
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Clinical Trials |
Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905 [P. A. B., G. S., D. M. S., T. A. B.]; Nebraska Oncology Group-Creighton University, University of Nebraska Medical Center and Associates, Omaha, Nebraska 68131 [M. B., J. A. M.]; Illinois Oncology Research Association CCOP, Peoria, Illinois 61602 [J. W. K.]; Siouxland Hematology-Oncology Associates, Sioux City, Iowa 51105 [J. C. M.]; Carle Cancer Center CCOP, Urbana, Illinois 6180 [A. K. H.]; Cedar Rapids Oncology Project CCOP, Cedar Rapids, Iowa 52403 [K. W.]; and Duluth CCOP, Duluth, Minnesota 55805 [S. A. K.]
| ABSTRACT |
|---|
|
|
|---|
| INTRODUCTION |
|---|
|
|
|---|
Unfortunately, the efficacy of chemotherapy have been poor. Most Phase II studies have not produced response rates reliably above 20%. Median survival typically is in the 3- to 5-month range (2 , 3) . Combination chemotherapy has not been proven to be superior to FU4 alone (4 , 5) . More recently, clinical response and survival have been improved modestly with the introduction of gemcitabine (3) . Clearly, there is a continued need for more effective treatment in this disease.
Somatostatin is a naturally occurring tetradecapeptide originally isolated from the hypothalamus (6) . Its name is derived from its ability to inhibit the release of pituitary growth hormone, but it is known to inhibit the secretion of many hormones and neurotransmitters (6) . The somatostatin analogue octreotide is a synthetic octapeptide that exhibits a pharmacological effect similar to that of native somatostatin but possesses a much longer duration of action (7) .
Octreotide, RC-160, and somatuline are the primary somatostatin analogues that have undergone testing for oncological applications. There is evidence that these analogues suppress the growth of both endocrine and nonendocrine tumors. In 1983, Redding and Schally (8) demonstrated growth inhibition of the SWARM chondrosarcoma in Sprague Dawley rats after injection of somatostatin analogues. Reubi (9) independently reported similar findings in his studies with the same tumor using octreotide. Subsequently, a number of investigators reported that somatostatin analogues inhibit cell growth of a number of tumor models including small cell lung (NCI-H69), breast (MCF-7, MTX), colon (HA/K121), and glioblastoma (U-87, U-373) (10, 11, 12, 13, 14) . Finally, a variety of pancreatic cancer cell lines have exhibited sensitivity to these agents (15, 16, 17, 18, 19, 20, 21, 22) .
Somatostatin analogues may suppress tumor growth in carcinoma of the exocrine pancreas through a variety of actions. In vitro studies have suggested that various gastrointestinal hormones that are suppressed by somatostatin such as cholecystokinin, secretin, and gastrin may stimulate growth of pancreatic adenocarcinoma cancer cells (23) . A direct inhibitory effect on pancreatic cell growth is likely to be mediated through cellular SSTRs. Five such receptors have been characterized (SSTR-1 to SSTR-5) (23 , 24) . Native somatostatin binds to all five subtypes similarly, but different somatostatin analogues vary in their affinity for these receptors (24) . The somatostatin analogues RC-160 and octreotide inhibit the proliferation of cells expressing SSTR-2 through stimulation of tyrosine phosphatase (25) . Somatostatin analogues may also work indirectly in tumors that do not possess somatostatin receptors by suppression of growth factors such as epidermal growth factor and insulin-like growth factor (9 , 23 , 24) . Finally, inhibition of angiogenesis has been reported with these agents (26) .
There has been extensive experience with octreotide therapy in gastrointestinal neuroendocrine carcinomas (27 , 28) . Not only have the endocrine symptoms associated with these neoplasms been well palliated with this therapy but also objective tumor responses have been seen (27 , 28) . Toxicity has been remarkably low at therapeutically effective doses. These reactions consist primarily of mild and transient discomfort at the site of injection, infrequent nausea and vomiting, transient elevations of blood sugar levels, steatorrhea which is seldom significantly symptomatic, and rare development of cholelithiasis (29) . Given the above laboratory and clinical data coupled with the need for new agents in advanced pancreatic cancer, we designed a study to test the value of a somatostatin analogue in advanced pancreatic cancer.
