the intracellular organelles can be
significantly involved in the mechanism of drug resistance [20-22].
There are several proposed mechanisms involved in this phenomenon,
including decreased uptake or neutralization of weakly basic drugs by
the acidic tumor microenvironment or the confinement of chemotherapy
drugs within lysosomal vesicles [21-25].
An accelerated turnover of acidic vesicles may represent an additional
tumor strategy of drug resistance based on counteracting current
transportation [26,27].
Interestingly, the expression of proton pumps is increased in
chemoresistant phenotypes and is increased by anticancer drugs [28-31].
Investigation in xenograft models with different human tumor
histologies have shown as proton pump inhibition may on one hand induce
chemosensibilization, on the other hand trigger a clear tumor
cytotoxicity [26,27].
Proton pump inhibitors are normally adopted in the treatment of
gastritis, Zollinger-Ellison syndrome and, limitedly to veterinary
oncology, gastric hyperacidity secondary to mast cell tumors in dogs and
cats [32-36].
These drugs have been shown to be highly effective at inhibiting
V-ATPases in vitro and well tolerated and extremely efficacious in
murine models, resulting in increased chemotherapy efficacy and improved
tumor control [27,31,37,38].
Moreover, according to data reported in current veterinary literature,
at least in two dogs with gastrinoma, PPI therapy with omeprazole
resulted in survivals in excess of 2 years. Such long survivals, are
potentially more due to tumor control secondary to cancer
microenvironment manipulation than to palliation of hyper acidic
syndrome and prevention of gastrointestinal ulcerations [33,35].
Aim of this study was to investigate the feasibility, tolerability and
efficacy of high dose proton pump inhibitor lansoprazole as a rescue to
revert chemoresistance in companion animals affected by neoplasms non
responsive to anticancer drugs.
Methods
Patient selection
Privately
owned canine and feline patients with advanced neoplasms that showed
progression despite chemotherapy were selected for the study. Upon tumor
escape from pharmaceutical control, owners were offered three options:
a) discontinuation of all therapies, b) continuation of chemotherapy
alone, c) continuation of chemotherapy with the addition of high dose
lansoprazole.
Previous informed consent was obtained
from the owners. In order to be enrolled in the study, according to the
Italian law (116/92) and the guidelines defined by the ethical committee
of the National Cancer Institute " Regina Elena" of Rome, Italy,
patients, staged according to the World Health Organization (WHO)
grading system, were considered eligible if they fulfilled the following
criteria:
1 Normal renal function (normal serum blood urea nitrogen [BUN], creatinine, phosphorus, and urine specific gravity).
2 Absence of underlying life threatening diseases or other medical complications (e.g. diabetes mellitus).
3 Compliance of the owner for follow-up rechecks.
4 A presumptive life expectancy of at least four weeks.
5 Overall performance status assessed according to the modified Karnowsky system, had to be less than 3 (Table (Table11).
Modified Kamofsky's performance criteria
Staging
process included a thorough anamnesis, physical examination, caliper or
ultrasonographic measurement of the neoplasm, complete blood cell count
(CBC), serum biochemistry profile, thoracic radiographs (three
projections: two laterals and one ventro-dorsal), and abdominal
ultrasonography. In order to confirm the diagnoses, histological
re-examination of the biopsies were performed following standard
protocols, using Hematoxylin/Eosin and Hematoxylin/Van Gieson stainings
by one of the authors (AB).
Treatment
Twenty-seven
privately owned dogs and seven cats presented to the Regina Elena
Cancer Institute with clinically chemoresistant neoplasms and were
entered the proton pump inhibitors arm in the modified phase I/II study
between September 2009 and April 2011. Similarly, a group of seventeen
pets whose owners declined to enroll their pets in the study but chose
to continue standard chemotherapy was followed as control group.
Treatment
protocol in the experimental arm consisted with lansoprazolo at 5 mg/Kg
SID for three consecutive days, at the time of each chemotherapy
administration, to decrease tumor pH and increase response to therapy,
followed by four days at the dose of 1 mg/Kg SID to prevent gastric
hyperacidity rebound. This schedule has been chosen on the basis of
previous studies on rodents and based on the currently ongoing clinical
trials in humans [27].
Response
to treatment in terms of toxicity and tumor response were assessed
prior each therapy. At that time a physical exam and tumor measure were
performed. Moreover thoracic radiographs and abdominal ultrasonography
were performed every two months to check for tumor spread. Toxicity was
defined as disease processes that occurred secondary to therapy and
accordingly scored (table (table2).2).
In order to have the best assessment of therapy toxicoses, after every
therapy owners were sent home with a questionnaire to be completed in
order to record possible gastrointestinal side effects of the protocol
(Table (Table3).3). Tumor response was defined as follows:
Modified Eastern Cooperative Oncology Group evaluation
Daily evaluation form sent home and made out by the owners
Complete Remission (CR) - the disappearance of all evidence of cancer in all sites for a defined period of time.
