ALBERT

Description: For climate services to be relevant and informative for users, scientific data definitions need to match users’ perceptions or beliefs. This study proposes and tests novel yet simple methods to compare beliefs of timing of recurrent climatic events with empirical evidence from multiple historical time series. The methods are tested by applying them to the onset date of the monsoon in Bangladesh, where several scientific monsoon definitions can be applied, yielding different results for monsoon onset dates. It is a challenge to know which monsoon definition compares best with people’s beliefs. Time series from eight different scientific monsoon definitions in six regions are compared with respondent beliefs from a previously completed survey concerning the monsoon onset. Beliefs about the timing of the monsoon onset are represented probabilistically for each respondent by constructing a probability mass function (PMF) from elicited responses about the earliest, normal, and latest dates for the event. A three-parameter circular modified triangular distribution (CMTD) is used to allow for the possibility (albeit small) of the onset at any time of the year. These distributions are then compared to the historical time series using two approaches: likelihood scores, and the mean and standard deviation of time series of dates simulated from each belief distribution. The methods proposed give the basis for further iterative discussion with decision-makers in the development of eventual climate services. This study uses Jessore, Bangladesh, as an example and finds that a rainfall definition, applying a 10 mm day−1 threshold to NCEP–NCAR reanalysis (Reanalyis-1) data, best matches the survey respondents’ beliefs about monsoon onset.

Description: A simple model of an internal wave advected by an oscillating barotropic flow suggests flaws in standard approaches to estimating properties of the internal tide. When the M2 barotropic tidal current amplitude is of similar size to the phase speed of the M2 baroclinic tide, spectral and harmonic analysis techniques lead to erroneous estimates of the amplitude, phase, and energy in the M2 internal tide. In general, harmonic fits and bandpass or low-pass filters that attempt to isolate the lowest M2 harmonic significantly underestimate the strength of M2 baroclinic energy fluxes in shelf seas. Baroclinic energy flux estimates may show artificial spatial variability, giving the illusion of sources and sinks of energy where none are actually present. Analysis of previously published estimates of baroclinic energy fluxes in the Celtic Sea suggests this mechanism may lead to values being 25%–60% too low.

Description: This study describes a systematic approach to selecting optimal statistical recalibration methods and hindcast designs for producing reliable probability forecasts on seasonal-to-decadal time scales. A new recalibration method is introduced that includes adjustments for both unconditional and conditional biases in the mean and variance of the forecast distribution and linear time-dependent bias in the mean. The complexity of the recalibration can be systematically varied by restricting the parameters. Simple recalibration methods may outperform more complex ones given limited training data. A new cross-validation methodology is proposed that allows the comparison of multiple recalibration methods and varying training periods using limited data. Part I considers the effect on forecast skill of varying the recalibration complexity and training period length. The interaction between these factors is analyzed for gridbox forecasts of annual mean near-surface temperature from the CanCM4 model. Recalibration methods that include conditional adjustment of the ensemble mean outperform simple bias correction by issuing climatological forecasts where the model has limited skill. Trend-adjusted forecasts outperform forecasts without trend adjustment at almost 75% of grid boxes. The optimal training period is around 30 yr for trend-adjusted forecasts and around 15 yr otherwise. The optimal training period is strongly related to the length of the optimal climatology. Longer training periods may increase overall performance but at the expense of very poor forecasts where skill is limited.

Description: The inclusion of carbon cycle processes within CMIP5 Earth system models provides the opportunity to explore the relative importance of differences in scenario and climate model representation to future land and ocean carbon fluxes. A two-way analysis of variance (ANOVA) approach was used to quantify the variability owing to differences between scenarios and between climate models at different lead times. For global ocean carbon fluxes, the variance attributed to differences between representative concentration pathway scenarios exceeds the variance attributed to differences between climate models by around 2025, completely dominating by 2100. This contrasts with global land carbon fluxes, where the variance attributed to differences between climate models continues to dominate beyond 2100. This suggests that modeled processes that determine ocean fluxes are currently better constrained than those of land fluxes; thus, one can be more confident in linking different future socioeconomic pathways to consequences of ocean carbon uptake than for land carbon uptake. The contribution of internal variance is negligible for ocean fluxes and small for land fluxes, indicating that there is little dependence on the initial conditions. The apparent agreement in atmosphere–ocean carbon fluxes, globally, masks strong climate model differences at a regional level. The North Atlantic and Southern Ocean are key regions, where differences in modeled processes represent an important source of variability in projected regional fluxes.

