First-in-human study of an OX40 (ivuxolimab) and 4-1BB (utomilumab) agonistic antibody combination in patients with advanced solid tumors

BACKGROUND

Ivuxolimab (PF-04518600) and utomilumab (PF-05082566) are humanized agonistic IgG2 monoclonal antibodies against OX40 and 4-1BB, respectively. This first-in-human, multicenter, open-label, phase I, dose-escalation/dose-expansion study explored safety, tolerability, pharmacokinetics, pharmacodynamics, and antitumor activity of ivuxolimab+utomilumab in patients with advanced solid tumors.

METHODS

Dose-escalation: patients with advanced bladder, gastric, or cervical cancer, melanoma, head and neck squamous cell carcinoma, or non-small cell lung cancer (NSCLC) who were unresponsive to available therapies, had no standard therapy available or declined standard therapy were enrolled into five dose cohorts: ivuxolimab (0.1-3 mg/kg every 2 weeks (Q2W)) intravenously plus utomilumab (20 or 100 mg every 4 weeks (Q4W)) intravenously. Dose-expansion: patients with melanoma (n=10) and NSCLC (n=20) who progressed on prior anti-programmed death receptor 1/programmed death ligand-1 and/or anti-cytotoxic T-lymphocyte-associated antigen 4 (melanoma) received ivuxolimab 30 mg Q2W intravenously plus utomilumab 20 mg Q4W intravenously. Adverse events (AEs) were graded per National Cancer Institute Common Terminology Criteria for Adverse Events V.4.03 and efficacy was assessed using Response Evaluation Criteria in Solid Tumors (RECIST) V.1.1 and immune-related RECIST (irRECIST). Paired tumor biopsies and whole blood were collected to assess pharmacodynamic effects and immunophenotyping. Whole blood samples were collected longitudinally for immunophenotyping.

RESULTS

Dose-escalation: 57 patients were enrolled; 2 (3.5%) patients with melanoma (0.3 mg/kg+20 mg and 0.3 mg/kg+100 mg) achieved partial response (PR), 18 (31.6%) patients achieved stable disease (SD); the disease control rate (DCR) was 35.1% across all dose levels. Dose-expansion: 30 patients were enrolled; 1 patient with NSCLC achieved PR lasting >77 weeks. Seven of 10 patients with melanoma (70%) and 7 of 20 patients with NSCLC (35%) achieved SD: median (range) duration of SD was 18.9 (13.9-49.0) weeks for the melanoma cohort versus 24.1 (14.3-77.9+) weeks for the NSCLC cohort; DCR (NSCLC) was 40%. Grade 3-4 treatment-emergent AEs were reported in 28 (49.1%) patients versus 11 (36.7%) patients in dose-escalation and dose-expansion, respectively. There were no grade 5 AEs deemed attributable to treatment. Ivuxolimab area under the concentration-time curve increased in a dose-dependent manner at 0.3-3 mg/kg doses.

CONCLUSIONS

Ivuxolimab+utomilumab was found to be well tolerated and demonstrated preliminary antitumor activity in selected groups of patients.

TRIAL REGISTRATION NUMBER

NCT02315066.

Tapering thrombopoietin receptor agonists in primary immune thrombocytopenia: Expert consensus based on the RAND/UCLA modified Delphi panel method

BACKGROUND

Thrombopoietin receptor agonists (TPO-RAs) are used to treat primary immune thrombocytopenia (ITP). Some patients have discontinued treatment while maintaining a hemostatic platelet count.

OBJECTIVES

To develop expert consensus on when it is appropriate to consider tapering TPO-RAs in ITP, how to taper patients off therapy, how to monitor patients after discontinuation, and how to restart therapy.

METHODS

We used a RAND/UCLA modified Delphi panel method. Ratings were completed independently by each expert before and after a meeting. Second-round ratings were used to develop the panel's guidance. The panel was double-blinded: The sponsor and nonchair experts did not know each other's identities.

RESULTS

Guidance on when it is appropriate to taper TPO-RAs in children and adults was developed based on patient platelet count, history of bleeding, intensification of treatment, trauma risk, and use of anticoagulants/platelet inhibitors. For example, it is appropriate to taper TPO-RAs in patients who have normal/above-normal platelet counts, have no history of major bleeding, and have not required an intensification of treatment in the past 6 months; it is inappropriate to taper TPO-RAs in patients with low platelet counts. Duration of ITP, months on TPO-RA, or timing of platelet response to TPO-RA did not have an impact on the panel's guidance on appropriateness to taper. Guidance on how to taper patients off therapy, how to monitor patients after discontinuation, and how to restart therapy is also provided.

CONCLUSION

This guidance could support clinical decision making and the development of clinical trials that prospectively test the safety of tapering TPO-RAs.

Baseline Plasma Tumor Mutation Burden Predicts Response to Pembrolizumab-based Therapy in Patients with Metastatic Non-Small Cell Lung Cancer

PURPOSE

The role of plasma-based tumor mutation burden (pTMB) in predicting response to pembrolizumab-based first-line standard-of-care therapy for metastatic non-small cell lung cancer (mNSCLC) has not been explored.

EXPERIMENTAL DESIGN

A 500-gene next-generation sequencing panel was used to assess pTMB. Sixty-six patients with newly diagnosed mNSCLC starting first-line pembrolizumab-based therapy, either alone or in combination with chemotherapy, were enrolled (Clinicaltrial.gov identifier: NCT03047616). Response was assessed using RECIST 1.1. Associations were made for patient characteristics, 6-month durable clinical benefit (DCB), progression-free survival (PFS), and overall survival (OS).

RESULTS

Of 66 patients, 52 (78.8%) were pTMB-evaluable. Median pTMB was 16.8 mutations per megabase (mut/Mb; range, 1.9-52.5) and was significantly higher for patients achieving DCB compared with no durable benefit (21.3 mut/Mb vs. 12.4 mut/Mb, P = 0.003). For patients with pTMB ≥ 16 mut/Mb, median PFS was 14.1 versus 4.7 months for patients with pTMB < 16 mut/Mb [HR, 0.30 (0.16-0.60); P < 0.001]. Median OS for patients with pTMB ≥ 16 was not reached versus 8.8 months for patients with pTMB < 16 mut/Mb [HR, 0.48 (0.22-1.03); P = 0.061]. Mutations in ERBB2 exon 20, STK11, KEAP1, or PTEN were more common in patients with no DCB. A combination of pTMB ≥ 16 and absence of negative predictor mutations was associated with PFS [HR, 0.24 (0.11-0.49); P < 0.001] and OS [HR, 0.31 (0.13-0.74); P = 0.009].

CONCLUSIONS

pTMB ≥ 16 mut/Mb is associated with improved PFS after first-line standard-of-care pembrolizumab-based therapy in mNSCLC. STK11/KEAP1/PTEN and ERBB2 mutations may help identify pTMB-high patients unlikely to respond. These results should be validated in larger prospective studies.

Systematic literature review of treatments used for adult immune thrombocytopenia in the second-line setting

Immune thrombocytopenia (ITP) is a rare platelet disorder that is often persistent or chronic in adults. Patient management is dependent upon physician judgment and patient preference, given both the rarity of the condition and a paucity of high-quality clinical trial evidence to inform practice guidelines. A systematic literature review was conducted to provide an up-to-date summary of studies evaluating the safety and efficacy/effectiveness of therapies used to treat adults with primary ITP in the second-line setting. Using comprehensive search strings, several medical research databases were queried. Final abstraction was performed on 186 articles. Most (75%) studies were observational in nature; nearly half were conducted in Europe. Splenectomy was the most commonly studied (n = 83, 47%), followed by rituximab (n = 49, 26%) and the thrombopoietin-receptor agonists (TPO-RAs) romiplostim (n = 34, 18%) and eltrombopag (n = 24, 13%). Twelve prospective, randomized controlled trials (RCTs) with a placebo or standard-of-care arm evaluating the safety and efficacy of either rituximab or a TPO-RA were identified and described in detail. These trials provide important information on the safety and efficacy of these treatments, and in the absence of head-to-head data, offer insights on how these therapies compare with one another in treating adult ITP in the second-line setting. This review confirms that for most second-line ITP treatment options, there remains a lack of rigorous evidence derived from RCTs, and for many treatments, there is limited evidence of any kind. The need for additional research to guide treatment choices in this setting and greater use of standardized ITP terminology are highlighted.

Epacadostat Plus Pembrolizumab in Patients With Advanced Solid Tumors: Phase I Results From a Multicenter, Open-Label Phase I/II Trial (ECHO-202/KEYNOTE-037)

PURPOSE

Tumors may evade immunosurveillance through upregulation of the indoleamine 2,3-dioxygenase 1 (IDO1) enzyme. Epacadostat is a potent and highly selective IDO1 enzyme inhibitor. The open-label phase I/II ECHO-202/KEYNOTE-037 trial evaluated epacadostat plus pembrolizumab, a programmed death protein 1 inhibitor, in patients with advanced solid tumors. Phase I results on maximum tolerated dose, safety, tolerability, preliminary antitumor activity, and pharmacokinetics are reported.