Partial Remission (PR)
- the decrease in size of all tumors by 50% or greater as measured by
the sum of the product of two diameters of each tumor for a defined
period of time.
Stable Disease (SD) -
the decrease of < 50% or an increase of < 25% in the sum of the
product of two diameters for a defined period of time.
Progressive Disease (PD) - the increase of 25% or more in the sum of the product of two diameters for a defined period of time.
No evidence of disease - absence of tumor growth (local recurrence or distant metastases) after PPI and chemotherapy for a defined period of time.
Finally,
the owners were questioned prior to each therapy on the activity level,
performance status and food and water consumption of their animals.
Treatment were scheduled to be continued for six additional months in
lymphoma patients, upon achievement of complete remission and for 3
additional months in patients with solid tumors.
Results
Dogs
PPI
COHORT: Twenty-seven dogs entered the study over a 19 months period and
their characteristics and treatment protocols are summarized in tables tables4,4, ,55 and and6.6.
There were 8 mixed breed dogs, 4 Boxers, 3 West Highland White
Terriers, and one each of the following breeds: Great Dane, Bull
Mastiff, Bull dog, Schnauzer, Husky, Labrador, Rottweiler, German
Shepherd, Argentine Dogo, Setter, Poodle, and Beagle. There were 16
males and 11 females (all of them spayed). The age ranged from 5 to 15
years with a mean a mode of 10 years. There were eleven cases of
lymphoma, three of osteosarcoma, three of mammary carcinoma, two of
bladder carcinoma, and finally, one each of the following: acute
lymphocytic leukemia, hemangiosarcoma, anal sac carcinoma, melanoma,
fibrosarcoma, oral squamous cell carcinoma, nasal carcinoma, mammary
carcinosarcoma. All the patients had previous treatment with
chemotherapy: lymphoma patients had been previously treated with first
and rescue protocols (Madison Wisconsin or COP and upon failure, rescue
with MOPP. Protocols details are provided in tables tables44 and and5).5).
Upon failure they were treated with reinstituted MOPP coupled with PPI.
Only exception a patient with cutaneous lymphoma who developed
intolerance to vincristine and, in consideration of its reduced cardiac
fraction shortening, was treated with the doxorubin analogue
mitoxantrone, coupled with PPI. Dogs with solid tumors who had been
treated with a variable number of cycles of platinum drugs and/or
anthracyclines (or their synthetic analogue mitoxantrone), were treated,
upon tumor progression, with mitoxantrone in association with PPI. The
only exceptions were a patient affected by vesical transitional cell
carcinoma whose owners elected to be treated with piroxicam alone,
because of financial issues, and three dogs with osteosarcoma whose
tumor type is not responsive to veterinary adopted chemotherapy regimens
that were treated with the calcifying agent clodronate. Upon failure,
clodronate has been reinstituted with high dose PPI. In table table66 are summarized the data on the PPI cohort.
Madison Wisconsin lymphoma protocol
MOPP lymphoma protocol
Characteristics and outcome of canine patients treated with pump inhibitors and chemotherapy
CONTROL
COHORT: ten dogs were treated just with conventional chemotherapy
during the study and their characteristics and therapies are summarized
in table table7.7.
There were 3 mixed breed dogs and one each of the following breeds:
Setter, Boxer, Labrador, German Shepherd, Argentine Dogo, West Higland
White Terrier and Rottweiler. Overall there were 5 lymphoma patients,
one with acute lymphocytic leukemia, one with cutaneous carcinoma, one
with liposarcoma and two affected by mammary carcinoma. All failed their
therapies at different times but the owners elected to pursue
additional chemotherapies without chemosensitizers.
Characteristics and outcome of canine patients treated with chemotherapy alone for refractory cancers
TOXICITY:
Twenty-three dogs tolerated the dose of lansoprazole without need of
reduction or discontinuation. Four dogs experienced grade 1 and two dogs
had grade 2 gastrointestinal toxicity (diarrhea) that was managed with
probiotics. Five dogs had flatulence (grade 1-3). One dog had grade 3
vomiting that required lansoprazole dose reduction (from 5 to 3 mg/kg).
Three dogs had to be withdrawn due to lansoprazole intolerance.
Hematological toxicity of chemotherapy was not worsened by the addition
of PPI, being limited to two episodes of grade 1 neutropenia and one
case of grade 2 neutropenia that did not require treatment. Seven out of
ten controls experienced progressive anemia and neutrophilia with left
shift due to poor responses to therapy or progressive disease.
