P14.50 Clinicopathological spectrum of intracranial germ cell tumors: an Indian tertiary cancer center experience

BACKGROUND

Incidence of intracranial germ cell tumors (ICGCT) in Western literature is low (0.3–0.6 %) as compared to East Asia (3–4 %), & their clinicopathological features are well documented. However, there are scant studies on ICGCT from India.

MATERIAL AND METHODS

Retrospective observational study of all ICGCT histologically diagnosed in our hospital from 2007–2018. Metastasis were excluded. Clinicopathological features were retrieved from hospital’s electronic medical records.

RESULTS

We diagnosed 82 primary ICGCT, forming approx. 0.54 % of all primary brain tumors, & 3.5% of pediatric brain tumors. Age range: 2 months-32 yrs (Median age 14 yrs). M:F ratio: 1.82:1 (53M,29F). Nearly 80% patients were pediatric (<18 yrs), & 8 very young (<3 yrs, 7M1F). Majority were suprasellar & pineal (31/82, 37% each), with one bifocal presentation. Other rarer sites: posterior fossa (4), midbrain (1), corpus callosum (1) & 11 non midline (4 thalamic, 4 frontal, 2 cerebellar, 1 CP angle). Predominant histology was germinoma (G) (51/82, 62%), while non germinomatous (NGGCT) were 31/82 (38%), of which 9 were mixed. Pure teratoma were 11 (9 immature (IT), 2 mature), & 5 pure yolk sac tumor (YST). Interestingly, all very young age group patients (<3 yrs), showed only NGGCT histology (5/8 IT, 3/8 pure YST). In contrast, G histology formed nearly 70% of all patients >3 yrs. Females were associated mainly with G (21/29, 72%). NGGCT were predominantly seen in males (M:F=2.9:1). Also, pure IT (9) were seen only in males. Posterior fossa tumors were all IT (4/4). Spinal tumors were NGGCT (1 mature teratoma, 1 YST). Majority of suprasellar tumors (25/31, 80.6%), other midline locations like corpus callosal, midbrain, & all thalamic tumors were G. However, pineal tumors showed equal distribution of G (15/31) & NGGCT (16/31). Spine screening was positive in 8 patients (6 G, 2 IT)- 7 on MRI and 1 only on CSF cytology. Serum tumor markers were raised in 13/54 cases- 6/34G(17.6%), vs 7/20 NGGCT (35%). CSF tumor markers were raised in 14/34-10/23 G (43.4%), vs 4/11 NGGCT (36.3%). Follow up was available for 37 patients (Duration 3 months-10 yrs, median 2 yrs). On f/u 6/15 (40%) NGGCT showed progression/death, while only 2/32 G relapsed (6.5%). Four deaths in G group were not directly attributable to the tumor.

CONCLUSION

Frequency of ICGCT in our hospital similar to western data rather than Asian, albeit with less striking male preponderance. ICGCT were tumors of 2nd decade & majority occurred in pineal/suprasellar areas. About 2/3rd were pure G on histology, and showed good prognosis. NGGCT were common in infants, males and in posterior fossa. IT were seen exclusively in males and pure YST mainly in males. Although majority of ICGCT are in midline, rarely non midline involvement also occurs, and it’s essential to exclude metastasis before considering primary ICGCT. Expectedly, NGGCT showed poorer prognosis, compared to pure germinomas.

Variations in the retromandibular approach to the condyle-transparotid versus anteroparotid transmasseteric - a prospective clinical comparative study

BACKGROUND

The management of mandibular condylar fracture remains controversial many surgeons still favour the open reduction and internal fixation (ORIF) which provides good result and immediate functioning as compared to closed reduction. With proven consensus for ORIF, dilemma remains in choosing the surgical approach to condyle due to proximity of complex and important anatomic structure. Various extra-oral surgical approaches are available for ORIF including preauricular, submandibular, retromandibular, transmasseteric anteroparotid etc. Variations in retromandibular approach such as transparotid, retro-parotid and anteroparotid are reported in literature. In our study we compared the retromandibular transparotid and retromandibular anteroparotid transmasseteric variations.