PATIENTS AND METHODS

Patients received escalating doses of oral epacadostat (25, 50, 100, or 300 mg) twice per day plus intravenous pembrolizumab 2 mg/kg or 200 mg every 3 weeks. During the safety expansion, patients received epacadostat (50, 100, or 300 mg) twice per day plus pembrolizumab 200 mg every 3 weeks.

RESULTS

Sixty-two patients were enrolled and received one or more doses of study treatment. The maximum tolerated dose of epacadostat in combination with pembrolizumab was not reached. Fifty-two patients (84%) experienced treatment-related adverse events (TRAEs), with fatigue (36%), rash (36%), arthralgia (24%), pruritus (23%), and nausea (21%) occurring in ≥ 20%. Grade 3/4 TRAEs were reported in 24% of patients. Seven patients (11%) discontinued study treatment because of TRAEs. No TRAEs led to death. Epacadostat 100 mg twice per day plus pembrolizumab 200 mg every 3 weeks was recommended for phase II evaluation. Objective responses (per Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1) occurred in 12 (55%) of 22 patients with melanoma and in patients with non-small-cell lung cancer, renal cell carcinoma, endometrial adenocarcinoma, urothelial carcinoma, and squamous cell carcinoma of the head and neck. The pharmacokinetics of epacadostat and pembrolizumab and antidrug antibody rate were comparable to historical controls for monotherapies.

CONCLUSION

Epacadostat in combination with pembrolizumab generally was well tolerated and had encouraging antitumor activity in multiple advanced solid tumors.

Rate of bleeding-related episodes in elderly patients with primary immune thrombocytopenia: a retrospective cohort study

OBJECTIVE

Immune thrombocytopenia (ITP) is characterized by low platelet counts and a tendency toward increased bleeding and bruising. We aimed to describe bleeding frequency and use of rescue ITP therapy to treat or prevent bleeding in elderly ITP patients in a real-world setting.

METHODS

Using Medicare 20% sample data, 2007-2012, we identified elderly (ages ≥67 years) Medicare fee-for-service enrollees diagnosed with primary ITP between 1 January 2009 and 30 September 2012. Bleeding-related episodes (BREs) were defined as ≥1 bleeding event or use of ITP therapies commonly considered for rescue or emergency therapy. BRE rates were examined for the cohort overall, by time since ITP onset, and by splenectomy status. Patients were followed from ITP onset until the earliest of death, disenrollment from fee-for-service coverage, or 31 December 2012.

RESULTS

We identified 3007 elderly patients diagnosed with primary ITP (mean [SD] age: 79.6 [7.5] years; 55% female); 2178 (72%) experienced at least one BRE (8867 BREs); 92 (3%) underwent splenectomy. Nearly half of BREs were defined by rescue therapy use alone. The overall rate was 1.72 BREs per patient-year (95% CI; 1.68-1.75); rates were higher during the first 3 months after ITP onset and after splenectomy.

CONCLUSION

Elderly ITP patients experienced about two BREs per patient-year after ITP onset. Most patients experienced at least one BRE. These real-world results demonstrate the importance of examining both bleeding and use of rescue or emergency ITP therapy in the assessment of disease burden in elderly patients with ITP.

Cytokines and metabolic factors regulate tumoricidal T-cell function during cancer immunotherapy

Recent advances in cancer biology and genetics have fostered precision therapies targeting tumor-specific attributes. Immune-based therapies that elicit cytolytic T cells (CTL) specific for tumor antigens can provide therapeutic benefit to cancer patients, however, cure rates are typically low. This largely results from immunosuppressive mechanisms operating within the tumor microenvironment, many of which inflict metabolic stresses upon CTL. Conversely, immunotherapies can mitigate specific metabolic stressors. For instance, dual costimulation immunotherapy with CD134 (OX40) plus CD137 (4-1BB) agonists appears to mediate tumor control in part by engaging cytokine networks that enable infiltrating CTL to compete for limiting supplies of glucose. Future efforts combining modalities that endow CTL with complimentary metabolic advantages should improve therapeutic efficacies.

Safety of epacadostat 100 mg bid plus pembrolizumab 200 mg Q3W in advanced solid tumors: Phase 2 data from ECHO-202/KEYNOTE-037

3012

Background: The immunosuppressive enzyme indoleamine 2, 3-dioxygenase 1 (IDO1) facilitates immune tolerance in cancer via T-cell suppression, and IDO1 overexpression is associated with poor survival. Epacadostat, an oral inhibitor of IDO1, has been shown to be well tolerated as monotherapy and in combination with checkpoint inhibitors. ECHO-202/KEYNOTE-037 is a phase 1/2 study evaluating the safety and efficacy of oral epacadostat plus IV pembrolizumab in patients (pts) with advanced tumors. Based on phase 1 outcomes, epacadostat 100 mg BID plus pembrolizumab 200 mg Q3W was selected for phase 2 evaluation. This analysis summarizes phase 2 safety experience in the overall population of ECHO-202/KEYNOTE-037 (pooled across tumor types) at an October 29, 2016 data cutoff. Methods: Phase 2 pts were ≥18 years of age with advanced or recurrent melanoma (MEL), non–small cell lung cancer (NSCLC), renal cell carcinoma (RCC), urothelial carcinoma (UC), triple-negative breast cancer, squamous cell carcinoma of head and neck (SCCHN), ovarian cancer, diffuse large B-cell lymphoma, or microsatellite instability–high colorectal cancer. Results: The overall safety population comprised 244 pts receiving ≥1 study treatment dose. Median age was 63 years, 52% were women, and 91% were white. As of data cutoff, 134 study pts (55%) discontinued study treatment, primarily due to disease progression (n = 97). Median exposure to study treatment was 86 days (range, 1–374 days). TRAEs occurring in ≥5% of pts were fatigue (23%); rash (16%); diarrhea and nausea (7% each); increased alanine aminotransferase, increased aspartate aminotransferase, and pruritus (6% each); and pyrexia (5%). A total of 37 pts (15%) had grade ≥3 TRAEs; the most common grade ≥3 TRAEs were increased lipase (asymptomatic) and rash (3% each). TRAEs led to discontinuation in 3% of pts. Conclusions: Epacadostat 100 mg BID plus pembrolizumab 200 mg Q3W was associated with an acceptable safety profile in pts with advanced cancers, supporting continued evaluation of the combination. The phase 3 ECHO-301/KEYNOTE-252 MEL study is ongoing and additional phase 3 studies (NSCLC, UC, RCC, SCCHN) are planned. Clinical trial information: NCT02178722.

Epacadostat plus pembrolizumab in patients with SCCHN: Preliminary phase I/II results from ECHO-202/KEYNOTE-037

6010

Background: Indoleamine 2,3-dioxygenase 1 (IDO1) is a tryptophan-catabolizing enzyme that induces immune tolerance by T-cell suppression. IDO1 overexpression has been associated with poor survival in SCCHN. Epacadostat (E) is a potent, selective oral IDO1 inhibitor. ECHO-202/KEYNOTE-037 is an open-label, phase I/II (P1/2) study evaluating E plus PD-1 inhibitor pembrolizumab (P) in multiple tumor types. We report preliminary P1/2 efficacy, safety, and tolerability findings in the SCCHN cohort as of a 29OCT2016 data cutoff. Methods: Eligible adult patients (pts) had metastatic SCCHN and received ≥1 prior chemotherapy regimen that included a platinum agent. Prior checkpoint inhibitor therapy (tx) was not permitted, and pts with carcinoma of the nasopharynx or salivary gland were excluded. In P1 dose escalation (3+3+3), pts received E (25, 50, 100, or 300 mg PO BID) + P (2 mg/kg or 200 mg IV Q3W); MTD was not exceeded. E (100 mg BID) + P (200 mg Q3W) dosing was selected for P2 cohort expansion. Response was assessed in RECIST 1.1 evaluable pts. Results: A total of38 pts (P1, n = 2; P2, n = 36) were evaluated. Median age was 63 years, 87% of pts were men, 95% were white, and 66% received prior cetuximab. Of 36 efficacy-evaluable pts, 81% (n = 29) received 1–2 prior lines of tx and 19% (n = 7) received ≥3 prior lines of tx. ORR (CR+PR) and DCR (CR+PR+SD) for pts with 1–2 prior tx were 34% (2 CR, 8 PR) and 62% (8 SD), respectively; for pts with ≥3 prior tx, ORR and DCR were 14% (1 PR) and 43% (2 SD). Response was observed regardless of HPV status. At data cutoff, 9/11 responses were ongoing (range, 1+ to 563+ days). PFS and biomarker analyses are ongoing. The most common TRAEs in all 38 pts were fatigue (24%), nausea (11%), and decreased weight (11%). Grade ≥3 TRAEs occurred in 11% of pts; only increased amylase and lipase (both asymptomatic) were grade ≥3 TRAEs that occurred in > 1 pt. TRAEs led to discontinuation in 1 pt (increased amylase and lipase). Conclusions: In pts with advanced SCCHN, E + P was generally well tolerated and associated with encouraging response rates, particularly in pts with 1–2 prior lines of tx. A phase III SCCHN study is planned. Clinical trial information: NCT02178722.

