CLINICAL PHARMACOLOGY
Mechanism of Action
Mitoxantrone, a DNA-reactive agent that intercalates into
deoxyribonucleic acid (DNA) through hydrogen bonding, causes crosslinks and
strand breaks. Mitoxantrone also interferes with ribonucleic acid (RNA) and is
a potent inhibitor of topoisomerase II, an enzyme responsible for uncoiling and
repairing damaged DNA. It has a cytocidal effect on both proliferating and
nonproliferating cultured human cells, suggesting lack of cell cycle phase
specificity.
NOVANTRONE® has been shown in vitro to
inhibit B cell, T cell, and macrophage proliferation and impair antigen
presentation, as well as the secretion of interferon gamma, TNFα, and IL-2.
Pharmacokinetics
Pharmacokinetics of mitoxantrone in patients following a
single intravenous administration of NOVANTRONE® can be
characterized by a three-compartment model. The mean alpha half-life of
mitoxantrone is 6 to 12 minutes, the mean beta half-life is 1.1 to 3.1 hours
and the mean gamma (terminal or elimination) half-life is 23 to 215 hours
(median approximately 75 hours). Pharmacokinetic studies have not been
performed in humans receiving multiple daily dosing. Distribution to tissues is
extensive: steady-state volume of distribution exceeds 1,000 L/m². Tissue
concentrations of mitoxantrone appear to exceed those in the blood during the
terminal elimination phase. In the healthy monkey, distribution to brain,
spinal cord, eye, and spinal fluid is low.
In patients administered 15-90 mg/m² of NOVANTRONE
intravenously, there is a linear relationship between dose and the area under
the concentration-time curve (AUC).
Mitoxantrone is 78% bound to plasma proteins in the observed
concentration range of 26455 ng/mL. This binding is independent of
concentration and is not affected by the presence of phenytoin, doxorubicin, methotrexate, prednisone, prednisolone, heparin, or aspirin.
Metabolism and Elimination
Mitoxantrone is excreted in urine and feces as either
unchanged drug or as inactive metabolites. In human studies, 11% and 25% of the
dose were recovered in urine and feces, respectively, as either parent drug or
metabolite during the 5-day period following drug administration. Of the
material recovered in urine, 65% was unchanged drug. The remaining 35% was
composed of monocarboxylic and dicarboxylic acid derivatives and their
glucuronide conjugates. The pathways leading to the metabolism of NOVANTRONE
have not been elucidated.
Special Populations
Gender
The effect of gender on mitoxantrone pharmacokinetics is
unknown.
Geriatric In elderly patients with breast cancer, the
systemic mitoxantrone clearance was 21.3 L/hr/m², compared with 28.3 L/hr/m² and
16.2 L/hr/m² for non-elderly patients with nasopharyngeal carcinoma and
malignant lymphoma, respectively.
Pediatric
Mitoxantrone pharmacokinetics in the pediatric population
are unknown.
Race
The effect of race on mitoxantrone pharmacokinetics is
unknown.
Renal Impairment
Mitoxantrone pharmacokinetics in patients with renal
impairment are unknown.
Hepatic Impairment
Mitoxantrone clearance is reduced by hepatic impairment.
Patients with severe hepatic dysfunction (bilirubin > 3.4 mg/dL) have an AUC
more than three times greater than that of patients with normal hepatic
function receiving the same dose. Patients with multiple sclerosis who have
hepatic impairment should ordinarily not be treated with NOVANTRONE. Other
patients with hepatic impairment should be treated with caution and dosage
adjustment may be required.
Drug Interactions
In vitro drug interaction studies have
demonstrated that mitoxantrone did not inhibit CYP450 1A2, 2A6, 2C9, 2C19, 2D6,
2E1, and 3A4 across a broad concentration range. The results of in vitro
induction studies are inconclusive, but suggest that mitoxantrone may be a weak
inducer of CYP450 2E1 activity.
Pharmacokinetic studies of the interaction of NOVANTRONE
with concomitantly administered medications in humans have not been performed.
The pathways leading to the metabolism of NOVANTRONE have not been elucidated.
To date, post-marketing experience has not revealed any significant drug
interactions in patients who have received NOVANTRONE for treatment of cancer.
Information on drug interactions in patients with multiple sclerosis is
limited.
Clinical Trials
Multiple Sclerosis
The safety and efficacy of NOVANTRONE in multiple sclerosis
were assessed in two randomized, multicenter clinical studies.
One randomized, controlled study (Study 1) was conducted in
patients with secondary progressive or progressive relapsing multiple
sclerosis. Patients in this study demonstrated significant neurological
disability based on the Kurtzke Expanded Disability Status Scale (EDSS). The
EDSS is an ordinal scale with 0.5 point increments ranging from 0.0 to 10.0
(increasing score indicates worsening) and based largely on ambulatory
impairment in its middle range (EDSS 4.5 to 7.5 points). Patients in this study
had experienced a mean deterioration in EDSS of about 1.6 points over the 18
months prior to enrollment.