METHODOLOGY

Thirty condylar fracture in 26 patients, 15 in each group (group A - Retromandibular transparotid approach & group B - Retromandibular anteroparotid approach) were treated under general anaesthesia with naos-tracheal intubation and by the same surgeon having 20 years of experience in maxillofacial surgeries. We evaluated time taken for the procedure, amount of bone exposure, intra-operative haemorrhage. Postoperative presence of infection, sinus and fistula formation at the incision site, parotid fistula formation, facial nerve functioning using House-Brackman scale in immediate postoperative period, 3^rd month postoperatively and 6 month postoperatively.

RESULT

The mean average time taken for group A was 78.2minutes and mean average time taken for group B was 64.8minutes. None of the patient had haemorrhage intra-operatively in both the groups. Exposure was sufficient in both the groups with same length of the incision. None of the patient suffered from postoperative infection in both the groups. Parotid fistula formation was present in 2 patients in group A while none of the patient had parotid fistula in group B. Three patients out of 15 had the transient facial nerve weakness in group A which got resolved in 6 month while none of the patient had facial nerve weakness in group B. All patients had adequate mouth opening with no occlusal discrepancies.

CONCLUSION

Retromandibular anteroparotid approach as described in this study has proven to be an extremely useful approach provides good access, and associated with minimal complications and morbidity compare to retromandibular transparotid approach. It is hence safe to say that this approach is relatively useful for an inexperienced and novice surgeon as well.

Feasibility of molecular testing in a multicenter study with geographical variation in India: Epidermal growth factor receptor mutation as a model molecular test

Context: Trends in epidermal growth factor receptor (EGFR) mutation based on ethnicity assist the initial selection of targeted therapy regimen. Reported incidence of EGFR mutation in Indian NSCLC patients is variable, ranging from 22% to 51.8%.

Aim and Settings and Design: This multicenter, noninterventional study evaluated the prevalence of EGFR mutation in Indian NSCLC patients, its association with patients’ demographics, and for the first time used a central laboratory for molecular testing.

Subjects and Methods: Tissue samples from 252 NSCLC patients were tested at a Central Laboratory at Tata Memorial Hospital. Statistical Analysis Used: Patient demographics, baseline characteristics including smoking status from routine examination were recorded in a single visit. Chi-square or Fisher's exact test was used for association of EGFR mutation status with gender, age, smoking status, and histological subtypes.

Results: The prevalence of EGFR mutation in Indian NSCLC patients was 23.4%. Among these, 55.9% patients had mutations in exon 19, 39% in exon 21, and 1.7% in exon 18. The incidence of EGFR mutation was higher in females than males (32.5% vs. 18.9%, respectively), and in 30.6% patients that had never smoked, 26.3% smokers, and 5.8% former smokers. The mean duration of transportation of tissue samples to the central laboratory was 48 h with an average turnaround time of 5 days for molecular testing.

Conclusions: Molecular testing at a central laboratory is a feasible option in India. Prevalence of EGFR mutation in Indian NSCLC patients was similar across western and southern centers in India. A statistically significant association between EGFR mutation and gender as well as the smoking status of the patients was observed. Majority of the patients had in-frame deletions in exon 19.