Epacadostat plus pembrolizumab in patients with advanced urothelial carcinoma: Preliminary phase I/II results of ECHO-202/KEYNOTE-037

4503

Background: Pembrolizumab (P), a PD-1 inhibitor, is active and well tolerated in platinum-treated, advanced urothelial carcinoma (UC). Epacadostat (E) potently and selectively inhibits indoleamine 2,3-dioxygenase 1 (IDO1), a tryptophan-catabolizing enzyme that suppresses T-cell–mediated immune surveillance. IDO1 overexpression is associated with tumor progression and shortened patient (pt) survival. ECHO-202/KEYNOTE-037 is an open-label, phase I/II study of E + P in pts with advanced tumors. We report phase I/II efficacy and safety outcomes for the UC cohort at an October 29, 2016 data cutoff. Methods: Adult pts with advanced UC, prior platinum therapy (adjuvant or advanced disease setting) or alternative therapy (if platinum was not appropriate), and no prior checkpoint inhibitor therapy were eligible to participate. In phase I, pts received E (25, 50, 100, or 300 mg PO BID) + P (2 mg/kg or 200 mg IV Q3W); MTD was not exceeded. E (100 mg BID) + P (200 mg Q3W) dosing was selected for phase II. Response was assessed in RECIST 1.1–evaluable pts. Safety was assessed in pts receiving ≥1 E + P dose. Results: A total of 40 pts (phase I, n = 5; phase II, n = 35) were evaluated. Median age was 67 years, 75% were men, 88% were white, 100% had prior platinum therapy, and 75% had 0–1 prior line of therapy for advanced disease. Preliminary ORR (CR+PR) and DCR (CR+PR+SD) for all efficacy-evaluable pts were 35% (13/37; all PR) and 57% (21/37; 13 PR, 8 SD), respectively; for pts with 0–1 prior line of therapy for advanced disease, ORR and DCR were 37% (10/27) and 63% (17/27). At data cutoff, 12/13 responses were ongoing (range, 1+ to 652+ days). PFS and biomarker analyses are ongoing. The most common TRAEs (≥10% of 40 pts) were fatigue (28%), rash (18%), and increased amylase (10%; asymptomatic). Grade ≥3 TRAEs occurred in 20% of pts (rash was the only grade ≥3 TRAE to occur in > 1 pt [n = 3]). Three pts discontinued due to TRAEs (grade 3 rash [n = 1]; grade 3 COPD exacerbation [n = 1], grade 2 diarrhea [n = 1]). Conclusions: E + P was generally well tolerated and associated with increased response compared with previously reported PD-1 inhibitor monotherapy in pts with advanced UC. A phase III UC study is planned. Clinical trial information: NCT02178722.

Efficacy and safety of epacadostat plus pembrolizumab treatment of NSCLC: Preliminary phase I/II results of ECHO-202/KEYNOTE-037

9014

Background: ECHO-202/KEYNOTE-037 is an open-label, phase 1/2 study of epacadostat (a potent and selective oral inhibitor of the immunosuppressive enzyme indoleamine 2,3-dioxygenase 1) plus pembrolizumab (E + P) in patients (pts) with advanced tumors. We report preliminary efficacy and safety outcomes for the phase 1/2 NSCLC cohort. Methods: Adult pts with prior platinum-based therapy (tx) and no prior checkpoint inhibitor tx were eligible. Phase 1 dose-escalation tx was E (25, 50, 100, 300 mg PO BID) + P (2 mg/kg or 200 mg IV Q3W); MTD was not exceeded. E (100 mg BID) + P (200 mg Q3W) tx doses were selected for phase 2 cohort expansion. Efficacy was evaluated by tumor proportion score (TPS [% viable tumor cells, PD-L1 staining]: < 50% and ≥50%) and by prior lines of tx in RECIST 1.1 evaluable pts. Safety was assessed in pts receiving ≥1 E + P dose. Results: As of 29OCT2016,43 pts (phase 1, n = 12; phase 2, n = 31) were evaluated. Median age was 65 years, 58% of pts were women, 12% were EGFR-positive, and 23% were KRAS-positive. Most pts had a history of smoking (84%), ≤2 prior lines of tx (84%), and no prior TKI tx (93%). For the 40 efficacy-evaluable pts, ORR (CR+PR) and DCR (CR+PR+SD) were 35% (14/40; 14 PR) and 60% (24/40; 10 SD), respectively. PD-L1 TPS test results were available in 28/40 efficacy-evaluable pts. ORR and DCR for pts with TPS ≥50% and ≤2 prior tx were 43% (3/7; all PR) and 57% (4/7; 1 SD), respectively; for pts with TPS < 50% and ≤2 prior tx, ORR and DCR were 35% (6/17; all PR) and 53% (9/17; 3 SD). Among the 40 efficacy-evaluable pts, 12/14 responses were ongoing (range, 1+ to 519 days) at data cutoff. PFS and biomarker analyses are ongoing. Across all 43 pts, most frequent TRAEs were fatigue (19%), arthralgia (9%), and increased AST (9%); 16% of pts had grade ≥3 TRAEs, and increased lipase (asymptomatic) was the only grade ≥3 TRAE that occurred in > 1 pt (n = 2). Two pts discontinued due to TRAEs (grade 3 increased AST, grade 2 increased ALT [n = 1]; grade 2 brain edema [n = 1]). Conclusions: E + P was generally well tolerated and associated with promising responses in pts with NSCLC. A phase 3 NSCLC study is planned. Clinical trial information: NCT02178722.

Efficacy/safety of epacadostat plus pembrolizumab in triple-negative breast cancer and ovarian cancer: Phase I/II ECHO-202 study

1103

Background: Epacadostat is an oral, potent, and selective inhibitor of indoleamine 2,3-dioxygenase 1, a tryptophan-catabolizing enzyme that induces immune tolerance via T-cell suppression and is associated with poor patient (pt) survival when overexpressed in some cancers. The ongoing, open-label, phase 1/2 (P1/2) ECHO-202/KEYNOTE-037 study is evaluating the efficacy, safety, and tolerability of epacadostat plus PD-1 inhibitor pembrolizumab (E + P) in pts with advanced/recurrent cancers. We report P1/2 study outcomes for triple-negative breast cancer (TNBC) pts and P2 outcomes for ovarian cancer (OVC; no P1) pts as of a 29OCT2016 data cutoff. Methods: Eligible pts were ≥18 years old with no prior checkpoint inhibitor treatment (tx); prior platinum/taxane tx was required for OVC pts. As part of P1 dose escalation, TNBC pts received E (300 mg BID) + P (200 mg Q3W). In P2, TNBC and OVC pts received E (100 mg BID) + P (200 mg Q3W). Response (RECIST v1.1) was assessed in evaluable pts. Safety and tolerability were assessed in pts with ≥1 dose of E + P. Results: A total of 39 pts with TNBC and 37 with OVC were enrolled. The majority of TNBC pts (56%, n = 22) and OVC pts (78%, n = 29) received ≥3 prior lines of tx. For TNBC pts, ORR (CR+PR) was 10% (n = 4; all PR) and DCR (CR+PR+SD) was 36% (n = 14; 10 SD); ORR and DCR for pts with ≤2 prior tx were 12% (n = 2) and 29% (n = 5), respectively, and for ≥3 prior tx were 9% (n = 2) and 41% (n = 9). For OVC pts, ORR was 8% (n = 3; all PR) and DCR was 35% (n = 13; 10 SD); ORR and DCR for pts with ≤2 prior tx were 13% (n = 1) and 25% (n = 2), and for ≥3 prior tx were 7% (n = 2) and 38% (n = 11). The most common TRAEs (≥15% of pts) were rash (18%), fatigue (15%), and nausea (15%) in the 39 TNBC pts, and fatigue (19%) in the 37 OVC pts. Grade ≥3 TRAEs occurred in 13% of TNBC pts (n = 5; none in > 1 pt) and 19% of OVC pts (n = 7; only rash occurred in > 1 pt [n = 3]). TRAEs led to discontinuation in 1 TNBC pt (grade 3 ascites) and 1 OVC pt (grade 2 arthralgia). Conclusions: E + P tx was generally well tolerated and showed antitumor activity consistent with previously reported P monotherapy in pts with advanced TNBC or OVC. Biomarker analysis is ongoing to characterize pt populations enrolled in this study. Clinical trial information: NCT02178722.

