Randomized phase 2 study of tivantinib plus erlotinib versus single-agent chemotherapy in previously treated KRAS mutant advanced non-small cell lung cancer.

BACKGROUND: KRAS mutations are identified in approximately 25% of non-small cell lung cancer (NSCLC) cases and are associated with resistance to currently available targeted therapies. The MET oncogene may be implicated in malignant progression of KRAS-mutant tumors. In a pre-specified subset analysis of KRAS mutant cancers in an earlier phase 2 study of erlotinib plus the oral MET inhibitor tivantinib, combination therapy was associated with substantial clinical benefit compared to erlotinib alone (progression-free survival [PFS] HR 0.18; P < 0.01). The current study was conducted to evaluate this combination further in KRAS mutant non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: Previously treated patients with advanced KRAS mutant NSCLC were randomized to receive either oral tivantinib (360 mg twice daily) plus erlotinib (150 mg daily) (ET) or single-agent chemotherapy (investigator's choice of pemetrexed, docetaxel, or gemcitabine) (C). The primary endpoint was PFS. At progression, crossover from C to ET was permitted. RESULTS: Ninety-six patients were randomly assigned to ET (n = 51) or to C (n = 45). Median PFS was 1.7 months (mos) for ET and 4.3 mos for C (HR 1.19; 95% CI, 0.71-1.97; P = 0.50). There was no difference in overall survival (HR 1.20; 95% CI, 0.76-1.88; P = 0.44). There were 4 partial responses in the C arm, and none in the ET arm. Overall, adverse events occurred more frequently in the C arm, with more cytopenias, nausea, fatigue, and alopecia. Dermatologic toxicities were more common in the ET arm. CONCLUSION: In previously treated patients with advanced KRAS mutant NSCLC, the combination of the MET inhibitor tivantinib and erlotinib is not superior to conventional single-agent chemotherapy.

Institutional Scientific Review of Cancer Clinical Research Protocols: A Unique Requirement That Affects Activation Timelines.

PURPOSE: The National Cancer Institute (NCI) requirement that clinical trials at NCI-designated cancer centers undergo institutional scientific review in addition to institutional review board evaluation is unique among medical specialties. We sought to evaluate the effect of this process on protocol activation timelines. METHODS: We analyzed oncology clinical trials that underwent full board review by the Harold C. Simmons Comprehensive Cancer Center Protocol Review and Monitoring Committee (PRMC) from January 1, 2009, through June 30, 2013. We analyzed associations between trial characteristics, PRMC decisions, protocol modifications, and process timelines using the χ2 test, Fisher's exact test, Wilcoxon rank sum test, Kruskal-Wallis test, and logistic regression. RESULTS: A total of 226 trials were analyzed. Of these, 77% were industry sponsored and 23% were investigator initiated. The median time from submission to PRMC approval was 55 days. The length of review was associated with trial phase, timing of approval, and number of committee changes/clarifications requested. The median process time was 35 days for those approved at first decision, 68 days for second decision, and 116 days for third decision ( P < .001). The median process time was 39 days if no changes/clarifications were requested, 64 days for one to three changes/clarifications, and 73 days for four or more changes/clarifications ( P < .001). Requested changes/clarifications had a greater effect on industry-sponsored trials than on investigator-initiated trials. CONCLUSION: NCI-mandated institutional scientific review of oncology clinical trials contributes substantially to protocol activation timelines. Further evaluation of this process and the value added to research quality is warranted.

Expression of a recombinant full-length LRP1B receptor in human non-small cell lung cancer cells confirms the postulated growth-suppressing function of this large LDL receptor family member.

Low-density lipoprotein (LDL) receptor-related protein 1B (LRP1B), a member of the LDL receptor family, is frequently inactivated in multiple malignancies including lung cancer. LRP1B is therefore considered as a putative tumor suppressor. Due to its large size (4599 amino acids), until now only minireceptors or receptor fragments have been successfully cloned. To assess the effect of LRP1B on the proliferation of non-small cell lung cancer cells, we constructed and expressed a transfection vector containing the 13.800 bp full-length murine Lrp1b cDNA using a PCR-based cloning strategy. Expression of LRP1B was analyzed by quantitative RT-PCR (qRT-PCR) using primers specific for human LRP1B or mouse Lrp1b. Effective expression of the full length receptor was demonstrated by the appearance of a single 600 kDa band on Western Blots of HEK 293 cells. Overexpression of Lrp1b in non-small cell lung cancer cells with low or absent endogenous LRP1B expression significantly reduced cellular proliferation compared to empty vector-transfected control cells. Conversely, in Calu-1 cells, which express higher endogenous levels of the receptor, siRNA-mediated LRP1B knockdown significantly enhanced cellular proliferation. Taken together, these findings demonstrate that, consistent with the postulated tumor suppressor function, overexpression of full-length Lrp1b leads to impaired cellular proliferation, while LRP1B knockdown has the opposite effect. The recombinant Lrp1b construct represents a valuable tool to unravel the largely unknown physiological role of LRP1B and its potential functions in cancer pathogenesis.

Chemotherapy for Advanced Non-small Cell Lung Cancer.

Non-small cell lung cancer has seen an unprecedented augmentation of therapeutic options over the last couple of years. Improved understanding of molecular drivers and the role of the immune system in cancer therapy have brought new drugs to the armamentarium. Despite these advances, cytotoxic chemotherapy remains a substantial part of therapy for most patients in locally advanced and metastatic stage. Initially thought to be a chemotherapy-resistant entity, meta-analyses in the mid-1990s demonstrated modest efficacy of platinum-based therapy. Further combination trials demonstrated enhanced efficacy for several regimen in first and second lines, including the introduction of antimetabolites, taxanes, and anti-angiogenic agents. Maintenance chemotherapy has been another novel, successful approach for management of metastatic disease. Herein, we summarize the current concepts of chemotherapy, its applicability to the different histologies, and novel concepts of therapy.