Chiral separation and thermodynamic investigation of WCK 3023: A novel oxazolidinone antibacterial agent, application to pre-clinical pharmacokinetic study

A chiral liquid chromatographic method was developed and validated for the quantification of R-enantiomer impurity (RE) in WCK 3023 (S-enantiomer), a new drug substance. The separation was achieved on Chiralpak IA (amylose-based immobilized chiral stationary phase), using a mobile phase consisting of n-hexane-ethanol-trifluoroacetic acid (70:30:0.2, v/v/v) at a flow rate of 1.0 mL/min. The method was extensively validated for the quantification of RE in WCK 3023 and proved to be robust. For RE the detector response was linear over the concentration range of 0.11-5 μg/mL. The limit of quantitation and limit of detection for RE were 0.11 and 0.04 μg/mL respectively. Average recovery of the RE was in the range of 98.11-99.55%. The developed method was specific, sensitive, precise and accurate for quantitative determination of RE in WCK 3023. The impact of thermodynamic parameters on the chiral separation was evaluated. The method was employed for controlling the enantiomeric impurity in the lots of WCK 3023 used for pre-clinical studies. The method was successfully applied to evaluate the possible conversion of WCK 3023 to RE in rat serum samples during pre-clinical pharmacokinetic studies.

Phase III Non-inferiority Study Evaluating Efficacy and Safety of Low Dose Gemcitabine Compared to Standard Dose Gemcitabine With Platinum in Advanced Squamous Lung Cancer

BACKGROUND

Prolonged infusion of low dose gemcitabine (PLDG) in combination with platinum has shown promising activity in terms of improved response rate and progression free survival (PFS); especially in squamous non-small cell lung cancer (NSCLC). Hence, we conducted a phase 3 randomized non-inferiority study with the primary objective of comparing the overall survival (OS) between PLDG and standard dose of gemcitabine with platinum.

METHODOLOGY

Adult subjects (age ≥ 18 years), with stages IIIB-IV, NSCLC (squamous) and ECOG performance status of ≤ 2 were randomized 1:1 into either carboplatin with standard dose gemcitabine (1000 mg/m² intravenous over 30 min, days 1 and 8) (STD-G arm) or carboplatin along with low dose gemcitabine (250 mg/m² intravenous over 6 h, days 1 and 8) (LOW-G arm) for a maximum of 6 cycles. Tumor response was assessed by RECIST criteria version 1.1 every 2 cycles till 6th cycle and thereafter at 2 monthly intervals till progression. The primary endpoint was overall survival. 308 patients were randomized, 155 in STD-G arm and 153 in LOW-G arm, respectively.

RESULTS

The median overall survival in STD-G arm was 6.8 months (95%CI 5.3-8.5) versus 8.4 months (95%CI 7-10.3) in the LOW-G arm (HR-0.890 (90%CI 0.725-1.092). The results with per protocol analysis were in line with these results. There was no statistical difference in progression free survival (HR-0.949; 90%CI 0.867-1.280) and adverse event rate between the 2 arms.

CONCLUSION

This study suggests that PLDG is an alternative to the standard gemcitabine schedule in squamous NSCLC, and either of these can be selected subject to patient convenience.

ROS1 mutation non-small cell lung cancer-access to optimal treatment and outcomes

INTRODUCTION

ROS1 oncogenic fusion, which was first identified by Rikova et al, is reported to be present in 1%-2% of non-small cell lung cancers (NSCLCs) and is defined as a distinct molecular sub-group. Crizotinib is very effective in ROS1-positive patients and is now Food and Drug Administration (FDA) approved for the treatment of patients with advanced ROS1-positive NSCLC. We report our experience in a tertiary cancer care hospital in India in ROS-1 positive patients.

MATERIALS AND METHOD

The present series is a retrospective analysis of 22 patients from the prospectively maintained lung cancer audit. Demographic data were collected which included age, performance status, gender, stage, co-morbidities, sites of metastasis and smoking history. Data were also collected regarding the source of financing for crizotinib whether self-financed, through insurance or Non-Governmental Organisation (NGO) sponsored. Patients who had tested negative for epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) and were subsequently found to be ROS1-mutation negative by fluorescence in situ hybridization (FISH) were evaluated on similar lines. All the data were entered and statistical analyses were performed using the SPSS software version 22.0. Response evaluation was done by RECIST 1.1 criteria.