A novel, dual-specific antibody conjugate targeting CD134 and CD137 costimulates T cells and elicits antitumor immunity

Checkpoint inhibiting antibodies targeting CTLA-4 and PD-1, along with costimulatory agonists, exhibit impressive anticancer efficacy and evidence of durable tumor regression in patients. Despite this success however, many patients fail to respond, likely due to multiple immunosuppressive tactics employed by cancer cells. Combination therapies designed to counteract these immunosuppressive features show promise, but strategies relying on multiple agents suffer from logistical and regulatory challenges, as well as increased risks of adverse events. We developed a novel immunotherapeutic agent by fusing two TNFR family costimulatory agonists (anti-CD134/CD137) into a single biologic encompassing the therapeutic benefits of both agents while avoiding many of the drawbacks associated with traditional combination therapies. Our preliminary data show that this dual-specific, tetravalent antibody conjugate induces potent and differential in vitro potentiation of cytokine secretion from CD3-stimulated splenocytes, compared to that observed with single agonists alone or in combination. We hypothesize that this a consequence of unique signaling and hybrid costimulatory events. Secondly, this conjugate, referred to as OrthomAb, potently delayed tumor growth and reduced tumor burden in the aggressive B16 melanoma model. In vivo antitumor efficacy exceeded that of either individual unconjugated agonist. Importantly, this work establishes a framework for fusion of immunomodulatory biologics into a single drug with the benefit of combination immunotherapy to treat cancer.

Melanoma and immunotherapy bridge 2015 : Naples, Italy. 1-5 December 2015

MELANOMA BRIDGE 2015

KEYNOTE SPEAKER PRESENTATIONS

Molecular and immuno-advances

K1 Immunologic and metabolic consequences of PI3K/AKT/mTOR activation in melanoma

Vashisht G. Y. Nanda, Weiyi Peng, Patrick Hwu, Michael A. Davies

K2 Non-mutational adaptive changes in melanoma cells exposed to BRAF and MEK inhibitors help the establishment of drug resistance

Gennaro Ciliberto, Luigi Fattore, Debora Malpicci, Luigi Aurisicchio, Paolo Antonio Ascierto, Carlo M. Croce, Rita Mancini

K3 Tumor-intrinsic beta-catenin signaling mediates tumor-immune avoidance

Stefani Spranger, Thomas F. Gajewski

K4 Intracellular tumor antigens as a source of targets of antibody-based immunotherapy of melanoma

Yangyang Wang, Soldano Ferrone

Combination therapies

K5 Harnessing radiotherapy to improve responses to immunotherapy in cancer

Claire Vanpouille-Box, Erik Wennerberg, Karsten A. Pilones, Silvia C. Formenti, Sandra Demaria

K6 Creating a T cell-inflamed tumor microenvironment overcomes resistance to checkpoint blockade

Haidong Tang, Yang Wang, Yang-Xin Fu

K7 Biomarkers for treatment decisions?

Reinhard Dummer

K8 Combining oncolytic therapies in the era of checkpoint inhibitors

Igor Puzanov

K9 Immune checkpoint blockade for melanoma: should we combine or sequence ipilimumab and PD-1 antibody therapy?

Michael A. Postow

News in immunotherapy

K10 An update on adjuvant and neoadjuvant therapy for melanom

Ahmad Tarhini

K11 Targeting multiple inhibitory receptors in melanoma

Joe-Marc Chauvin, Ornella Pagliano, Julien Fourcade, Zhaojun Sun, Hong Wang, Cindy Sanders, John M. Kirkwood, Tseng-hui Timothy Chen, Mark Maurer, Alan J. Korman, Hassane M. Zarour

K12 Improving adoptive immune therapy using genetically engineered T cells

David F. Stroncek

Tumor microenvironment and biomarkers

K13 Myeloid cells and tumor exosomes: a crosstalk for assessing immunosuppression?

Veronica Huber, Licia Rivoltini

K14 Update on the SITC biomarker taskforce: progress and challenges

Magdalena Thurin

World-wide immunoscore task force: an update

K15 The immunoscore in colorectal cancer highlights the importance of digital scoring systems in surgical pathology

Tilman Rau, Alessandro Lugli

K16 The immunoscore: toward an integrated immunomonitoring from the diagnosis to the follow up of cancer’s patients

Franck Pagès

Economic sustainability of melanoma treatments: regulatory, health technology assessment and market access issues

K17 Nivolumab, the regulatory experience in immunotherapy

Jorge Camarero, Arantxa Sancho

K18 Evidence to optimize access for immunotherapies

Claudio Jommi

ORAL PRESENTATIONS

Molecular and immuno-advances

O1 Ipilimumab treatment results in CD4 T cell activation that is concomitant with a reduction in Tregs and MDSCs

Yago Pico de Coaña, Maria Wolodarski, Yuya Yoshimoto, Giusy Gentilcore, Isabel Poschke, Giuseppe V. Masucci, Johan Hansson, Rolf Kiessling

O2 Evaluation of prognostic and therapeutic potential of COX-2 and PD-L1 in primary and metastatic melanoma

Giosuè Scognamiglio, Francesco Sabbatino, Federica Zito Marino, Anna Maria Anniciello, Monica Cantile, Margherita Cerrone, Stefania Scala, Crescenzo D’alterio, Angela Ianaro, Giuseppe Cirino, Paolo Antonio Ascierto, Giuseppina Liguori, Gerardo Botti

O3 Vemurafenib in patients with BRAFV600 mutation–positive metastatic melanoma: final overall survival results of the BRIM-3 study

Paul B. Chapman, Caroline Robert, James Larkin, John B. Haanen, Antoni Ribas, David Hogg, Omid Hamid, Paolo Antonio Ascierto, Alessandro Testori, Paul Lorigan, Reinhard Dummer, Jeffrey A. Sosman, Keith T. Flaherty, Huibin Yue, Shelley Coleman, Ivor Caro, Axel Hauschild, Grant A. McArthur

O4 Updated survival, response and safety data in a phase 1 dose-finding study (CA209-004) of concurrent nivolumab (NIVO) and ipilimumab (IPI) in advanced melanoma

Mario Sznol, Margaret K. Callahan, Harriet Kluger, Michael A. Postow, RuthAnn Gordan, Neil H. Segal, Naiyer A. Rizvi, Alexander Lesokhin, Michael B. Atkins, John M. Kirkwood, Matthew M. Burke, Amanda Ralabate, Angel Rivera, Stephanie A. Kronenberg, Blessing Agunwamba, Mary Ruisi, Christine Horak, Joel Jiang, Jedd Wolchok

Combination therapies

O5 Efficacy and correlative biomarker analysis of the coBRIM study comparing cobimetinib (COBI) + vemurafenib (VEM) vs placebo (PBO) + VEM in advanced BRAF-mutated melanoma patients (pts)

Paolo A. Ascierto, Grant A. McArthur, James Larkin, Gabriella Liszkay, Michele Maio, Mario Mandalà, Lev Demidov, Daniil Stoyakovskiy, Luc Thomas, Luis de la Cruz-Merino, Victoria Atkinson, Caroline Dutriaux, Claus Garbe, Matthew Wongchenko, Ilsung Chang, Daniel O. Koralek, Isabelle Rooney, Yibing Yan, Antoni Ribas, Brigitte Dréno

O6 Preliminary clinical safety, tolerability and activity results from a Phase Ib study of atezolizumab (anti-PDL1) combined with vemurafenib in BRAFV600-mutant metastatic melanoma

Ryan Sullivan, Omid Hamid, Manish Patel, Stephen Hodi, Rodabe Amaria, Peter Boasberg, Jeffrey Wallin, Xian He, Edward Cha, Nicole Richie, Marcus Ballinger, Patrick Hwu

O7 Preliminary safety and efficacy data from a phase 1/2 study of epacadostat (INCB024360) in combination with pembrolizumab in patients with advanced/metastatic melanoma

Thomas F. Gajewski, Omid Hamid, David C. Smith, Todd M. Bauer, Jeffrey S. Wasser, Jason J. Luke, Ani S. Balmanoukian, David R. Kaufman, Yufan Zhao, Janet Maleski, Lance Leopold, Tara C. Gangadhar

O8 Primary analysis of MASTERKEY-265 phase 1b study of talimogene laherparepvec (T-VEC) and pembrolizumab (pembro) for unresectable stage IIIB-IV melanoma

Reinhard Dummer, Georgina V. Long, Antoni Ribas, Igor Puzanov, Olivier Michielin, Ari VanderWalde, Robert H.I. Andtbacka, Jonathan Cebon, Eugenio Fernandez, Josep Malvehy, Anthony J. Olszanski, Thomas F. Gajewski, John M. Kirkwood, Christine Gause, Lisa Chen, David R. Kaufman, Jeffrey Chou, F. Stephen Hodi

