Anticancer treatment for advanced non-small cell lung cancer

Introduction

Advanced non-small cell lung cancer (NSCLC) is defined as a disease that cannot be treated by a curative approach. It corresponds to stages where surgery and/or chest irradiation cannot be performed. Practically, it consists mainly in stage-IV or in some advanced stage-III of the 2009 International Staging System.

In order to optimally manage a patient with advanced NSCLC, the following information is required for the treatment plan: histological type, TNM (tumour, node, metastasis) stage, sites of metastases, performance status, age, existence of comorbidities, and organ (lung, heart, bone marrow, liver) function assessment. This treatment plan should be proposed after a multidisciplinary discussion including representatives of the following disciplines: pathology, chest medicine, radiation oncology, medical oncology, thoracic surgery, radiology, nuclear medicine and palliative care.

The management of patients with advanced NSCLC has become more sophisticated. Progress in imaging procedures including brain nuclear magnetic resonance (NMR) and positron emission tomography–computed tomography (PET-CT) scan has allowed earlier diagnosis of advanced disease. More anticancer drugs are now available, allowing multiple lines of treatment. Local treatment of some metastatic sites, such as brain by stereotactic irradiation, is associated with better disease control. Supportive care, including intensive care, improves the treatment of complications. Although it is difficult to demonstrate using clinical trials, all these ameliorations have led to better survival and quality of life.

In routine practice, in many multidisciplinary rounds, treatment is based on a local programme established using published guidelines which are mainly oriented by the results of meta-analyses and randomised trials (see www.pneumocancero.com), using the principles of evidence-based medicine. It is very important for the physician to understand the objectives of those studies which are the background of most clinical practice recommendations. Indeed, a trial can be performed for three main reasons: scientific, clinical and commercial. The scientific objective deals with a better understanding of the treatment effect but this information is usually not directly helpful for the patient management. The clinical objective determines the effect of the treatment in terms of benefits for the patients (survival, quality of life, symptom control). The commercial purpose is a main objective in the studies sponsored by the industry but it is usually not reported and has to be figured out by the physician, requiring some expertise in the field. Today, for the studies conducted in the European Union, Eudrapharm provides the information in the EU Clinical Trials Register, using the terminology of commercial or non-commercial according to the type of sponsorship. The EU Clinical Trials Register is free to access on the internet.

Keeping this introduction in mind and without fully reviewing the literature, which has been the topic of a recent report [1], we will now address the questions that have to be solved in the practical management of patients with advanced NSCLC.

What are the benefits of the medical treatment?

This is a frequently asked question by the patient. Randomised trials performed in the 1980s and 1990s have shown benefits with chemotherapy (mainly cisplatin-based) in terms of palliation, improvement of survival, symptom control, quality of life and cost. Seven meta-analyses published in the 1990s, including one performed with individual patients’ data (table 1) which has been recently updated [2], have confirmed a modest but significant effect with chemotherapy in terms of survival.

There will be no more trials in patients fit for chemotherapy to demonstrate its benefits in advanced NSCLC. However, from a clinical point of view, the control arm in new studies should always correspond to a regimen shown, by formal comparison, equivalent or superior to those that have established the survival benefit.

Which drugs are available in Europe?

The active drugs registered and marketed in the European Union for the treatment of NSCLC (table 2) can be divided in three main groups: 1) the agents with generic forms; 2) the agents with generic forms but with restricted indications; and 3) the agents protected by patents. In the second group, there is only docetaxel which has been registered for first-line treatment in association with cisplatin and also for salvage chemotherapy. There are only four commercially available drugs protected by a patent, all with restricted indications. One cytotoxic agent (pemetrexed) with the same restriction as docetaxel in addition to a limitation to non-squamous non-small cell histology but with a possibility to be used in as single-agent therapy for maintenance. Two tyrosine kinase inhibitors: erlotinib for second-line treatment or for maintenance in case of stable disease after first-line platinum-based chemotherapy, and gefitinib in the presence of an activating mutation on the EGFr gene whatever the line of treatment. One antiangiogenic agent (bevacizumab) for non-squamous non-small cell tumours in combination with chemotherapy. Those drugs, which are extremely expensive, are not automatically reimbursed by the national social security system, limiting their availability in the routine management of NSCLC.

Which regimen as first-line treatment?

