ABSTRACT
Since the first approval of the anti-CD3 recombinant monoclonal antibody (mAb), muromonab-CD3, a mouse antibody for the prevention of transplant rejection, by the US Food and Drug Administration (FDA) in 1986, mAb therapeutics have become increasingly important to medical care. A wealth of information about mAbs regarding their structure, stability, post-translation modifications, and the relationship between modification and function has been reported. Yet, substantial resources are still required throughout development and commercialization to have appropriate control strategies to maintain consistent product quality, safety, and efficacy. A typical feature of mAbs is charge heterogeneity, which stems from a variety of modifications, including modifications that are common to many mAbs or unique to a specific molecule or process. Charge heterogeneity is highly sensitive to process changes and thus a good indicator of a robust process. It is a high-risk quality attribute that could potentially fail the specification and comparability required for batch disposition. Failure to meet product specifications or comparability can substantially affect clinical development timelines. To mitigate these risks, the general rule is to maintain a comparable charge profile when process changes are inevitably introduced during development and even after commercialization. Otherwise, new peaks or varied levels of acidic and basic species must be justified based on scientific knowledge and clinical experience for a specific molecule. Here, we summarize the current understanding of mAb charge variants and outline risk-based control strategies to support process development and ultimately commercialization.
ABSTRACT
The MET protein is involved in the malignant progression of different tumors. This study aimed to analyze the relationship of MET expression with tumor phenotype and clinical outcome in bladder cancer and the role of gene amplification for MET overexpression. A bladder cancer tissue microarray containing 686 bladder cancers was analyzed by immunohistochemistry and by fluorescence in situ hybridization. MET immunostaining was seen in normal urothelium and was recorded in 459 of 560 analyzable urothelial carcinomas (82.0%). Low MET staining was associated with a more unfavorable tumor phenotype. MET staining was seen in 89.8% of 266 pTa, 81.1% of 132 pT1, and 69.4% of 160 pT2-4 cancers (P < 0.0001). MET staining was detectable in 92.4% of 66 grade 1, 85.6% of 257 grade 2, and 75.1% of 237 grade 3 cancers (P = 0.001). MET expression status was not associated with overall or tumor-specific survival in muscle-invasive cancers (pT2-4), tumor progression in pT1 cancers, or recurrences in pTa tumors. Only four of the analyzed tumors (0.8%) showed amplification of the MET gene. We conclude that MET is not overexpressed in urothelial cancer but rather downregulated in a fraction of cancers. Accordingly, rare amplification of the genomic area including the MET gene was not associated with MET protein overexpression.