News in immunotherapy

O9 Two-year survival and safety update in patients (pts) with treatment-naïve advanced melanoma (MEL) receiving nivolumab (NIVO) or dacarbazine (DTIC) in CheckMate 066

Victoria Atkinson, Paolo A. Ascierto, Georgina V. Long, Benjamin Brady, Caroline Dutriaux, Michele Maio, Laurent Mortier, Jessica C. Hassel, Piotr Rutkowski, Catriona McNeil, Ewa Kalinka-Warzocha, Celeste Lebbé, Lars Ny, Matias Chacon, Paola Queirolo, Carmen Loquai, Parneet Cheema, Alfonso Berrocal, Karmele Mujika Eizmendi, Luis De La Cruz-Merino, Gil Bar-Sela, Christine Horak, Joel Jiang, Helene Hardy, Caroline Robert

O10 Efficacy and safety of nivolumab (NIVO) in patients (pts) with advanced melanoma (MEL) who were treated beyond progression in CheckMate 066/067

Georgina V. Long, Jeffrey S. Weber, James Larkin, Victoria Atkinson, Jean-Jacques Grob, Reinhard Dummer, Caroline Robert, Ivan Marquez-Rodas, Catriona McNeil, Henrik Schmidt, Karen Briscoe, Jean-François Baurain, F. Stephen Hodi, Jedd D. Wolchok

Tumor microenvironment and biomarkers

O11 New biomarkers for response/resistance to BRAF inhibitor therapy in metastatic melanoma

Rosamaria Pinto, Simona De Summa, Vito Michele Garrisi, Sabino Strippoli, Amalia Azzariti, Gabriella Guida, Michele Guida, Stefania Tommasi

O12 Chemokine receptor patterns in lymphocytes mirror metastatic spreading in melanoma and response to ipilimumab

Nicolas Jacquelot, David Enot, Caroline Flament, Jonathan M. Pitt, Nadège Vimond, Carolin Blattner, Takahiro Yamazaki, Maria-Paula Roberti, Marie Vetizou, Romain Daillere, Vichnou Poirier-Colame, Michaëla Semeraro, Anne Caignard, Craig L Slingluff Jr, Federica Sallusto, Sylvie Rusakiewicz, Benjamin Weide, Aurélien Marabelle, Holbrook Kohrt, Stéphane Dalle, Andréa Cavalcanti, Guido Kroemer, Anna Maria Di Giacomo, Michaele Maio, Phillip Wong, Jianda Yuan, Jedd Wolchok, Viktor Umansky, Alexander Eggermont, Laurence Zitvogel

O13 Serum levels of PD1- and CD28-positive exosomes before Ipilimumab correlate with therapeutic response in metastatic melanoma patients

Passarelli Anna, Tucci Marco, Stucci Stefania, Mannavola Francesco, Capone Mariaelena, Madonna Gabriele, Ascierto Paolo Antonio, Silvestris Franco

O14 Immunological prognostic factors in stage III melanomas

María Paula Roberti, Nicolas Jacquelot, David P Enot, Sylvie Rusakiewicz, Michaela Semeraro, Sarah Jégou, Camila Flores, Lieping Chen, Byoung S. Kwon, Ana Carrizossa Anderson, Caroline Robert, Christophe Borg, Benjamin Weide, François Aubin, Stéphane Dalle, Michele Maio, Jedd D. Wolchok, Holbrook Kohrt, Maha Ayyoub, Guido Kroemer, Aurélien Marabelle, Andréa Cavalcanti, Alexander Eggermont, Laurence Zitvogel

POSTER PRESENTATIONS

Molecular and immuno-advances

P1 Human melanoma cells resistant to B-RAF and MEK inhibition exhibit mesenchymal-like features

Anna Lisa De Presbiteris, Fabiola Gilda Cordaro, Rosa Camerlingo, Federica Fratangelo, Nicola Mozzillo, Giuseppe Pirozzi, Eduardo J. Patriarca, Paolo A. Ascierto, Emilia Caputo

P2 Anti-proliferative and pro-apoptotic effect of ABT888 on melanoma cell lines and its potential role in the treatment of melanoma resistant to B-RAF inhibitors

Federica Fratangelo, Rosa Camerlingo, Emilia Caputo, Maria Letizia Motti, Rosaria Falcone, Roberta Miceli, Mariaelena Capone, Gabriele Madonna, Domenico Mallardo, Maria Vincenza Carriero, Giuseppe Pirozzi and Paolo Antonio Ascierto

P3 Involvement of the L-cysteine/CSE/H2S pathway in human melanoma progression

Elisabetta Panza, Paola De Cicco, Chiara Armogida, Giuseppe Ercolano, Rosa Camerlingo, Giuseppe Pirozzi, Giosuè Scognamiglio, Gerardo Botti, Giuseppe Cirino, Angela Ianaro

P4 Cancer stem cell antigen revealing pattern of antibody variable region genes were defined by immunoglobulin repertoire analysis in patients with malignant melanoma

Beatrix Kotlan, Gabriella Liszkay, Miri Blank, Timea Balatoni, Judit Olasz, Emil Farkas, Andras Szollar, Akos Savolt, Maria Godeny, Orsolya Csuka, Szabolcs Horvath, Klara Eles, Yehuda Shoenfeld and Miklos Kasler

P5 Upregulation of Neuregulin-1 expression is a hallmark of adaptive response to BRAF/MEK inhibitors in melanoma

Debora Malpicci, Luigi Fattore, Susan Costantini, Francesca Capone, Paolo Antonio Ascierto, Rita Mancini, Gennaro Ciliberto

P6 HuR positively regulates migration of HTB63 melanoma cells

Farnaz Moradi, Pontus Berglund, Karin Leandersson, Rickard Linnskog, Tommy Andersson, Chandra Prakash Prasad

P7 Prolyl 4- (C-P4H) hydroxylases have opposing effects in malignant melanoma: implication in prognosis and therapy

Cristiana Lo Nigro, Laura Lattanzio, Hexiao Wang, Charlotte Proby, Nelofer Syed, Marcella Occelli, Carolina Cauchi, Marco Merlano, Catherine Harwood, Alastair Thompson, Tim Crook

P8 Urokinase receptor antagonists: novel agents for the treatment of melanoma

Maria Letizia Motti, Katia Bifulco, Vincenzo Ingangi, Michele Minopoli, Concetta Ragone, Federica Fratangelo, Antonello Pessi, Gennaro Ciliberto, Paolo Antonio Ascierto, Maria Vincenza Carriero

P9 Exosomes released by melanoma cell lines enhance chemotaxis of primary tumor cells

Francesco Mannavola, Stella D’Oronzo, Claudia Felici, Marco Tucci, Antonio Doronzo, Franco Silvestris

P10 New insights in mitochondrial metabolic reprogramming in melanoma

Anna Ferretta, Gabriella Guida, Stefania Guida, Imma Maida, Tiziana Cocco, Sabino Strippoli, Stefania Tommasi, Amalia Azzariti, Michele Guida

P11 Lenalidomide restrains the proliferation in melanoma cells through a negative regulation of their cell cycle

Stella D’Oronzo, Anna Passarelli, Claudia Felici, Marco Tucci, Davide Quaresmini, Franco Silvestris

Combination therapies

P12 Chemoimmunotherapy elicits polyfunctional anti-tumor CD8 + T cells depending on the activation of an AKT pathway sustained by ICOS

Ornella Franzese, Belinda Palermo, Cosmo Di Donna, Isabella Sperduti, MariaLaura Foddai, Helena Stabile, Angela Gismondi, Angela Santoni, Paola Nisticò

P13 Favourable toxicity profile of combined BRAF and MEK inhibitors in metastatic melanoma patients

Andrea P. Sponghini, Francesca Platini, Elena Marra, David Rondonotti, Oscar Alabiso, Maria T. Fierro, Paola Savoia, Florian Stratica, Pietro Quaglino

P14 Electrothermal bipolar vessel sealing system dissection reduces seroma output or time to drain removal following axillary and ilio-inguinal node dissection in melanoma patients: a pilot study

Di Monta Gianluca, Caracò Corrado, Di Marzo Massimiliano, Marone Ugo, Di Cecilia Maria Luisa, Mozzillo Nicola

News in immunotherapy

P15 Clinical and immunological response to ipilimumab in a metastatic melanoma patient with HIV infection

Francesco Sabbatino, Celeste Fusciello1, Antonio Marra, Rosario Guarrasi, Carlo Baldi, Rosa Russo, Di Giulio Giovanni, Vincenzo Faiola, Pio Zeppa, Stefano Pepe

P16 Immunotherapy and hypophysitis: a case report

Elisabetta Gambale, Consiglia Carella, Alessandra Di Paolo, Michele De Tursi

Tumor microenvironment and biomarkers

P17 New immuno- histochemical markers for the differential diagnosis of atypical melanocytic lesions with uncertain malignant potential

