Components:
Method of action:
Treatment option:
Medically reviewed by Militian Inessa Mesropovna, PharmD. Last updated on 26.06.2023
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Temozolomide Hexal is indicated for the treatment of:
| - adult patients with newly-diagnosed glioblastoma multiforme concomitantly with radiotherapy (RT) and subsequently as monotherapy treatment. | |
| - children from the age of three years, adolescents and adult patients with malignant glioma, such as glioblastoma multiforme or anaplastic astrocytoma, showing recurrence or progression after standard therapy. |
Temozolomide Hexal should only be prescribed by physicians experienced in the oncological treatment of brain tumours.
Anti-emetic therapy may be administered.
Posology
Adult patients with newly-diagnosed glioblastoma multiforme
Temozolomide Hexal is administered in combination with focal radiotherapy (concomitant phase) followed by up to 6 cycles of temozolomide (TMZ) monotherapy (monotherapy phase).
Concomitant phase
TMZ is administered orally at a dose of 75 mg/m2 daily for 42 days concomitant with focal radiotherapy (60 Gy administered in 30 fractions). No dose reductions are recommended, but delay or discontinuation of TMZ administration should be decided weekly according to haematological and non-haematological toxicity criteria. TMZ administration can be continued throughout the 42 day concomitant period (up to 49 days) if all of the following conditions are met:
- absolute neutrophil count (ANC) > 1.5 x 109/l - thrombocyte count > 100 x 109/l - common toxicity criteria (CTC) non-haematological toxicity ≤ Grade 1 (except for alopecia, nausea and vomiting). |
During treatment a complete blood count should be obtained weekly. TMZ administration should be temporarily interrupted or permanently discontinued during the concomitant phase according to the haematological and non-haematological toxicity criteria as noted in Table 1.
| Table 1.TMZ dosing interruption or discontinuation during concomitant radiotherapy and TMZ | ||
| Toxicity | TMZ interruptiona | TMZ discontinuation |
| Absolute neutrophil count | > 0.5 and < 1.5 x 109/l | < 0.5 x 109/l |
| Thrombocyte count | > 10 and < 100 x 109/l | < 10 x 109/l |
| CTC non-haematological toxicity (except for alopecia, nausea, vomiting) | CTC Grade 2 | CTC Grade 3 or 4 |
a: Treatment with concomitant TMZ can be continued when all of the following conditions are met: absolute neutrophil count > 1.5 x 109/l; thrombocyte count > 100 x 109/l; CTC non-haematological toxicity ≤ Grade 1 (except for alopecia, nausea, vomiting).
Monotherapy phase
Four weeks after completing the TMZ + RT phase, TMZ is administered for up to 6 cycles of monotherapy treatment. Dose in Cycle 1 (monotherapy) is 150 mg/m2 once daily for 5 days followed by 23 days without treatment. At the start of Cycle 2, the dose is escalated to 200 mg/m2 if the CTC non-haematological toxicity for Cycle 1 is Grade ≤ 2 (except for alopecia, nausea and vomiting), absolute neutrophil count (ANC) is > 1.5 x 109/l, and the thrombocyte count is > 100 x 109/l. If the dose was not escalated at Cycle 2, escalation should not be done in subsequent cycles. Once escalated, the dose remains at 200 mg/m2 per day for the first 5 days of each subsequent cycle except if toxicity occurs. Dose reductions and discontinuations during the monotherapy phase should be applied according to Tables 2 and 3.
During treatment a complete blood count should be obtained on Day 22 (21 days after the first dose of TMZ). The dose should be reduced or administration discontinued according to Table 3.
