BACKGROUND: Tyrosine kinase inhibitors (TKIs) of the epidermal growth factor receptor (EGFR) have activity in solid tumors. The authors evaluated an oral EGFR TKI, erlotinib, in patients with previously treated esophageal cancer. METHODS: Thirty patients with measurable, metastatic cancer of the esophageal and gastroesophageal junction received 150 mg erlotinib daily. EGFR-negative tumors (6 patients; 20%) and EGFR-over expressing tumors (24 patients; 80%) were treated. Most patients were men (70%) with adenocarcinoma (57%) and had received previous chemotherapy (97%). RESULTS: Two partial responses were observe d in the EGFR-positive cohort (2 of 24 patients; 8%), and no responses were observed in the EGFR-negative cohort (0 of 6 patients). Reponses were limited to patients who had squamous cell carcinoma (2 of 13 patients; 15%; response duration, 5.5-7 months). The time to tumor progression was longer in patients who had squamous cell carcinoma (3.3 months; range, 1-24 months) compared with patients who had adenocarcinoma (1.6 months; range, 1-6 months; P ¼ .026). Therapy was tolerable with the expected toxicity of skin rash (grade 1-2, 67%; grade 3, 10%). CONCLUSIONS: Erlotinib had limited activity in patients with esophageal cancer, and responses and some protracted stable disease were observed in those with squamous cell carcinoma. Efficacy according to EGFR status could not be assessed given the rarity of EGFR-negative tumors. The current results indicated that further evaluation of this agent in squamous cell carcinoma is warranted.

We present the case of a patient with multiple EGFR mutations that highlights tumor heterogeneity leading to a mixed response to osimertinib and emphasizes the complexity of EGFR-driven lung cancer. Subclonal tumor evolution was proved by tissue biopsy, monitored by serial analyses of cell-free circulating tumor DNA

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The treatment of metastatic renal cell carcinoma has evolved quickly over the last few years from a disease managed primarily with sequential oral tyrosine kinase inhibitors (TKIs) targeting the vascular endothelial growth factor (VEGF) pathway, to now with a combination of therapies incorporating immune checkpoint blockade (ICB). Patient outcomes have improved with these innovations, however, controversy persists regarding optimal sequence and patient selection amongst the available combinations. Ideally, predictive biomarkers would aid in guiding treatment decisions and personalizing care. However, clinically-actionable biomarkers have remained elusive. We aim to review the available evidence regarding biomarkers for both TKIs and ICB and will present where the field may be headed in the years to come.

Purpose: Mutations in KRAS/NRAS (RAS) predict lack of anti-EGFR efficacy in metastatic colorectal cancer (mCRC). However, it is unclear if all RAS mutations have similar impact, and atypical mutations beyond those in standard guidelines exist. Experimental Design: We reviewed 7 tissue and 1 cell-free DNA cohorts of 9,485 patients to characterize atypical RAS variants. Using an in vitro cell-based assay (functional annotation for cancer treatment), Ba/F3 transformation, and in vivo xenograft models of transduced isogenic clones, we assessed signaling changes across mutations. Results: KRAS exon 2, extended RAS, and atypical RAS mutations were noted in 37.8%, 9.5%, and 1.2% of patients, respectively. Among atypical variants, KRAS L19F, Q22K, and D33E occurred at prevalence ≥0.1%, whereas no NRAS codon 117/146 and only one NRAS codon 59 mutation was noted. Atypical RAS mutations had worse overall survival than RAS/BRAF wild-type mCRC (HR, 2.90; 95% confidence interval, 1.24–6.80; P = 0.014). We functionally characterized 114 variants with the FACT assay. All KRAS exon 2 and extended RAS mutations appeared activating. Of 57 atypical RAS variants characterized, 18 (31.6%) had signaling below wild-type, 23 (40.4%) had signaling between wild-type and activating control, and 16 (28.1%) were hyperactive beyond the activating control. Ba/F3 transformation (17/18 variants) and xenograft model (7/8 variants) validation was highly concordant with FACT results, and activating atypical variants were those that occurred at highest prevalence in clinical cohorts. Conclusions: We provide best available evidence to guide treatment when atypical RAS variants are identified. KRAS L19F, Q22K, D33E, and T50I are more prevalent than many guideline-included RAS variants and functionally relevant.