Laura Marra, Giosuè Scognamiglio, Monica Cantile, Margherita Cerrone, Fara De Murtas, Valeria Sorrentino, Anna Maria Anniciello, Gerardo Botti

P18 Utility of simultaneous measurement of three serum tumor markers in melanoma patients

Angela Sandru, Silviu Voinea, Eugenia Panaitescu, Madalina Bolovan, Adina Stanciu, Sabin Cinca

P19 The significance of various cut-off levels of melanoma inhibitory activity in evaluation of cutaneous melanoma patients

Angela Sandru, Silviu Voinea, Eugenia Panaitescu, Madalina Bolovan, Adina Stanciu, Sabin Cinca

P20 The long noncoding RNA HOTAIR is associated to metastatic progression of melanoma and it can be identified in the blood of patients with advanced disease

Chiara Botti, Giosuè Scognamiglio, Laura Marra, Gabriella Aquino, Rosaria Falcone, Annamaria Anniciello, Paolo Antonio Ascierto, Gerardo Botti, Monica Cantile

Other

P21 The effect of Sentinel Lymph Node Biopsy in melanoma mortality: timing of dissection

Cristina Fortes, Simona Mastroeni, Alessio Caggiati, Francesca Passarelli, Alba Zappalà, Maria Capuano, Riccardo Bono, Maurizio Nudo, Claudia Marino, Paola Michelozzi

P22 Epidemiological survey on related psychopathology in melanoma

Valeria De Biasio, Vincenzo C. Battarra

IMMUNOTHERAPY BRIDGE

KEYNOTE SPEAKER PRESENTATIONS

Immunotherapy beyond melanoma

K19 Predictor of response to radiation and immunotherapy

Silvia Formenti

K20 Response and resistance to PD-1 pathway blockade: clues from the tumor microenvironment

Maria Libera Ascierto, Tracee L. McMiller, Alan E. Berger, Ludmila Danilova, Robert A. Anders, George J. Netto, Haiying Xu, Theresa S. Pritchard, Jinshui Fan, Chris Cheadle, Leslie Cope, Charles G. Drake, Drew M. Pardoll, Janis M. Taube and Suzanne L. Topalian

K21 Combination immunotherapy with autologous stem cell transplantation, protein immunization, and PBMC reinfusion in myeloma patients

Sacha Gnjatic, Sarah Nataraj, Naoko Imai, Adeeb Rahman, Achim A. Jungbluth, Linda Pan, Ralph Venhaus, Andrew Park, Frédéric F. Lehmann, Nikoletta Lendvai, Adam D. Cohen, and Hearn J. Cho

K22 Anti-cancer immunity despite T cell “exhaustion”

Speiser Daniel

Immunotherapy in oncology (I-O): data from clinical trial

K23 The Checkpoint Inhibitors for the Treatment of Metastatic Non-small Cell Lung Cancer (NSCLC)

Vera Hirsh

Rate of bleeding-related episodes in adult patients with primary immune thrombocytopenia: a retrospective cohort study using a large administrative medical claims database in the US

Background

Methods

Results

Conclusion

Enhancing the safety of antibody-based immunomodulatory cancer therapy without compromising therapeutic benefit: Can we have our cake and eat it too?

INTRODUCTION

Monoclonal antibodies (mAbs) targeting checkpoint inhibitors have demonstrated clinical benefit in treating patients with cancer and have paved the way for additional immune-modulating mAbs such as those targeting costimulatory receptors. The full clinical utility of these agents, however, is hampered by immune-related adverse events (irAEs) that can occur during therapy.

AREAS COVERED

We first provide a general overview of tumor immunity, followed by a review of the two major classes of immunomodulatory mAbs being developed as cancer therapeutics: checkpoint inhibitors and costimulatory receptor agonists. We then discuss therapy-associated adverse events. Finally, we describe in detail the mechanisms driving their therapeutic activity, with an emphasis on interactions between antibody fragment crystallizable (Fc) domains and Fc receptors (FcR).

EXPERT OPINION

Given that Fc-FcR interactions appear critical in facilitating the ability of immunomodulatory mAbs to elicit both therapeutically useful as well as adverse effects, the engineering of mAbs that can effectively engage their targets while limiting interaction with FcRs might represent a promising future avenue for developing the next generation of immune-enhancing tumoricidal agents with increased safety and retention of efficacy.

Tumor-Unrelated CD4 T Cell Help Augments CD134 plus CD137 Dual Costimulation Tumor Therapy

The ability of immune-based cancer therapies to elicit beneficial CD8(+) CTLs is limited by tolerance pathways that inactivate tumor-specific CD4 Th cells. A strategy to bypass this problem is to engage tumor-unrelated CD4 Th cells. Thus, CD4 T cells, regardless of their specificity per se, can boost CD8(+) CTL priming as long as the cognate epitopes are linked via presentation on the same dendritic cell. In this study, we assessed the therapeutic impact of engaging tumor-unrelated CD4 T cells during dual costimulation with CD134 plus CD137 that provide help via the above-mentioned classical linked pathway, as well as provide nonlinked help that facilitates CTL function in T cells not directly responding to cognate Ag. We found that engagement of tumor-unrelated CD4 Th cells dramatically boosted the ability of dual costimulation to control the growth of established B16 melanomas. Surprisingly, this effect depended upon a CD134-dependent component that was extrinsic to the tumor-unrelated CD4 T cells, suggesting that the dual costimulated helper cells are themselves helped by a CD134(+) cell(s). Nevertheless, the delivery of therapeutic help tracked with an increased frequency of tumor-infiltrating granzyme B(+) effector CD8 T cells and a reciprocal decrease in Foxp3(+)CD4(+) cell frequency. Notably, the tumor-unrelated CD4 Th cells also infiltrated the tumors, and their deletion several days following initial T cell priming negated their therapeutic impact. Taken together, dual costimulation programs tumor-unrelated CD4 T cells to deliver therapeutic help during both the priming and effector stages of the antitumor response.

Targeting HER2 in the treatment of non-small cell lung cancer

Oncogenic driver mutations have emerged as major treatment targets for molecular therapies in a variety of cancers. HER2 positivity has been well-studied in breast cancer, but its importance is still being explored in non-small cell lung cancer (NSCLC). Laboratory methods for assessment of HER2 positivity in NSCLC include immunohistochemistry (IHC) for protein overexpression, fluorescent in situ hybridization (FISH) for gene amplification, and next generation sequencing (NGS) for gene mutations. The prognostic and predictive significance of these tests remain to be validated, with an emerging association between HER2 gene mutations and response to HER2 targeted therapies. Despite the assay used to determine the HER2 status of lung tumors, all patients with advanced HER2 positive lung adenocarcinoma should be evaluated for treatment with targeted agents. Several clinical approaches for inclusion of these drugs into patient treatment plans exist, but there is no defined algorithm specific to NSCLC.

Efficacy of romiplostim in patients with chronic immune thrombocytopenic purpura: a double-blind randomised controlled trial

BACKGROUND

Chronic immune thrombocytopenic purpura (ITP) is characterised by accelerated platelet destruction and decreased platelet production. Short-term administration of the thrombopoiesis-stimulating protein, romiplostim, has been shown to increase platelet counts in most patients with chronic ITP. We assessed the long-term administration of romiplostim in splenectomised and non-splenectomised patients with ITP.

METHODS

In two parallel trials, 63 splenectomised and 62 non-splenectomised patients with ITP and a mean of three platelet counts 30x10(9)/L or less were randomly assigned 2:1 to subcutaneous injections of romiplostim (n=42 in splenectomised study and n=41 in non-splenectomised study) or placebo (n=21 in both studies) every week for 24 weeks. Doses of study drug were adjusted to maintain platelet counts of 50x10(9)/L to 200x10(9)/L. The primary objectives were to assess the efficacy of romiplostim as measured by a durable platelet response (platelet count > or =50x10(9)/L during 6 or more of the last 8 weeks of treatment) and treatment safety. Analysis was per protocol. These studies are registered with ClinicalTrials.gov, numbers NCT00102323 and NCT00102336.

FINDINGS

A durable platelet response was achieved by 16 of 42 splenectomised patients given romplostim versus none of 21 given placebo (difference in proportion of patients responding 38% [95% CI 23.4-52.8], p=0.0013), and by 25 of 41 non-splenectomised patients given romplostim versus one of 21 given placebo (56% [38.7-73.7], p<0.0001). The overall platelet response rate (either durable or transient platelet response) was noted in 88% (36/41) of non-splenectomised and 79% (33/42) of splenectomised patients given romiplostim compared with 14% (three of 21) of non-splenectomised and no splenectomised patients given placebo (p<0.0001). Patients given romiplostim achieved platelet counts of 50x10(9)/L or more on a mean of 13.8 (SE 0.9) weeks (mean 12.3 [1.2] weeks in splenectomised group vs 15.2 [1.2] weeks in non-splenectomised group) compared with 0.8 (0.4) weeks for those given placebo (0.2 [0.1] weeks vs 1.3 [0.8] weeks). 87% (20/23) of patients given romiplostim (12/12 splenectomised and eight of 11 non-splenectomised patients) reduced or discontinued concurrent therapy compared with 38% (six of 16) of those given placebo (one of six splenectomised and five of ten non-splenectomised patients). Adverse events were much the same in patients given romiplostim and placebo. No antibodies against romiplostim or thrombopoietin were detected.

