SARS-CoV-2 antibody response duration and neutralization following natural infection.

Background: The role of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) neutralizing antibody response from natural infection and vaccination, and the potential determinants of this response are poorly understood. Characterizing this antibody response and the factors associated with neutralization can help inform future prevention efforts and improve clinical outcomes in those infected. Objectives: The goals of this study were to prospectively evaluate SARS-CoV-2 antibody levels and the neutralizing antibody responses among naturally infected adults and to determine demographic and behavioral factors independently associated with these responses. Methods: Serum was collected from seropositive individuals at baseline, four-weeks, and three-months following their first study visit to be evaluated for antibody levels. Detection of neutralizing antibodies was performed at baseline. Participant demographic and behavioral information was collected via web questionnaire prior to their first visit. Results: At baseline, higher antibody levels were associated with better neutralization capacity, with 83% of participants having detectable neutralizing antibodies. We found an age-dependent effect on antibody level and neutralization capacity with participants over 65 years having significantly higher levels. Ethnicity, heart disease, autoimmune disease, and COVID symptoms were associated with higher antibody levels, but not with increased neutralization capacity. Work environment during the pandemic correlated with increased neutralization capacity, while kidney or liver disease and traveling out of state after February 2020 correlated with decreased neutralization capacity, however neither correlated with antibody levels. Conclusions: Our data show that natural infection by SARS-CoV-2 can induce a humoral response reflected by high antibody levels and neutralization capacity.

Safety and immunogenicity of a third dose of mRNA-1273 vaccine among cancer patients.

BACKGROUND: Compared to the general population, cancer patients are at higher risk of morbidity and mortality following SARS-CoV-2 infection. The immune response to a two-dose regimen of mRNA vaccines in cancer patients is generally lower than in immunocompetent individuals. Booster doses may meaningfully augment immune response in this population. We conducted an observational study with the primary objective of determining the immunogenicity of vaccine dose three (100 µg) of mRNA-1273 among cancer patients and a secondary objective of evaluating safety at 14 and 28 days. METHODS: The mRNA-1273 vaccine was administered ∼7 to 9 months after administering two vaccine doses (i.e., the primary series). Immune responses (enzyme-linked immunosorbent assay [ELISA]) were assessed 28 days post-dose three. Adverse events were collected at days 14 (± 5) and 28 (+5) post-dose three. Fisher exact or X2 tests were used to compare SARS-CoV-2 antibody positivity rates, and paired t-tests were used to compare SARS-CoV-2 antibody geometric mean titers (GMTs) across different time intervals. RESULTS: Among 284 adults diagnosed with solid tumors or hematologic malignancies, dose three of mRNA-1273 increased the percentage of patients seropositive for SARS-CoV-2 antibody from 81.7% pre-dose three to 94.4% 28 days post-dose three. GMTs increased 19.0-fold (15.8-22.8). Patients with lymphoid cancers or solid tumors had the lowest and highest antibody titers post-dose three, respectively. Antibody responses after dose three were reduced among those who received anti-CD20 antibody treatment, had lower total lymphocyte counts and received anticancer therapy within 3 months. Among patients seronegative for SARS-CoV-2 antibody pre-dose three, 69.2% seroconverted after dose three. A majority (70.4%) experienced mostly mild, transient adverse reactions within 14 days of dose three, whereas severe treatment-emergent events within 28 days were very rare (<2%). CONCLUSION: Dose three of the mRNA-1273 vaccine was well-tolerated and augmented SARS-CoV-2 seropositivity in cancer patients, especially those who did not seroconvert post-dose two or whose GMTs significantly waned post-dose two. Lymphoid cancer patients experienced lower humoral responses to dose three of the mRNA-1273 vaccine, suggesting that timely access to boosters is important for this population.

Neutralizing Antibody Response following a Third Dose of the mRNA-1273 Vaccine among Cancer Patients.