RESULTS

Between January 2015 and December 2017, there were 22 patients who were ROS1 positive from a total of 535 patients in whom ROS1 testing was performed. A total of 16 patients could receive crizotinib and 6 patients were never exposed to crizotinib. Among the 16 patients who received crizotinib, 2 (12.5%) achieved complete response (CR) as their best response and continue to remain in CR at follow-up. 13 (81%) had a partial response as best response and of which on follow-up 5 (38%) have progressed, while 8 (62%) continue to maintain response. The patients who were on crizotinib had good tolerance with none experiencing any grade 3/4 toxicity. The median follow-up of the entire cohort was 15.2 months in ROS1-positive cohort and 11.4 months in ROS1-negative cohort. In ROS1-positive cohort median, progression-free survival (PFS) was not reached and the estimated 2-year PFS was 54% and in ROS1-negative cohort, it was 5.1 months. The median overall survival of the entire ROS1-positive cohort was not reached and the estimated 1- and 2-year overall survival (OS) was 72% and 54%, respectively, and was 8.8 months in ROS1-negative cohort.

CONCLUSION

ROS1 rearrangement with an incidence of 4% of lung adenocarcinoma which is EGFR and ALK negative represents an important targetable driver mutation in the Indian population. Crizotinib also represents an effective treatment option with outcomes similar to those reported. Access to treatment remains an important roadblock to improve outcomes but innovative methods may improve access to these drugs.

Outcome of uncommon EGFR mutation positive newly diagnosed advanced non-small cell lung cancer patients: a single center retrospective analysis

Background

The significance of uncommon EGFR mutations in newly diagnosed advanced non-small-cell lung cancer (NSCLC) patients is incompletely known. We aimed to analyze the demographic profile, outcome, and treatment attributes of these patients.

Patients and methods

We retrospectively surveyed 5,738 advanced NSCLC patients who underwent EGFR testing in our center from 2013 to 2017 by in-house primer probes on real time PCR platform. Descriptive data were accumulated from electronic medical records. Survival plot was calculated using Kaplan-Meier method and compared between groups using log-rank test.

Results

Out of 1,260 EGFR mutation-positive patients, 83 (6.58%) had uncommon mutations in isolation or in various combinations. Uncommon mutations were more frequent in men, never-smokers, and adenocarcinomas. Overall, exon 18 G719X, exon 20 insertion, exon 20 T790M, exon 20 S768I, and exon 21 (L858R/L861Q) were present in 9.6%, 19.3%, 12%, 3.6%, and 3.6% patients, respectively. Dual mutation positivity was found in 50.6% patients. On classifying patients as per tyrosine kinase inhibitor (TKI) sensitivity, it was found that majority of the patients had a combination TKI sensitive and insensitive mutations. The median duration of follow-up was 13 months. Five patients were lost to follow-up. Median progression-free survival on first line therapy was 6.7 months (95% CI: 4.8-8.5). Median overall survival (OS) of patients who received TKI during the course of their disease was 20.2 months (95% CI: 11.4-28.9). Median overall survival (mOS) of the entire cohort was 15.8 months (95% CI: 10.1-21.5). Among all uncommon mutations, patients with dual mutations did better, with an mOS time of 22.6 months (95% CI: 8.2-37.0, P=0.005). It was observed that TKI sensitive/TKI insensitive dual mutations had a superior OS of 28.2 months (95% CI: 15.2-41.2, P=0.039) as compared to TKI sensitive and TKI insensitive EGFR mutations.

Conclusion

Uncommon EGFR mutations constitute a heterogeneous group, hence, it is imperative to understand each subgroup more to define optimal treatment.

