Key Points Activation of BCR and canonical NF-κB signaling in the lymph node correlates with survival in MCL. Mutations and polymorphisms in BCR and NF-κB pathways may confer cell autonomous signaling and affect response to ibrutinib.

We examined whether draft 2020 United States Preventive Services Task Force (USPSTF) lung-cancer screening recommendations “partially ameliorate racial disparities in screening eligibility” compared to 2013 guidelines, as claimed. Using data from the 2015 National Health Interview Survey, USPSTF-2020 increased eligibility by similar proportions for minorities (97.1%) and Whites (78.3%). Contrary to the intent of USPSTF-2020, the relative disparity (differences in percentages of model-estimated gainable life-years from National Lung Screening Trial-like screening by eligible Whites vs minorities) actually increased from USPSTF-2013 to USPSTF-2020 (African Americans: 48.3%–33.4%=15.0% to 64.5%–48.5%=16.0%; Asian Americans: 48.3%–35.6%=12.7% to 64.5%–45.2%=19.3%; Hispanic Americans: 48.3%–24.8%=23.5% to 64.5%–37.0%=27.5%). However, augmenting USPSTF-2020 with high-benefit individuals selected by the Life-Years From Screening with Computed Tomography (LYFS-CT) model nearly eliminated disparities for African Americans (76.8%–75.5%=1.2%), and improved screening efficiency for Asian/Hispanic Americans, although disparities were reduced only slightly (Hispanic Americans) or unchanged (Asian Americans). Draft USPSTF-2020 guidelines increased the number of eligible minorities versus USPSTF-2013 but may inadvertently increase racial/ethnic disparities. LYFS-CT could reduce disparities in screening eligibility by identifying ineligible people with high predicted benefit, regardless of race/ethnicity.

Purpose Clinical trials of ibrutinib combined with anti-CD20 monoclonal antibodies (mAbs) for chronic lymphocytic leukemia (CLL) report encouraging results. Paradoxically, in pre-clinical studies in vitro ibrutinib was reported to decrease CD20 expression and inhibits cellular effector mechanisms. We therefore set out to investigate effects of in vivo ibrutinib treatment that could explain this paradox. Experimental Design Patients received single agent ibrutinib (420mg daily) on an investigator-initiated phase 2 trial. Serial blood samples were collected pre-treatment and during treatment for ex vivo functional assays to examine the effects on CLL cell susceptibility to anti-CD20 mAbs. Results We demonstrate that CD20 expression on ibrutinib was rapidly and persistently down-regulated (median reduction 74%, day 28, P<0.001) compared to baseline. Concomitantly, CD20 mRNA was decreased concurrent with reduced NF-κB signaling. An NF-κB binding site in the promoter of MS4A1 (encoding CD20) and down-regulation of CD20 by NF-κB inhibitors support a direct transcriptional effect. Ex vivo, tumor cells from patients on ibrutinib were less susceptible to anti-CD20 mAb-mediated complement-dependent cytotoxicity than pre-treatment cells (median reduction 75%, P<0.001); however, opsonization by the complement protein C3d, which targets cells for phagocytosis, was relatively maintained. Expression of decay accelerating factor (CD55) decreased on ibrutinib, providing a likely mechanism for the preserved C3d opsonization. Additionally, ibrutinib significantly inhibited trogocytosis, a major contributor to antigen loss and tumor escape during mAb therapy. Conclusions Our data indicate that ibrutinib promotes both positive and negative interactions with anti-CD20 mAbs, suggesting that successfully harnessing maximal anti-tumor effects of such combinations requires further investigation.

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Recombinant immunotoxins (RITs) are fusion proteins that join antibodies to protein toxins for targeted cell killing. RITs armed with Pseudomonas exotoxin A (PE) are undergoing clinical trials for the treatment of cancer. The current design of PE-based RITs joins an antibody fragment to the catalytic domain of PE using a polypeptide linker that is cleaved by the protease furin. Intracellular cleavage of native PE by furin is required for cytotoxicity, yet the PE cleavage site has been shown to be a poor furin substrate. Here we describe the rational design of more efficiently cleaved furin linkers in PE-based RITs, and experiments evaluating their effects on cleavage and cytotoxicity. We found that changes to the furin site could greatly influence both cleavage and cytotoxicity, but the two parameters were not directly correlated. Furthermore, the effects of alterations to the furin linker were not universal. Identical mutations in the anti-CD22 RIT HA22-LR often displayed different cytotoxicity from mutations in the anti-mesothelin RIT SS1-LR/GGS, underscoring the prominent role of the target site in their intoxication pathways. Combining several beneficial mutations in HA22-LR resulted in a variant (HA22-LR/FUR) with a remarkably enhanced cleavage rate and improved cytotoxicity against five B cell lines and similar or enhanced cytotoxicity in five out of six hairy cell leukemia patient samples. This result informs the design of protease-sensitive linkers and suggests that HA22-LR/FUR may be a candidate for further preclinical development.

