Osimatab80 mg

Osimatab 80 mg is an oral, third-generation EGFR tyrosine kinase inhibitor indicated for:

• Adjuvant treatment following tumour resection in adult patients with non-small cell lung cancer (NSCLC) whose tumours have EGFR exon 19 deletions or exon 21 L858R mutations
• First-line treatment of metastatic NSCLC with EGFR exon 19 deletions or exon 21 L858R mutations, alone or in combination with chemotherapy
• Treatment of metastatic EGFR T790M mutation-positive NSCLC, in patients whose disease has progressed on or after EGFR tyrosine kinase inhibitor therapy

Osimatab 80 mg is used only after confirmation of the specific EGFR mutation status through an approved test, since its benefit is specific to tumours with these particular mutations.

Contains Osimatab 80 mg (as Osimatab 80 mg mesylate) as the active ingredient, available as oral film-coated tablets, commonly in 40 mg and 80 mg strengths.

Osimatab 80 mg is a third-generation, targeted oral cancer therapy specifically designed for non-small cell lung cancer driven by particular EGFR gene mutations, including the T790M resistance mutation that can develop after treatment with earlier-generation EGFR inhibitors. It is taken once daily and has transformed treatment for EGFR-mutant lung cancer, though it is associated with a higher rate of certain cardiac effects (including QT prolongation and, less commonly, reduced heart pumping function) compared to earlier EGFR inhibitors, alongside a recognized risk of interstitial lung disease, both of which require monitoring throughout treatment.

Therapeutic Class: Targeted Anticancer Agent (Antineoplastic)

Osimatab 80 mg has a long elimination half-life of approximately 48-59 hours, supporting once-daily dosing, and a high volume of distribution with minimal first-pass metabolism and low clearance. It is metabolized mainly by CYP3A4, making it susceptible to interactions with strong inhibitors and inducers of this enzyme. Osimatab 80 mg and its active metabolites specifically and selectively inhibit both the EGFR-activating mutations that drive tumour growth and the T790M resistance mutation that commonly develops in patients previously treated with earlier-generation EGFR inhibitors.

• Taken orally, once daily, at approximately the same time each day, with or without food
• Swallow the tablet whole with water; if unable to swallow whole, the tablet can be dispersed in water (non-carbonated) and taken immediately, per the specific product's instructions
• Do not chew or crush the tablet unless following the specific dispersion instructions for patients unable to swallow whole tablets
• If a dose is missed and it is more than 12 hours until the next scheduled dose, take the missed dose; if less than 12 hours remain, skip the missed dose and take the next dose as scheduled

The following should be assessed and managed by the treating oncology team:

• Strong CYP3A4 inducers (such as rifampicin, phenytoin, carbamazepine, and St. John's Wort): can significantly reduce Osimatab 80 mg blood levels, potentially reducing its anticancer effect; concurrent use should be avoided if possible, or the Osimatab 80 mg dose increased and resumed at 80 mg 3 weeks after the last dose of the strong inducer, per the treating oncologist's protocol.
• Strong CYP3A4 inhibitors: Osimatab 80 mg exposure is not significantly affected based on available data, though monitoring for toxicity is still reasonable if combined.
• Breast cancer resistance protein (BCRP) substrates: Osimatab 80 mg may increase blood levels of these medicines; monitor for increased toxicity if combined.
• Other QT-prolonging medicines: combining with Osimatab 80 mg may increase the risk of cardiac rhythm disturbances; use with caution and ECG monitoring if combined.

Common side effects

• Diarrhoea
• Rash, dry skin
• Nail toxicity (paronychia)
• Fatigue
• Stomatitis (mouth sores)
• Loss of appetite

Serious side effects (require prompt medical attention)