Description: Predictability estimates of ensemble prediction systems are uncertain because of limited numbers of past forecasts and observations. To account for such uncertainty, this paper proposes a Bayesian inferential framework that provides a simple 6-parameter representation of ensemble forecasting systems and the corresponding observations. The framework is probabilistic and thus allows for quantifying uncertainty in predictability measures, such as correlation skill and signal-to-noise ratios. It also provides a natural way to produce recalibrated probabilistic predictions from uncalibrated ensembles forecasts. The framework is used to address important questions concerning the skill of winter hindcasts of the North Atlantic Oscillation for 1992–2011 issued by the Met Office Global Seasonal Forecast System, version 5 (GloSea5), climate prediction system. Although there is much uncertainty in the correlation between ensemble mean and observations, there is strong evidence of skill: the 95% credible interval of the correlation coefficient of [0.19, 0.68] does not overlap zero. There is also strong evidence that the forecasts are not exchangeable with the observations: with over 99% certainty, the signal-to-noise ratio of the forecasts is smaller than the signal-to-noise ratio of the observations, which suggests that raw forecasts should not be taken as representative scenarios of the observations. Forecast recalibration is thus required, which can be coherently addressed within the proposed framework.

Description: CD74, also known as HLA-DR-associated invariant chain, is a type II transmembrane glycoprotein highly expressed in many B-cell malignancies. The limited expression of CD74 in normal tissues suggests it may be a suitable ADC target for these tumor types. Accordingly, we engineered an anti-CD74 human IgG1 antibody (SP7219) using novel Fab-based ribosome display methods. The selected Fabs were readily reformatted and directly screened as IgGs using Sutro's unique high-throughput, cell-free protein synthesis platform, Xpress CFTM. We then developed novel, potent ADCs, SP7676 and SP7675 (STRO-001), comprised of our lead antibody (SP7219) conjugated to non-cleavable DBCO-maytansinoid linker-warheads with an average drug-antibody ratios (DAR) of 2. We used site-specific conjugation technology which results in a high degree of homogeneity characterized by the drug linker covalently binding to a single defined site. The sites for conjugation were selected based on highest cell killing activity and stablity in vitro and in vivo. Both ADCs demonstrate potent cell killing activity across multiple B-cell tumor lines in vitro, and anti-tumor activity in preclinical multiple myeloma xenograft models. In vitro cytotoxicity assays show nanomolar potency of STRO-001 in four MM cell lines: Mc/CAR (IC50 0.8 nM), MM.1S (IC50 10-11 nM), U266B1 (IC50 8.5 -9.3 nM), and ARP-1 (IC50 4.3-22 nM). CD74 cell surface expression is required for ADC anti-proliferative effect but the expression level does not seem to correlate with in vitro potency. SP7676 elicited a robust anti-tumor response in the ANBL-6 multiple myeloma xenograft model. Durable regressions were observed in all mice at ≥ 3 mg/kg, with equivalent efficacy (regression) at 3 mg/kg (every 3 days x5) and 10 mg/kg (every 3 days x5 or weekly x3). SP7676 also elicited a clear survival benefit in a disseminated multiple myeloma CAG xenograft model starting at 1mg/kg every 3 days x 5 doses. Similarly, both SP7676 and STRO-001 inhibited the formation of internal visceral tumors in the ARP-1 xenograft model after 3 weekly doses of 3 mg/kg. Evaluation of our lead candidate, STRO-001 in additional MM cell lines and primary patient samples is planned. The tolerability of STRO-001 in non-human primates is under evaluation. STRO-001 was administered to cynomolgous monkeys in an exploratory dose-escalating study up to 30 mg/kg x 2 doses on Day 1 and 15. STRO-001 reduces normal B-cell populations at ≥1 mg/kg after a single dose, providing pharmacodynamic evidence of B-cell targeting while other hematopoietic lineages are mostly affected only at the highest dose studied. Anticipated hematologic toxicities were readily reversible at 1, 3 and 10 mg/kg and target organs of interest were identified. Based on these encouraging data, STRO-001 is advancing to IND-enabling studies for the treatment of CD74 expressing multiple myeloma and other B-cell malignancies. Disclosures Abrahams: Sutro Biopharma: Employment. Li:Sutro Biopharma: Employment. Yu:Sutro Biopharma: Employment. Krimm:Sutro Biopharma: Employment. Kahana:Celgene: Employment. Narla:Celgene: Employment. Schwartz:Celgene: Employment. Boylan:Celgene: Employment. Hoffmann:Sutro Biopharma: Employment. Steiner:Sutro Biopharma: Employment. Zawada:Sutro Biopharma: Employment. Stephenson:Sutro Biopharma: Employment. Bruhns:Sutro Biopharma: Employment. DeAlmeida:Sutro Biopharma: Employment. Matheny:Sutro Biopharma: Employment. Bussell:Sutro Biopharma: Employment. Galan:Sutro Biopharma: Employment. Kline:Sutro Biopharma: Employment. Vasquez:Sutro Biopharma: Employment. Yam:Sutro Biopharma: Employment. Stafford:Sutro Biopharma: Employment. Heinsohn:Sutro Biopharma: Employment. Sato:Sutro Biopharma: Employment. Molina:Sutro Biopharma: Employment. Hallam:Sutro Biopharma: Employment. Lupher:Sutro Biopharma: Employment.