Patients were randomized to receive placebo, 5 mg/m² NOVANTRONE,
or 12 mg/m² NOVANTRONE administered IV every 3 months for 2 years. High-dose
methylprednisolone was administered to treat relapses. The intent-to-treat analysis cohort consisted of 188 patients; 149 completed the 2-year study.
Patients were evaluated every 3 months, and clinical outcome was determined
after 24 months. In addition, a subset of patients was assessed with magnetic
resonance imaging (MRI) at baseline, Month 12, and Month 24. Neurologic
assessments and MRI reviews were performed by evaluators blinded to study drug
and clinical outcome, although the diagnosis of relapse and the decision to
treat relapses with steroids were made by unblinded treating physicians. A
multivariate analysis of five clinical variables (EDSS, Ambulation Index [AI],
number of relapses requiring treatment with steroids, months to first relapse
needing treatment with steroids, and Standard Neurological Status [SNS]) was
used to determine primary efficacy. The AI is an ordinal scale ranging from 0
to 9 in one point increments to define progressive ambulatory impairment. The
SNS provides an overall measure of neurologic impairment and disability, with
scores ranging from 0 (normal neurologic examination) to 99 (worst possible
score).
Results of Study 1 are summarized in Table 1.
Table 1 : Efficacy Results at Month 24 Study 1
Primary Endpoints |
Treatment Groups |
p-value |
Placebo
(N = 64) |
NOVANTRONE |
Placebo vs 12 mg/m² NOVANTRONE |
5 mg/m²
(N = 64) |
12 mg/m²
(N = 60) |
Primary efficacy multivariate analysis* |
- |
- |
- |
< 0.0001 |
EDSS change** (mean) |
0.23 |
– 0.23 |
– 0.13 |
0.0194 |
Ambulation Index change** (mean) |
0.77 |
0.41 |
0.30 |
0.0306 |
Mean number of relapses per patient requiring corticosteroid treatment (adjusted for discontinuation) |
1.20 |
0.73 |
0.40 |
0.0002 |
Months to first relapse requiring corticosteroid treatment (median [1st quartile]) |
14.2 [6.7] |
NR [6.9] |
NR [20.4] |
0.0004 |
Standard Neurological Status change** (mean) |
0.77 |
– 0.38 |
– 1.07 |
0.0269 |
MRI‡ |
- |
5/32 (16%) |
4/37 (11%) |
0/31 |
0.022 |
Change in number of T2-weighted lesions, mean (n)** |
1.94 (32) |
0.68 (34) |
0.29 (28) |
0.027 |
NR = not reached within 24 months; MRI = magnetic resonance
imaging.
* Wei-Lachin test.
** Month 24 value minus baseline.
‡ A subset of 110 patients was selected for MRI analysis. MRI results were not
available for all patients at all time points. |
A second randomized, controlled study (Study 2) evaluated
NOVANTRONE in combination with methylprednisolone (MP) and was conducted in
patients with secondary progressive or worsening relapsing-remitting multiple
sclerosis who had residual neurological deficit between relapses. All patients
had experienced at least two relapses with sequelae or neurological
deterioration within the previous 12 months. The average deterioration in EDSS
was 2.2 points during the previous 12 months. During the screening period,
patients were treated with two monthly doses of 1 g of IV MP and underwent
monthly MRI scans. Only patients who developed at least one new Gdenhancing MRI
lesion during the 2-month screening period were eligible for randomization. A
total of 42 evaluable patients received monthly treatments of 1 g of IV MP
alone (n = 21) or ~12 mg/m² of IV NOVANTRONE plus 1 g of IV MP (n = 21) (NOV +
MP) for 6 months. Patients were evaluated monthly, and study outcome was
determined after 6 months. The primary measure of effectiveness in this study
was a comparison of the proportion of patients in each treatment group who
developed no new Gd-enhancing MRI lesions at 6 months; these MRIs were assessed
by a blinded panel. Additional outcomes were measured, including EDSS and
number of relapses, but all clinical measures in this trial were assessed by an
unblinded treating physician. Five patients, all in the MP alone arm, failed to
complete the study due to lack of efficacy.
The results of this trial are displayed in Table 2.