The recent recommendations of various scientific and academic associations are summarised in table 3. In the fit patient, European guidelines recommend cisplatin-based chemotherapy while American ones propose platinum-based doublets. The cytotoxic drug associated with the platinum derivative should be one of the active compounds listed in table 2, such as gemcitabine, docetaxel, paclitaxel, vinorelbine or pemetrexed. That choice is based on two types of meta-analyses [3]. In the first, the trials are compared according to the number of drugs in the regimen: two-drug regimens are superior to one-drug regimens, both in terms of response and survival; three-drug combinations are better to two drugs only in terms of response but with higher toxicity [4]. In the second type, the role of specific drugs is analysed. Addition of a drug to a platinum derivative is beneficial in term of survival [5].

Non-platinum-based regimens as first-line treatment should be only used in cases where platinum-based chemotherapy is contra-indicated. Indeed, as reported in a meta-analysis of the published literature [11], when all trials were considered (irrespectively of using old or new drugs), there was a significant advantage both for response rate and 1-year survival in favour of platinum-based treatment. The increase in 1-year survival was 5%. When the analysis was restricted to combination regimens with newer drugs, there was no significant difference in survival but response rate was significantly improved with platinum-based treatment.

There is no demonstration that high dosages of cisplatin (100–120 mg·m⁻²) provide better results than standard lower dosages (50–60 mg·m⁻²) in terms of survival. None of the published randomised trials was indeed able to report a significant advantage in favour of high dosages [1]. In fact, the use of high-dose cisplatin is based on an old observation that responders to cisplatin plus vindesine survived longer when 120 mg·m⁻² of cisplatin was administered instead of 60 mg·m⁻². This difference was observed in a very small group of patients (35 patients). The ELCWP was unable to replicate the results in a much higher number of patients [12]. In addition, a high dosage of cisplatin has the disadvantage of significantly higher renal, auditory and neurological toxicities [13]. Based on all those considerations, standard dosages, associated with reduced toxicity, can thus be recommended.

Cisplatin should be preferred to carboplatin because of a better effect on survival. In randomised trials, the trend is in favour of cisplatin, both in terms of response and survival. The meta-analyses confirm this impression; the results are statistically significant in favour of cisplatin if the analysis is restricted to the regimens using newer drugs combined with platinum derivatives [14–16].

Usually, 4–6 cycles of induction chemotherapy are administered. The level of evidence supporting that attitude is poor, based on a limited number of randomised trials with methodological problems in most of them. Maintenance by prolongation of the treatment after response achievement appears to significantly improve progression-free survival with a modest effect on overall survival [17]. Usually, it is started in the trials after a limited number of cycles of induction chemotherapy. There is, so far, no reported study comparing maintenance after a short induction treatment to induction alone continued until achievement of best response. Nevertheless, the concept of maintenance with a single agent after four cycles of cisplatin-based chemotherapy has been shown associated with survival advantages in comparison with induction only in studies conducted by the pharmaceutical industry. Two drugs have been registered in that indication: pemetrexed [18] for nonprogressing disease and erlotinib [19] for stable disease. Those commercial data have so far not been validated by academic independent trials.

Which treatment at relapse?

Second-line therapy is today recommended in all guidelines (table 3). This is based on a randomised trial having tested second-line chemotherapy versus supportive care alone in advanced NSCLC [20]. Survival was significantly improved in the arm where treatment was chemotherapy. Implementation studies [21, 22] have reported results similar to randomised trials when docetaxel was used in routine application. Weekly administration of docetaxel has not been shown to be better [23] than 3-weekly treatment. A dosage of 75 mg·m^-2 appears associated with better tolerance than 100 mg·m^-2 [24].

For second-line treatment, other drugs have been compared with docetaxel in large randomised trials. They include pemetrexed, erlotinib, gefitinib, vinflunine and oral topotecan. None appeared superior in term of survival and response rate. Two of those drugs have been specifically registered in the European Union for that indication: erlotinib [25] and, in non-squamous NSCLC, pemetrexed [26]. Some improvement was reported with pemetrexed in term of tolerance.

A systematic review of the literature with meta-analysis [27] found a small but significant survival improvement with second-line chemotherapy compared to supportive care alone. The use of drugs other than docetaxel did not improve survival. The authors concluded that docetaxel administered every 3 weeks remains the gold standard.