Table 2. TMZ dose levels for monotherapy treatment
| Dose level | TMZ dose (mg/m2 /day) | Remarks |
| -1 | 100 | Reduction for prior toxicity |
| 0 | 150 | Dose during Cycle 1 |
| 1 | 200 | Dose during Cycles 2-6 in absence of toxicity |
Table 3. TMZ dose reduction or discontinuation during monotherapy treatment
| Toxicity | Reduce TMZ by 1 dose levela | Discontinue TMZ |
| Absolute neutrophil count | < 1.0 x 109 /l | See footnote b |
| Thrombocyte count | < 50 x 109 /l | See footnote b |
| CTC non-haematological Toxicity (except for alopecia, nausea, vomiting) | CTC Grade 3 | CTC Grade 4b |
| a : TMZ dose levels are listed in Table 2. b : TMZ is to be discontinued if: - dose level -1 (100 mg/m2 ) still results in unacceptable toxicity - the same Grade 3 non-haematological toxicity (except for alopecia, nausea, vomiting) recurs after dose reduction. | ||
Adult and paediatric patients 3 years of age or older with recurrent or progressive malignant glioma:
A treatment cycle comprises 28 days. In patients previously untreated with chemotherapy, TMZ is administered orally at a dose of 200 mg/m2 once daily for the first 5 days followed by a 23 day treatment interruption (total of 28 days). In patients previously treated with chemotherapy, the initial dose is 150 mg/m2 once daily, to be increased in the second cycle to 200 mg/m2 once daily, for 5 days if there is no haematological toxicity
Special populations
Paediatric population
In patients 3 years of age or older, TMZ is only to be used in recurrent or progressive malignant glioma. Experience in these children is very limited. The safety and efficacy of TMZ in children under the age of 3 years have not been established. No data are available.
Patients with hepatic or renal impairment
The pharmacokinetics of TMZ were comparable in patients with normal hepatic function and in those with mild or moderate hepatic impairment. No data are available on the administration of TMZ in patients with severe hepatic impairment (Child's Class C) or with renal impairment. Based on the pharmacokinetic properties of TMZ, it is unlikely that dose reductions are required in patients with severe hepatic impairment or any degree of renal impairment. However, caution should be exercised when TMZ is administered in these patients.
Elderly patients
Based on a population pharmacokinetic analysis in patients 19-78 years of age, clearance of TMZ is not affected by age. However, elderly patients (>70 years of age) appear to be at increased risk of neutropenia and thrombocytopenia.
Method of administration
Temozolomide Hexalshould be administered in the fasting state.
The capsules must be swallowed whole with a glass of water and must not be opened or chewed.
If vomiting occurs after the dose is administered, a second dose should not be administered that day.
Hypersensitivity to dacarbazine (DTIC).
Severe myelosuppression.
Opportunistic infections and reactivation of infections
Opportunistic infections (such as Pneumocystis jirovecii pneumonia) and reactivation of infections (such as HBV, CMV) have been observed during the treatment with TMZ.
Pneumocystis jirovecii pneumonia
Patients who received concomitant TMZ and RT in a pilot trial for the prolonged 42-day schedule were shown to be at particular risk for developing Pneumocystis jirovrcci pneumonia (PCP). Thus, prophylaxis against PCP is required for all patients receiving concomitant TMZ and RT for the 42 day regimen (with a maximum of 49 days) regardless of lymphocyte count. If lymphopenia occurs, they are to continue the prophylaxis until recovery of lymphopenia to grade ≤1.
There may be a higher occurrence of PCP when TMZ is administered during a longer dosing regimen. However, all patients receiving TMZ, particularly patients receiving steroids, should be observed closely for the development of PCP, regardless of the regimen. Cases of fatal respiratory failure have been reported in patients using TMZ, in particular in combination with dexamethasone or other steroids.
HBV
Hepatitis due to hepatitis B virus (HBV) reactivation, in some cases resulting in death, has been reported. Experts in liver disease should be consulted before treatment is initiated in patients with positive hepatitis B serology (including those with active disease). During treatment patients should be monitored and managed appropriately.
Hepatotoxicity
Hepatic injury, including fatal hepatic failure, has been reported in patients treated with TMZ. Baseline liver function tests should be performed prior to treatment initiation. If abnormal, physicians should assess the benefit/risk prior to initiating temozolomide including the potential for fatal hepatic failure. For patients on a 42 day treatment cycle liver function tests should be repeated midway during this cycle. For all patients, liver function tests should be checked after each treatment cycle. For patients with significant liver function abnormalities, physicians should assess the benefit/risk of continuing treatment. Liver toxicity may occur several weeks or more after the last treatment with temozolomide.
