⚠️ Warnings
Patients with clinically unstable APL are at particular risk, and electrolyte and blood glucose levels, haematological and renal parameters, coagulation parameters and liver function tests will need to be monitored more frequently.
Leukocyte activation syndrome (APL differentiation syndrome)
A total of 27% of patients with relapsed/refractory APL treated with arsenic trioxide reported symptoms similar to a syndrome known as RA-acute promyelocytic leukaemia (retinoic-acid-acute promyelocytic leukaemia, RA-APL) or APL differentiation syndrome, characterised by fever, dyspnoea, weight gain, pulmonary infiltrates and pleural or pericardial effusions,
with or without leukocytosis. This syndrome can be fatal. In patients with newly diagnosed APL treated with arsenic trioxide and all-trans retinoic acid (ATRA), APL differentiation syndrome was identified in 19% of cases, including 5 severe cases. At the first signs that could suggest the onset of this syndrome (unexplained fever, dyspnoea and/or weight gain, abnormal auscultation findings or abnormalities visible on chest X-ray), arsenic trioxide treatment must be temporarily interrupted and high-dose steroid therapy (dexamethasone 10 mg intravenously twice daily) must be started immediately, regardless of the leukocyte count; treatment must continue for at least three days or longer until signs and symptoms have resolved. Concomitant treatment with diuretics is also recommended as clinically indicated/as needed. In the majority of patients, permanent discontinuation of arsenic trioxide during treatment of APL differentiation syndrome is not necessary. Once signs
and symptoms have resolved, arsenic trioxide treatment can be restarted at a dose corresponding to 50% of the previous dose during the first 7 days. Thereafter, if the previous toxicity does not recur, arsenic trioxide treatment may be resumed at full dose. If symptoms recur, the arsenic trioxide dose must be reduced to the previous level. To prevent the development of APL differentiation syndrome during induction therapy, prednisone (0.5 mg/kg body weight daily throughout the induction period) may be given to APL patients from day 1 of arsenic trioxide administration until the end of induction therapy. It is recommended not to combine steroid treatment with chemotherapy, as there is no experience with the administration of steroids and chemotherapy during treatment of leukocyte activation syndrome induced by arsenic trioxide. Post-marketing experience suggests that a similar syndrome may occur in patients with other types of malignant diseases. Monitoring and treatment of these patients should be performed as described above.
Electrocardiogram (ECG) abnormalities
Arsenic trioxide may cause QT interval prolongation and complete atrioventricular block. QT interval prolongation may lead to a ventricular arrhythmia of the torsades de pointes type, which may be fatal. Prior treatment with anthracyclines may increase the risk of QT prolongation. The risk of developing torsades de pointes is related to the extent of QT prolongation, concomitant administration of QT-prolonging medicinal products (such as class Ia and III antiarrhythmics, e.g. quinidine, amiodarone, sotalol, dofetilide), antipsychotics (e.g. thioridazine), antidepressants (e.g. amitriptyline), certain macrolides (e.g. erythromycin), certain antihistamines (e.g. terfenadine and astemizole), certain quinolone antibiotics (e.g. sparfloxacin) and other individual medicinal products that prolong the QT interval (e.g. cisapride), a history of torsades de pointes, pre-existing QT prolongation, congestive heart failure, administration of potassium-wasting diuretics, amphotericin B or other conditions resulting in hypokalaemia or hypomagnesaemia. In clinical studies conducted in patients with relapsed/refractory disease, 40% of patients treated with arsenic trioxide experienced at least one prolongation of the corrected QT interval (QTc) exceeding 500 ms. QTc prolongation was observed between the first and fifth week after arsenic trioxide infusion, with return to baseline within eight weeks after arsenic trioxide infusion. In one patient (who was concomitantly receiving several medicinal products including amphotericin B), asymptomatic torsades de pointes appeared during induction therapy for relapsed APL with arsenic trioxide. In newly diagnosed APL, when arsenic trioxide was administered in combination with ATRA (see section
4.8
), 15.6% of patients experienced QTc interval prolongation. In one newly diagnosed patient, induction therapy was discontinued due to severe QTc interval prolongation and electrolyte abnormalities on day 3 of induction therapy.
Recommendations for ECG and electrolyte monitoring
A 12-lead ECG must be performed before starting arsenic trioxide treatment and serum electrolyte levels (potassium, calcium and magnesium) and creatinine must be evaluated; existing electrolyte abnormalities must be corrected and, if possible, medicinal products causing QT interval prolongation should be discontinued. Cardiac activity in patients with risk factors for QTc interval prolongation or risk factors for torsades de pointes should be continuously monitored (by ECG). If the QTc interval is longer than 500 ms, corrective measures must be completed and the QTc interval must be reassessed by serial ECGs; if possible, specialist advice may be sought before considering administration of arsenic trioxide. During arsenic trioxide treatment, potassium concentrations must be maintained above 4 mEq/L and magnesium concentrations above 1.8 mg/dL. Patients whose absolute QT interval value exceeds 500 ms must be reassessed and immediate action must be taken to correct concomitant risk factors, if present, while the risks and benefits of continuing or discontinuing arsenic trioxide treatment must be considered. If syncope, rapid or irregular heartbeat occurs, the patient must be hospitalised and continuously monitored, serum electrolytes must be evaluated and arsenic trioxide therapy must be temporarily interrupted until the QTc interval decreases below 460 ms, electrolyte abnormalities are corrected and syncope and irregular heartbeat have resolved. After recovery, treatment should be restarted at a dose corresponding to 50% of the previous daily dose. If QTc prolongation does not recur within 7 days of resuming treatment at the reduced dose, arsenic trioxide treatment may be restarted in the second week at a dose of
0.11 mg/kg body weight per day. If no prolongation occurs, the daily dose may be increased back to
100% of the original dose. Data on the effect of arsenic trioxide on the QTc interval during infusion are not
available. Electrocardiograms must be performed twice weekly during induction and consolidation; more frequently in clinically unstable patients.