INTERPRETATION

Romiplostim was well tolerated, and increased and maintained platelet counts in splenectomised and non-splenectomised patients with ITP. Many patients were able to reduce or discontinue other ITP medications. Stimulation of platelet production by romiplostim may provide a new therapeutic option for patients with ITP.

AMG 531, a thrombopoiesis-stimulating protein, for chronic ITP

BACKGROUND

Most current treatments for chronic immune thrombocytopenic purpura (ITP) act by decreasing platelet destruction. In a phase 1-2 study, we administered a thrombopoiesis-stimulating protein, AMG 531, to patients with ITP.

METHODS

In phase 1, 24 patients who had received at least one treatment for ITP were assigned to escalating-dose cohorts of 4 patients each and given two identical doses of AMG 531 (0.2 to 10 microg per kilogram of body weight). In phase 2, 21 patients were randomly assigned to receive six weekly subcutaneous injections of AMG 531 (1, 3, or 6 microg per kilogram) or placebo. The primary objective was to assess the safety of AMG 531; the secondary objective was to evaluate platelet counts during and after treatment.

RESULTS

No major adverse events that could be attributed directly to AMG 531 occurred during the treatment period; 4 of 41 patients had transient post-treatment worsening of thrombocytopenia. In phase 1, a platelet count that was within the targeted range (50,000 to 450,000 per cubic millimeter) and at least twice the baseline count was achieved in 4 of 12 patients given 3, 6, or 10 mug of AMG 531 per kilogram. Overall, a platelet count of at least 50,000 per cubic millimeter was achieved in 7 of 12 patients, including 3 with counts exceeding 450,000 per cubic millimeter. Increases in the platelet count were dose-dependent; mean peak counts were 163,000, 309,000, and 746,000 per cubic millimeter with 3, 6, and 10 microg of AMG 531 per kilogram [corrected], respectively. In phase 2, the targeted platelet range was achieved in 10 of 16 patients treated with 1 or 3 mug of AMG 531 per kilogram per week for 6 weeks. Mean peak counts were 135,000, 241,000, and 81,000 per cubic millimeter in the groups that received the 1-mug dose, the 3-mug dose, and placebo, respectively.

CONCLUSIONS

AMG 531 caused no major adverse events and increased platelet counts in patients with ITP. (ClinicalTrials.gov number, NCT00111475 [ClinicalTrials.gov].).

Activation of heat-shock factor by stretch-activated channels in rat hearts

BACKGROUND

Previously, we have observed that the isolated, erythrocyte-perfused rabbit heart has increased levels of heat-shock protein (HSP) 72 after a mild mechanical stress. We hypothesized that stretch-activated ion channels (SACs) mediated this increase. Methods and Results-- To test this hypothesis, we subjected isolated, perfused rat hearts to mechanical stretch. Gel mobility shift assay showed that heat-shock factor (HSF) was activated in hearts with mechanical stretch, but not in controls. Supershift experiments demonstrated that HSF1 was the transcription factor. Northern blots revealed the concomitant increase in HSP72 mRNA in stretched rat hearts. In a separate set of experiments, gadolinium, an inhibitor of SACs, was added to the perfusate. Gadolinium inhibited the activation of HSF and decreased HSP72 mRNA level. Because gadolinium can inhibit both SACs and L-type calcium channels, we perfused a group of hearts with diltiazem, a specific L-type calcium channel blocker, to eliminate the involvement of L-type calcium channels. Diltiazem failed to inhibit the activation of HSF.

CONCLUSIONS

Stretch in the rat heart results in activation of HSF1 and an increase in HSP72 mRNA through SACs. This represents a novel mechanism of HSF activation and may be an important cardiac signaling pathway for hemodynamic stress.

Activation of the heat shock response: relationship to energy metabolites. A (31)P NMR study in rat hearts

Heat shock factor (HSF), the transcription factor for the heat shock proteins, is activated by cardiac ischemia, but the mechanism of activation is unknown. Ischemia is accompanied by changes in the energy state and acid-base conditions. We hypothesized that decreased ATP and/or intracellular pH (pH(i)) might activate HSF. To test this hypothesis, we perfused rat hearts within an NMR spectrometer. NMR data showed that after 6.5, 13, and 20 min of ischemia, ATP dropped to 62.7, 23.1, and 6.9% of the control level, and pH(i) was 6.16, 5.94, and 5.79, respectively. Reperfusion after ischemia partially restored ATP levels, and this was associated with greater activation of HSF1. HSF1 was also activated after 6.5 min of ischemia. Activation of HSF1 was less after 13 min of ischemia and barely detectable after 20 min of ischemia. In conclusion, 1) a moderate decrease in intracellular ATP correlates with activation of HSF1 in the heart; and 2) a severe depletion in ATP correlates with an attenuation in HSF1 activation, and the restoration of ATP leads to greater activation of HSF1, suggesting that a critical ATP level is required for activation of HSF1.

Simultaneous optical and nuclear magnetic resonance spectroscopy for monitoring cardiac energetics in vivo

There are a number of applications in which it is useful to simultaneously collect data from what are traditionally separate instrumentation modalities. In particular, in vivo physiological investigations in which data from parallel experiments must be correlated would benefit from simultaneous data collection through 1) elimination of subject variability, 2) elimination of treatment variability, and 3) a reduction in the number of animal preparations required. Here we describe the simultaneous collection of fluo-3 optical fluorescence and 31P nuclear magnetic resonance (NMR) spectra to measure intracellular calcium levels and high-energy phosphate metabolism, respectively, in vivo. This work is part of ongoing research into the profound anoxia tolerance exhibited by the hearts of certain turtle species. An NMR compatible optical fluorescence spectrometer was constructed and tested. In the 31-cm bore of a 2 T superconducting magnet, NMR and optical spectra were collected every 10-15 min from the in situ, in vivo hearts of anesthetized turtle subjects prior to and during one to three hours of anoxia. It was found that while PCr stores became significantly depleted during anoxia, beta-adenosine triphosphate (ATP) levels remained within 20% of control values, and intracellular diastolic calcium levels did not vary by more than 10%. The ability to make simultaneous phosphorus and calcium measurements on a single subject is important to understanding the exact relationship between phosphorus energy state and maintenance of calcium homeostasis.

Brain high energy phosphate responses to alcohol exposure in neonatal rats: an in vivo 31P-NMR study

BACKGROUND

The mechanisms that mediate fetal brain injury which results from maternal alcohol consumption are not well understood. Although fetal hypoxia is a popularly proposed mechanism, it has been difficult to assess brain oxygenation in vivo. We measured intracellular high energy phosphate concentrations and estimated intracellular pH (pHi) in brains of unanesthetized neonatal rat pups by using in vivo 31P-NMR spectroscopy. We reasoned that decreases in brain oxygenation sufficient to result in brain injury would also reduce high energy phosphates and pHi.

METHODS

On postnatal day 4, before alcohol administration, pups were placed into a 20 mm diameter NMR probe, their heads were positioned carefully in the center of the 31P detection coil, and spectra were collected over 20 min. Animals were then fed diet with or without 4.5 g/kg of ethanol in two (in succession) of 12 daily feedings via artificial rearing methods. A second spectrum was collected at 90 min after the beginning of the second alcohol feeding, at the time that coincided with the peak blood alcohol concentration (BAC). Identical feedings were performed daily until day 9, when pre- and postfeeding spectra were again obtained. Positive control groups were fed control diet and were studied in atmospheres of 5% oxygen, 95% nitrogen or 0% oxygen, 100% nitrogen.

RESULTS

Phosphocreatine (PCr), beta-adenosine triphosphate (ATP), and pHi decreased and inorganic phosphate (Pi) increased in day 4 animals subjected to 0% oxygen (20 min) compared with pretreatment and all other treatment groups. Day 9 animals did not tolerate these conditions. There were no significant changes in response to 5% oxygen on day 4, but Pi increased and beta-ATP decreased compared with pretreatment values and compared with alcohol and control groups on day 9. There were no changes in PCr, beta-ATP, or pHi in response to alcohol treatment at either age. PCr was significantly increased in the alcohol and 5% oxygen groups and apparently increased in the control group on day 9 compared with day 4, most likely due to increases in cranial muscle mass within the NMR coil.

CONCLUSIONS

We conclude that acute alcohol exposure that results in peak BACs of 315 mg/dl does not alter brain high energy phosphate concentrations or pHi in neonatal rat pups, although these BACs are known to result in significant brain injury. These findings do not support hypoxia as a mechanism of alcohol-mediated brain injury during the third trimester equivalent in the rat pup model.

