Risk of relapse after discontinuation of mobosetinib and follow-up strategies

Mobocertinib, also known as mobocertinib, is an oral tyrosine kinase inhibitor (TKI) that mainly targets rare EGFR exon 20 insertion mutations (EGFR exon 20 insertion), used to treat advanced non-small cell lung cancer (NSCLC) caused by such mutations. As the first targeted drug specifically for EGFR 20 insertion mutations, mobotinib provides patients with new treatment hope. However, when a certain course of treatment is completed or drug resistance or side effects require discontinuation, how to assess the risk of recurrence and formulate an effective follow-up strategy has become a focus of concern for both clinicians and patients.

1. Analysis of recurrence risk after discontinuation of Mobotinib

1.The probability of recurrence is affected by many factors

Whether recurrence will occur after discontinuation of treatment depends on many factors, including tumor burden, imaging response before and after treatment, the patient's sensitivity to the drug, the presence of residual disease, and the patient's physical and immune status. Overall, patients who respond well but do not complete the course of treatment or discontinue medication due to side effects are still at moderate to high risk of relapse. Especially if the drug is stopped before the disease reaches complete remission (CR), the chance of recurrence is higher.

2. Targeted drug resistance is one of the main causes of recurrence

During long-term treatment with mobotinib, tumor cells may gradually develop drug resistance mechanisms, such as EGFR structural secondary mutations (such as C797S), METamplification, HER2 mutations, etc. The emergence of these mechanisms means that even if a patient has a good initial response, the tumor may progress rapidly after drug withdrawal, so it is necessary to be alert to the risk of recurrence caused by potential drug resistance.

3.The recurrence time window is uncertain

Clinically, it has been observed that some patients experience recurrence of imaging or clinical symptoms within weeks to months after stopping the drug, and some patients can maintain a stable disease for a long time. Therefore, the time of recurrence is not absolute, but the first 3 to 6 months is a high-risk period, and the condition should be closely monitored.

2. Suggestions on follow-up strategies after drug withdrawal

1. Regular imaging examinations are the key to follow-up

After discontinuation of Mobotinib, it is recommended that patients undergo CT (or PET-CT) follow-up at the following pace:

Reexamine the chest once every 4~6weeks+AbdomenCT;

After 36months, review every812 weeks;

If the treatment is still stable after 6 months, it can be extended to once every 3 months according to the clinical situation.

The focus of imaging examination is to evaluate whether the original lesion has enlarged in size, changed in density, or developed new lesions.

2. Combined with tumor markers to monitor changing trends

Some EGFR mutated lung cancer patients can reflect changes in their disease through tumor markers (such as CEA, CYFRA 21-1, NSE, etc.). Although the sensitivity and specificity of these markers are limited, in individual patients, elevations in markers may precede radiographic progression. Therefore, it is recommended that tumor marker detection be used as an auxiliary follow-up method in conjunction with imaging results.

3. Symptom monitoring and quality of life assessment in parallel

Patients should maintain sensitivity to their own body perception after stopping the drug. If new symptoms such as cough, chest pain, shortness of breath, weight loss, etc. occur, they should promptly inform the doctor. Combining changes in the patient's quality of life and physical performance status (such as ECOG score) is also an important reference for determining whether recurrence or treatment needs to be restarted.

4.Consider if necessaryctDNAdynamic monitoring of detection

In recent years, ctDNA (circulating tumor DNA) testing has been considered a sensitive, non-invasive disease monitoring method that can detect changes at the molecular level before imaging abnormalities appear. For high-risk patients, especially those who have residual or drug-resistant mutations after surgery, regular ctDNA testing is recommended to detect small signs of recurrence as early as possible.

3. How to deal with relapse

1. Challenging Mobotinib again can be one of the options

If the patient's disease relapses after stopping the drug for a period of time and there is no obvious evidence of resistance mechanism, some patients can try to use mobotinib again (rechallenge). Clinical case reports have shown that restarting mobotinib may still be effective.

2. Explore combination treatment or dressing strategies

For patients who clearly have drug-resistant mutations, the treatment plan can be adjusted based on NGS test results, for example:

CombinedMET inhibitors (such asCapmatinib);

Consider participating in clinical trials of new generationEGFR exon 20 mutation inhibitors;

Transition to chemotherapy, immunotherapy, or supportive care regimens.

3.Psychological support and relapse risk education are equally important

During the follow-up process, doctor-patient communication cannot be ignored. Patients need to be fully informed of the possibility of relapse, the importance of follow-up, and coping options in the event of relapse to help relieve anxiety and improve compliance. Support from family and healthcare team is critical to long-term patient management.

Mobotinib brings new hope for the treatment of lung cancer patients with EGFRexon20 insertion mutations, but the risk of recurrence after discontinuation cannot be ignored. Through scientific and systematic follow-up strategies, combined with individualized monitoring methods and clinical assessment, the rate of missed diagnosis of recurrence can be minimized and early intervention in the development of the disease can be achieved. Patients should strictly follow the doctor's advice, maintain good living habits and a positive attitude, and lay a solid foundation for subsequent long-term management.

Reference materials:https://www.drugs.com/