EFFICACY:
In terms of efficacy nineteen out of twenty-eight dogs experienced
various degrees of response lasting from two to twelve months, these
responses were more evident in dogs affected by lymphoma (9 out 11). A
paradigmatic example is shown in Figure Figure1,1,
depicting the complete regression of a necrotic lymphomatous ulcer upon
addition of PPI to the chemotherapy regimen of a dog with refractory
lymphoma. In osteosarcoma patients the efficacy consisted in
potentiation of clodronate efficacy in dogs with progressive disease
that resulted in 2 partial responses. An additional benefit, beside the
arrest of tumor progression has been a significant improvement of their
Karnofsky performance status, characterized by a significant decrease of
the pain perception shown by a better weight bearing condition and
weight gain. In dogs with melanoma, carcinoma and sarcoma the addition
of lansoprazole resulted in high response rates as shown by table table66 with one melanoma patient that died of thoracic lymphosarcoma while still in remission for the melanocytic tumor.
Necrotized
scrotal ulcer secondary to lymphosarcoma infiltration in a bull dog at
presentation (A & B) and after initiation of rescue protocol (C
& D).
Besides the
osteosarcoma patients, two other dogs with advanced disease (one
affected by acute lymphocytic leukemia and one by lymphoma) with a poor
Karnofsky performance status, upon clinical response, moved to a lower
grade condition (one moved from grade 3 to grade 1, the other from grade
2 to grade 1). On the contrary, only two dogs in the control group
benefited from the continuation of chemotherapy, experiencing short
lived partial responses (complete responses were not documented) while
the others had progressive disease that ultimately resulted in their
death. Upon questioning, all the owners reported a decreased/poor
quality of life for their pets.
Cats
PPI
COHORT: Seven cats entered the study during the enrollment period,
their characteristics and treatment schedules are summarized in table table8.8.
All of them where Domestic Short Hair cats, four were females and three
were males, age ranged from 7 to 12 years. Tumor types included three
oral squamous cell carcinomas, two lymphomas, one fibrosarcoma and one
breast carcinoma that failed chemotherapy or various combinations of
surgery and chemotherapy. Upon recurrence or progressive disease, PPI
inhibitor lansoprazole has been added to the chemotherapy protocol.
Characteristics and outcome of feline patients treated with pump inhibitors and chemotherapy
CONTROL COHORT: Seven cats entered the study during the enrollment period, their characteristics are summarized in table table9.9.
All but a Norwegian cat where Domestic Short Hair cats, three were
females and four were males, age ranged from 5 to 13 years. All the
owners of these patients elected the continuation of chemotherapy
despite its declining efficacy.
Characteristics and outcome of feline patients treated chemotherapy alone for chemoresistant cancers
TOXICITY:
Regarding the cats, gastrointestinal side effects were limited to mild
anorexia in one cat while they were not noted in the remaining six.
Systemic toxycoses were limited to one cat that experienced a severe
neutropenia (grade 3) leading to infection (grade 3) that required
hospitalization and antibiotic therapy. Again, the control group
patients had a much worse tolerance to the therapy due to progressive
disease.
EFFICACY: Six cats benefited with variable
degrees of response from the therapy. Four cats showed tumor response (2
CR, 2 PR ), two cats had stabilization of the disease and one was a non
responder. The complete responders were a cat with an aggressive
lymphoma that had spread to the pancreas, the other was a cat with oral
squamous cell carcinoma. Figure Figure22
shows the regression of the pancreatic dissemination in the lymphoma
patients. The partial responders were a cat with nasal lymphoma and a
cat with mammary carcinoma. Interestingly, the two cats with oral
squamous cell carcinoma that had stabilization of their disease showed a
significant improvement of their quality of life, in terms of decreased
bleeding, activity level, interaction with the owners, improved
grooming and increased appetite. In terms of performance, they moved
from a grade 3 to a grade 1 Karnofsky status, mostly due to a
significantly decreased tumor induced pain. Again, the response rate in
the control group was much smaller with only two control cats (one with a
soft tissue sarcoma and the other with lymphoma) experiencing a brief
partial response lasting two months during the therapy (see Table Table99).
Lymphosarcoma nodules in the pancreas of a cat, diagnosed by fine needle aspiration with ultrasonographic guidance. Ultrasonographic appearance of pancreatic lesions at presentation (A & B) and after initiation of rescue protocol (C & ...
At
the time of writing a total of 15 patients (12 dogs and 3 cats) are
still alive and periodically monitored leading to a survival rate of
44.4% and 42.8%, respectively. Questioning the owners regarding their
degree of satisfaction with the outcome of the therapy yielded a total
of 85% of appreciation that ranged from "moderate" to "enthusiastic".
The major cause of complain being the gastrointestinal side effects
(specifically the flatulence) experienced by some dogs rather than the
degree of tumor response.