Cancer patients are at an increased risk of morbidity and mortality from SARS-CoV-2 infection and have a decreased immune response to vaccination. We conducted a study measuring both the neutralizing and total antibodies in cancer patients following a third dose of the mRNA-1273 COVID-19 vaccine. Immune responses were measured with an enzyme-linked immunosorbent assay (ELISA) and neutralization assays. Kruskal-Wallis tests were used to evaluate the association between patient characteristics and neutralization geometric mean titers (GMTs), and paired t-tests were used to compare the GMTs between different timepoints. Spearman correlation coefficients were calculated to determine the correlation between total antibody and neutralization GMTs. Among 238 adults diagnosed with cancer, a third dose of mRNA-1273 resulted in a 37-fold increase in neutralization GMT 28 days post-vaccination and maintained a 14.6-fold increase at 6 months. Patients with solid tumors or lymphoid cancer had the highest and lowest neutralization GMTs, respectively, at both 28 days and 6 months post-dose 3. While total antibody GMTs in lymphoid patients continued to increase, other cancer types showed decreases in titers between 28 days and 6 months post-dose 3. A strong correlation (p < 0.001) was found between total antibody and neutralization GMTs. The third dose of mRNA-1273 was able to elicit a robust neutralizing antibody response in cancer patients, which remained for 6 months after administration. Lymphoid cancer patients can benefit most from this third dose, as it was shown to continue to increase total antibody GMTs 6 months after vaccination.

Long-Term CD4+ T-Cell and Immunoglobulin G Immune Responses in Oncology Workers following COVID-19 Vaccination: An Interim Analysis of a Prospective Cohort Study.

We conducted a prospective study to evaluate immune responses to SARS-CoV-2 in oncology workers in which we collected blood and clinical data every 6 months. Spike-specific CD4+ T-cells and immunoglobulin G responses were measured using interferon-gamma enzyme-linked immunosorbent spot and enzyme-linked immunosorbent assay, respectively. Sixty (81%) vaccinated and 14 (19%) unvaccinated individuals were enrolled. CD4+ T-cell responses of those individuals currently naturally infected were comparable to those who were 6 months from receiving their last dose of the vaccine; both responses were significantly higher than among those who were unvaccinated. Unvaccinated participants who became vaccinated while in the study showed a significant increase in both types of spike-specific immune responses. Previously vaccinated individuals who received a third dose (booster) showed a similar response to the spike protein. However, this response decreases as soon as 3 months but does not dip below the established response following two doses. Response to variants of concern B.1.617.2 (Delta) and B.1.1.529 (Omicron) also increased, with the Omicron variant having a significantly lower response when compared to Delta and the wild type. We conclude that antibody and T-cell responses increase in oncology workers after serial vaccination but can wane over time.

Evaluation of Antibody Response to SARS-CoV-2 mRNA-1273 Vaccination in Patients With Cancer in Florida.

Importance: Patients with cancer experience high rates of morbidity and mortality after SARS-CoV-2 infection. Immune response to mRNA-1273 vaccination across multiple cancer types and treatments remains to be established. Objective: To quantitate antibody responses after mRNA-1273 vaccination among patients with solid tumors and hematologic cancer and to assess clinical and treatment factors associated with vaccine response. Design, Setting, and Participants: This cohort study included patients with cancer who were aged 18 years or older, spoke English or Spanish, had received their first mRNA-1273 dose between January 12 and 25, 2021, and agreed to blood tests before and after vaccination. Exposures: Receipt of 1 and 2 mRNA-1273 SARS-CoV-2 vaccine doses. Main Outcomes and Measures: Seroconversion after each vaccine dose and IgG levels against SARS-CoV-2 spike protein obtained immediately before the first and second vaccine doses and 57 days (plus or minus 14 days) after the first vaccine dose. Cancer diagnoses and treatments were ascertained by medical record review. Serostatus was assessed via enzyme-linked immunosorbent assay. Paired t tests were applied to examine days 1, 29, and 57 SARS-CoV-2 antibody levels. Binding antibody IgG geometric mean titers were calculated based on log10-transformed values. Results: The 515 participants were a mean (SD) age of 64.5 (11.4) years; 262 (50.9%) were women; and 32 (6.2%) were Hispanic individuals and 479 (93.0%) White individuals; race and ethnicity data on 4 (0.7%) participants were missing. Seropositivity after vaccine dose 2 was 90.3% (465; 95% CI, 87.4%-92.7%) among patients with cancer, was significantly lower among patients with hematologic cancer (84.7% [255]; 95% CI, 80.1%-88.6%) vs solid tumors (98.1% [210]; 95% CI, 95.3%-99.5%), and was lowest among patients with lymphoid cancer (70.0% [77]; 95% CI, 60.5%-78.4%). Patients receiving a vaccination within 6 months after anti-CD20 monoclonal antibody treatment had a significantly lower seroconversion (6.3% [1]; 95% CI, 0.2%-30.2%) compared with those treated 6 to 24 months earlier (53.3% [8]; 95% CI, 26.6%-78.7%) or those who never received anti-CD20 treatment (94.2% [456]; 95% CI, 91.7%-96.1%). Low antibody levels after vaccination were observed among patients treated with anti-CD20 within 6 months before vaccination (GM, 15.5 AU/mL; 95% CI, 9.8-24.5 AU/mL), patients treated with small molecules (GM, 646.7 AU/mL; 95% CI, 441.9-946.5 AU/mL), and patients with low lymphocyte (GM, 547.4 AU/mL; 95% CI, 375.5-797.7 AU/mL) and IgG (GM, 494.7 AU/mL; 95% CI, 304.9-802.7 AU/mL) levels. Conclusions and Relevance: This cohort study found that the mRNA-1273 SARS-CoV-2 vaccine induced variable antibody responses that differed by cancer diagnosis and treatment received. These findings suggest that patients with hematologic cancer and those who are receiving immunosuppressive treatments may need additional vaccination doses.

