Tyrosine kinase inhibitors (TKI) targeting epidermal growth factor receptor (EGFR) are approved for use in metastatic non-small cell lung cancer (NSCLC).
Here we present a case of a African American ...patient with stage IIIA NSCLC treated with osimertinib in the neoadjuvant setting with concurrent radiation, followed by resection. The patient remains disease-free 4 months after surgery.
This case report suggests that osimertinib may be effective as neoadjuvant therapy in resectable stage III disease. Additionally, we provide a summary of previous case reports and ongoing clinical trials for neoadjuvant EGFR inhibition in stage III NSCLC patients.
The proton-coupled folate transporter (PCFT) mediates intestinal folate absorption, and loss-of-function mutations in this gene result in the autosomal recessive disorder hereditary folate ...malabsorption. The current study, focused on a structure-functional analysis of this transporter, identified Gly-189 and Gly-192 (a GxxG motif) located in the fifth transmembrane domain as residues that could not be replaced with alanine without a loss of function. In contrast, function was preserved when Gly-56 and Gly-59 (the other conservative GXXG motif in human PCFT) were replaced with alanine. Similarly, Gly-93 and Gly-97, which constitute the only conserved GXXXG dimerization motif in human PCFT, tolerated alanine substitution. To explore the role of this region in folate binding, the residues around Gly-189 and Gly-192 were analyzed by the substituted cysteine accessibility method. Both I188C and M193C mutants were functional and were inhibited by membrane-impermeable sulfhydryl-reactive reagents; this could be prevented with PCFT substrate, but the protection was sustained at 0°C only for the I188C mutant, consistent with localization of Ile-188 in the PCFT folate binding pocket. The functional role of residues around Gly-189 and Gly-192 is consistent with a molecular structural model in which these two residues along with Ieu-188 are accessible to the PCFT aqueous translocation pathway.
The proton-coupled folate transporter (PCFT, SLC46A1) mediates folate transport across the apical brush-border membrane of the proximal small intestine and the basolateral membrane of choroid plexus ...ependymal cells. Two loss-of-function mutations in PCFT, which are the basis for hereditary folate malabsorption, have been identified within the fourth transmembrane domain (TMD4) in subjects with this disorder. We have employed the substituted Cys accessibility method (SCAM) to study the accessibilities of all residues in TMD4 and their roles in folate substrate binding to the carrier. When residues 146-167 were replaced by Cys, all except R148C were expressed at the cell surface. Modification of five of these substituted Cys residues (positions 147, 152, 157, 158, and 161) by methanethiosulfonate (MTS) reagents led to reduction of PCFT function. All five residues could be labeled with N-biotinylaminoethyl-MTS, and this could be blocked by the high-affinity PCFT substrate pemetrexed. Pemetrexed also protected PCFT mutant function from inhibitory modification of the substituted Cys at positions 157, 158, and 161 by a MTS. The findings indicate that these five residues in TMD4 are accessible to the aqueous translocation pathway, play a role in folate substrate binding, and are likely located within or near the folate binding pocket. A homology model of PCFT places three of these residues, Phe¹⁵⁷, Gly¹⁵⁸, and Leu¹⁶¹, within a breakpoint in the midportion of TMD4, a region that likely participates in alterations in the PCFT conformational state during carrier cycling.
The proton-coupled folate transporter (PCFT) mediates intestinal folate absorption. Loss-of-function mutations in this gene are the molecular basis for the autosomal recessive disorder, hereditary ...folate malabsorption. In this study, the substituted cysteine accessibility method was utilized to localize extra- or intracellular loops connecting predicted PCFT transmembrane domains. Cysteine-less PCFT was generated by replacement of all seven cysteine residues with serine and was shown to be functional, following which cysteine residues were introduced into predicted loops. HeLa cells, transiently transfected with these PCFT mutants, were then labeled with an impermeant, cysteine-specific biotinylation reagent (MTSEA-biotin) with or without permeabilization of cells. The biotinylated proteins were precipitated by streptavidin beads and assessed by Western blotting analysis. The biotinylation of PCFT was further confirmed by blocking cysteine residues with impermeant 2-sulfonatoethyl methanethiosulfonate. Two extracellular cysteine residues (66, 298) present in WT-PCFT were not biotinylated; however, in the absence of either one, biotinylation occurred. Likewise, biotinylation occurred after treatment with β-mercaptoethanol. Taken together, these analyses establish a PCFT secondary structure of 12 transmembrane domains with the N- and C- termini directed to the cytoplasm. The data indicate further that there is a disulfide bridge, which is not required for function, between the native C66 and C298 residues in the first and fourth transmembrane domains, respectively.