We believed the best way to evaluate a potentially cytostatic-like somatostatin analogue for this disease was in a controlled study with a primary end point of overall survival. We therefore designed a randomized Phase III clinical trial comparing octreotide to chemotherapy with FU with or without leucovorin in a select group of patients with small volume metastatic disease and good performance status. We purposely did not collect data on tumor response in this study given the inability of tumor response to predict enhanced survival in Phase III trials of advanced pancreatic carcinoma. For pancreatic carcinoma, we believed that survival was a more appropriate end point than tumor response. A secondary goal was to determine the survival benefit of biochemical modulation of FU with leucovorin compared with FU alone. This report addresses the primary goal of this study.
| PATIENTS AND METHODS |
|---|
|
|
|---|
Before randomization, all patients underwent a history and physical examination, an evaluation of tumor status, and chest radiograph. Baseline chemistries (bilirubin, aspartate aminotransferase, alkaline phosphatase, calcium, creatinine, glucose) and total thyroxine were obtained. Women of childbearing age were required to have a negative pregnancy test. After signing informed consent, patients were randomized using an imbalanced design with one-half of the patients assigned to octreotide, one-fourth to FU alone, and one-fourth to FU plus leucovorin. Randomization was stratified by site of metastatic disease (abdominal only, abdominal with liver involvement, or extraabdominal) and by the presence or absence of measurable disease.
Treatment Protocol.
The first 12 patients on the octreotide arm were treated at a dose of
200 µg by s.c. injection three times daily. We then became aware of
the results of a small trial where patients with advanced pancreatic
cancer had shown no discernible benefit with the use of octreotide at
this dose (30)
. Data also became available that octreotide
could be given in doses as high as 2000 µg three times daily with
acceptable toxicity and evidence of tumor regressions in patients with
carcinoid tumors (28)
. We therefore escalated the dose of
octreotide in the remaining patients to 500 µg three times daily.
Higher doses than 500 µg would have required multiple injections per
dose or s.c. infusions. Patients on the chemotherapy arms received
either FU 500 mg/m2
by i.v. bolus injection for 5
consecutive days or FU 425 mg/m2
plus leucovorin
20 mg/m2
daily for 5 consecutive days.
Chemotherapy cycles were repeated every 5 weeks.
Evaluation of Progression.
Patients were evaluated every 5 weeks. Patients were coded at each
evaluation as either "stable" or "progression." For patients
with nonmeasurable disease, progression was declared if any of the
following occurred: appearance of new areas of disease; a decrease of
>1 level on the Eastern Cooperative Oncology Group performance scale;
the development of new jaundice or ascites; or definite increase in
areas of previously existing disease. For patients with measurable
disease, progression was declared according to the criteria above or
when there was a >25% increase in measurements of indicator lesions.
Statistical Methods.
The primary efficacy analysis consisted of a comparison of octreotide
to the combination of the two chemotherapy arms. The trial was designed
to enroll 160 patients to provide 95% power to detect a 50% reduction
in the hazard rate of death for patients randomized to the octreotide
arm using a 2-sided logrank test at significance level 0.05. An interim
analysis was specified after 30 deaths had occurred in 1 of the 2
treatment groups. If at the time of the interim analysis the
P from a one-sided logrank test for overall survival for the
superiority of the octreotide regimen exceeded 0.50, accrual to the
octreotide arm would be discontinued (31)
.
Comparisons of octreotide to FU-based chemotherapy are based on only patients who were randomized while the octreotide arm was open. Comparisons between FU and FU plus leucovorin are based on patients randomized at any time during the study. Toxicity figures include all eligible patients randomized to each arm.
Survival curves were generated using the Kaplan-Meier method (32) . Survival and time to progression distributions were compared by the logrank test (33) . The Cox proportional hazards model was used to adjust for covariates in multivariate analyses (34) . All Ps reported are two-sided, and P < 0.05 is used for statistical significance.
| RESULTS |
|---|
|
|
|---|
The patient characteristics are shown in Table 1
. Two randomized patients were declared
ineligible, one patient on the octreotide arm due to insufficient time
from surgery to randomization and one patient on the FU arm due to
primary bile duct cancer instead of pancreatic cancer. All 84 eligible
patients are evaluable for study end points. The patient groups were
evenly distributed with respect to sites of metastatic disease and the
presence or absence of measurable disease. Of the 84 patients, 81
developed progressive disease and died. Three patients died before
disease progression. Two of these deaths were due to treatment-related
toxicity and the other from a stroke at day 101 with stable disease.
|
|
|
Toxicity.
