Citations

Abstract Cisplatin chemotherapy, although efficacious in positive resolution of cancer, adversely potentiates off-target cognitive dysfunction and affects approximately 14 million cancer survivors in the United States alone. Despite the high prevalence of chemotherapy induced cognitive impairments (known as chemobrain), there is little information on how memory and learning are impaired and no known cure. To elucidate the mechanisms by which chemobrain impairs cognition, we implement a novel experimental mouse model resembling clinical cisplatin-chemotherapy. Our results reveal that repeated cisplatin administration impairs hippocampal neuronal functional morphology, while inducing significant emotional and memory deficits. Although the molecular targets and pathways vulnerable to cisplatin in the central nervous system (CNS) are currently unknown, RNA-sequencing derived from mice administered cisplatin or vehicle revealed the G-protein coupled adenosine A2A receptor (Adora2a) known to be critical for synaptic plasticity and memory, as a promising therapeutic target for chemobrain. Bioinformatic analysis and qRT-PCR validation revealed significant induction of Adora2a mRNA expression by cisplatin in the adult hippocampus, a brain structure critical for learning and memory. Interestingly, while Adora2a is known to be expressed by neurons, astrocytes and other brain glia, confocal microscopy demonstrates that cisplatin specifically increases Adora2a expression in hippocampal neurons without affecting astrocytes, indicating that Adora2a expressing neurons are particularly vulnerable. To mechanistically determine whether elevated neuronal Adora2a functionality are implicated in cisplatin-induced chemobrain, we assessed the efficacy of Istradefylline (KW-6002), a selective Adora2a inhibitor, in preventing cisplatin-induced chemobrain. Our results indicate that selective pharmacological inhibition of Adora2a prevented cisplatin induced anxiety and cognitive impairments in the elevated plus maze, the Morris water maze and novel object recognition test. In addition, our translational approach employing the non-specific Adora2a antagonist caffeine, protected against cisplatin-induced impairments in body weight, motor learning and motor function. Therefore, our results suggest a critical regulatory role for Adora2a in cisplatin-induced cognitive and motor dysfunction. Given that Adora2a antagonists are proven to be safe and neuroprotective in neurodegeneration as well as in enhancing anti-tumor activity, inhibiting Adora2a may have far-reaching synergistic effects on cancer treatment and chemobrain. This work was supported by Mayo Clinic Breast SPORE (R50CA116201) and Regenerative Medicine Minnesota (RMM 091718 DS 005) to M.H.J. and the Bosarge Family Foundation-Waun Ki Hong Scholar Award to A.O. Citation Format: Alfredo Oliveros, Ki-Hyun Yoo, jun Tang, Ana M. Corujo, Danielle Brogren, Yuanhang Liu, Mi-Hyeon Jang. Adora2a inhibition as a novel therapeutic target for cisplatin chemobrain-induced cognitive dysfunction [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4141.

8579 Background: The ERIVANCE BCC study is the pivotal trial of vismodegib (GDC-0449), a first-in-class small-molecule inhibitor of Hedgehog signaling, for treatment of locally advanced (laBCC) and metastatic BCC (mBCC), for whom there are no other effective therapy options. The study met the primary endpoint of overall response rate by independent review (Sekulic, Melanoma Res 2011). Here we report a 6-mo update of investigator-assessed (I-A) efficacy and safety endpoints as of May 26, 2011. Methods: This multicenter, international, nonrandomized 2-cohort study enrolled patients (pts) with laBCC (deemed inoperable or for whom surgery would be significantly disfiguring), and mBCC pts with RECIST-measurable disease. Pts received 150 mg oral vismodegib daily. Results: 104 pts (71 laBCC/33 mBCC) enrolled at 31 sites in the US, Europe, and Australia. I-A efficacy endpoints are shown in the table. One-year survival rate was 77.3% (95% CI 62.48–92.09%) for mBCC and 93.1% (95% CI 86.49–99.63%) for laBCC. Adverse events (AEs) in >30% of pts were muscle spasms, alopecia, dysgeusia, weight decrease, fatigue, nausea, and amenorrhea (33.3%; 2/6 pts). Serious AEs were reported in 32 pts (31%). No additional fatal AEs were reported since the prior data cut (n=7, 7%; none considered related to vismodegib). Conclusions: This 6-mo update of I-A efficacy and safety endpoints from the ERIVANCE BCC study supports the significant clinical benefit of vismodegib in both laBCC and mBCC reported at the primary analysis. Median DOR and PFS increased numerically with follow-up. The AE profile was consistent with the prior data cut. These results further support the efficacy of vismodegib for treatment of advanced BCC. [Table: see text]