Melphalan and Exportin 1 Inhibitors Exert Synergistic Antitumor Effects in Preclinical Models of Human Multiple Myeloma.

High-dose chemotherapy with melphalan followed by autologous transplantation is a first-line treatment for multiple myeloma. Here, we present preclinical evidence that this treatment may be significantly improved by the addition of exportin 1 inhibitors (XPO1i). The XPO1i selinexor, eltanexor, and KOS-2464 sensitized human multiple myeloma cells to melphalan. Human 8226 and U266 multiple myeloma cell lines and melphalan-resistant cell lines (8226-LR5 and U266-LR6) were highly sensitized to melphalan by XPO1i. Multiple myeloma cells from newly diagnosed and relapsed/refractory multiple myeloma patients were also sensitized by XPO1i to melphalan. In NOD/SCIDγ mice challenged with either parental 8226 or U266 multiple myeloma and melphalan-resistant multiple myeloma tumors, XPO1i/melphalan combination treatments demonstrated stronger synergistic antitumor effects than single-agent melphalan with minimal toxicity. Synergistic cell death resulted from increased XPO1i/melphalan-induced DNA damage in a dose-dependent manner and decreased DNA repair. In addition, repair of melphalan-induced DNA damage was inhibited by selinexor, which decreased melphalan-induced monoubiquitination of FANCD2 in multiple myeloma cells. Knockdown of FANCD2 was found to replicate the effect of selinexor when used with melphalan, increasing DNA damage (γH2AX) by inhibiting DNA repair. Thus, combination therapies that include selinexor or eltanexor with melphalan may have the potential to improve treatment outcomes of multiple myeloma in melphalan-resistant and newly diagnosed patients. The combination of selinexor and melphalan is currently being investigated in the context of high-dose chemotherapy and autologous transplant (NCT02780609). SIGNIFICANCE: Inhibition of exportin 1 with selinexor synergistically sensitizes human multiple myeloma to melphalan by inhibiting Fanconi anemia pathway-mediated DNA repair.

Phase I Clinical Trial of Selinexor in Combination with Daunorubicin and Cytarabine in Previously Untreated Poor-Risk Acute Myeloid Leukemia.