Frequently occurring toxicities are shown in Table 2
. These toxicities were generally
predictable and manageable. The most common adverse events for patients
treated with octreotide were nausea, vomiting, and diarrhea; only four
grade 3 (National Cancer Institute Common Toxicity Criteria)
toxicities occurred on this arm. The occurrence of toxicity was greater
for patients randomized to the chemotherapy arms and did not differ
between FU and FU plus leucovorin. The most common severe toxicities
(
grade 3) included diarrhea (16%), nausea (14%), stomatitis (14%),
and leukopenia (25%). Toxicity of patients on chemotherapy after
crossover from octreotide was similar to that of those initially
assigned to a chemotherapy arm. There were two deaths due to
treatment-related toxicity, both on FU plus leucovorin. One patient
died of diabetic ketoacidosis and ventricular tachycardia, and the
other died due to respiratory arrest.
|
| DISCUSSION |
|---|
|
|
|---|
Unfortunately, the therapeutic results of our study were disappointing. The patients who were treated with octreotide fared worse with significantly shorter time to progression than those treated with a cytotoxic agent which at best has modest activity in advanced pancreatic cancer. The survival did not differ between the two treatment groups, but this may be due to crossover to FU-based chemotherapy at the time of disease progression on octreotide.
At least seven Phase II trials have been conducted with somatostatin
analogues in patients with advanced pancreatic cancer
(35, 36, 37, 38, 39)
. Table 3
details
the results of these studies. All but 1 have included <25 patients.
Rare tumor responses have been recorded, and median survival times are
similar (range, 8.625.7 weeks) to the current study. The addition of
a luteinizing hormone-releasing hormone agonist to octreotide does not
appear to improve these results (40, 41, 42)
. However,
Rosenberg et al. (42)
reported a small study of
12 patients who enjoyed a median survival of 1 year with the use of
tamoxifen in combination with octreotide. A historical control group
had a median survival of only 3 months. Although the survival of the
patients receiving tamoxifen and octreotide is intriguing, the number
of patients was small, it was not a prospective randomized trial, and
the extent of disease is not stated. As shown by our data, the extent
of disease has significant bearing on the outcome of treatment.
|
|
Growth factor inhibition has been one proposed mechanism for tumor suppression by somatostatin analogues. Klijn et al. (36) assayed somatomedin C levels in their patients and demonstrated some reduction in serum levels with the initiation of somatostatin treatment, but levels quickly returned to baseline despite continued drug administration. Similarly, Fisher et al. (47) have shown in their animal studies that plasma levels of epidermal growth factor and insulin-like growth factor were not altered by ongoing octreotide treatment.
Recent laboratory investigations provide more insight into the failure of somatostatin analogues to improve results in the treatment of advanced pancreatic cancer. Gillespie et al. (48) reported that the growth of two human pancreatic cancer cell lines was not altered by RC-160 but that a rat pancreatic cancer cell line was. The two human pancreatic lines did not express somatostatin receptors whereas the rat cell line did, suggesting somatostatin receptor expression is important for somatostatin analogues to exert their antitumor effect. Fisher et al. (47) examined the effect of octreotide on five human pancreatic cancer cell lines in nude mice. Growth inhibition was seen in only one of the cell lines, MIA PaCa-2, which was the only one of the five lines that expressed SSTR-2 receptors. Interestingly, the gene for SSTR-2 was detected in all five tumor lines. Reubi et al. (49) were unable to detect somatostatin cellular receptors in the specimens of 12 human pancreatic tumors. Fisher et al. (50) have extended their studies to include more human pancreatic cell lines as well as 11 tumor specimens. mRNA for SSTR-1, -2, and -5 was seen in most of the tumors and cell lines. No mRNA was detected for SSTR-3 or -4. As seen in their earlier studies, only the MIA PaCa-2 cells expressed surface cellular somatostatin receptors. It appears that lack of expression of specific functional somatostatin cell surface receptors may be the best explanation for the lack of therapeutic impact of the somatostatin analogues in advanced pancreatic cancer.
