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Irinotecan Plus Cisplatin in Patients With Advanced Non- Small-Cell Lung Cancer

Irinotecan Plus Cisplatin in Patients With Advanced Non- Small-Cell Lung Cancer

ABSTRACT: During the 1980s, platinum-based regimens were yielding response rates typically less than 25%, median survival durations of about 25 weeks, and 1-year survival rates less than 25% in patients with advanced non-small-cell lung cancer (NSCLC). Currently, results from single institution phase II trials of agents introduced in the 1990s show a doubling of these numbers, and results from multiinstitutional trials are demonstrating response rates ranging from 30% to 40%, median survival durations of 40 weeks, and 1 year survivals of 40%. Single agent irinotecan shows significant activity against NSCLC in preclinical and early phase I/II clinical studies, with activity similar to that for other new agents. Therapeutic synergy is observed in preclinical tumor models when irinotecan and cisplatin are combined, and phase I/II trials of this combination have demonstrated response rates ³ 50% . Herein the author provides an overview of data from phase II trials of irinotecan and focuses on preliminary results of a large US multicenter phase II trial of weekly irinotecan plus monthly cisplatin in 52 patients with advanced NSCLC. A response rate of 28.9% (95% CI, 16.5% - 41.2%) and a median survival of 9.9 months were observed in this trial. US studies to design a more optimal irinotecan/cisplatin regimen in the same patient population are ongoing, and early results are encouraging. [ONCOLOGY 12(Suppl 6):79-83, 1998]

Introduction

Preclinical and early phase clinical studies have demonstrated that
irinotecan (CPT-11 [Camptosar]) is active against non-small cell lung
cancer, [1-8] with single-agent activity similar to that reported for
other newer agents introduced during the 1990s, including vinorelbine
(Navelbine), gemcitabine (Gemzar), paclitaxel (Taxol), and docetaxel (Taxotere).

During the 1980s, platinum-based regimens for advanced non-small cell
lung cancer were yielding response rates typically less than 25%,
median survival durations of about 25 weeks, and 1-year survival
rates less than 25%. Currently, results from single institution phase
II trials of agents introduced during the 1990s are showing a
doubling of these numbers, with response rates of 50%, median
survival durations of 50 weeks, and 1-year survival of 50%.
Multiinstitutional trials are showing response rates ranging from 30%
to 40%, median survival durations of 40 weeks, and 1 year survivals
of 40%.

This review will provide an overview of data from phase II trials of
irinotecan both as a single agent and in combination with cisplatin
in Japan and in the United States. The focus will be on preliminary
data from the first US trial of irinotecan plus cisplatin in patients
with advanced non-small-cell lung cancer.

An Overview of Phase II Data

Japan Multicenter Trial of Single-Agent Irinotecan

In the first large multicenter phase II trial of irinotecan,
described by Fukuoka and colleagues,[7] 73 patients with
chemotherapy-naïve, advanced non-small-cell lung cancer received
single-agent irinotecan (100 mg/m2/wk). An overall
response rate of 32% and median survival time of 9.8 months were
observed. Grade 3 or 4 toxicities included leukopenia (25%), diarrhea
(21%), nausea/vomiting (22%), anemia (15%), alopecia (4%), and
pneumonitis (3%). Patients did not routinely receive antiemetics or
antidiarrheal medications.

Preliminary results of a US multicenter trial of single-agent
irinotecan were reported at the American Society of Clinical Oncology
meeting in 1997.[9] Irinotecan (100 mg/m2) produced a
response rate of 15% and median survival of 6.2 months in 48 patients
with chemotherapy-naïve, advanced non-small-cell lung cancer

Phase I/II Trial of Irinotecan Plus Cisplatin

Recent biological studies have indicated that topoisomerase I may
have a role in the subsequent DNA degradation and cell death that
follow DNA damage induced by other sources, including cisplatin
(Platinol).[10,11] Furthermore, camptothecin appears to enhance this
process by stimulating the DNA-cleaving activity of the enzyme.
Preclinical studies in lung cancer models demonstrate therapeutic
synergy when topoisomerase I-targeting agents are used in combination
with cisplatin.[1,12] Because cisplatin is a staple in the management
of non-small-cell lung cancer, it is logical to combine these two
agents in clinical trials.

To this end, Masuda and colleagues conducted a phase I-II trial of
irinotecan and cisplatin in patients with advanced non-small-cell
lung cancer.[8] The recommended phase II doses were 80 mg/m2
of cisplatin and 60 mg/m2 of irinotecan. Cisplatin dose
was fixed at 80 mg/m2 and given on day 1 of each 4-week
treatment cycle. Irinotecan doses were gradually escalated and given
on days 1, 8, and 15. Dose-limiting toxicities included diarrhea and
neutropenia. The response rate was 54%. Survival data were not reported.