PURPOSE: Induction chemotherapy results in complete remission (CR) rates of 20% to 50% among patients with poor-risk AML. Selinexor is an oral selective inhibitor of nuclear export with promising single-agent activity. By inhibiting the primary export protein, XPO1, selinexor localizes and activates tumor suppressor proteins in the nucleus and inhibits DNA damage repair, rationalizing combination with DNA-damaging agents. PATIENTS AND METHODS: This was a single-arm phase I clinical trial of selinexor combined with cytarabine and daunorubicin (7+3). Dose escalation was selinexor alone (3+3) with an expansion at the MTD. Cohorts 1 and 2 received 60 and 80 mg orally, respectively, twice weekly during induction. Consolidation cycles (≤ 2) with selinexor at induction dose plus 5+2 were allowed for patients who achieved CR. MTD and recommended phase II dose of selinexor were the primary endpoints. RESULTS: Twenty-one patients with poor-risk AML were enrolled. All 21 patients were included in the safety evaluations and survival analyses (4 in each of 2 cohorts; 13 in the expansion); 8 (53%) of the 19 patients evaluable for response achieved CR/CRi. MTD was not reached. Selinexor 80 mg (orally, twice weekly) was used in the expansion phase. The most common grade 3/4 nonhematologic treatment-emergent adverse events were febrile neutropenia (67%), diarrhea (29%), hyponatremia (29%), and sepsis (14%). At median follow-up (28.9 months), 38% of patients were alive. Median overall survival was 10.3 months. CONCLUSIONS: Selinexor plus 7+3 is a safe regimen for patients with newly diagnosed poor-risk AML and warrants further investigation in a larger clinical trial.

Small molecule inhibition of lysine-specific demethylase 1 (LSD1) and histone deacetylase (HDAC) alone and in combination in Ewing sarcoma cell lines.

Ewing Sarcoma (ES) is characterized by recurrent translocations between EWSR1 and members of the ETS family of transcription factors. The transcriptional activity of the fusion oncoprotein is dependent on interaction with the nucleosome remodeling and deactylase (NuRD) co-repressor complex. While inhibitors of both histone deacetylase (HDAC) and lysine-specific demethylase-1 (LSD1) subunits of the NuRD complex demonstrate single agent activity in preclinical models, combination strategies have not been investigated. We selected 7 clinically utilized chemotherapy agents, or active metabolites thereof, for experimentation: doxorubicin, cyclophosphamide, vincristine, etoposide and irinotecan as well as the HDAC inhibitor romidepsin and the reversible LSD1 inhibitor SP2509. All agents were tested at clinically achievable concentrations in 4 ES cell lines. All possible 2 drug combinations were then tested for potential synergy. Order of addition of second-line conventional combination therapy agents was tested with the addition of SP2509. In two drug experiments, synergy was observed with several combinations, including when SP2509 was paired with topoisomerase inhibitors or romidepsin. Addition of SP2509 after treatment with second-line combination therapy agents enhanced treatment effect. Our findings suggest promising combination treatment strategies that utilize epigenetic agents in ES.

Neurofibromin level directs RAS pathway signaling and mediates sensitivity to targeted agents in malignant peripheral nerve sheath tumors.

Malignant peripheral nerve sheath tumor (MPNST) is a type of soft-tissue sarcoma strongly associated with dysfunction in neurofibromin; an inhibitor of the RAS pathway. We performed high-throughput screening of an array of FDA approved and promising agents in clinical development both alone and in combination at physiologically achievable concentrations against a panel of established MPNST cell line models. We found that drugs targeting a variety of factors in the RAS pathway can effectively lead to cell death in vitro with considerable drug combination synergy in regimens that target MEK or mTOR. We observed that the degree of relative sensitivity to chemotherapeutic agents was associated with the status of neurofibromin in these cell line models. Using a combination of agents that target MEK and mTORC1/2, we effectively silenced RAS/PI3K/MEK/mTOR signaling in vitro. Moreover, we employed RNAi against NF1 to establish that MPNST drug sensitivity is directly proportional to relative level of intracellular neurofibromin. Thus, two-drug combinations that target MEK and mTORC1/2 are most effective in halting the RAS signaling cascade, and the relative success of this and related small molecule interventions in MPNSTs may be predicated upon the molecular status of neurofibromin.

A Phase II Study of CLAG Regimen Combined With Imatinib Mesylate for Relapsed or Refractory Acute Myeloid Leukemia.

