Central serotonin-producing neurons are heterogeneous-differing in location, morphology, neurotoxin sensitivity and associated clinical disorders-but the underpinnings of this heterogeneity are ...largely unknown, as are the markers that distinguish physiological subtypes of serotonergic neurons. Here we redefined serotonergic subtypes on the basis of genetic programs that are differentially enacted in progenitor cells. We uncovered a molecular framework for the serotonergic system that, having genetic lineages as its basis, is likely to have physiological relevance and will permit access to genetically defined subtypes for manipulation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Abstract
Delta-like protein 3 (DLL3) is highly expressed in solid tumors, including neuroendocrine carcinomas/neuroendocrine tumors (NEC/NET). Rovalpituzumab tesirine (Rova-T) is a DLL3-targeting ...antibody-drug conjugate. Patients with NECs and other advanced DLL3-expressing tumors were enrolled in this phase I/II study (NCT02709889). The primary endpoint was safety. Two hundred patients were enrolled: 101 with NEC/NET (large-cell NEC, gastroenteropancreatic NEC, neuroendocrine prostate cancer, and other NEC/NET) and 99 with other solid tumors (melanoma, medullary thyroid cancer MTC, glioblastoma, and other). The recommended phase II dose (RP2D) was 0.3 mg/kg every 6 weeks (q6w) for two cycles. At the RP2D, grade 3/4 adverse events included anemia (17%), thrombocytopenia (15%), and elevated aspartate aminotransferase (8%). Responses were confirmed in 15/145 patients (10%) treated at 0.3 mg/kg, including 9/69 patients (13%) with NEC/NET. Rova-T at 0.3 mg/kg q6w had manageable toxicity, with antitumor activity observed in patients with NEC/NET, melanoma, MTC, and glioblastoma.
Small cell lung cancer (SCLC) presents as a highly chemosensitive malignancy but acquires cross-resistance after relapse. This transformation is nearly inevitable in patients but has been difficult ...to capture in laboratory models. Here, we present a preclinical system that recapitulates acquired cross-resistance, developed from 51 patient-derived xenograft (PDX) models. Each model was tested in vivo against three clinical regimens: cisplatin plus etoposide, olaparib plus temozolomide, and topotecan. These drug-response profiles captured hallmark clinical features of SCLC, such as the emergence of treatment-refractory disease after early relapse. For one patient, serial PDX models revealed that cross-resistance was acquired through MYC amplification on extrachromosomal DNA (ecDNA). Genomic and transcriptional profiles of the full PDX panel revealed that MYC paralog amplifications on ecDNAs were recurrent in relapsed cross-resistant SCLC, and this was corroborated in tumor biopsies from relapsed patients. We conclude that ecDNAs with MYC paralogs are recurrent drivers of cross-resistance in SCLC.
SCLC is initially chemosensitive, but acquired cross-resistance renders this disease refractory to further treatment and ultimately fatal. The genomic drivers of this transformation are unknown. We use a population of PDX models to discover that amplifications of MYC paralogs on ecDNA are recurrent drivers of acquired cross-resistance in SCLC. This article is featured in Selected Articles from This Issue, p. 695.
Fusions involving tropomyosin receptor genes are noted in cancers affecting children and adults. The TRK inhibitor larotrectinib induced a response in 75% of patients, regardless of age, tissue of ...origin, or
TRK
fusion partner. Toxic effects were generally mild.
The lower rhombic lip (LRL) is a germinal zone in the dorsal hindbrain productive of tangentially migrating neurons, streaming extramurally (mossy fiber neurons) or intramurally (climbing fiber ...neurons). Here we show that LRL territory, operationally defined by
Wnt1 expression, is parceled into molecular subdomains predictive of cell fate. Progressing dorsoventrally,
Lmx1a and
Gdf7 expression identifies the primordium for hindbrain choroid plexus epithelial cells;
Math1, for mossy fiber neurons; and immediately ventral to
Math1 yet within
Wnt1
+ territory, a climbing fiber primordium dominated by
Ngn1-expressing cells. Elimination of Pax6 results in expansion of this
Ngn1
+ progenitor pool and reduction in the
Math1
+ pool, with accompanying later enlargement of the climbing fiber nucleus and reductions in mossy fiber nuclei. Pax6 loss also disrupts
Msx expression cell-nonautonomously, suggesting Pax6 may influence LRL progenitor identity indirectly through potentiating BMP signaling. These studies suggest that underlying the diversity and proportions of fates produced by the LRL is a precise suborganization regulated by Pax6.
Lung cancer patients with tumors harboring actionable alterations can achieve very durable responses to first-line targeted therapy. However, identifying targetable alterations using next-generation ...sequencing (NGS) is a complex and time-intensive process. As actionable genetic alterations are enriched in lung cancers arising in patients with limited smoking history, we designed a workflow to expedite NGS testing for this group.
We developed a protocol to allow for next-day extraction of nucleic acids from frozen tissue. Specimens were designated as high priority during sequencing. We determined the interval between biopsy and NGS results to evaluate whether the workflow reduced the pre-analytical period and in-laboratory turnaround time and allowed for rapid initiation of genotype-matched therapy.
Between January 2017 and May 2018, 21 patients participated in the expedited sequencing program. The median interval between biopsy and NGS results was 10.7 days. Six patients received results within 1 week of biopsy. Performing molecular analysis on frozen tissue and prioritizing sequencing and analysis of these specimens reduced the pre-analytical period from 3.5 to 1.3 days (p < 0.0001) and shortened in-laboratory turnaround time by 3 days (11.8 versus 8.4 business days, p < 0.0001). Ninety-three percent of patients with an actionable molecular alteration received first-line targeted therapy. The median time-to-initiation of treatment was 19.7 days from biopsy.
Sequencing and analyzing nucleic acids from frozen tissue is a practical strategy for shortening the time to matched therapy. The significant advantage of upfront treatment with targeted therapies in subsets of lung cancer patients provides rationale for developing workflows that accelerate comprehensive molecular analysis.
In small cell lung cancer (SCLC), acquired resistance to DNA-damaging therapy is challenging to study because rebiopsy is rarely performed. We used patient-derived xenograft models, established ...before therapy and after progression, to dissect acquired resistance to olaparib plus temozolomide (OT), a promising experimental therapy for relapsed SCLC. These pairs of serial models reveal alterations in both cell cycle kinetics and DNA replication and demonstrate both inter- and intratumoral heterogeneity in mechanisms of resistance. In one model pair, up-regulation of translesion DNA synthesis (TLS) enabled tolerance of OT-induced damage during DNA replication. TLS inhibitors restored sensitivity to OT both in vitro and in vivo, and similar synergistic effects were seen in additional SCLC cell lines. This represents the first described mechanism of acquired resistance to DNA damage in a patient with SCLC and highlights the potential of the serial model approach to investigate and overcome resistance to therapy in SCLC.
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