Table 2 : Efficacy Results Study 2
Primary Endpoint |
MP alone
(N = 21) |
NOV + MP
(N = 21) |
p-value |
Patients (%) without new Gd-enhancing lesions on MRIs (primary endpoint)* |
5 (31%) |
19 (90%) |
0.001 |
EDSS change (Month 6 minus baseline)* (mean) |
-0.1 |
-1.1 |
0.013 |
Annualized relapse rate (mean per patient) |
3.0 |
0.7 |
0.003 |
Patients (%) without relapses |
7 (33%) |
14 (67%) |
0.031 |
MP = methylprednisolone; NOV + MP = NOVANTRONE plus
methylprednisolone.
* Results at Month 6, not including data for 5 withdrawals in the MP alone
group. |
Advanced Hormone-Refractory Prostate Cancer
A multicenter Phase 2 trial of NOVANTRONE and low-dose
prednisone (N + P) was conducted in 27 symptomatic patients with
hormone-refractory prostate cancer. Using NPCP (National Prostate Cancer
Project) criteria for disease response, there was one partial responder and 12
patients with stable disease. However, nine patients or 33% achieved a
palliative response defined on the basis of reduction in analgesic use or pain
intensity.
These findings led to the initiation of a randomized
multicenter trial (CCI-NOV22) comparing the effectiveness of (N + P) to
low-dose prednisone alone (P). Eligible patients were required to have
metastatic or locally advanced disease that had progressed on standard hormonal
therapy, a castrate serum testosterone level, and at least mild pain at study
entry. NOVANTRONE was administered at a dose of 12 mg/m² by short IV infusion
every 3 weeks. Prednisone was administered orally at a dose of 5 mg twice a
day. Patients randomized to the prednisone arm were crossed over to the N + P
arm if they progressed or if they were not improved after a minimum of 6 weeks of
therapy with prednisone alone.
A total of 161 patients were randomized, 80 to the N + P arm
and 81 to the P arm. The median NOVANTRONE dose administered was 12 mg/m² per
cycle. The median cumulative NOVANTRONE dose administered was 73 mg/m² (range
of 12 to 212 mg/m²).
A primary palliative response (defined as a 2-point decrease
in pain intensity in a 6-point pain scale, associated with stable analgesic
use, and lasting a minimum of 6 weeks) was achieved in 29% of patients
randomized to N + P compared to 12% of patients randomized to P alone (p =
0.011). Two responders left the study after meeting primary response criterion
for two consecutive cycles. For the purposes of this analysis, these two
patients were assigned a response duration of zero days. A secondary palliative
response was defined as a 50% or greater decrease in analgesic use, associated with
stable pain intensity, and lasting a minimum of 6 weeks. An overall palliative
response (defined as primary plus secondary responses) was achieved in 38% of
patients randomized to N + P compared to 21% of patients randomized to P (p =
0.025).
The median duration of primary palliative response for
patients randomized to N + P was 7.6 months compared to 2.1 months for patients
randomized to P alone (p = 0.0009). The median duration of overall palliative
response for patients randomized to N + P was 5.6 months compared to 1.9 months
for patients randomized to P alone (p = 0.0004).
Time to progression was defined as a 1-point increase in
pain intensity, or a > 25% increase in analgesic use, or evidence of disease
progression on radiographic studies, or requirement for radiotherapy. The
median time to progression for all patients randomized to N + P was 4.4 months
compared to 2.3 months for all patients randomized to P alone (p = 0.0001).
Median time to death was 11.3 months for all patients on the N + P arm compared
to 10.8 months for all patients on P alone (p = 0.2324).
Forty-eight patients on the P arm crossed over to receive N
+ P. Of these, thirty patients had progressed on P, while 18 had stable disease
on P. The median cycle of crossover was 5 cycles (range of 2 to 16 cycles).
Time trends for pain intensity prior to crossover were significantly worse for
patients who crossed over than for those who remained on P alone (p = 0.012).
Nine patients (19%) demonstrated a palliative response on N + P after
crossover. The median time to death for patients who crossed over to N + P was
12.7 months.
The clinical significance of a fall in prostate-specific
antigen (PSA) concentrations after chemotherapy is unclear. On the CCI-NOV22
trial, a PSA fall of 50% or greater for two consecutive follow-up assessments
after baseline was reported in 33% of all patients randomized to the N + P arm
and 9% of all patients randomized to the P arm. These findings should be
interpreted with caution since PSA responses were not defined prospectively. A
number of patients were inevaluable for response, and there was an imbalance
between treatment arms in the numbers of evaluable patients. In addition, PSA
reduction did not correlate precisely with palliative response, the primary
efficacy endpoint of this study. For example, among the 26 evaluable patients
randomized to the N + P arm who had a ≥ 50% reduction in PSA, only 13
had a primary palliative response. Also, among 42 evaluable patients on this
arm who did not have this reduction in PSA, 8 nonetheless had a primary
palliative response.