Description: Introduction: Chronic graft versus host disease (cGVHD) remains a major source of morbidity and mortality following allogeneic transplantation. While corticosteroids remain first line therapy for cGVHD, they are associated with significant toxicity, and a substantial proportion of patients fail to completely respond. Treatments for steroid-refractory cGVHD are limited. While the pathophysiology of chronic GVHD is complex, activated T cells play a critical role, driven by allo-antigen stimulation. As such, inhibition of T cell activation via blockade of co-stimulation has potential as a therapeutic target in cGVHD. Abatacept is a recombinant fusion protein consisting of the extracellular domain of human CTLA-4 and a fragment of the Fc domain of human IgG1 that has been modified to prevent complement fixation and antibody-dependent cellular cytotoxicity. Abatacept is the first drug in a class of agents termed "selective co-stimulation modulators." The CTLA-4 moiety of Abatacept binds specifically to CD80 and CD86 and down-modulates the CD28-mediated co-stimulation of T cells. We conducted a phase I clinical trial was conducted to evaluate the safety, clinical and immune effects of Abatacept in patients with steroid-refractory cGVHD. Methods: The study followed a 3+3 design with two escalating doses of Abatacept to determine the maximum tolerated dose (MTD): 3 mg/kg and 10 mg/kg. Dose-limiting toxicities (DLTs) were defined as Grade 3 or 4 toxicities judged to be probably or definitely related to Abatacept. Infection was not considered a DLT. Abatacept was administered for a total of 6 doses. Doses 1-3 were administered at two-week intervals. One month following Dose 3, Abatacept was given at four-week intervals for three doses (Doses 4-6). Inclusion criteria included recipients of allogeneic bone marrow or stem cell transplantation with myeloablative or reduced intensity conditioning, with cGVHD defined by NIH consensus criteria. Patients must have had treatment with ≥ 0.5 mg/kg/day of prednisone for at least 4 weeks. Patients with active malignant disease relapse or other active malignancy and patients with uncontrolled infection were excluded. Peripheral blood was drawn prior to each dose of Abatacept and following completion of therapy to assess the effect of treatment on circulating T cells. PD-1 expression on circulating T cells, and T cell expression of interferon gamma versus IL-10 was assessed by multichannel FACS analysis. Results: 17 subjects were treated. Three patients were treated at a dose of 3 mg/kg without DLT. Three evaluable patients completed treatment on cohort 2, at a dose of 10mg/kg without DLT. A forth participant withdrew consent following one dose of treatment and therefore is not evaluable. Ten patients were treated on an expansion cohort at a dose of 10mg/kg. We observed one grade 4 pulmonary infection, and three grade 3 pulmonary infections which resolved. Other Abatacept related adverse events included grade 2 gastritis (n=1), grade 2 pain (n=1), and grade 1 diarrhea (n=2), fatigue (n=2), rash (n=1), and skin pain (n=1). Of the 16 evaluable patients, 7 (44%) achieved a clinical partial response as defined by improvement of two disease systems based on the 2011 NIH consensus criteria. Abatacept resulted in a 51.3% reduction in prednisone usage in clinical responders with a mean baseline dose of 27mg compared to a mean dose of 14mg 1 month following the 6th dose of Abatacept (p = 0.01). PD-1 expression on circulating CD4+ and CD8+ T cells increased from a mean of 3.4% and 2.7% respectively at baseline to a mean of 8.9% and 7.6% respectively at one month following the 6thdose of Abatacept in clinical responders (n=3; p