In summary, our study fails to show any advantage to the use of single agent octreotide in advanced pancreatic cancer. In is unclear whether there is a future role for the use of somatostatin analogues in this disease. The study of tamoxifen and octreotide by Rosenberg et al. (42) is intriguing but needs to be confirmed. Cytotoxic analogues of somatostatin containing doxorubicin is one other area under current investigation (51) . Finally, transfection of cells with SSTR-2 receptors may offer a gene therapeutic approach in the future (52) .
| FOOTNOTES |
|---|
1 This study was conducted as a trial of the North
Central Cancer Treatment Group and was supported in part by USPHS
Grants CA-25224, CA-37404, CA-15083, CA-35113, CA-63849, CA-35103,
CA-35195, CA-52352, CA-35269, CA-35101, CA-37417, CA-35103,
CA-35415, CA-35448, CA-35272, CA-63849, and CA-60276. ![]()
2 To whom requests for reprints should be
addressed, at Mayo Clinic, 200 First Street, SW, Rochester, MN 55905. ![]()
3 Additional participating institutions include:
Iowa Oncology Research Association CCOP, Des Moines, IA 50309-1014
(Roscoe Morton, M.D.); Meritcare Hospital CCOP, Fargo, ND 58122 (Ralph
Levitt, M.D.); Saskatoon Cancer Centre, Saskatoon, Saskatchewan, Canada
S7N 4H4 (Maria Tria Tirona, M.D.); Sioux Community Cancer Consortium,
Sioux Falls, SD (Loren K. Tschetter, M.D.); Toledo Community Hospital
Oncology Program CCOP, Toledo, OH 43610 (Paul L. Schaefer, M.D.);
Geisinger Clinic and Medical Center CCOP, Danville, PA 17822 (Suresh
Nair, M.D.); Ochsner CCOP, New Orleans, LA 70121 (Carl G. Kardinal,
M.D.); and Rapid City Regional Oncology Group, Rapid City, SD 59709
(Larry P. Ebbert, M.D.). ![]()
4 The abbreviations used are: FU, 5-fluorouracil;
SSTR, somatostatin receptor; CCOP, Community Clinical Oncology
Program. ![]()
Received 11/15/99; revised 6/ 5/00; accepted 6/12/00.
| REFERENCES |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
A. Jatoi {Omega}-3 Fatty Acid Supplements for Cancer-Associated Weight Loss Nutr Clin Pract, August 1, 2005; 20(4): 394 - 399. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Kumar, Z.-R. Liu, L. Thapa, and R.-Y. Qin Anti-angiogenic effects of somatostatin receptor subtype 2 on human pancreatic cancer xenografts Carcinogenesis, November 1, 2004; 25(11): 2075 - 2081. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. J. Loehrer Sr, W. Wang, D. H. Johnson, and D. S. Ettinger Octreotide Alone or With Prednisone in Patients With Advanced Thymoma and Thymic Carcinoma: An Eastern Cooperative Oncology Group Phase II Trial J. Clin. Oncol., January 15, 2004; 22(2): 293 - 299. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. D. Berlin, P. Catalano, J. P. Thomas, J. W. Kugler, D. G. Haller, and A. B. Benson III Phase III Study of Gemcitabine in Combination With Fluorouracil Versus Gemcitabine Alone in Patients With Advanced Pancreatic Carcinoma: Eastern Cooperative Oncology Group Trial E2297 J. Clin. Oncol., August 1, 2002; 20(15): 3270 - 3275. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Szepeshazi, A. V. Schally, G. Halmos, B. Sun, F. Hebert, B. Csernus, and A. Nagy Targeting of Cytotoxic Somatostatin Analog AN-238 to Somatostatin Receptor Subtypes 5 and/or 3 in Experimental Pancreatic Cancers Clin. Cancer Res., September 1, 2001; 7(9): 2854 - 2861. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Cancer Research | Clinical Cancer Research |
| Cancer Epidemiology Biomarkers & Prevention | Molecular Cancer Therapeutics |
| Molecular Cancer Research | Cancer Prevention Research |
| Cancer Prevention Journals Portal | Cancer Reviews Online |
| Annual Meeting Education Book | Meeting Abstracts Online |