Impact of tumour RAS/BRAF status in a first-line study of panitumumab + FOLFIRI in patients with metastatic colorectal cancer.

BACKGROUND: To investigate tumour biomarker status and efficacy of first-line panitumumab+FOLFIRI for metastatic colorectal carcinoma (mCRC). METHODS: 154 patients received first-line panitumumab + FOLFIRI every 14 days. Primary end point was objective response rate (ORR). Data were analysed by tumour RAS (KRAS/NRAS) and BRAF status, and baseline amphiregulin (AREG) expression. RESULTS: Objective responses occurred more frequently in RAS wild type (WT) (59%) vs RAS mutant (MT) (41%) mCRC and in RAS WT/BRAF WT (68%) vs RAS or BRAF MT (37%) disease. Median response duration was longer in RAS WT (13.0 months) vs RAS MT (5.8 months) (hazard ratio (HR): 0.16). Median progression-free survival was longer in RAS WT vs MT (11.2 vs 7.3 months; HR, 0.37) and was also longer in RAS WT/BRAF WT vs RAS or BRAF MT (13.2 vs 6.9 months; HR, 0.25). Incidence of adverse events was similar regardless of RAS/BRAF status, and no new safety signals were noted. Among patients with RAS WT tumours, ORR was 67% with high AREG expression and 38% with low AREG expression. CONCLUSIONS: First-line panitumumab+FOLFIRI was associated with favourable efficacy in patients with RAS WT and RAS WT/BRAF WT vs MT mCRC tumours and was well tolerated.

A novel method for detecting neutralizing antibodies against therapeutic proteins by measuring gene expression.

The presence of neutralizing antibodies against protein therapeutics is a concern in the biomedical field. Such antibodies not only reduce the efficacy of protein therapeutics, but also impose potential dangers to the patients receiving them. To date, a small number of in vitro cell-based bioassays for detecting neutralizing antibodies against therapeutic proteins have been developed. Most of the existing assays, however, either involve the use of radioactive materials or have limited sensitivities and/or poor specificities. With advances in mRNA profiling and detection techniques, we have established a novel and non-radioactive bioassay system using branched DNA (bDNA) technology for detecting protein-therapeutic neutralizing antibodies in patient serum. Our assay measures the variations of target gene expression that reflect the biologic effect of the therapeutic agent and the capability of the antibodies, if present, to neutralize the therapeutics. Compared with most existing assays, the new assay is more sensitive and specific, and completely eliminates the use of radioactive materials. Application of the new assay system can be widely expanded if new target genes and responding cell lines for other therapeutics are identified or engineered.

AMG 595, an Anti-EGFRvIII Antibody-Drug Conjugate, Induces Potent Antitumor Activity against EGFRvIII-Expressing Glioblastoma.

Epidermal growth factor receptor variant III (EGFRvIII) is a cancer-specific deletion mutant observed in approximately 25% to 50% of glioblastoma multiforme (GBM) patients. An antibody drug conjugate, AMG 595, composed of the maytansinoid DM1 attached to a highly selective anti-EGFRvIII antibody via a noncleavable linker, was developed to treat EGFRvIII-positive GBM patients. AMG 595 binds to the cell surface and internalizes into the endo-lysosomal pathway of EGFRvIII-expressing cells. Incubation of AMG 595 with U251 cells expressing EGFRvIII led to potent growth inhibition. AMG 595 treatment induced significant tumor mitotic arrest, as measured by phospho-histone H3, in GBM subcutaneous xenografts expressing EGFRvIII. A single intravenous injection of AMG 595 at 17 mg/kg (250 µg DM1/kg) generated complete tumor regression in the U251vIII subcutaneous xenograft model. AMG 595 mediated tumor regression in the D317 subcutaneous xenograft model that endogenously expresses EGFRvIII. Finally, AMG 595 treatment inhibited the growth of D317 xenografts orthotopically implanted into the brain as determined by magnetic resonance imaging. These results demonstrate that AMG 595 is a promising candidate to evaluate in EGFRvIII-expressing GBM patients.

Evaluation of an integrated clinical workflow for targeted next-generation sequencing of low-quality tumor DNA using a 51-gene enrichment panel.

BACKGROUND: Improvements in both performance and cost for next-generation sequencing (NGS) have spurred its rapid adoption for clinical applications. We designed and optimized a pan-cancer target-enrichment panel for 51 well-established oncogenes and tumor suppressors, in conjunction with a bioinformatic pipeline informed by in-process controls and pre- and post-analytical quality control measures. METHODS: The evaluation of this workflow consisted of sequencing mixtures of intact DNA to establish analytical sensitivity and precision, utilization of heuristics to identify systematic artifacts, titration studies of intact and FFPE samples for input optimization, and incorporation of orthogonal sequencing strategies to increase both positive predictive value and variant detection. We also used 128 FFPE samples to assess clinical accuracy and incorporated the previously described quantitative functional index (QFI) for sample qualification as part of detailing complete system performance. RESULTS: We observed a concordance correlation coefficient of 0.99 between the observed versus expected percent variant at 250 ng input across 4 independent sequencing runs. A subset of the systematic variants were confirmed to be barely detectable on an independent sequencing platform (Wilcox signed-rank test p-value <10(-16)), and the incorporation of orthogonal sequencing strategies increased the harmonic mean of sensitivity and positive predictive value of mutation detection by 41%. In one cohort of FFPE tumor samples, coverage and inter-platform concordance were positively correlated with the QFI, emphasizing the need for pre-analytical sample quality control to reduce the risk of false positives and negatives. In a separate cohort of FFPE samples, the 51-gene panel achieved 78% sensitivity (95% CI = 56.3, 92.5) with 100% PPV (95% CI = 81.5, 100.0) based on known mutations at 7.9% median abundance. By sequencing specimens using an orthogonal NGS technology, sensitivity was improved to 87.0% (95% CI = 66.4,97.2) while maintaining PPV. CONCLUSIONS: The results highlight the value of process integration in a comprehensive targeted NGS system, enabling both discovery and diagnostic applications, particularly when sequencing low-quality cancer specimens.