These same investigators attempted to increase irinotecan doses in
this regimen by adding granulocyte colony-stimulating factor (G-CSF
[Neupogen]).[4] Irinotecan doses could be safely escalated to 80 mg/m2
with growth factor support, but further dose escalation was precluded
by dose-limiting diarrhea. The response rate was an encouraging 50%.

US Multicenter Study

The first US trial of irinotecan plus cisplatin in patients with
advanced non-small-cell lung cancer described herein employed the
phase II regimen recommended by Masuda and colleagues without growth
factor.[8] End points included response, survival, quality of life,
irinotecan pharmacokinetics/pharmacodynamics, and pharmacoeconomics.
A preliminary analysis of toxicity and primary efficacy end points is described.

Patients and Methods

Entry criteria included cytologically or histologically confirmed
stage IIIB or IV non-small-cell lung cancer with bidimensionally
measurable disease; Southwest Oncology Group (SWOG) performance
status of 0 to 2; predicted life expectancy of at least 12 weeks; no
prior chemotherapy; pretreatment granulocyte count > 1,500/mL;
hemoglobin > 9.0 g/dL; and platelet count > 100,000/mL.
Patients had to have adequate liver function (bilirubin £
2.0 mg/dL and serum glutamic oxaloacetic transaminase [SGOT] £
3 times the upper limit of normal) and adequate renal function (serum
creatinine £ 1.5 mg/dL). Patients
with controlled brain metastases were eligible.

Treatment Schedule

Irinotecan (60 mg/m2) was administered as a 90-minute
infusion in 500 mL of 5% dextrose in water (D5W) on days 1, 8, and 15
of each 28-day treatment cycle. Two hours following the completion of
the irinotecan infusion on day 1 only, cisplatin (80 mg/m2)
was given as a 30-minute infusion. Patients received aggressive
intravenous hydration and conventional antiemetics prior to cisplatin
administration. All patients received 10 mg of dexamethasone prior to
chemotherapy unless they had a relative or absolute contraindication
to corticosteroids.

Irinotecan dose adjustments are outlined in Table
1
. Doses were adjusted differently depending on whether
adjustments were made during a given cycle of therapy or on day 1 of
a subsequent treatment cycle. Dose adjustments were based on the
worst grade of toxicity occurring since the last treatment if
adjusted during a treatment cycle, or on the worst toxicities
occurring during the entire previous cycle of therapy if adjusted on
day 1 of a subsequent cycle.

Cisplatin doses were fixed, and dose adjustment was not allowed.
Patients who developed prohibitive cisplatin toxicities or a serum
creatinine ³ 1.5 g/dL were removed
from the study.

Loperamide was used for diarrhea in the following manner: All
patients were instructed to begin taking loperamide at the earliest
sign of diarrhea and/or abdominal cramping that occurred more than 8
hours after receiving irinotecan. They were told to take 4 mg of
loperamide orally at the first onset of diarrhea and then 2 mg every
2 hours (except at night during sleep) until they were free of
diarrhea for at least 12 hours. During sleeping hours, patients were
instructed to take 4 mg of loperamide every 4 hours.

Treatment was continued until the development of regimen intolerance
or progressive disease.

Treatment Evaluation

Measurable disease was evaluated prior to each treatment cycle.
Conventional definitions of partial and complete response and of
stable and progressive disease were used. Classification of a partial
or complete response required confirmation after at least 4 weeks.

Toxicity was graded weekly using the National Cancer Institute (NCI)
Common Toxicity Scale. Quality of life was evaluated prior to each
treatment cycle using the Functional Assessment of Cancer
Therapy-Lung (FACT-L) questionnaire.[13]

 Plasma for irinotecan pharmacokinetics was sampled prior to
treatment and 1, 2, 4, and 24 hours following the completion of the
irinotecan infusion during weeks 1 and 3 of the first treatment
cycle. Data relating to medical resource utilization were collected
weekly and were categorized as related to chemotherapy,
hospitalization, outpatient visits, or home care.

Preliminary results of toxicity, response, and survival analyses are
reported here. A more detailed report is planned once the final
analysis is complete.

Patient characteristics are summarized in Table
2
. A total of 52 patients were enrolled, all of whom were evaluable for response, survival, and toxicity. A majority (79%) of
patients had stage IV disease, and 85% of patients had a SWOG
performance status of 0 or 1. Median age was 61 years.

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