Meningoencephalitis herpetic
In post marketing cases, meningoencephalitis herpetic (including fatal cases) has been observed in patients receiving TMZ in combination with radiotherapy, including cases of concomitant steroids administration.
Malignancies
Cases of myelodysplastic syndrome and secondary malignancies, including myeloid leukaemia, have also been reported very rarely.
Anti-emetic therapy
Nausea and vomiting are very commonly associated with TMZ.
Anti-emetic therapy may be administered prior to or following administration of TMZ.
Adult patients with newly-diagnosed glioblastoma multiforme:
Anti-emetic prophylaxis is recommended prior to the initial dose of concomitant phase and it is strongly recommended during the monotherapy phase.
Patients with recurrent or progressive malignant glioma
Patients who have experienced severe (Grade 3 or 4) vomiting in previous treatment cycles may require anti-emetic therapy.
Laboratory parameters
Patients treated with TMZ may experience myelosuppression, including prolonged pancytopenia, which may result in aplastic anaemia, which in some cases has resulted in a fatal outcome. In some cases, exposure to concomitant medicinal products associated with aplastic anaemia, including carbamazepine, phenytoin, and sulfamethoxazole/trimethoprim, complicates assessment. Prior to dosing, the following laboratory parameters must be met: ANC >1.5 x 109/l and platelet count > 100 x 109/l. A complete blood count should be obtained on Day 22 (21 days after the first dose) or within 48 hours of that day, and weekly until ANC > 1.5 x 109/l and platelet count > 100 x 109/l. If ANC falls to < 1.0 x 109/l or the platelet count is < 50 x109/l during any cycle, the next cycle should be reduced one dose level. Dose levels include 100 mg/m2, 150 mg/m2, and 200 mg/m2. The lowest recommended dose is 100 mg/m2.
Paediatric population
There is no clinical experience with use of TMZ in children under the age of 3 years. Experience in older children and adolescents is very limited.
Elderly patients (> 70 years of age)
Elderly patients appear to be at increased risk of neutropenia and thrombocytopenia, compared with younger patients. Therefore, special care should be taken when TMZ is administered in elderly patients.
Male patients
Men being treated with TMZ should be advised not to father a child up to 6 months after receiving the last dose and to seek advice on cryoconservation of sperm prior to treatment.
Lactose
This medicinal product contains lactose. Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine.
TMZ has minor influences on the ability to drive and use machines due to fatigue and somnolence.
Clinical trial experience
In patients treated with TMZ, whether used in combination with RT or as monotherapy following RT for newly-diagnosed glioblastoma multiforme, or as monotherapy in patients with recurrent or progressive glioma, the reported very common adverse reactions were similar: nausea, vomiting, constipation, anorexia, headache and fatigue.
Convulsions were reported very commonly in the newly-diagnosed glioblastoma multiforme patients receiving monotherapy, and rash was reported very commonly in newly-diagnosed glioblastoma multiforme patients receiving TMZ concurrent with RT and also as monotherapy, and commonly in recurrent glioma. Most haematologic adverse reactions were reported commonly or very commonly in both indications (Tables 4 and 5); the frequency of grade 3-4 laboratory findings is presented after each table.
In the tables, undesirable effects are classified according to System Organ Class and frequency. Frequency groupings are defined according to the following convention: Very Common (>1/10); Common (>1/100 to <1/10); Uncommon (>1/1,000 to <1/100); Rare (>1/10,000 to <1/1,000); Very rare (<1/10,000). Within each frequency grouping, undesirable effects are presented in order of decreasing seriousness.