In conclusion, second-line chemotherapy should be proposed in patients with good performance status, failing after platinum-based first-line chemotherapy. Evidence is in favour of docetaxel (if not administered in first-line treatment) given on a 3-weekly schedule at a dosage of 75 mg·m^-2. It should be noted that in routine management, although not supported by good evidence, third-line treatment with active drugs is often proposed in fit patients.

Are there indications for tailored chemotherapy?

Customised or tailored chemotherapy is a personalised treatment decision based on an analysis of biomarkers of response and resistance to cytotoxic drugs. Customised or tailored chemotherapy results from a treatment decision based on an analysis of biomarkers of response and resistance to cytotoxic drugs. Evidence in favour of that approach comes from post hoc analysis of adjuvant chemotherapy trials in resected NSCLC and from chemotherapy trials where the enzymes RRM1 (regulatory subunit of the ribonucleotide reductase) and ERCC1 (excision repair cross-complementation group 1) were assessed. If their increased expression was associated with a better prognosis after surgery, a lower expression in the tumour resulted in a better survival for platinum- and gemcitabine-based chemotherapy. The first randomised trial performed on the topic showed improved response rate when treatment was guided by the tumour ERCC1 [28].

Today, there is no validated application of tailored therapy in the routine management of advanced NSCLC, partly because the molecular marker thresholds for selecting treatment have not yet been defined. An indirect approach is to select agents on the basis of the histological subtype. This concept has been used for >40 years in the management of lung cancer with the subclassification separating small cell lung cancer from the other subtypes called NSCLC. Recently, there have been newer applications of histology for drug selection with non-squamous NSCLC for pemetrexed and bevacizumab. This has led to a new IASLC/ATS/ERS definition of adenocarcinoma [29]. For bevacizumab, the restriction to non-squamous histology is due to toxicity reason related to haemorrhagic risks in squamous cell carcinoma. For pemetrexed which is a multitarget antifolate, it is based on the fact that the drug is more active on non-squamous tumours which have high activity of enzymes of the folate pathways such as the thymidilate synthase (TS). Those laboratory data could provide an explanation for the findings of the registration trial for NSCLC, which compared cisplatin plus pemetrexed versus cisplatin plus gemcitabine; although no overall difference was found in the trial, survival in the pemetrexed arm improved in non-squamous NSCLC whereas it reduced in squamous cell lung cancer [30]. A retrolective analysis found the same observation in the registered trial performed for second-line therapy. This has led to a restricted indication to non-squamous NSCLC. It should be noted that those survival differences have not been confirmed in a later trial assessing as first-line chemotherapy carboplatin plus pemetrexed versus carboplatin plus gemcitabine [31]. A possible explanation for those discrepancies may be the absence of histology confirmation by an expert panel in all those trials.

What are the specific indications of targeted therapies?

Targeted therapies are another way to provide personalised treatment by selecting therapeutic agents according to a target that has been identified on the patient's tumour. There is now a drug marketed in the European Union with that purpose: the tyrosine kinase inhibitor (TKI) gefitinib. Initially developed, as erlotinib, in a patient population unselected for the target, results obtained in control trials were disappointed [32] until the target was identified. The target [33] is located on the receptor of the epithelial growth factor (EGF-R) and is related to activating mutations on exon 19 (deletions) or 21 (L858R point mutation) of the gene. Resistance can be acquired during treatment by secondary EGFR mutation (most commonly, T790M in exon 20) or by the amplification of the MET oncogene.

Some clinical characteristics are associated with the target: adenocarcinoma histology, female sex, nonsmoking and East-Asian ethnicity. It is indeed very frequent in Japan, China and Korea. For that reason, most of the main studies were performed in those countries. In Asiatic non- or ex-smoker patients with adenocarcinoma, gefitinib was shown to be superior to chemotherapy by paclitaxel and carboplatin in term of response rate and progression-free survival [34]. In the subgroup of patients who were positive for EGFR mutation, progression-free survival was significantly longer among those who received gefitinib, while in the subgroup who was negative for the mutation, progression-free survival was significantly longer among those who received carboplatin–paclitaxel. There was no difference in overall survival, probably because there was effective crossover salvage therapy. Those data were confirmed by a trial specifically performed in patients who had a tumour with an activating mutation [35]. The observation that gefitinib is as active in first-line as in salvage treatment has been confirmed in European patients [36].

Based on those data, it is recommended to search for an activating mutation of EGFr, particularly in adenocarcinoma [29] and to treat accordingly the patient by gefitinib, whatever the line of treatment.

How to manage patients in special situations?