• Interstitial lung disease (ILD)/pneumonitis: new or worsening shortness of breath, cough, and fever require immediate evaluation; withhold treatment for suspected ILD and permanently discontinue if confirmed. Transient, clinically benign areas of localized ground-glass opacity (sometimes mistaken for progression or early pneumonitis) have also been observed and may resolve during continued treatment - your oncology team will help distinguish these.
• Cardiac effects: Osimatab 80 mg can prolong the QT interval and, less commonly, reduce heart pumping function (reversible cardiomyopathy has been reported); report palpitations, dizziness, fainting, or shortness of breath promptly; baseline and periodic ECG and, where indicated, cardiac function monitoring are recommended, particularly in patients with cardiac risk factors.
• Severe skin reactions (Stevens-Johnson syndrome, erythema multiforme major, toxic epidermal necrolysis): withhold if suspected and permanently discontinue if confirmed.
• Diarrhoea can occasionally be severe, requiring dose interruption or reduction and standard antidiarrheal management.
• Rare gastrointestinal complications, including reports of unusual bowel obstruction-type events, have been described; report severe or persistent abdominal pain promptly.

Pregnancy

Osimatab 80 mg can cause fetal harm based on its mechanism of action and animal data. Effective contraception is recommended for patients of reproductive potential during treatment and for a defined period afterward (commonly at least 6 weeks for women and 4 months for men, per the treating oncologist's guidance), and pregnancy status should be verified before starting treatment where relevant.

Breastfeeding

Breastfeeding is not recommended during Osimatab 80 mg treatment and for a period afterward, given the potential for serious adverse effects in a nursing infant.

• Interstitial lung disease: a potentially fatal complication; evaluate promptly for any new or worsening pulmonary symptoms, and interrupt treatment pending diagnosis.
• Cardiac monitoring: baseline and periodic ECG monitoring is recommended, particularly in patients with risk factors for QT prolongation, electrolyte abnormalities, or pre-existing cardiac disease; monitor left ventricular function in patients with cardiac risk factors or symptoms suggestive of cardiomyopathy.
• Severe skin reactions: monitor for early signs and discontinue promptly if a severe cutaneous reaction is suspected.
• Correct electrolyte abnormalities (potassium, magnesium, calcium) before starting treatment and monitor periodically, given the QT prolongation risk.
• This medicine should only be prescribed and monitored by a physician experienced in the use of targeted cancer therapies.

Clinical experience with Osimatab 80 mg overdose is limited; doses studied in early clinical trials ranged up to 240 mg (three times the standard dose) without dose-limiting toxicity in some patients, though individual tolerance varies. Suspected significant overdose should be reported to the treating oncology team immediately; management is supportive, provided in a specialist facility, with monitoring for known toxicities, particularly cardiac and pulmonary effects.

Store at controlled room temperature (generally 15-30°C), protected from moisture, in the original container. Keep out of reach of children, given the potency of this oncology medicine.

• Hepatic impairment: No dose adjustment recommended for mild to moderate impairment; limited data are available for severe impairment, and use requires careful consideration by the treating oncologist.
• Renal impairment: No specific dose adjustment is generally required for mild to moderate impairment; limited data are available for severe impairment.
• Elderly: No specific dose adjustment based on age alone, though monitoring for cardiac and other known toxicities applies as in any patient.
• Patients with cardiac risk factors: Require closer baseline and ongoing cardiac monitoring, given Osimatab 80 mg's higher rate of cardiac effects compared to earlier-generation EGFR inhibitors.

Treatment continues for as long as the cancer responds and the patient tolerates therapy, or until disease progression or unacceptable toxicity occurs, as determined by the treating oncologist. In the adjuvant setting (after tumour resection), treatment is typically given for a defined period (commonly up to 3 years) per the specific approved protocol.

Drug Class: Third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor

Osimatab 80 mg selectively and irreversibly binds to and blocks mutant forms of the epidermal growth factor receptor (EGFR), including the activating exon 19 deletion and exon 21 L858R mutations that drive tumour growth in certain lung cancers, as well as the T790M mutation that some tumours develop as a resistance mechanism against earlier EGFR inhibitors. By blocking this abnormal signalling, Osimatab 80 mg slows or stops the growth of EGFR-mutant cancer cells, while having comparatively less effect on normal, non-mutated EGFR, which may account for its generally more favourable tolerability profile compared to earlier-generation EGFR inhibitors regarding certain skin and gastrointestinal side effects.

Osimatab 80 mg is used in adult oncology practice for EGFR-mutant non-small cell lung cancer; safety and effectiveness have not been established in pediatric patients, and it is not recommended for use in children.