Newly-diagnosed glioblastoma multiforme
Table 4 provides treatment-emergent adverse reactions in patients with newly-diagnosed glioblastoma multiforme during the concomitant and monotherapy phases of treatment.
| Table 4. Treatment-emergent reactions during concomitant and monotherapy treatment phases in patients with newly diagnosed glioblastoma multiforme | ||
| System organ class | TMZ + concomitant RT n=288* | TMZ monotherapy n=224 |
| Infections and infestations | ||
| Common: | Infection, Herpes simplex, wound infection, pharyngitis, candidiasis oral | Infection, candidiasis oral |
| Uncommon: | Herpes simplex, Herpes zoster, influenza-like symptoms | |
| Blood and lymphatic system disorders | ||
| Common: | Neutropenia, thrombocytopenia, lymphopenia, leukopenia | Febrile neutropenia, thrombocytopenia, anaemia, leukopenia |
| Uncommon: | Febrile neutropenia, anaemia | Lymphopenia, petechiae |
| Endocrine disorders | ||
| Uncommon: | Cushingoid | Cushingoid |
| Metabolism and nutrition disorders | ||
| Very common | Anorexia | Anorexia |
| Common: | Hyperglycaemia, weight decreased | Weight decreased |
| Uncommon: | Hypokalemia, alkaline phosphatase increased, weight increased | Hyperglycaemia, weight increased |
| Psychiatric disorders | ||
| Common: | Anxiety, emotional lability, insomnia | Anxiety, depression, emotional lability, insomnia |
| Uncommon: | Agitation, apathy, behaviour disorder, depression, hallucination | Hallucination, amnesia |
| Nervous system disorders | ||
| Very common: | Headache | Convulsions, headache |
| Common: | Convulsions, consciousness decreased, somnolence, aphasia, balance impaired, dizziness, confusion, memory impairment, concentration impaired, neuropathy, paresthesia, speech disorder, tremor | Hemiparesis, aphasia, balance impaired, somnolence, confusion, dizziness, memory impairment, concentration impaired, dysphasia, neurological disorder (NOS), neuropathy, peripheral neuropathy, paresthesia, speech disorder, tremor |
| Uncommon: | Status epilepticus, extrapyramidal disorder, hemiparesis, ataxia, cognition impaired, dysphasia, gait abnormal, hyperesthesia, hypoesthesia, neurological disorder (NOS), peripheral neuropathy | Hemiplegia, ataxia, coordination abnormal, gait abnormal, hyperesthesia, sensory disturbance |
| Eye disorders | ||
| Common: | Vision blurred | Visual field defect, vision blurred, diplopia |
| Uncommon: | Hemianopia, visual acuity reduced, vision disorder, visual field defect, eye pain | Visual acuity reduced, eye pain, eyes dry |
| Ear and labyrinth disorders | ||
| Common: | Hearing impairment | Hearing impairment, tinnitus |
| Uncommon: | Otitis media, tinnitus, hyperacusis, earache | Deafness, vertigo, earache |
| Cardiac disorders | ||
| Uncommon: | Palpitation | |
| Vascular disorders | ||
| Common: | Haemorrhage, oedema, oedema leg | Haemorrhage, deep venous thrombosis, oedema leg |
| Uncommon: | Cerebral haemorrhage, hypertension | Embolism pulmonary, oedema, oedema peripheral |
| Respiratory, thoracic and mediastinal disorders | ||
| Common: | Dyspnoea, coughing | Dyspnoea, coughing |
| Uncommon: | Pneumonia, upper respiratory infection, nasal congestion | Pneumonia, sinusitis, upper respiratory infection, bronchitis |
| Gastrointestinal disorders | ||
| Very Common: | Constipation, nausea, vomiting | Constipation, nausea, vomiting |
| Common: | Stomatitis, diarrhoea, abdominal pain, dyspepsia, dysphagia | Stomatitis, diarrhoea, dyspepsia, dysphagia, mouth dry |
| Uncommon: | Abdominal distension, faecal incontinence, gastrointestinal disorder (NOS), gastroenteritis, haemorrhoids | |
| Skin and subcutaneous tissue disorders | ||
| Very common: | Rash, alopecia | Rash, alopecia |
| Common: | Dermatitis, dry skin, erythema, pruritus | Dry skin, pruritus |
| Uncommon: | Skin exfoliation, photosensitivity reaction, pigmentation abnormal | Erythema, pigmentation abnormal, sweating increased |
| Musculoskeletal and connective tissue disorders | ||
| Common: | Muscle weakness, arthralgia | Muscle weakness, arthralgia, musculoskeletal pain, myalgia |
| Uncommon: | Myopathy, back pain, musculoskeletal pain, myalgia | Myopathy, back pain |
| Renal and urinary disorders | ||
| Common: | Micturition frequency, urinary incontinence | Urinary incontinence |
| Uncommon: | Dysuria | |
| Reproductive system and breast disorders | ||
| Uncommon: | Impotence | Vaginal haemorrhage, menorrhagia, amenorrhea, vaginitis, breast pain |
| General disorders and administration site conditions | ||
| Very common: | Fatigue | Fatigue |
| Common: | Allergic reaction, fever, radiation injury, face oedema, pain, taste perversion | Allergic reaction, fever, radiation injury, pain, taste perversion |
| Uncommon: | Asthenia, flushing, hot flushes, condition aggravated, rigors, tongue discolouration, parosmia, thirst | Asthenia, face oedema, pain, condition aggravated, rigors, tooth disorder |
| Investigations | ||
| Common: | ALT increased | ALT increased |
| Uncommon: | Hepatic enzymes increased, Gamma GT increased, AST increased | |
*A patient who was randomised to the RT arm only, received TMZ + RT.