INTRODUCTION: No standard salvage chemotherapy regimen is available for relapsed or refractory (RR) acute myeloid leukemia (AML). Preclinical data have suggested synergy in vitro between cytarabine and imatinib mesylate (IM) on AML cell growth inhibition. After demonstrating the safety and feasibility in a phase I study, we conducted a phase II clinical study of CLAG (cladribine, cytarabine, granulocyte colony-stimulating factor) regimen combined with IM for patients with RR-AML. PATIENTS AND METHODS: We performed a single-institution 2-stage phase II study. The primary endpoint was the remission rate measured using the standard AML response criteria. The secondary endpoints included overall survival (OS) and progression-free survival (PFS). RESULTS: From August 2009 to April 2011, 38 patients were treated at the Moffitt Cancer Center. Their median age was 62 years (range, 26-79 years). Of the 38 patients, 7 (18%) had refractory AML, 19 (50%) had early relapse, and 12 (32%) had late relapse. At the original diagnosis, only 2 patients had favorable risk factors, 18 had intermediate risk, and 16 had poor risk; for 2 patients, the karyotype was missing. The overall response rate for all 38 evaluable patients was 37%. The median OS was 11.1 months (95% CI, 4.8-13.4 months), the median PFS was 4.9 months (95% CI, 1.6-11.7 months). Among the responders, 8 of 14 patients subsequently underwent allogeneic hematopoietic cell transplantation. CONCLUSION: CLAG plus IM was well tolerated, with encouraging signs of activity in patients with poor-risk AML.

An Ex Vivo Platform for the Prediction of Clinical Response in Multiple Myeloma.

Multiple myeloma remains treatable but incurable. Despite a growing armamentarium of effective agents, choice of therapy, especially in relapse, still relies almost exclusively on clinical acumen. We have developed a system, Ex vivo Mathematical Myeloma Advisor (EMMA), consisting of patient-specific mathematical models parameterized by an ex vivo assay that reverse engineers the intensity and heterogeneity of chemosensitivity of primary cells from multiple myeloma patients, allowing us to predict clinical response to up to 31 drugs within 5 days after bone marrow biopsy. From a cohort of 52 multiple myeloma patients, EMMA correctly classified 96% as responders/nonresponders and correctly classified 79% according to International Myeloma Working Group stratification of level of response. We also observed a significant correlation between predicted and actual tumor burden measurements (Pearson r = 0.5658, P < 0.0001). Preliminary estimates indicate that, among the patients enrolled in this study, 60% were treated with at least one ineffective agent from their therapy combination regimen, whereas 30% would have responded better if treated with another available drug or combination. Two in silico clinical trials with experimental agents ricolinostat and venetoclax, in a cohort of 19 multiple myeloma patient samples, yielded consistent results with recent phase I/II trials, suggesting that EMMA is a feasible platform for estimating clinical efficacy of drugs and inclusion criteria screening. This unique platform, specifically designed to predict therapeutic response in multiple myeloma patients within a clinically actionable time frame, has shown high predictive accuracy in patients treated with combinations of different classes of drugs. The accuracy, reproducibility, short turnaround time, and high-throughput potential of this platform demonstrate EMMA's promise as a decision support system for therapeutic management of multiple myeloma. Cancer Res; 77(12); 3336-51. ©2017 AACR.

ERBB4 Expression in Ovarian Serous Carcinoma Resistant to Platinum-Based Therapy.

Few data exist on the prognostic and predictive impact of erb-b2 receptor tyrosine kinase 4 (ERBB4) in ovarian cancer. Thus, we evaluated ERBB4 expression by immunohistochemistry in a tumor microarray consisting of 100 ovarian serous carcinoma specimens (50 complete responses [CRs] and 50 incomplete responses [IRs] to platinum-based therapy), 51 normal tissue controls, and 16 ovarian cancer cell lines. H scores were used to evaluate expression and were semiquantitatively classified into low, intermediate, and high categories. Category frequencies were compared between tumor specimens vs controls using an unpaired t test. Among tumors, category frequencies were compared between CR and IR to chemotherapy. Overall survival (OS) was stratified by category. In total, 74 ovarian serous carcinoma samples (32 CRs and 42 IRs), 28 normal controls, and 16 ovarian cancer cell lines were evaluable. High-level ERBB4 expression was observed at a significantly higher frequency in ovarian serous carcinoma compared with normal control tissue. Among tumor specimens, ERBB4 expression was significantly higher for those with an IR to chemotherapy compared with CR (P = .033). OS was inversely correlated with ERBB4 expression levels. Median rates of OS were 18, 22, and 58 months among high-, intermediate-, and low-expression tumors, respectively. Our results indicate that ERBB4 expression by immunohistochemistry may correlate with chemotherapy-resistant ovarian serous carcinoma and shortened OS.

Targeting Aurora kinase A and JAK2 prevents GVHD while maintaining Treg and antitumor CTL function.