Investigators at Cancer and Leukemia Group B (CALGB)
conducted a Phase 3 comparative trial of NOVANTRONE plus hydrocortisone (N + H)
versus hydrocortisone alone (H) in patients with hormone-refractory prostate
cancer (CALGB 9182). Eligible patients were required to have metastatic disease
that had progressed despite at least one hormonal therapy. Progression at study
entry was defined on the basis of progressive symptoms, increases in measurable
or osseous disease, or rising PSA levels. NOVANTRONE was administered
intravenously at a dose of 14 mg/m2 every 21 days and hydrocortisone
was administered orally at a daily dose of 40 mg. A total of 242 subjects were
randomized, 119 to the N + H arm and 123 to the H arm. There were no
differences in survival between the two arms, with a median of 11.1 months in
the N + H arm and 12 months in the H arm (p = 0.3298).
Using NPCP criteria for response, partial responses were
achieved in 10 patients (8.4%) randomized to the N + H arm compared with 2
patients (1.6%) randomized to the H arm (p = 0.018). The median time to
progression, defined by NPCP criteria, for patients randomized to the N + H arm
was 7.3 months compared to 4.1 months for patients randomized to H alone (p =
0.0654).
Approximately 60% of patients on each arm required
analgesics at baseline. Analgesic use was measured in this study using a
5-point scale. The best percent change from baseline in mean analgesic use was
-17% for 61 patients with available data on the N + H arm, compared with +17%
for 61 patients on H alone (p = 0.014). A time trend analysis for analgesic use
in individual patients also showed a trend favoring the N + H arm over H alone but
was not statistically significant.
Pain intensity was measured using the Symptom Distress Scale
(SDS) Pain Item 2 (a 5point scale). The best percent change from baseline in
mean pain intensity was -14% for 37 patients with available data on the N + H
arm, compared with +8% for 38 patients on H alone (p = 0.057). A time trend
analysis for pain intensity in individual patients showed no difference between
treatment arms.
Acute Nonlymphocytic Leukemia
In two large randomized multicenter trials, remission induction
therapy for acute nonlymphocytic leukemia (ANLL) with NOVANTRONE 12 mg/m² daily
for 3 days as a 10-minute intravenous infusion and cytarabine 100 mg/m² for 7
days given as a continuous 24-hour infusion was compared with daunorubicin 45
mg/m² daily by intravenous infusion for 3 days plus the same dose and schedule
of cytarabine used with NOVANTRONE. Patients who had an incomplete antileukemic
response received a second induction course in which NOVANTRONE or daunorubicin
was administered for 2 days and cytarabine for 5 days using the same daily
dosage schedule. Response rates and median survival information for both the
U.S. and international multicenter trials are given in Table 3:
Table 3 : Response Rates, Time to Response, and Survival
in U.S. and International Trials
Trial |
% Complete Response (CR) |
Median Time to CR (days) |
Survival (days) |
NOV |
DAUN |
NOV |
DAUN |
NOV |
DAUN |
U.S. |
63 (62/98) |
53 (54/102) |
35 |
42 |
312 |
237 |
International |
50 (56/112) |
51 (62/123) |
36 |
42 |
192 |
230 |
NOV = NOVANTRONE® + cytarabine
DAUN = daunorubicin + cytarabine |
In these studies, two consolidation courses were
administered to complete responders on each arm. Consolidation therapy
consisted of the same drug and daily dosage used for remission induction, but
only 5 days of cytarabine and 2 days of NOVANTRONE or daunorubicin were given.
The first consolidation course was administered 6 weeks after the start of the
final induction course if the patient achieved a complete remission. The second
consolidation course was generally administered 4 weeks later. Full hematologic
recovery was necessary for patients to receive consolidation therapy. For the
U.S. trial, median granulocyte nadirs for patients receiving NOVANTRONE +
cytarabine for consolidation courses 1 and 2 were 10/mm³ for both courses, and
for those patients receiving daunorubicin + cytarabine nadirs were 170/mm³ and
260/mm³, respectively. Median platelet nadirs for patients who received
NOVANTRONE + cytarabine for consolidation courses 1 and 2 were 17,000/mm³ and
14,000/mm³, respectively, and were 33,000/mm³ and 22,000/mm³ in courses 1 and 2
for those patients who received daunorubicin + cytarabine. The benefit of
consolidation therapy in ANLL patients who achieve a complete remission remains
controversial. However, in the only well-controlled prospective, randomized
multicenter trials with NOVANTRONE in ANLL, consolidation therapy was given to
all patients who achieved a complete remission. During consolidation in the
U.S. study, two myelosuppression-related deaths occurred on the NOVANTRONE arm
and one on the daunorubicin arm. However, in the international study there were
eight deaths on the NOVANTRONE arm during consolidation which were related to
the myelosuppression and none on the daunorubicin arm where less
myelosuppression occurred.