Laboratory results
Myelosuppression (neutropenia and thrombocytopenia), which is known dose-limiting toxicity for most cytotoxic agents, including TMZ, was observed. When laboratory abnormalities and adverse reactions were combined across concomitant and monotherapy treatment phases, Grade 3 or Grade 4 neutrophil abnormalities including neutropenic reactions were observed in 8% of the patients. Grade 3 or Grade 4 thrombocyte abnormalities, including thrombocytopenic reactions were observed in 14% of the patients who received TMZ.
Recurrent or progressive malignant glioma
In clinical trials, the most frequently occurring treatment-related undesirable effects were gastrointestinal disorders, specifically nausea (43%) and vomiting (36%). These reactions were usually Grade 1 or 2 (0 - 5 episodes of vomiting in 24 hours) and were either self-limiting or readily controlled with standard anti-emetic therapy. The incidence of severe nausea and vomiting was 4%.
Table 5 includes adverse reactions reported during clinical trials for recurrent or progressive malignant glioma and following the marketing of TMZ.
Table 5. Adverse reactions in patients with recurrent or progressive malignant glioma
| Infections and infestations | |
| Rare: | Opportunistic infections, including PCP |
| Blood and lymphatic system disorders | |
| Very common: | Neutropenia or lymphopenia (grade 3-4), thrombocytopenia (grade 3-4) |
| Uncommon: | Pancytopenia, anaemia (grade 3-4), leukopenia |
| Metabolism and nutrition disorders | |
| Very common: | Anorexia |
| Common: | Weight decrease |
| Nervous system disorders | |
| Very common: | Headache |
| Common: | Somnolence, dizziness, paresthesia |
| Respiratory, thoracic and mediastinal disorders | |
| Common: | Dyspnoea |
| Gastrointestinal disorders | |
| Very common: | Vomiting, nausea, constipation |
| Common: | Diarrhoea, abdominal pain, dyspepsia |
| Skin and subcutaneous tissue disorders | |
| Common: | Rash, pruritus, alopecia |
| Very rare: | Erythema multiforme, erythroderma, urticaria, exanthema |
| General disorders and administration site conditions | |
| Very common: | Fatigue |
| Common: | Fever, asthenia, rigors, malaise, pain, taste perversion |
| Very rare: | Allergic reactions, including anaphylaxis, angioedema |
Laboratory results
Grade 3 or 4 thrombocytopenia and neutropenia occurred in 19% and 17% respectively, of patients treated for malignant glioma. This led to hospitalisation and/or discontinuation of TMZ in 8% and 4%, respectively. Myelosuppression was predictable (usually within the first few cycles, with the nadir between Day 21 and Day 28), and recovery was rapid, usually within 1-2 weeks. No evidence of cumulative myelosuppression was observed. The presence of thrombocytopenia may increase the risk of bleeding, and the presence of neutropenia or leukopenia may increase the risk of infection.