Graft-versus-host disease (GVHD) is a leading cause of nonrelapse mortality after allogeneic hematopoietic cell transplantation. T cell costimulation by CD28 contributes to GVHD, but prevention is incomplete when targeting CD28, downstream mammalian target of rapamycin (mTOR), or Aurora A. Likewise, interleukin-6 (IL-6)-mediated Janus kinase 2 (JAK2) signaling promotes alloreactivity, yet JAK2 inhibition does not eliminate GVHD. We provide evidence that blocking Aurora A and JAK2 in human T cells is synergistic in vitro, prevents xenogeneic GVHD, and maintains antitumor responses by cytotoxic T lymphocytes (CTLs). Aurora A/JAK2 inhibition is immunosuppressive but permits the differentiation of inducible regulatory T cells (iTregs) that are hyperfunctional and CD39 bright and efficiently scavenge adenosine triphosphate (ATP). Increased iTreg potency is primarily a function of Aurora A blockade, whereas JAK2 inhibition suppresses T helper 17 (TH17) differentiation. Inhibiting either Aurora A or JAK2 significantly suppresses TH1 T cells. However, CTL generated in vivo retains tumor-specific killing despite Aurora A/JAK2 blockade. Thus, inhibiting CD28 and IL-6 signal transduction pathways in donor T cells can increase the Treg/Tconv ratio, prevent GVHD, and preserve antitumor CTL.

Impact of chemotherapy on medium-term physical function and activity of older breast cancer survivors, and associated biomarkers.

OBJECTIVE: Chemotherapy is less often prescribed in older individuals due to concerns about post-treatment morbidity and quality of life. We evaluated the physical performance of breast cancer survivors treated with and without adjuvant chemotherapy. MATERIALS AND METHODS: We conducted a case-control study in 56 estrogen receptor positive breast cancer survivors (BCS) on adjuvant aromatase inhibitors 1-2years after definitive surgery. Cases had received adjuvant chemotherapy (n=27; age 70.5±3.6years) versus age-matched controls who had not (n=29; age 70.0±4.3years). Measures of grip strength, physical activity and performance, walking speed, fatigue, and self-reported physical function were collected. Biological correlates of inflammation, frailty and markers of DNA and RNA oxidation were compared. RESULTS: Grip strength (controls: 21±7.4 vs. CASES: 29.7±5.0kg, p=0.20), physical activity (5403±3204 vs. 6801±9320steps/day, p=0.45), physical performance (short physical performance battery score: 10.1±1.8 vs. 10.4±1.1, p=0.52) and long-distance walking speed (1.2±0.21 vs. 1.3±0.41m/s, p=0.17) were similar between the two groups. Self-reported physical function was marginally lower in cases than controls (controls: 72±24 vs. CASES: 57±34AU, p=0.07). Fatigue disruptiveness was not different between groups (controls: 11.1±13.0 vs. CASES: 15.7±16.2AU, p=0.24). Similarly, the inflammation, oxidation, and frailty markers did not present a significant difference between groups, except for vitamin D levels (p=0.04). CONCLUSION: Older women who received chemotherapy reported having slightly lower physical function, but a similar physical performance compared to women who did not. These data suggest that older BCS treated with chemotherapy recover to an extent similar to survivors who only received hormonal therapy.

Identification of clinically achievable combination therapies in childhood rhabdomyosarcoma.

PURPOSE: Systemic therapy has improved rhabdomyosarcoma event-free and overall survival; however, approximately 40 % of patients will have progressive or recurrent disease which is difficult to cure and remains a considerable challenge. Minimal progress has been made in improving outcomes for metastatic or relapsed RMS due to a lack of effective therapeutic agents. Targeted therapies are likely to be incorporated into regimens which rely on conventional cytotoxic chemotherapy. A system to evaluate novel combinations of interest is needed. METHODS: In this study, we explored 8 agents, 5 that are routinely used or similar to agents used in the clinical management of RMS and 3 biologically targeted agents with novel mechanisms of action, the Wee1 inhibitor AZD1775, the tyrosine kinase inhibitor cabozantinib, and the proteasome inhibitor bortezomib. All were tested individually at clinically achievable concentrations for activity in 4 RMS cell lines and then for potential synergy in two-drug combinations. RESULTS: We found single-agent activity in five of the agents (or their active metabolites) that constitute the standard of care in RMS and for AZD1775 with mean IC50 values of 207 ng/ml, well below clinically achievable levels. In addition, the combination of individual cytotoxic chemotherapeutics currently used for RMS demonstrated largely synergistic activity with higher, but clinically achievable concentrations of AZD1775 in our assays. CONCLUSIONS: Prioritization of chemotherapeutics in RMS is possible using an in vitro system that can define novel drug combinations worthy of future investigation. AZD1775 exhibits single-agent activity, as well as synergy with conventional cytotoxic chemotherapy, and is a novel targeted agent that warrants further study in RMS.