Background
A phase I clinical study for patients with locally advanced H&N cancer with a new class of botanical drug APG‐157 provided hints of potential synergy with immunotherapy. We sought to ...evaluate the efficacy of the combination of APG‐157 and immune checkpoint inhibitors.
Methods
CCL23, UM‐SCC1 (human), and SCCVII (HPV−), MEER (HPV+) (murine) H&N cancer cell lines were utilized for in vitro and in vivo studies. We measured tumor growth by treating the mice with APG‐157, anti‐PD‐1, and anti‐CTLA‐4 antibody combinations (8 groups). The tumor microenvironments were assessed by multi‐color flow cytometry, immunohistochemistry, and RNA‐seq analysis. Fecal microbiome was analyzed by 16S rRNA sequence.
Results
Among the eight treatment groups, APG‐157 + anti‐CTLA‐4 demonstrated the best tumor growth suppression (p = 0.0065 compared to the control), followed by anti‐PD‐1 + anti‐CTLA‐4 treatment group (p = 0.48 compared to the control). Immunophenotype showed over 30% of CD8+ T cells in APG‐157 + anti‐CTLA‐4 group compared to 4%–5% of CD8+ T cells for the control group. Differential gene expression analysis revealed that APG‐157 + anti‐CTLA‐4 group showed an enriched set of genes for inflammatory response and apoptotic signaling pathways. The fecal microbiome analysis showed a substantial difference of lactobacillus genus among groups, highest for APG‐157 + anti‐CTLA‐4 treatment group. We were unable to perform correlative studies for MEER model as there was tumor growth suppression with all treatment conditions, except for the untreated control group.
Conclusions
The results indicate that APG‐157 and immune checkpoint inhibitor combination treatment could potentially lead to improved tumor control.
Proton-coupled folate transporter (PCFT) mediates folate intestinal absorption and transport across the choroid plexus, processes defective in subjects with hereditary folate malabsorption (HFM). ...PCFT is also widely expressed in human solid tumors where it contributes to the transport of pemetrexed and other antifolates. This study defines the basis for the functional changes due to a P425R mutation detected in a subject with HFM. Among various substitutions, only positively charged mutants (P425R and P425K) lost function but in a highly selective manner. Transport of reduced folates mediated by P425R-PCFT was virtually abolished; the methotrexate influx K(t) was increased fivefold (from 2 to 10 μM). In contrast, the pemetrexed influx K(t) mediated by P425R-PCFT was decreased 30% compared with wild-type (WT)-PCFT. Methotrexate inhibition of pemetrexed influx was competitive with a K(i) for WT-PCFT comparable to its influx K(t). However, the methotrexate influx K(i) for P425R-PCFT was ∼15-fold higher than the WT-PCFT influx K(t) and threefold higher than the methotrexate influx K(t) for the P425R-PCFT mutant. The confirmed secondary structure and homology modeling place the P425 residue at the junction of the 6th external loop and 12th transmembrane domain, remote from the aqueous translocation pathway, a prediction confirmed by the failure to label P425C-PCFT with N-biotinylaminoethyl methanethiosulfonate-biotin and the absence of inhibition of P425C-PCFT function by water-soluble sulfhydryl reagents. Hence, despite its location, the P425R-PCFT mutation produces a conformational change that fully preserves pemetrexed binding but markedly impairs binding of methotrexate and other folates to the carrier.