Gender
In a population pharmacokinetics analysis of clinical trial experience there were 101 female and 169 male subjects for whom nadir neutrophil counts were available and 110 female and 174 male subjects for whom nadir platelet counts were available. There were higher rates of Grade 4 neutropenia (ANC < 0.5 x 109/l), 12% vs 5%, and thrombocytopenia (< 20 x 109/l), 9% vs 3%, in women vs men in the first cycle of therapy. In a 400 subject recurrent glioma data set, Grade 4 neutropenia occurred in 8% of female vs 4% of male subjects and Grade 4 thrombocytopenia in 8% of female vs 3% of male subjects in the first cycle of therapy. In a study of 288 subjects with newly diagnosed glioblastoma multiforme, Grade 4 neutropenia occurred in 3% of female vs 0% of male subjects and Grade 4 thrombocytopenia in 1% of female vs 0% of male subjects in the first cycle of therapy.
Paediatric population
Oral TMZ has been studied in paediatric patients (age 3-18 years) with recurrent brainstem glioma or recurrent high grade astrocytoma, in a regimen administered daily for 5 days every 28 days. Although the data is limited, tolerance in children is expected to be the same as in adults. The safety of TMZ in children under the age of 3 years has not been established.
Post-marketing experience
The following additional serious adverse reactions have been identified during post-marketing exposure:
| Table 6. Summary of events reported with temozolomide in the post-marketing setting* | |
| Infections and infestations* | |
| Uncommon: | cytomegalovirus infection, infection reactivation such as cytomegalovirus, hepatitis B virus†, Meningoencephalitis herpetic†, sepsis†|
| Blood and lymphatic system disorders | |
| Very rare: | prolonged pancytopenia, aplastic anaemia†|
| Neoplasm benign, malignant and unspecified | |
| Very rare: | myelodysplastic syndrome (MDS), secondary malignancies, including myeloid leukaemia |
| Endocrine disorders* | |
| Uncommon: | diabetes insipidus |
| Respiratory, thoracic and mediastinal disorders | |
| Very rare: | interstitial pneumonitis/pneumonitis, pulmonary fibrosis, respiratory failure†|
| Hepatobiliary disorders | |
| Common | liver enzymes elevations |
| Uncommon: | hyperbilirubinemia, cholestasis, hepatitis hepatic injury, hepatic failure†|
| Skin and subcutaneous tissue disorders | |
| Very rare: | toxic epidermal necrolysis, Stevens-Johnson syndrome |
* Frequencies estimated based on relevant clinical trials.
†Including cases with fatal outcome
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via Yellow Card Scheme, Website: www.mhra.gov.uk/yellowcard.
Doses of 500, 750, 1,000, and 1,250 mg/m2 (total dose per cycle over 5 days) have been evaluated clinically in patients. Dose-limiting toxicity was haematological and was reported with any dose but is expected to be more severe at higher doses. An overdose of 10,000 mg (total dose in a single cycle, over 5 days) was taken by one patient and the adverse reactions reported were pancytopenia, pyrexia, multi-organ failure and death. There are reports of patients who have taken the recommended dose for more than 5 days of treatment (up to 64 days) with adverse reaction reported including bone marrow suppression, with or without infection, in some cases severe and prolonged and resulting in death. In the event of an overdose, haematological evaluation is needed. Supportive measures should be provided as necessary.
Pharmacotherapeutic group: Antineoplastic agents - Other alkylating agents, ATC code: L01A X03
Mechanism of action
Temozolomide is a triazene, which undergoes rapid chemical conversion at physiologic pH to the active monomethyl triazenoimidazole carboxamide (MTIC). The cytotoxicity of MTIC is thought to be due primarily to alkylation at the O6 position of guanine with additional alkylation also occurring at the N7 position. Cytotoxic lesions that develop subsequently are thought to involve aberrant repair of the methyl adduct.