Sensitivity of ovarian cancer cells to acetaminophen reveals biological pathways that affect patient survival.

Experimental and epidemiological data support the potential activity of acetaminophen against ovarian cancer (OVCA). In this study, we sought to confirm the activity of acetaminophen in OVCA cell lines and to investigate the molecular basis of response. A total of 16 OVCA cell lines underwent pretreatment (baseline) genome-wide expression measurements and were then treated with and analyzed for acetaminophen sensitivity. Pearson's correlation analysis was performed to identify genes that were associated with OVCA acetaminophen response. The identified genes were subjected to pathway analysis, and the expression of each represented pathway was summarized using principal component analysis. OVCA acetaminophen response pathways were analyzed in 4 external clinico-genomic datasets from 820 women for associations with overall survival from OVCA. Acetaminophen exhibited antiproliferative activity against all tested OVCA cell lines, with half maximal inhibitory concentration values ranging from 63.2 to 403 µM. Pearson's correlation followed by biological pathway analysis identified 13 pathways to be associated with acetaminophen sensitivity (P<0.01). Associations were observed between patient survival from OVCA and expression of the following pathways: Development/angiotensin signaling via ß-arrestin (P=0.04), protein folding and maturation/angiotensin system maturation (P=0.02), signal transduction/c-Jun N-terminal kinase (JNK) pathway (P=0.03) and androstenedione and testosterone biosynthesis and metabolism (P=0.02). We confirmed that acetaminophen was active against OVCA cells in vitro. Furthermore, we identified 4 molecular signaling pathways associated with acetaminophen response that may also affect overall survival in women with OVCA, including the JNK pathway, which has been previously implicated in the mechanism of action of acetaminophen and is predictive of decreased survival in women with OVCA.

Identification of Synergistic, Clinically Achievable, Combination Therapies for Osteosarcoma.

Systemic therapy has improved osteosarcoma event-free and overall survival, but 30-50% of patients originally diagnosed will have progressive or recurrent disease, which is difficult to cure. Osteosarcoma has a complex karyotype, with loss of p53 in the vast majority of cases and an absence of recurrent, targetable pathways. In this study, we explored 54 agents that are clinically approved for other oncologic indications, agents in active clinical development, and others with promising preclinical data in osteosarcoma at clinically achievable concentrations in 5 osteosarcoma cell lines. We found significant single-agent activity of multiple agents and tested 10 drugs in all permutations of two-drug combinations to define synergistic combinations by Chou and Talalay analysis. We then evaluated order of addition to choose the combinations that may be best to translate to the clinic. We conclude that the repurposing of chemotherapeutics in osteosarcoma by using an in vitro system may define novel drug combinations with significant in vivo activity. In particular, combinations of proteasome inhibitors with histone deacetylase inhibitors and ixabepilone and MK1775 demonstrated excellent activity in our assays.

Inhibition of ER stress-associated IRE-1/XBP-1 pathway reduces leukemic cell survival.