Actionable Activating Oncogenic ERBB2/HER2 Transmembrane and Juxtamembrane Domain Mutations

Deregulated HER2 is a target of many approved cancer drugs. We analyzed 111,176 patient tumors and identified recurrent mutations in HER2 transmembrane domain (TMD) and juxtamembrane domain (JMD) that include G660D, R678Q, E693K, and Q709L. Using a saturation mutagenesis screen and testing of patient-derived mutations we found several activating TMD and JMD mutations. Structural modeling and analysis showed that the TMD/JMD mutations function by improving the active dimer interface or stabilizing an activating conformation. Further, we found that HER2 G660D employed asymmetric kinase dimerization for activation and signaling. Importantly, anti-HER2 antibodies and small-molecule kinase inhibitors blocked the activity of TMD/JMD mutants. Consistent with this, a G660D germline mutant lung cancer patient showed remarkable clinical response to HER2 blockade.

Demographic profile, clinicopathological spectrum, and treatment outcomes of primary central nervous system tumors: Retrospective audit from an academic neuro-oncology unit

Primary tumors of the central nervous system are relatively uncommon, comprising only 1%-2% of all neoplasms. However, they constitute the second most common type of malignancy in children (after leukemia) and the leading cause of cancer-related morbidity and mortality in children and young adults worldwide. Globally, there is substantial variability with nearly five-fold difference in incidence between various parts of the world. Brain tumors are quite heterogeneous with regard to histology, biological behavior, and prognosis mandating multidisciplinary therapeutic decision-making. This retrospective audit of all consecutive patients registered in a single calendar year (2013) in the neuro-oncology disease management group at Tata Memorial Centre is reflective of the ground reality and fair representation of outcomes in routine neuro-oncologic practice.

Thromboembolic events in patients with advanced stage non-small cell lung cancer treated with platinum-based chemotherapy: a prospective observational study

Objectives

Cancer is frequently complicated by thromboembolic events (TEs). We aimed to determine the incidence of TEs in lung cancer patients treated with platinum-based chemotherapy and study patients’ baseline and treatment attributes correlating with its onset.

Materials and methods

Advanced lung cancer patients started on platinum-based chemotherapy were evaluated at baseline and during routine visits for the development of TEs. The duration of follow-up was 4 weeks from the last chemotherapy. A TE occurring between the first dose of chemotherapy and 4 weeks after the last dose was considered to be chemotherapy associated.

Results

Of the 165 patients on platinum chemotherapy who completed follow-up, TEs occurred in 4.8% (8 out of 165) patients. Among these, three patients had developed venous pulmonary thromboembolism and five patients had developed cerebral infarction, out of which four had arterial cerebral infarction and one patient had a superior sagittal sinus thrombosis. The majority of events (7 out of 8) occurred within 100 days of starting platinum chemotherapy. Overall, the median time until occurrence of TE was 48 days (range, 10–130 days). None of the presumed risk factors were found be associated with the occurrence of TEs on univariate analysis.

Conclusions

Advanced lung cancer patients on platinum chemotherapy are predisposed to thromboembolism due to many factors. Despite its lower incidence in our study, exclusion of patients with prior thrombosis suggests the incidence of de novo thrombosis, and hence raises a valid question of the need of thromboprophylaxis in a selected group of patients.

Patterns of epidermal growth factor receptor testing across 111 tertiary care centers in India: Result of a questionnaire-based survey

Background:

We conducted a survey of 111 medical oncologists across India to understand the current pattern of epidermal growth factor receptor (EGFR) mutation testing at their respective centers.

Methods:

Medical oncologists from 111 institutes across India were interviewed face to face using a structured questionnaire. They were divided into two groups – Group 1 with in-house EGFR testing and Group 2 who send samples to central/commercial laboratories outside their institutions. Answers of the two groups were analyzed to see the prevailing patterns of EGFR testing and differences between the two groups if any.

