AGAPP: efficacy of first-line cisplatin, 5-fluorouracil with afatinib in inoperable gastric and gastroesophageal junction carcinomas. A Hellenic Cooperative Oncology Group study

PURPOSE

Gastric cancer is the fifth most common neoplasm worldwide with high rates of mortality. Afatinib, a low molecular, irreversible potent inhibitor of ErbB trans-membrane receptor family, has shown promising results according to preclinical and phase I clinical trial data when combined with chemotherapy. We aimed at evaluating the safety and efficacy of the combination of cisplatin, 5FU with afatinib in molecularly unselected patients with advanced gastric cancer.

METHODS

Patients with locally advanced or metastatic gastric/gastroesophageal junction adenocarcinoma received first line combination therapy of cisplatin, 5FU and afatinib every 21 days, followed by afatinib maintenance monotherapy. The primary endpoint was the Objective Response Rate (ORR); secondary endpoints included Overall Survival (OS), Progression Free Survival (PFS) and the safety profile. Unplanned exploratory analysis of HER2 and tumor mutational profile was performed.

RESULTS

Among 55 patients (ITT population) enrolled, 19 (34.5%) achieved an objective tumor response; stable disease was observed in 16 patients (29.1%) and progressive disease in 10 patients (18.2%). The ORR in the per protocol population (PP) was 42.9%. Within a median follow-up of 56 months, the median PFS and OS in the ITT population was 5.0 and 8.7 months, respectively. Seven of the 47 HER2 informative cases carried HER2 positive tumors while TP53, BRCA2 and SMAD4 were the most frequently mutated genes. The most common toxicities were neutrophil count and white blood cell decrease occurring in 56.4% of patients, followed by anemia (50.9%), hyperglycemia (40%), and diarrhea (38.2%).

CONCLUSIONS

The combination of cisplatin/5FU with afatinib did not surpass the benchmarks of efficacy of the contemporary therapeutic regimens that are being applied for the treatment of patients with advanced gastric cancer. However, the observed efficacy and the improved safety profile support that our administration schedule may be further investigated to overcome toxicity problems when integrating afatinib to cytotoxic chemotherapy.

CLINICAL TRIAL REGISTRATION

NCT01743365.

Afatinib pharmacokinetics and metabolism after oral administration to healthy male volunteers

PURPOSE

To investigate the pharmacokinetics, metabolism and tolerability of afatinib (BIBW 2992), an oral irreversible ErbB family blocker, in healthy male volunteers.

METHODS

In this open-label, single-center study, 8 healthy male volunteers received a single oral dose of 15 mg [(14)C]-radiolabeled afatinib (equivalent to 22.2 mg of the dimaleinate salt) as a solution. Blood, urine and fecal samples were collected for at least 96 hours (h) after dosing. Plasma and urine concentrations of afatinib were analyzed using high-performance liquid chromatography-tandem mass spectrometry. [(14)C]-radioactivity levels in plasma, whole blood, urine and feces were measured by liquid scintillation counting methods. Metabolite patterns were assessed by high-performance liquid chromatography.

RESULTS

[(14)C]-radioactivity was mainly excreted via feces (85.4%). Overall recovery of [(14)C]-radioactivity was 89.5%, indicative of a complete mass balance. Afatinib was slowly absorbed, with maximum plasma concentrations achieved at a median of 6 h after dosing, declining thereafter in a biexponential manner. The geometric mean terminal half-life of afatinib was 33.9 h in plasma and longer for [(14)C]-radioactivity in plasma and whole blood. Apparent total body clearance for afatinib was high (geometric mean 1,530 mL/min). The high volume of distribution (4,500 L) in plasma may indicate a high tissue distribution. Afatinib was metabolized to only a minor extent, with the main metabolite afatinib covalently bound to plasma proteins. Oxidative metabolism mediated via cytochrome P-450 was of negligible importance for the elimination of afatinib. Afatinib was well tolerated.

CONCLUSIONS

Afatinib displayed a complete mass balance with the main route of excretion via feces. Afatinib undergoes minimal metabolism.

The role of irreversible HER family inhibition in the treatment of patients with non-small cell lung cancer

Small-molecule tyrosine kinase inhibitors (TKIs) of the human epidermal growth factor receptor (HER) include the reversible epidermal growth factor receptor (EGFR/HER-1) inhibitors gefitinib and erlotinib. EGFR TKIs have demonstrated activity in the treatment of patients with non-small cell lung cancer (NSCLC) harboring activating EGFR mutations; however, multiple mechanisms of resistance limit the benefit of these drugs. Although resistance to EGFR TKIs can be intrinsic and correlated with molecular lesions such as in Kirsten rat sarcoma viral oncogene homolog (KRAS; generally observed in a wild-type EGFR background), acquired resistance to EGFR TKIs can evolve in the setting of activating EGFR mutations, such as in the case of EGFR T790M mutations. Several irreversible inhibitors that target multiple members of the HER family simultaneously are currently in clinical development for NSCLC and may have a role in the treatment of TKI-sensitive and TKI-resistant disease. These include PF00299804, an inhibitor of EGFR/HER-1, HER-2, and HER-4, and afatinib (BIBW 2992), an inhibitor of EGFR/HER-1, HER-2, and HER-4. Results of large, randomized trials of these agents may help to determine their potential for the treatment of NSCLC.