Description: Reliable model systems are critical for investigating the genetic and molecular drivers of disease pathogenesis. Although the number of cell line model systems for multiple myeloma is extensive, recent studies showed patient tumors and cell lines clustering separately based on gene expression profiles. Furthermore, the hyperdiploid karyotype, present in approximately 50% of myeloma patients, is also extremely underrepresented in established human myeloma cell lines (HMCLs): only one of 59 HMCLs contains this phenotype. These data suggests that the average HMCL does not accurately represent the average myeloma patient and questions the validity of using HMCLs as model systems. However, most HMCLs were established from patients with pleural effusions or plasma cell leukemia, which are highly progressed and rare forms of myeloma. To assess how cell lines correlate with patient material, we performed a copy number abnormality (CNA) comparison between four myeloma primary tumors and their corresponding HMCLs. Here, we show that established HMCLs maintain the majority of the CNAs, contain a ten-fold greater frequency of 7q gains compared to patients, and that KP-6 is the second hyperdiploid HMCL known to date. CNAs were identified using array comparative genomic hybridization (Agilent 244k) with data analyzed at a resolution of 26kb. On average 59% (46.7-77.3) of the CNAs were shared between the tumors and their cell lines, 17% (8.5-25.9) were unique to the patient samples, and 24% (13.6-36.6) were only detected in the HMCLs. To put these differences in context we also compared the diagnostic material from which JMW-1 was established with a progression sample collected 9 months later after 3 cycles of VAD followed by an autologous peripheral blood stem cell transplant. The patient diagnostic and relapse tumors showed 58% similarity based on CNAs while the diagnostic and relapse tumors contained 8% and 34% unique events respectively. These results indicate that established HMCLs are no more divergent from their primary cells as is the same patient's relapse material. Overall the HMCLs studied appear highly representative of the patient from which they were derived, with most differences attributed to an enrichment of subclonal populations present in the primary tumor admixture. Of particular interest, ubiquitous 7q gains were an unexpected unifying event across all patient tumors and their HMCLs. We then analyzed the 729 baseline myeloma tumors with copy number data from the MMRF CoMMpass study against our panel of 59 similarly characterized HMCLs. We observed that HMCLs contained a 10-fold increase in the occurrence of 7q gains with respect to non-hyperdiploid patients with 7q gains (35/59 in HMCLs and 19/344 in patients). Because 97% of HMCLs are non-hyperdiploid and 7q gains are extremely rare in this population, over-representation of 7q gains in cell lines suggests that this event may promote extra-medullary growth and the establishment of cell lines. Profiling of patient tumors for gains on 7q may therefore increase the probability of establishing a new HMCL and help expand our model systems for understanding this disease. Further studies are required to understand the potential biological significance of this event in vitro . We also identified the KP-6 cell line as a novel hyperdiploid HMCL established from an extramedullary site of an advanced hyperdiploid patient. The presence of trisomies for at least four of the odd-numbered chromosomes is characteristic of a hyperdiploid myeloma patient. From the patient's tumor, clear trisomies were observed on chromosomes 3, 7, 11, 15, 19, and 21 and the HMCL established from this hyperdiploid patient maintains full trisomies of chromosomes 15, 19, and 21, with partial p-arm trisomies on chromosomes 7, 11, and 17. Since this is only the second bona fied hyperdiploid myeloma cell line to date, KP-6 promises to play a major role in our ability to understand the pathogenesis and progression of this prominent patient population. Overall, our research indicates that, based on CNAs, HMCLs are as representative of the primary tumor as is the same patient's tumor at a later time point. Additionally, HMCLs contain a 10-fold overabundance of 7q gains. Finally, we showed that KP-6 is the second hyperdiploid HMCL known to date. Taken together, these results suggest that HMCLs are reliable model systems for investigating the underlying biology of multiple myeloma. Disclosures No relevant conflicts of interest to declare.