Results:

Ninety-five percent (105/111) of medical oncologists recommended testing for EGFR mutations in patients with adenocarcinoma histology and 40% (44/111) recommended EGFR testing in squamous cell histology. The average time duration to get EGFR test results was 10 days in Group 1 centers versus 18 days in Group 2 centers. Ninety-six percent (106/111) of the medical oncologists from Group 1 centers requested for factoring additional sample for biomarker testing compared to 69% (77/111) of the oncologists from Group 2 centers. Sixty-nine percent (77/111) of medical oncologists in Group 1 centers would prefer to wait for the test results before initiating treatment compared to 46% (51/111) in Group 2. EGFR tyrosine-kinase inhibitors were used in only approximately 60% of patients with diagnosed EGFR mutation in the first line. For patients in whom chemotherapy was initiated while waiting for test results, 50% (56/111) of medical oncologists would prefer to complete 4–6 cycles before switching to targeted therapy. At the time of progression, rebiopsy was possible in approximately 25% of the patients.

Conclusions:

Turnaround time for molecular testing should improve so that eligible patients can benefit from targeted therapies in the first line. There is a need to increase the awareness among pulmonologists, oncologists, and interventional radiologists regarding the importance of adequate samples required for molecular tests.

Strategic Approaches to Overcome Resistance against Gram-Negative Pathogens Using β-Lactamase Inhibitors and β-Lactam Enhancers: Activity of Three Novel Diazabicyclooctanes WCK 5153, Zidebactam (WCK 5107), and WCK 4234

Limited treatment options exist to combat infections caused by multidrug-resistant (MDR) Gram-negative bacteria possessing broad-spectrum β-lactamases. The design of novel β-lactamase inhibitors is of paramount importance. Here, three novel diazabicyclooctanes (DBOs), WCK 5153, zidebactam (WCK 5107), and WCK 4234 (compounds 1-3, respectively), were synthesized and biochemically characterized against clinically important bacteria. Compound 3 inhibited class A, C, and D β-lactamases with unprecedented k₂/ K values against OXA carbapenemases. Compounds 1 and 2 acylated class A and C β-lactamses rapidly but not the tested OXAs. Compounds 1-3 formed highly stable acyl-complexes as demonstrated by mass spectrometry. Crystallography revealed that 1-3 complexed with KPC-2 adopted a "chair conformation" with the sulfate occupying the carboxylate binding region. The cefepime-2 and meropenem-3 combinations were effective in murine peritonitis and neutropenic lung infection models caused by MDR Acinetobacter baumannii. Compounds 1-3 are novel β-lactamase inhibitors that demonstate potent cross-class inhibition, and clinical studies targeting MDR infections are warranted.

Metastatic Renal Cell Cancer-Systemic Therapy

Management of metastatic renal cell carcinoma (mRCC) has evolved considerably in the past 10 years due to better understanding of tumor biology. This development has changed mRCC to a chronic progressive disease with several lines of treatment options. The introduction of several new targeted therapies including immunotherapy has improved median overall survival of approximately 1 year to >2 years in mRCC.

Efficacy of gefitinib in epidermal growth factor receptor-activating mutation-positive nonsmall cell lung cancer: Does exon 19 deletion differ from exon 21 mutation?

BACKGROUND

This study was designed to evaluate the differential effect of epidermal growth factor receptor (EGFR) mutation status (exon 19 vs. 21) on progression-free survival (PFS) and overall survival (OS) in treatment-naïve advanced EGFR mutation-positive nonsmall cell lung cancer (NSCLC) treated with gefitinib as first-line agent.

METHODS

This was a post hoc analysis of EGFR-mutated (exon 19 and 21) advanced-stage (Stage IIIB or IV), chemotherapy-naive NSCLC patients treated with gefitinib as first line in a phase 3 randomized study. Patients were treated with gefitinib 250 mg daily. Patients underwent axial imaging for response assessment on D42, D84, D126, and subsequently every 2 months till progression. Responding or stable patients were treated until progression or unacceptable toxicity. SPSS was used for statistical analysis. Kaplan-Meier method was used for survival estimation and log-rank test for comparison. Cox proportion hazard model was used for multivariate analysis.