e21209
Background: Precision medicine has shifted the paradigm of cancer treatment in the last two decades. Currently, with over ten targetable mutations in non-small cell lung cancer (NSCLC) and ...increasingly emerging biomarkers for immunotherapy, genomic testing is necessary for every NSCLC patient. However, this multiple biomarker-defined treatment approach is often compromised by many challenges including slow turnaround time (TAT), high rate of quantity not sufficient (QNS) resulting in inaccurate molecular testing or needs for second biopsy. These barriers lead to increased risk of developing medical complications from re-biopsy or treatment delay as well as additional social and financial support, which is not always available for veterans. A recent study reported that up a one third of veterans with NSCLC containing highly actionable mutations were not prescribed targeted treatment, among which, 25% of patients do not have a documented molecular testing results. Herein, we reported a pathologist-driven protocol to enhance the implement of molecular testing on guiding NSCLC treatment in veteran population. Methods: A pathologist-driven molecular testing protocol is applied West Los Angeles VA hospital since 2018. First, in preparation for diagnosis and molecular testing, tissue block will be cut in serial sections in the following priority: 2 slides for H&E, 4 slides for IHC, 2 slides for PD-L1 staining. An additional slide is made for quality control (QC) purpose before 10 additional slides are cut for molecular testing and 6 for FISH studies. The reminder of the tissue block will be cut in serial sections and preserved in a vial along with tissue shaved at initial block effacement. Every tissue block will be exhausted. Upon initial evaluation of H&E slides, the reviewing pathologist, independent of the treating oncologist, will order molecular testing including EGFR, ALK, ROS and BRAF by NGS if NSCLC is identified. PD-L1 IHC staining is also ordered automatically regardless of the histology. If a clinically actionable mutation is detected, a mutation notification is immediately sent via email by the molecular pathologist to alert the treating oncologist. Results: After implementing this protocol, we observed a decreased rate of QNS (~30% reduction) and subsequently the need for 2
nd
biopsy dropped substantially. We also observed a faster TAT between initial cancer diagnosis (within 7 days) and the resulting of molecular testing to guide subsequent treatment. Conclusions: Refined tissue processing and pathologist driven ordering system can significantly impact initial management of patients with NSCLC as it reduces the rate of QNS and repeat biopsy/TAT. This protocol can be easily implemented in VA system or other community based healthcare system.
Case 1: A 67-year-old Asian female was diagnosed with locally advanced high-grade salivary duct carcinoma in June 2011. Molecular analysis revealed human epidermal growth factor receptor 2 (HER-2) ...amplification. She received adjuvant therapy with carboplatin/paclitaxel/ trastuzumab and maintenance of trastuzumab. Upon disease progression, trastuzumab could not be continued due to lack of financial coverage. Instead, she was treated with compassionate use of lapatinib from April 2013 and standard 5-fluorouracil. Her disease ultimately progressed and she expired later in 2013. Case 2: A 68-year-old Asian male was diagnosed with extramammary Paget's disease of the scrotum with HER-2 amplification in May 2011. He received 6 cycles of adjuvant trastuzumab/docetaxel/carboplatin followed by maintenance trastuzumab, which was changed to compassionate use of lapatinib as his insurance did not cover further administration of trastuzumab. He showed clinical benefits from single-agent lapatinib and a combination of lapatinib/capecitabine upon progression to the single-agent lapatinib. Ultimately, he was started on ado-trastuzumab emtansine, which was approved at that time by the FDA for HER-2-positive breast cancer progressed on trastuzumab. He is having clinical and radiographic complete response based on current imaging and normalization of his tumor markers. Conclusion: HER-2-targeted therapy should be considered for tumors with HER-2 amplification. In our case series, we would like to emphasize this approach in other rare histologies. Specifically, our patient with extramammary Paget's disease of the scrotum represents the first reported case of a non-breast, non-gastric tumor with HER-2 overexpression with complete clinical and radiographic response to HER-2-targeted therapy.
We analyze the transcriptome of baseline and on-therapy tumor biopsies from 101 patients with advanced melanoma treated with nivolumab (anti-PD-1) alone or combined with ipilimumab (anti-CTLA-4). We ...find that T cell infiltration and interferon-γ (IFN-γ) signaling signatures correspond most highly with clinical response to therapy, with a reciprocal decrease in cell-cycle and WNT signaling pathways in responding biopsies. We model the interaction in 58 human cell lines, where IFN-γ in vitro exposure leads to a conserved transcriptome response unless cells have IFN-γ receptor alterations. This conserved IFN-γ transcriptome response in melanoma cells serves to amplify the antitumor immune response. Therefore, the magnitude of the antitumor T cell response and the corresponding downstream IFN-γ signaling are the main drivers of clinical response or resistance to immune checkpoint blockade therapy.
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•T cell-induced IFN-γ correlates the best to immune checkpoint blockade (ICB) therapy•Immune signatures increase in on-therapy patients regardless of response to therapy•ICB therapy decreases MYC and WNT signaling in patients with clinical response•IFN-γ exposure of melanoma cells leads to a conserved transcriptome signature
Analyzing the transcriptome of biopsies of patients during immune checkpoint blockade therapy, Grasso et al. show that the increase of T cell infiltration and the downstream IFN-γ signaling drive clinical responses.
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