Lack of Response to Imatinib in Melanoma Carrying Rare KIT Mutation р.T632I

Approximately 15% of acral and mucous melanomas carry activating mutations in KIT oncogene. There is a diversity of spectrum of KIT mutations, with some of them rendering tumors responsive to imatinib, while others being imatinib-resistant or not studied yet. Here we present an acral melanoma patient with KIT р.T632I mutation, who failed to respond to imatinib

Lack of Response to Vemurafenib in Melanoma Carrying BRAF K601E Mutation

Vemurafenib has been developed to target common BRAF mutation V600E. It also exerts activity towards some but not all rare BRAF substitutions. Proper cataloguing of drug-sensitive and -insensitive rare mutations remains a challenge, due to low occurrence of these events and inability of commercial PCR-based diagnostic kits to detect the full spectrum of BRAF gene lesions. We considered the results of BRAF exon 15 testing in 1872 consecutive melanoma patients. BRAF mutation was identified in 1,090 (58.2%) cases. While drug-sensitive codon 600 substitutions constituted the majority of BRAF gene lesions (V600E: 962 [51.4%]; V600K: 86 [4.6%]; V600R: 17 [0.9%]), the fourth common BRAF allele was K601E accounting for 9 (0.5%) melanoma cases. The data on BRAF inhibitor sensitivity of tumors with K601E substitution are scarce. We administered single-agent vemurafenib to a melanoma patient carrying BRAF K601E mutation as the first-line treatment. Unfortunately, this therapy did not result in a tumor response. Taken together with already published data, this report indicates lack of benefit from conventional BRAF inhibitors in patients with BRAF K601E mutated melanoma

Cancer Therapy Guided by Mutation Tests: Current Status and Perspectives

The administration of many cancer drugs is tailored to genetic tests. Some genomic events, e.g., alterations of EGFR or BRAF oncogenes, result in the conformational change of the corresponding proteins and call for the use of mutation-specific compounds. Other genetic perturbations, e.g., HER2 amplifications, ALK translocations or MET exon 14 skipping mutations, cause overproduction of the entire protein or its kinase domain. There are multilocus assays that provide integrative characteristics of the tumor genome, such as the analysis of tumor mutation burden or deficiency of DNA repair. Treatment planning for non-small cell lung cancer requires testing for EGFR, ALK, ROS1, BRAF, MET, RET and KRAS gene alterations. Colorectal cancer patients need to undergo KRAS, NRAS, BRAF, HER2 and microsatellite instability analysis. The genomic examination of breast cancer includes testing for HER2 amplification and PIK3CA activation. Melanomas are currently subjected to BRAF and, in some instances, KIT genetic analysis. Predictive DNA assays have also been developed for thyroid cancers, cholangiocarcinomas and urinary bladder tumors. There is an increasing utilization of agnostic testing which involves the analysis of all potentially actionable genes across all tumor types. The invention of genomically tailored treatment has resulted in a spectacular improvement in disease outcomes for a significant portion of cancer patients

Agnostic Administration of Targeted Anticancer Drugs: Looking for a Balance between Hype and Caution

Many tumors have well-defined vulnerabilities, thus potentially allowing highly specific and effective treatment. There is a spectrum of actionable genetic alterations which are shared across various tumor types and, therefore, can be targeted by a given drug irrespective of tumor histology. Several agnostic drug-target matches have already been approved for clinical use, e.g., immune therapy for tumors with microsatellite instability (MSI) and/or high tumor mutation burden (TMB), NTRK1-3 and RET inhibitors for cancers carrying rearrangements in these kinases, and dabrafenib plus trametinib for BRAF V600E mutated malignancies. Multiple lines of evidence suggest that this histology-independent approach is also reasonable for tumors carrying ALK and ROS1 translocations, biallelic BRCA1/2 inactivation and/or homologous recombination deficiency (HRD), strong HER2 amplification/overexpression coupled with the absence of other MAPK pathway-activating mutations, etc. On the other hand, some well-known targets are not agnostic: for example, PD-L1 expression is predictive for the efficacy of PD-L1/PD1 inhibitors only in some but not all cancer types. Unfortunately, the individual probability of finding a druggable target in a given tumor is relatively low, even with the use of comprehensive next-generation sequencing (NGS) assays. Nevertheless, the rapidly growing utilization of NGS will significantly increase the number of patients with highly unusual or exceptionally rare tumor-target combinations. Clinical trials may provide only a framework for treatment attitudes, while the decisions for individual patients usually require case-by-case consideration of the probability of deriving benefit from agnostic versus standard therapy, drug availability, associated costs, and other circumstances. The existing format of data dissemination may not be optimal for agnostic cancer medicine, as conventional scientific journals are understandably biased towards the publication of positive findings and usually discourage the submission of case reports. Despite all the limitations and concerns, histology-independent drug-target matching is certainly feasible and, therefore, will be increasingly utilized in the future

Efficacy of lorlatinib in lung carcinomas carrying distinct ALK translocation variants: The results of a single-center study

Background: Lorlatinib is a novel potent ALK inhibitor, with only a few studies reporting the results of its clinical use. Methods: This study describes the outcomes of lorlatinib treatment for 35 non-small cell lung cancer patients with ALK rearrangements, who had 2 (n = 5), 1 (n = 26) or none (n = 4) prior tyrosine kinase inhibitors and received lorlatinib mainly within the compassionate use program. Results: Objective tumor response (OR) and disease control (DC) were registered in 15/35 (43%) and 33/35 (94%) patients, respectively; brain metastases were particularly responsive to the treatment (OR: 22/27 (81%); DC: 27/27 (100%)). Median progression free survival (PFS) was estimated to be 21.8 months, and median overall survival (OS) approached to 70.1 months. Only 4 out of 35 patients experienced no adverse effects; two of them were the only subjects who had no clinical benefit from lorlatinib. PFS and OS in the no-adverse-events lorlatinib users were strikingly lower as compared to the remaining patients (1.1 months vs. 23.7 months and 10.5 months vs. not reached, respectively; p < 0.0001 for both comparisons). ALK translocation variants were known for 28 patients; there was no statistical difference between patients with V.1 and V.3 rearrangements with regard to the OS or PFS. Conclusion: Use of lorlatinib results in excellent disease outcomes, however caution must be taken for patients experiencing no adverse effects from this drug