Clinical efficacy and safety
Newly diagnosed glioblastoma multiforme
A total of 573 patients were randomised to receive either TMZ + RT (n=287) or RT alone (n=286). Patients in the TMZ + RT arm received concomitant TMZ (75 mg/m2) once daily, starting the first day of RT until the last day of RT, for 42 days (with a maximum of 49 days). This was followed by monotherapy TMZ (150 - 200 mg/m2) on Days 1 - 5 of every 28-day cycle for up to 6 cycles, starting 4 weeks after the end of RT. Patients in the control arm received RT only. Pneumocystis jirovecii pneumonia (PCP) prophylaxis was required during RT and combined TMZ therapy.
TMZ was administered as salvage therapy in the follow-up phase in 161 patients of the 282 (57%) in the RT alone arm, and 62 patients of the 277 (22%) in the TMZ + RT arm.
The hazard ratio (HR) for overall survival was 1.59 (95% CI for HR=1.33 -1.91) with a log-rank p < 0.0001 in favour of the TMZ arm. The estimated probability of surviving 2 years or more (26% vs 10%) is higher for the RT + TMZ arm. The addition of concomitant TMZ to RT, followed by TMZ monotherapy in the treatment of patients with newly diagnosed glioblastoma multiforme demonstrated a statistically significant improvement in overall survival (OS) compared with RT alone (Figure 1).
Figure 1 Kaplan-Meier curves for overall survival (intent-to-treat population)
The results from the trial were not consistent in the subgroup of patients with a poor performance status (WHO PS=2, n=70), where overall survival and time to progression were similar in both arms. However, no unacceptable risks appear to be present in this patient group.
Recurrent or progressive malignant glioma
Data on clinical efficacy in patients with glioblastoma multiforme (Karnofsky performance status [KPS] >70), progressive or recurrent after surgery and RT, were based on two clinical trials with oral TMZ. One was a non-comparative trial in 138 patients (29% received prior chemotherapy), and the other was a randomised active-controlled trial of TMZ vs. procarbazine in a total of 225 patients (67% received prior treatment with nitrosourea based chemotherapy). In both trials, the primary endpoint was progression-free survival (PFS) defined by MRI scans or neurological worsening. In the non-comparative trial, the PFS at 6 months was 19%, the median progression-free survival was 2.1 months, and the median overall survival 5.4 months. The objective response rate (ORR) based on MRI scans was 8%.
In the randomised active-controlled trial, the PFS at 6 months was significantly greater for TMZ than for procarbazine (21% vs. 8%, respectively - chi-square p = 0.008) with median PFS of 2.89 and 1.88 months respectively (log rank p = 0.0063). The median survival was 7.34 and 5.66 months for TMZ and procarbazine, respectively (log rank p = 0.33). At 6 months, the fraction of surviving patients was significantly higher in the TMZ arm (60%) compared with the procarbazine arm (44%) (chi-square p = 0.019). In patients with prior chemotherapy a benefit was indicated in those with a KPS > 80.
Data on time to worsening of neurological status favoured TMZ over procarbazine as did data on time to worsening of performance status (decrease to a KPS of < 70 or a decrease by at least 30 points). The median times to progression in these endpoints ranged from 0.7 to 2.1 months longer for TMZ than for procarbazine (log rank p = < 0.01 to 0.03).
Recurrent anaplastic astrocytoma
In a multicentre, prospective phase II trial evaluating the safety and efficacy of oral TMZ in the treatment of patients with anaplastic astrocytoma at first relapse, the 6 month PFS was 46%. The median PFS was 5.4 months. Median overall survival was 14.6 months. Response rate, based on the central reviewer assessment, was 35% (13 CR and 43 PR) for the intent-to-treat-population (ITT) n=162. In 43 patients stable disease was reported. The 6-month event-free survival for the ITT population was 44% with a median event-free survival of 4.6 months, which was similar to the results for the progression-free survival. For the eligible histology population, the efficacy results were similar. Achieving a radiological objective response or maintaining progression-free status was strongly associated with maintained or improved quality of life.
Paediatric population
Oral TMZ has been studied in paediatric patients (age 3-18 years) with recurrent brainstem glioma or recurrent high grade astrocytoma, in a regimen administered daily for 5 days every 28 days. Tolerance to TMZ is similar to adults.