Discussion
From
a strictly chemical evaluation of proton pump inhibitors, it is
conceivable that being pro-drugs needing acidity to be transformed in
the active drug [39],
they might be specifically active in the acidic tumor environments.
Some reports inferred that metastatic tumors are more acidic then
primary tumors, but also that solid tumors, either carcinoma or
melanomas or sarcomas, are more acidic than systemic tumors (i.e.
leukemia) [40].
Therefore, it can be speculated that proton pump inhibitors might be
more active against very malignant, often entirely unresponsive to
current therapies, tumors. These observations are at least partially
contradicted by our findings since in both PPI cohorts we observed
extended responses ( > 6 months) in patients affected by solid tumors
as well as in patients with hematological malignancies. In particular
we found intriguing the consistent responses obtained both in canine and
feline lymphoma patients that had shown a significant refractoriness to
standard multi-drug protocols. Pooling together dogs and cats with
lymphoma 8 patients out of 14 (57%) had responses in excess of 5 months.
When examining the outcome of patients with advanced solid tumors, we
observed a broad spectrum of tumors vulnerable to our novel strategy.
Among them, two of our canine responders suffered neoplasms that are
usually refractory to current treatments, including a spinal
osteosarcoma and a metastatic anal sac carcinoma. Sarcomas have been
shown to be clearly acidic, also by their ability to capture Acridine
Orange [41-43].
However, also metastatic neoplasms are particularly acidic as has been
shown for human melanomas, that thrive in particularly acidic
microenvironments, as compared to primary tumors [27].
In our study, the patient affected by melanoma, showed responsiveness
for the treatment of gross disease, being consistent with the
observation that acidic condition increases susceptibility of metastatic
melanoma cells to proton pump inhibitors [27].
We have showed a dramatic decrease of pain in dogs with osteosarcoma
and in cats affected by oral squamous cell carcinoma invading the
maxilla or the mandible, following clinical response to the treatment
with lansoprazole. This stabilization of tumor mass led to palliation of
bone cancer pain, resulting in improved quality of life as shown by
increased activity levels, improved grooming and feeding ability, and
weight gain, as well. Modulation of tumor microenvironment pH may be
postulated for pain control as well [44],
but it is conceivable that a general acidosis is involved in advanced
cancer, contributing to the establishment of the typical cachexia of
cancer patients [45].
These data are further substantiated by comparing the quality of life
of our PPI cohorts with that of controls that showed progressive weight
loss, decreased appetite, lower tolerance to chemotherapy (as shown by
worse hematological and gastrointestinal toxicities) and the general
tendency to move toward higher Karnowski levels. Bone cancer induces
bone lysis and remodeling leading to mechanical bone deformation and
inducing local tissue acidosis, as well, which in turn may activate pain
receptors through several molecular mechanisms, particularly by
activation of the capsaicin receptor (transient receptor potential
vanilloid, TRPV1) [46,47].
Compelling evidence has shown that TRPV1 is a crucial signal molecule
in the development of physiological and pathological pain [46].
In fact, it has been shown that the reduction of pH may induce both
osteoclast-mediated bone reabsorption, with direct stimulation of
nociceptive receptors, and the switch-on signal transmission by
acid-sensing channels such as TRPV 1 located on pain-sensing neurons [46-48].
The high response rate observed in this study is extremely promising,
considering that most patients suffered advanced cancers refractory to
chemotherapy. This PPI-induced response to anti-tumor therapy provides
the proof of concept that inhibition of the proton pump may represent a
new approach in the struggle against cancer. The mechanisms of this
efficacy lay in both the improvement of chemotherapy by countering the
acid mileu of the tumors [26], but also the induction of tumor self-digestion triggered by the increased cytoplasmic protonation [27-31].
Conclusions
The
results obtained in pets with spontaneous neoplasms will be
instrumental for the planning of further investigations to be pursued in
humans, thus hopefully shortening the time frame necessary for the
adoption of this approach in clinical oncology [49,50].
Our data are particularly comforting for patients with hematological
malignancies, due to the relatively high number of enrolled canine and
feline patients. The data on solid tumors response, albeit promising
need to be further substantiated by the enrollment of other patients.
Studies are currently ongoing for several specific solid tumor
histotypes that will be instrumental for the standardization of the PPI
protocols.
Extending the number of patients treated
with this new approach is needed to further support the result of this
study and to identify both the more sensitive tumor histotypes and the
better PPI and conventional chemotherapy combinations. Prospective
studies will be conducted to evaluate the efficacy of PPI administered
to non-chemoresistant tumors. Finally, we want to emphasize that this
study adds much on the set up of new anti-tumor therapies based on drugs
with low cost, minimal toxicity, effective pain palliation and
antitumor efficacy.
List of abbreviations
PPI: proton pump inhibitors; TRPV1: transient receptor potential vanilloid."
No comments:
Post a Comment