Hepatotoxicity (grade 3 or higher)
In the group of newly diagnosed APL patients at low-to-intermediate risk, 63.2% experienced grade 3 or 4 hepatotoxic effects during induction or consolidation treatment with arsenic trioxide in combination with ATRA (see section
4.8
). However, the toxic effects resolved upon temporary interruption of arsenic trioxide, ATRA or both. Arsenic trioxide treatment must be discontinued before the planned end of treatment whenever grade 3 or higher hepatotoxicity is detected based on the National Cancer Institute Common Toxicity Criteria. Once bilirubin, SGOT and/or alkaline phosphatase concentrations decrease below four times the upper limit of normal, arsenic trioxide treatment should be restarted
at a dose corresponding to 50% of the previous dose administered during the first 7 days. Thereafter, if the previous toxicity does not recur, arsenic trioxide treatment may be resumed at full dose. If hepatotoxicity recurs, arsenic trioxide treatment must be permanently discontinued.
Dose adjustment
Arsenic trioxide treatment must be temporarily interrupted before the end of the treatment cycle whenever grade 3 or higher toxicity is observed according to the National Cancer Institute Common Toxicity Criteria and if this toxicity is considered to be possibly related to arsenic trioxide treatment (see section
4.2
).
Laboratory tests
Serum electrolyte and blood glucose levels, haematological and renal parameters, coagulation parameters and liver function tests must be monitored at least twice weekly during the induction phase, more frequently in clinically unstable patients, and at least once weekly during the consolidation phase.
Renal impairment
Since no data are available for all groups of renal impairment, caution is recommended when using arsenic trioxide in patients with renal impairment. Experience in patients with severe renal impairment is insufficient to determine whether dose adjustment is necessary.
The use of arsenic trioxide in dialysis patients has not been studied.
Hepatic impairment
Since no data are available for all groups of hepatic impairment and hepatotoxic effects may occur during arsenic trioxide treatment, caution should be exercised when using arsenic trioxide
in patients with hepatic impairment (see section
4.4
on hepatotoxicity and section 4.8). Experience in patients with severe hepatic impairment is insufficient to determine whether dose adjustment is necessary.
Elderly population
There are limited clinical data on the use of arsenic trioxide in the elderly. Caution should be exercised in these patients.
Hyperleukocytosis
Treatment with arsenic trioxide in some patients with relapsed/refractory APL was associated with the development of hyperleukocytosis (≥ 10 x 10
3
/μL). There appeared to be no correlation between the baseline white blood cell count and the development of hyperleukocytosis, nor any correlation between the baseline white blood cell count and the peak white blood cell count. Hyperleukocytosis was never treated with additional chemotherapy and resolved with continued arsenic trioxide treatment. White blood cell counts during consolidation were not as high as during induction therapy, remaining below 10 x 10
3
/μL, with the exception of one patient whose white blood cell count during consolidation was 22 x 10
3
/μL. Twenty patients with relapsed/refractory APL (50%) developed leukocytosis, but in all of these patients white blood cell counts decreased or normalised by the time bone marrow remission occurred, and cytotoxic chemotherapy or leukapheresis was not required. In 35 of 74 (47%) newly diagnosed APL patients
at low-to-intermediate risk, leukocytosis developed during induction therapy (see section
4.8
). All cases, however, were successfully treated with hydroxycarbamide.
In patients with newly diagnosed relapsed/refractory APL who develop chronic leukocytosis after starting treatment, hydroxycarbamide should be administered. Hydroxycarbamide
at the appropriate dose should be continued to maintain a white blood cell count ≤ 10 x 10
3
/μL, and thereafter the dose should be gradually reduced.
Table 1 Recommendations for starting hydroxycarbamide therapy
White blood cell count
Hydroxycarbamide
10-50 x 10
3
/µL
500 mg four times daily
> 50 x 10
3
/µL
1,000 mg four times daily
Development of secondary primary malignancies
The active substance in Arsenic trioxide Accord, arsenic trioxide, is a human carcinogen. Monitor patients
for the development of secondary primary malignancies.
Encephalopathy
Cases of encephalopathy have been reported during arsenic trioxide treatment. In patients with vitamin B1 deficiency, Wernicke's encephalopathy has been reported following arsenic trioxide treatment. After starting arsenic trioxide, patients at risk of vitamin B1 deficiency should be carefully monitored for signs and symptoms of encephalopathy. Some cases resolved following vitamin B1 administration.
Excipient with known effect
This medicinal product contains less than 1 mmol sodium (23 mg) per dose, that is to say it is
essentially 'sodium-free'.