Activation of the ER stress response is associated with malignant progression of B cell chronic lymphocytic leukemia (CLL). We developed a murine CLL model that lacks the ER stress-associated transcription factor XBP-1 in B cells and found that XBP-1 deficiency decelerates malignant progression of CLL-associated disease. XBP-1 deficiency resulted in acquisition of phenotypes that are disadvantageous for leukemic cell survival, including compromised BCR signaling capability and increased surface expression of sphingosine-1-phosphate receptor 1 (S1P1). Because XBP-1 expression requires the RNase activity of the ER transmembrane receptor IRE-1, we developed a potent IRE-1 RNase inhibitor through chemical synthesis and modified the structure to facilitate entry into cells to target the IRE-1/XBP-1 pathway. Treatment of CLL cells with this inhibitor (B-I09) mimicked XBP-1 deficiency, including upregulation of IRE-1 expression and compromised BCR signaling. Moreover, B-I09 treatment did not affect the transport of secretory and integral membrane-bound proteins. Administration of B-I09 to CLL tumor-bearing mice suppressed leukemic progression by inducing apoptosis and did not cause systemic toxicity. Additionally, B-I09 and ibrutinib, an FDA-approved BTK inhibitor, synergized to induce apoptosis in B cell leukemia, lymphoma, and multiple myeloma. These data indicate that targeting XBP-1 has potential as a treatment strategy, not only for multiple myeloma, but also for mature B cell leukemia and lymphoma.

Inhibition of CRM1-dependent nuclear export sensitizes malignant cells to cytotoxic and targeted agents.

Nuclear-cytoplasmic trafficking of proteins is a significant factor in the development of cancer and drug resistance. Subcellular localization of exported proteins linked to cancer development include those involved in cell growth and proliferation, apoptosis, cell cycle regulation, transformation, angiogenesis, cell adhesion, invasion, and metastasis. Here, we examined the basic mechanisms involved in the export of proteins from the nucleus to the cytoplasm. All proteins over 40kDa use the nuclear pore complex to gain entry or exit from the nucleus, with the primary nuclear export molecule involved in these processes being chromosome region maintenance 1 (CRM1, exportin 1 or XPO1). Proteins exported from the nucleus must possess a hydrophobic nuclear export signal (NES) peptide that binds to a hydrophobic groove containing an active-site Cys528 in the CRM1 protein. CRM1 inhibitors function largely by covalent modification of the active site Cys528 and prevent binding to the cargo protein NES. In the absence of a CRM1 inhibitor, CRM1 binds cooperatively to the NES of the cargo protein and RanGTP, forming a trimer that is actively transported out of the nucleus by facilitated diffusion. Nuclear export can be blocked by CRM1 inhibitors, NES peptide inhibitors or by preventing post-translational modification of cargo proteins. Clinical trials using the classic CRM1 inhibitor leptomycin B proved too toxic for patients; however, a new generation of less toxic small molecule inhibitors is being used in clinical trials in patients with both hematological malignancies and solid tumors. Additional trials are being initiated using small-molecule CRM1 inhibitors in combination with chemotherapeutics such as pegylated liposomal doxorubicin. In this review, we present evidence that combining the new CRM1 inhibitors with other classes of therapeutics may prove effective in the treatment of cancer. Potential combinatorial therapies discussed include the use of CRM1 inhibitors and the addition of alkylating agents (melphalan), anthracyclines (doxorubicin and daunomycin), BRAF inhibitors, platinum drugs (cisplatin and oxaliplatin), proteosome inhibitors (bortezomib and carfilzomib), or tyrosine-kinase inhibitors (imatinib). Also, the sequence of treatment may be important for combination therapy. We found that the most effective treatment regimen involved first priming the cancer cells with the CRM1 inhibitor followed by doxorubicin, bortezomib, carfilzomib, or melphalan. This order sensitized both de novo and acquired drug-resistant cancer cell lines.

Rapid screening of novel agents for combination therapy in sarcomas.

For patients with sarcoma, metastatic disease remains very difficult to cure, and outcomes remain less than optimal. Treatment options have not largely changed, although some promising gains have been made with single agents in specific subtypes with the use of targeted agents. Here, we developed a system to investigate synergy of combinations of targeted and cytotoxic agents in a panel of sarcoma cell lines. Agents were investigated alone and in combination with varying dose ratios. Dose-response curves were analyzed for synergy using methods derived from Chou and Talalay (1984). A promising combination, dasatinib and triciribine, was explored in a murine model using the A673 cell line, and tumors were evaluated by MRI and histology for therapy effect. We found that histone deacetylase inhibitors were synergistic with etoposide, dasatinib, and Akt inhibitors across cell lines. Sorafenib and topotecan demonstrated a mixed response. Our systematic drug screening method allowed us to screen a large number of combinations of sarcoma agents. This method can be easily modified to accommodate other cell line models, and confirmatory assays, such as animal experiments, can provide excellent preclinical data to inform clinical trials for these rare malignancies.