RESULTS

One hundred and forty-one patients were eligible for analysis, of which 78 were males and 63 were females. A total of 127 patients (90.1%) were ECOG 0-1 while 14 patients (9.1%) were ECOG >1. Exon 21 mutation was present in 65 patients (46.1%) and exon 19 mutation in 76 patients (53.9%). One hundred and thirty-three of 141 patients were evaluable for response. Response rate of patients having exon 19 mutation was 72.9% (51 patients, n = 70) while it was 55.6% in patients having exon 21 mutation (35 patients, n = 63) (P = 0.046). Median PFS in exon 19-mutated patients was 9.3 months (95% confidence interval [CI] 6.832-11.768) compared to 7.8 months (95% CI 5.543-10.0) (P = 0.699) in exon 21-mutated patients. The median OS in exon 19-mutated patients was 19.8 months (95% CI 16.8-22.7), and it was 16.5 months (95% CI 10.9-22.1) in exon 21-mutated patients (P = 0.215).

CONCLUSION

There were no differential outcomes in the Indian patients of advanced-stage NSCLC with exon 19 and 21 EGFR mutations treated with gefitinib.

Ceritinib in anaplastic lymphoma kinase-positive nonsmall cell lung cancer among patients who were previously exposed to crizotinib: Experience from the Indian subcontinent

Ceritinib is a novel ALK inhibitor approved for advanced stage NSCLC with ALK gene rearrangement, progressed and/or intolerant to crizotinib. 13 patients were included in our study who received ceritinib. Majority of them were women and never smokers with a median age of 47 yrs. Nearly half of them had a compromised performance status and received ceritinib in third line and beyond. Ceritinib showed nearly 50% response rates. With a median follow up of 9 months for the entire cohort, median PFS and OS were not reached. However, the mean values for PFS and OS were 10.9 and 14.8 months,with an estimated 1 year PFS and OS being 56% and 78% respectively.1/3 of the patients had gastrointestinal and liver toxicities. Metabolic abnormalities were seen in 1/4 th of them. ceritinib was permanently discontinued in one patient due to pneumonitis. In conclusion, ceritinib has a favorable efficacy and side effect profile in our patient population., similar to that reported in large clinical trials. It has shown promising efficacy even in patients with compromised performance status; presence of brain metastases and heavily pre-treated disease.

Impact of exon 19 versus exon 21 EGFR-activating mutation on outcomes with upfront pemetrexed-carboplatin chemotherapy

Background

EGFR mutation subtype is a recognised factor impacting outcomes of patients receiving oral tyrosine kinase inhibitors (TKIs) in non-small-cell lung cancer (NSCLC). Evidence for the effect of this factor on outcomes in patients receiving pemetrexed is limited.

Methods

We completed a study comparing pemetrexed-platinum combination versus oral TKI in EGFR mutation-positive patients in lung cancer. We analysed the impact of EGFR mutation subtype, specifically, exon 19 and 21 on the PFS and OS of patients treated with pemetrexed (500 mg/m² on day 1) and carboplatin (AUC 5 on day 1) as first-line therapy. Patients underwent axial imaging for response assessment on D42, D84, D126 and subsequently every two months till progression. Patients post-progression were treated with gefitinib.

Results

Fifty-one patients (36%) had exon 21 mutation, while 92 patients (64%) had exon 19 mutation. Response rates in evaluable patients was 47.7% in exon 19 patients (41 patients, n = 86) and 42.9 % in exon 21 patients (18 patients, n = 42). There was a significant increase in median overall survival for patients with exon 19 mutations (24.5 months, 95% CI: 21.3-27.7 months ) over the exon 21-mutated patients (18.1 months, 95% Cl: 13.5-22.6 months, p = 0.002). This differential impact was due to second-line gefitinib having a differential outcome on these mutations.

Conclusion

Pemetrexed-based chemotherapy does not have a differential impact on exon 19- or exon 21-mutated patients. However, second-line treatment with gefitinib has a favourable response and outcome in exon 19-mutated patients.