Abstract It has been suggested that errors in the repair of DNA double strand breaks (DSB) can result in gross chromosomal rearrangements (GCR), including chromosomal amplifications, deletions, inversions, and translocations. To study repair of DNA DSB in vivo, we established a subclone of the U937 cell line designated F5, in which a single copy of the rare-cutting meganuclease I-SceI recognition site has been integrated into chromosome 7. We transfected an I-SceI expression vector into these cells and analyzed misrepair events. We recovered no GCR, but instead found that most DSBs were repaired by small (<50bp) indels (91.8%). We also noticed some DSBs were repaired by large (<50bp) deletions (6.4%) and rare DSBs were repaired by large (100-500 bp) insertions (1.8%). Surprisingly, the nucleotide sequence of these insertions matched distant regions of the genome. To determine if this templated sequence insertion (TSI) was peculiar to I-SceI induced DNA DSB, we repeated the experiment using TALENs to produce DNA DSB. Again, we found insertions that were derived from distant genomic regions. To determine whether this form of DNA repair was restricted to experimentally induced DNA DSB, we analyzed structural variations identified by whole genome sequence (WGS) of two myeloma cell lines (KP6, MC1286PE1), and identified 15 independent TSIs. These TSIs were verified by Sanger sequencing, and lengths of inserted fragment were 38 to 666 bp (median 189 bp). Six insertions were noted to be identical between the 2 cell lines, suggesting that these TSIs were germline polymorphic events. These TSIs were compared to a catalog of known structural variations identified by WGS of 52 healthy individuals; 13 of 15 TSI junctions were identified, suggesting that these represented polymorphic insertions in the human genome. Two TSIs were potential somatic mutations in the KP6 cell line, including one that had 85bp insertion at the junction of an acquired t(6;12) chromosomal translocation. Six TSIs showed the hallmarks of L1 retrotransposon-mediated insertions, with a 5’-TTTT/A-3’ integration site, a target site duplication (TSD), a polyA tract at the insertion site, and a polyadenylation signal. However, the inserted sequence was neither a LINE nor a SINE, but instead was a transcribed, genic region mapping to a distant genomic region. The presence of these L1 ORF1 hallmarks strongly suggests that these insertions were caused by the L1 integrase and reverse-transcriptase acting on nuclear pre-mRNA. A second class of TSI showed no preference for a 5’-TTTT/A-3’ integration site, no TSD, no poly A tract, but instead showed several bp of microhomology at the insertion junctions. This second class is similar to TSI detected at I-SceI induced DNA DSB, and we predict that these TSI were generated by reverse transcription of pre-mRNA creating a “patch” for a spontaneous DNA DSB that occurred in a germ cell. To determine if TSI at I-SceI induced DNA DSB could be repaired by RNA-templated sequences, we cotransfected murine RNA and an I-SceI expression vector into F5 cells. Approximately 10% of the TSI recovered from these experiments contained mouse sequences, indicating that they were derived from mouse RNA. To further support the contention that TSIs were derived from RNA, we again used I-SceI to induce a DNA DSB, and treated the cells with reverse transcriptase inhibitors. The TSI frequency was reduced by 70%. Finally, a subset of insertions were due to telomere repeat sequences, lending further support for the hypothesis that RNA could serve as a template for the repair of DNA DSB. TSI is novel form of potentially mutagenic DNA DSB repair, which should be considered as an alternative to a balanced chromosomal translocation in the interpretation of reciprocal interchromosomal structural variations identified by short-read deep sequencing. Disclosures: No relevant conflicts of interest to declare.

Background and Purpose— Nearly 30% of large vessel occlusion acute ischemic stroke clots are from an unknown source. We assessed histological clot composition in a series of patients with large vessel occlusion and investigated correlations between clot composition and stroke pathogenesis. Methods— As part of the multi-institutional STRIP registry (Stroke Thromboembolism Registry of Imaging and Pathology), consecutive emboli retrieved during mechanical thrombectomy were stained using Martius Scarlett Blue and analyzed using machine learning software. We assessed proportions of red blood cells, fibrin, platelets, and white blood cells. Correlations between clot components and stroke pathogenesis (large artery atherosclerosis, cardioembolism, and stroke of undetermined pathogenesis) were assessed using SPSS22. Results— One hundred five patients were included. The proportion of platelet-rich clots (55.0% versus 21.2%; P =0.005) and percentage of platelet content (22.1±4.2% versus 13.9±14.2%; P =0.03) was significantly higher in the large artery atherosclerosis group compared with the cardioembolic group. The proportion of platelet-rich clots (50.0% versus 21.2%; P =0.024) was also significantly higher in the cryptogenic group compared with cardioembolic cases. Large artery atherosclerosis and cryptogenic cases had a similar proportion of platelet-rich clots (55.0% versus 50.0%; P =0.636). There was no significant difference between stroke pathogenesis and the other major clot components. Conclusions— High platelet content of emboli is associated with a large artery atherosclerosis etiology of large vessel occlusion.

We describe the case of a 61-year-old woman who underwent functional endoscopic sinus surgery for chronic hyperplastic rhinosinusitis. During surgery, we were able to visualize the natural ostium of her left agger nasi cell. To our knowledge, such a finding has not been previously documented in the literature.