Introduction The coronavirus disease 2019 (COVID-19) pandemic is a global public health emergency causing a disparate burden of death and disability around the world. The molecular characteristics of the virus that predict better or worse outcome are largely still being discovered. Methods We downloaded 155,958 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genomes from GISAID. Of these genomes, 3,637 samples included useable metadata on patient outcomes. Using this subset, we evaluated whether SARS-CoV-2 viral genomic variants improved prediction of reported severity beyond age and region. First, we established whether including genomic variants as model features meaningfully increased predictive power of our model. Next, we evaluated specific variants in order to determine the magnitude of association with severity and the frequency of these variants among SARS-CoV-2 genomes. Results Logistic regression models that included viral genomic variants outperformed other models (AUC = 0.91 as compared with 0.68 for age and gender alone; p &lt; 0.001). Among individual variants, we found 17 single nucleotide variants in SARS-CoV-2 have more than two-fold greater odds of being associated with higher severity and 67 variants associated with ≤0.5 times the odds of severity. The median frequency of associated variants was 0.15% (interquartile range 0.09%-0.45%). Altogether 85% of genomes had at least one variant associated with patient outcome. Conclusion Numerous SARS-CoV-2 variants have two-fold or greater association with odds of mild or severe outcome and collectively, these variants are common. In addition to comprehensive mitigation efforts, public health measures should be prioritized to control the more severe manifestations of COVID-19 and the transmission chains linked to these severe cases. Lay Summary This study explores which, if any, SARS-CoV-2 viral genomic variants are associated with mild or severe COVID-19 patient outcomes. Our results suggest that there are common genomic variants in SARS-CoV-2 that are more often associated with negative patient outcomes, which may impact downstream public health measures.

Chronic lymphocytic leukemia (CLL) is a B-cell malignancy in need of new, effective, and safe therapies. The recently identified IgM receptor FcμR is overexpressed on malignant B cells in CLL and mediates the rapid internalization and lysosomal shuttling of IgM via its Fc fragment (Fcμ). To exploit this internalization and trafficking pathway for targeted drug delivery, we engineered an IgM derived protein scaffold (Fcμ) and linked it with the cytotoxic agent monomethylauristatin F. This Fcμ-drug conjugate was selectively toxic for FcμR expressing cell lines in vitro and for CLL cells but not autologous normal T cells ex vivo. Notably, the cytotoxic activity of the Fcμ-drug conjugate was maintained in CLL cells carrying a 17p deletion, which predicts resistance to standard chemotherapy. Next, we tested the possible therapeutic application of the Fcμ-drug conjugate in immunodeficient NSG mice engrafted with peripheral blood cells from leukemia patients. Three intravenous injections of the Fcμ-drug conjugate over a 10 day period were well tolerated and selectively killed the human CLL cells but not the co-engrafted autologous human T cells. In summary, we developed a novel strategy for targeted cytotoxic therapy of CLL based on the unique properties of FcμR. FcμR-targeted drug delivery showed potent and specific therapeutic activity in CLL, thus providing proof-of-concept for FcμR as a valuable therapeutic target in CLL and for IgM-based antibody drug conjugates as a new targeting platform.

IntroductionThe coronavirus disease 2019 (COVID-19) pandemic is a global public health emergency causing a disparate burden of death and disability around the world. The molecular characteristics of the virus that predict better or worse outcome are largely still being discovered.MethodsWe downloaded 155,958 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genomes from GISAID and evaluated whether variants improved prediction of reported severity beyond age and region. We also evaluated specific variants to determine the magnitude of association with severity and the frequency of these variants among the genomes.ResultsLogistic regression models that included viral genomic variants outperformed other models (AUC=0.91 as compared with 0.68 for age and gender alone; p<0.001). Among individual variants, we found 17 single nucleotide variants in SARS-CoV-2 have more than two-fold greater odds of being associated with higher severity and 67 variants associated with ≤ 0.5 times the odds of severity. The median frequency of associated variants was 0.15% (interquartile range 0.09%-0.45%). Altogether 85% of genomes had at least one variant associated with patient outcome.ConclusionNumerous SARS-CoV-2 variants have two-fold or greater association with odds of mild or severe outcome and collectively, these variants are common. In addition to comprehensive mitigation efforts, public health measures should be prioritized to control the more severe manifestations of COVID-19 and the transmission chains linked to these severe cases.