Histological Regression of Giant Cell Tumor of Bone Following RANK Ligand Inhibition.

Lung metastases are a rare complication of giant cell tumors of bone. We herein describe an interesting case of histological regression and size reduction of lung metastases originating from a primary giant cell tumor of bone in response to the RANK ligand inhibitor denosumab.

Lrp4 regulates initiation of ureteric budding and is crucial for kidney formation--a mouse model for Cenani-Lenz syndrome.

BACKGROUND: Development of the kidney is initiated when the ureteric bud (UB) branches from the Wolffian duct and invades the overlying metanephric mesenchyme (MM) triggering the mesenchymal/epithelial interactions that are the basis of organ formation. Multiple signaling pathways must be integrated to ensure proper timing and location of the ureteric bud formation. METHODS AND PRINCIPAL FINDINGS: We have used gene targeting to create an Lrp4 null mouse line. The mutation results in early embryonic lethality with a subpenetrant phenotype of kidney agenesis. Ureteric budding is delayed with a failure to stimulate the metanephric mesenchyme in a timely manner, resulting in failure of cellular differentiation and resulting absence of kidney formation in the mouse as well as comparable malformations in humans with Cenani-Lenz syndrome. CONCLUSION: Lrp4 is a multi-functional receptor implicated in the regulation of several molecular pathways, including Wnt and Bmp signaling. Lrp4(-/-) mice show a delay in ureteric bud formation that results in unilateral or bilateral kidney agenesis. These data indicate that Lrp4 is a critical regulator of UB branching and lack of Lrp4 results in congenital kidney malformations in humans and mice.

Ectodomains of the LDL receptor-related proteins LRP1b and LRP4 have anchorage independent functions in vivo.

BACKGROUND: The low-density lipoprotein (LDL) receptor gene family is a highly conserved group of membrane receptors with diverse functions in developmental processes, lipoprotein trafficking, and cell signaling. The low-density lipoprotein (LDL) receptor-related protein 1b (LRP1B) was reported to be deleted in several types of human malignancies, including non-small cell lung cancer. Our group has previously reported that a distal extracellular truncation of murine Lrp1b that is predicted to secrete the entire intact extracellular domain (ECD) is fully viable with no apparent phenotype. METHODS AND PRINCIPAL FINDINGS: Here, we have used a gene targeting approach to create two mouse lines carrying internally rearranged exons of Lrp1b that are predicted to truncate the protein closer to the N-terminus and to prevent normal trafficking through the secretary pathway. Both mutations result in early embryonic lethality, but, as expected from the restricted expression pattern of LRP1b in vivo, loss of Lrp1b does not cause cellular lethality as homozygous Lrp1b-deficient blastocysts can be propagated normally in culture. This is similar to findings for another LDL receptor family member, Lrp4. We provide in vitro evidence that Lrp4 undergoes regulated intramembraneous processing through metalloproteases and gamma-secretase cleavage. We further demonstrate negative regulation of the Wnt signaling pathway by the soluble extracellular domain. CONCLUSIONS AND SIGNIFICANCE: Our results underline a crucial role for Lrp1b in development. The expression in mice of truncated alleles of Lrp1b and Lrp4 with deletions of the transmembrane and intracellular domains leads to release of the extracellular domain into the extracellular space, which is sufficient to confer viability. In contrast, null mutations are embryonically (Lrp1b) or perinatally (Lrp4) lethal. These findings suggest that the extracellular domains of both proteins may function as a scavenger for signaling ligands or signal modulators in the extracellular space, thereby preserving signaling thresholds that are critical for embryonic development, as well as for the clear, but poorly understood role of LRP1b in cancer.

Triptolide sensitizes AML cells to TRAIL-induced apoptosis via decrease of XIAP and p53-mediated increase of DR5.

Acute myeloid leukemia (AML) cells are relatively resistant to tumor necrosis factor alpha-related apoptosis-inducing ligand (TRAIL). We previously reported that triptolide, a potent anticancer agent from a Chinese herb, decreases XIAP in leukemic cells. We evaluated the combination of triptolide and TRAIL and found synergistic promotion of apoptosis in AML cells. XIAP-overexpressing U937 cells (U937XIAP) were more resistant to TRAIL than U937neo cells, and inhibition of XIAP with the small-molecule inhibitor 1396-11 enhanced TRAIL-induced apoptosis, implying XIAP as a resistance factor in AML. Furthermore, triptolide increased DR5 levels in OCI-AML3, while the DR5 increase was blunted in p53-knockdown OCI-AML3 and p53-mutated U937 cells, confirming a role for p53 in the regulation of DR5. In support of this finding, disruption of MDM2-p53 binding with subsequent increase in p53 levels by nutlin3a increased DR5 levels and sensitized OCI-AML3 cells to TRAIL. The combination of 1396-11 plus nutlin3a plus TRAIL was more effective than either the 1396-11 and TRAIL or nutlin3a and TRAIL combinations in OCI-AML3 cells, further supporting the role of triptolide as a sensitizer to TRAIL-induced apoptosis in part by independent modulation of XIAP expression and p53 signaling. Thus, the combination of triptolide and TRAIL may provide a novel strategy for treating AML by overcoming critical mechanisms of apoptosis resistance.