TMZ is spontaneously hydrolyzed at physiologic pH primarily to the active species, 3-methyl-(triazen-1-yl)imidazole-4-carboxamide (MTIC). MTIC is spontaneously hydrolyzed to 5-amino-imidazole-4-carboxamide (AIC), a known intermediate in purine and nucleic acid biosynthesis, and to methylhydrazine, which is believed to be the active alkylating species. The cytotoxicity of MTIC is thought to be primarily due to alkylation of DNA mainly at the O6 and N7 positions of guanine. Relative to the AUC of TMZ, the exposure to MTIC and AIC is ~ 2.4% and 23%, respectively. In vivo, the t1/2 of MTIC was similar to that of TMZ, 1.8 hr.
Absorption
After oral administration to adult patients, TMZ is absorbed rapidly, with peak concentrations reached as early as 20 minutes post administration (mean times between 0.5 and 1.5 hours). After oral administration of 14C-labelled TMZ, mean faecal excretion of 14C over 7 days post-dose was 0.8% indicating complete absorption.
Distribution
TMZ demonstrates low protein binding (10% to 20%), and thus it is not expected to interact with highly protein-bound substances.
PET studies in humans and preclinical data suggest that TMZ crosses rapidly the blood-brain barrier and is present in the CSF. CSF penetration was confirmed in one patient; CSF exposure based on AUC of TMZ was approximately 30% of that in plasma, which is consistent with animal data.
Elimination
The half-life (t1/2) in plasma is approximately 1.8 hours. The major route of 14C elimination is renal. Following oral administration, approximately 5% to 10% of the dose is recovered unchanged in the urine over 24 hours, and the remainder excreted as temozolomide acid, 5-aminoimidazole-4-carboxamide (AIC) or unidentified polar metabolites.
Plasma concentrations increase in a dose-related manner. Plasma clearance, volume of distribution and half-life are independent of dose.
Special populations
Analysis of population-based pharmacokinetics of TMZ revealed that plasma TMZ clearance was independent of age, renal function or tobacco use. In a separate pharmacokinetic study, plasma pharmacokinetic profiles in patients with mild to moderate hepatic impairment were similar to those observed in patients with normal hepatic function.
Paediatric patients had a higher AUC than adult patients; however, the maximum tolerated dose (MTD) was 1,000 mg/m2 per cycle both in children and in adults.
Single-cycle (5-day dosing, 23 days non-treatment), 3- and 6-cycle toxicity studies were conducted in rats and dogs. The primary targets of toxicity included the bone marrow, lymphoreticular system, testes, the gastrointestinal tract and, at higher doses, which were lethal to 60% to 100% of rats and dogs tested, degeneration of the retina occurred. Most of the toxicity showed evidence of reversibility, except for adverse reactions on the male reproductive system and retinal degeneration. However, because the doses implicated in retinal degeneration were in the lethal dose range, and no comparable effect has been observed in clinical studies, this finding was not considered to have clinical relevance.
TMZ is an embryotoxic, teratogenic and genotoxic alkylating agent. TMZ is more toxic to the rat and dog than to humans, and the clinical dose approximates the minimum lethal dose in rats and dogs. Dose-related reductions in leukocytes and platelets appear to be sensitive indicators of toxicity. A variety of neoplasms, including mammary carcinomas, keratocanthoma of the skin and basal cell adenoma were observed in the 6-cycle rat study while no tumours or pre-neoplastic changes were evident in dog studies. Rats appear to be particularly sensitive to oncogenic effects of TMZ, with the occurrence of first tumours within 3 months of initiating dosing. This latency period is very short even for an alkylating agent.
Results of the Ames/salmonella and Human Peripheral Blood Lymphocyte (HPBL) chromosome aberration tests showed a positive mutagenicity response.
Not applicable.
Capsules should not be opened. If a capsule becomes damaged, contact of the powder contents with skin or mucous membrane must be avoided. If Temozolomide Hexal comes into contact with skin or mucosa, it should be washed immediately and thoroughly with soap and water.
Patients should be advised to keep capsules out of thesight and reach of children, preferably in a locked cupboard. Accidental ingestion can be lethal for children.
Any unused medicinal product or waste material should be disposed of in accordance with local requirements.