Description: CD74 is a type II transmembrane glycoprotein involved in the formation and transport of MHC class II protein. High expression of CD74 has been confirmed in follicular lymphoma, diffuse large B-cell lymphoma (DLBCL), chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) and other types of NHL with immunohistochemistry (IHC) using the LL1 antibody (Stein et al. Clin Cancer Res 2007). We employed site-specific conjugation technology to generate novel CD74-targeting ADCs, SP7676 and SP7675 (STRO-001) that exhibit a high degree of homogeneity characterized by the drug linker covalently binding to a single defined site. The human anti-CD74 IgG1 antibody (SP7219) used for ADCs SP7676 and STRO-001 was engineered using novel Fab-based ribosome display methods enabling selection from ~1012 different antibody variants. Hundreds of unique Fabs from this selection were converted to IgGs and expressed directly in Sutro's proprietary cell-free protein synthesis platform, Xpress CFTM, for extensive screening. The top antibody lead derived from this screen is further tested to identify the best sites for conjugation of linker-warheads. Sutro's SP7219 emerged as the top performing antibody and was conjugated to noncleavable DBCO-maytansinoid linker-warheads to form the ADCs SP7676 and STRO-001. Since conjugation sites were selected based on highest stability both in vitro and in vivo, these novel ADCs lose little drug moiety in circulation and have potential for improved PK, safety and activity profiles. In vitro cell proliferation/cytotoxicity assays show potent activity in 1) DLBCL (germinal center B-cell-like [GCB] and "double-hit") lines: SU-DHL-4, IC50 - 1nM; SU-DHL-6, IC50 - 0.4 nM; WSU-NHL, IC50 - 1.6 nM; Pfeiffer, IC50 - .09 nM; NUDUL-1, IC50 - 0.4 nM; HT, IC50 - 0.7 nM; OCI-LY-19, IC50 - 0.7 nM; WSU-DLBCL2, IC50 - 0.3 nM; 2) mantle cell lymphoma (MCL) cell lines: Mino, IC50 - 0.4-0.7 nM; JVM-2, IC50 - 1.7-2.9 nM; Jeko-1, IC50 - 0.4 - 0.6 nM; 3) Ph+ acute lymphoblastic leukemia (ALL): SUP-B15, IC50 - 3.9-4.6 nM; and 4) CLL (EBV-transformed): JVM-13, IC50 - 3.0-3.4 nM. SP7676 elicited strong anti-tumor response in the OCI-LY-10 lymphoma xenograft model with 100% of animals achieving complete regression of tumors at 3mg/kg every 3 days x 5 doses and 10 mg/kg weekly x 3 doses. In the WSU-DLCL2 "double-hit" lymphoma xenograft model, administration of SP7676 (with re-dosing at time of re-growth) produced tumor regressions at 10 mg/kg every 3 days x 5 (6/8 mice tumor free, remaining 2 with small tumors) and 10 mg/kg weekly x 3 (tumor regression in most animals, 4/8 tumor free). Additionally, STRO-001 exhibits dose-dependent tumor growth inhibition in SUDHL-6 xenografts starting at 2.5 mg/kg weekly x 3 doses. Exploratory testing of our lead candidate, STRO-001 in cynomologous monkeys showed dose-dependent B-cell depletion at 1 - 30 mg/kg doses on Day 1 and 15, confirming the intended pharmacodynamic effect. Our preliminary data demonstrate that SP7676 and STRO-001 generate potent cell killing activity across multiple B-cell lymphoma/leukemia cell lines in vitro, and anti-tumor activity in preclinical B-cell NHL xenografts. Evaluation of STRO-001 in other cell lines and xenograft models and in combination studies is ongoing. GLP toxicology and other IND-enabling studies are planned. Disclosures Li: Sutro Biopharma: Employment. Abrahams:Sutro Biopharma: Employment. Embry:Sutro Biopharma: Employment. Yu:Sutro Biopharma: Employment. Kahana:Celgene: Employment. Brown:Celgene: Employment. Narla:Celgene: Employment. Barnes:Celgene: Employment. Schwartz:Celgene: Employment. Boylan:Celgene: Employment. Zawada:Sutro Biopharma: Employment. Stephenson:Sutro Biopharma: Employment. Bruhns:Sutro Biopharma: Employment. Bussell:Sutro Biopharma: Employment. Steiner:Sutro Biopharma: Employment. Galan:Sutro Biopharma: Employment. Kline:Sutro Biopharma: Employment. Yam:Sutro Biopharma: Employment. Stafford:Sutro Biopharma: Employment. Hoffmann:Sutro Biopharma: Employment. Matheny:Sutro Biopharma: Employment. DeAlmeida:Sutro Biopharma: Employment. Vasquez:Sutro Biopharma: Employment. Heinsohn:Sutro Biopharma: Employment. Sato:Sutro Biopharma: Employment. Molina:Sutro Biopharma: Employment. Hallam:Sutro Biopharma: Employment. Lupher:Sutro Biopharma: Employment.