Expression of heat shock proteins in turtle and mammal hearts: relationship to anoxia tolerance

Heat shock proteins (HSPs) may play a cardioprotective role during hypoxia or ischemia. We hypothesized that cardiac tissue from hypoxia-tolerant animals might have high levels of specific HSPs. We measured myocardial HSP60 and HSP72/73 in painted and softshell turtles during normoxia and anoxia (12 h) and after recovery (12 or 24 h). We also measured myocardial HSPs in normoxic rats and rabbits. During normoxia, hearts from the most highly anoxia-tolerant species, the painted turtle, expressed the highest levels of HSP60 (22.6+/-2.0 mg/g total protein) followed by softshells (11.5+/-0.8 mg/g), rabbits (6.8+/-0.9 mg/g), and rats (4.5+/-0.5 mg/g). HSP72/73 levels, however, were not significantly different. HSP60 levels in hearts from both painted and softshell turtles did not deviate significantly from control values after either 12 h of anoxia or 12 or 24 h of recovery. The pattern of changes observed in HSP72/73 was quite different in the two turtle species. In painted turtles anoxia induced a significant increase in myocardial HSP72/73 (from 2.8+/-0.1 mg/g normoxic to 3.9+/-0.2 mg/g anoxic, P<0.05). By 12 h of recovery, HSP72/73 had returned to control levels (2.7+/-0.1 mg/g) and remained there through 24 h (2.6+/-0.2 mg/g). In softshell turtles, HSP72/73 decreased significantly after 12 h of anoxia (from 2.4+/-0.4 mg/g normoxic to 1.3+/-0.2 mg/g anoxic, P<0.05). HSP72/73 levels were still slightly below control after 12 h of recovery (2.1+/-0.1 mg/g) and then rose to significantly above control after 24 h of recovery (4.1+/-0.7 mg/g, P<0.05). We also conclude that anoxia-tolerant and anoxia-sensitive turtles exhibit different patterns of myocardial HSP changes during anoxia and recovery. Whether these changes correlate with their relative degrees of anoxia tolerance remains to be determined.

Biomedical device design discovery team approach to teaching physiology to undergraduate bioengineering students

Teaching effectiveness is enhanced by generating student enthusiasm, by using active learning techniques, and by convincing students of the value of acquiring knowledge in the area of study. We have employed a technique to teach physiology to bioengineering students that couples students' enthusiasm for their chosen field, bioengineering, with an active learning process in which students are asked to design a biomedical device to enhance, replace, or create a new cellular or organ system function. Each assignment is designed with specific constraints that serve to direct students' attention to specific areas of study and that require students to create original designs. Preventing students from using existing designs spurred student invention and enthusiasm for the projects. Students were divided into groups or "design discovery teams" as might be done in a biomedical device industry setting. Students then researched the physiological issues that would need to be addressed to produce an acceptable design. Groups met with faculty to brainstorm and to obtain approval for their general design concepts before proceeding. Students then presented their designs to the instructors in a structured, written outline form and to the class as a 10-minute oral presentation. Grades were based on the outline, oral presentation, and peer evaluations (group members anonymously rated contributions of other members of their team). We believe that this approach succeeded in generating enthusiasm for learning physiology by allowing the students to think creatively in their chosen field of study and that it has resulted in students developing a more thorough understanding of difficult physiological concepts than would have been achieved with a traditional didactic lecture approach.

31P-NMR determinations of cytosolic phosphodiesters in turtle hearts

As part of our ongoing research on cardiac hypoxia tolerance we have conducted 31P nuclear magnetic resonance (NMR) studies of isolated, perfused, working hearts from freshwater turtles, animals that are well known for their ability to tolerate prolonged periods of anoxia. A striking feature of turtle heart spectra is an extremely high concentration of NMR visible phosphodiesters (PDEs). Cardiac spectra from mammals, on the other hand, typically exhibit only a small resonance in the PDE region. Our aim in this study was to compare myocardial PDE profiles between the highly hypoxia tolerant western painted turtle (Chrysemys picta bellii) and the relatively hypoxia sensitive softshelled turtle (Trionyx spinifer) in order to begin to rest the hypothesis that high constitutive levels of cytosolic PDEs may play a role in conferring hypoxia and ischemia tolerance on the myocardium. We also collected 31P-NMR spectra of PCA extracts of tissue from these species and from Kemp's ridley sea turtles (Lepidochelys kempi), as well as spectra from isolated hearts and PCA extracts of red-eared sliders (Trachemys [formerly Pseudemys] scripta]). Total NMR visible phosphodiesters make up 24 +/- 8.6% of the total NMR visible phosphorus in Chrysemys hearts, 20.7 +/- 5.9% in Trachemys hearts, but only 12.2 +/- 5.1% in Trionyx hearts (P < 0.05). We have identified three distinct PDEs in turtle hearts: glycerophosphorylcholine (GPC); glycerophosphorylethanolamine (GPE); and serine ethanolamine phosphodiester (SEP). SEP is the dominant compound in Chrysemys and Trachemys (79.3 +/- 10.2% and 84.7 +/- 3.7% of total PDE, respectively), while GPC is most abundant in Trionyx (74.0 +/- 4.3% of total PDE) and Lepidochelys (not quantitated). The function of this class of compounds is unclear but it has been suggested that cytosolic PDEs may function as lysophospholipase inhibitors, a role that would decrease the rate of membrane phospholipid turnover. Our comparative data suggest that cytosolic PDEs could play a role in phospholipid sparing during anoxic or ischemic stress in turtles but a direct test of this hypothesis awaits future experimentation.

In vitro tolerance to anoxia and ischemia in isolated hearts from hypoxia sensitive and hypoxia tolerant turtles

Although freshwater turtles as a group are highly anoxia tolerant, dramatic interspecific differences in the degree of anoxia tolerance have been demonstrated in vivo. Painted turtles (Chrysemys picta bellii) appear to be the most hypoxia-tolerant species thus far studied, while softshelled turtles (Trionyx spinifer) are the most hypoxia-sensitive. We have assumed that this dichotomy persists in vitro but have not, until now, directly tested this assumption. We therefore, directly compared the responses of isolated, perfused, working hearts from these two species to either 240 min of anoxia, 90 min of global ischemia, or 240 min of global ischemia followed by reoxygenation/reperfusion. Isolated hearts were perfused at 20 degrees C and monitored continuously for phosphocreatine (PCr), adenosine triphosphate (ATP), inorganic phosphate (Pi), and intracellular pH (pHi) by 31P-nuclear magnetic resonance spectroscopy as well as for ventricular developed pressure and heart rate. Contrary to our expectations, we observed few significant differences in any of these parameters between painted and softshelled turtle hearts. Hearts from both species tolerated 240 min of anoxia equally well and both restored PCr, pHi, and Pi contents to control levels during reoxygenation. We did observe some significant interspecific differences in the 90 min (pHi and Pi) and 240 min (PCr) ischemia protocols although these seemed to suggest that Trionyx hearts might be more tolerant to these stresses than Chrysemys hearts. We conclude that: (a) the observed in vivo differences in anoxia tolerance between painted and softshelled turtles must either be due to differences in organ metabolism in organs other than the heart (e.g., brain) or to some integrative physiologic differences between the species; and (b) isolated hearts from a species known to be relatively anoxia sensitive in vivo can exhibit an apparent high degree of anoxia and ischemia tolerance in vitro.

Effects of dry season dormancy on oxygen uptake, heart rate, and blood pressures in the toad, Bufo paracnemis

The cardiodynamic consequences of dry season dormancy in ectothermic vertebrates is not well known. Our hypothesis was that dormancy would reduce cardiac activity. We therefore determined oxygen uptake and cardiovascular function in aestivating toads, Bufo paracnemis, native to São Paulo State, Brazil. Specimens were collected and kept in the laboratory under controlled temperature and light regimes. We compared oxygen uptake, heart rate, blood pressure, rate-pressure product (RPP), and blood gases in toads during aestivation (dry winter season) and their early active season (spring). Oxygen uptake of winter toads at 25 degrees C was considerably lower than that of spring toads (winter: 24.0 +/- 1.8 ml/(kgh); early spring: 44.4 +/- 5.1 ml/(kgh); mean +/- SE; same in the following). A seasonal dichotomy was also observed at 15 degrees C although the differences was less pronounced (15.8 +/- 1.8 ml/(kgh) winter; 23 +/- 2.1 ml/(kgh) early spring). Chronic arterial cannulation permitted measurements of cardiodynamic variables without any undesired change in VO2. Heart rates of winter toads were significantly lower than those of early spring animals at both experimental temperatures (25 degrees C: winter 25 +/- 1.4 beats/min.; early spring: 35.2 +/- 5.1 beats/min. 15 degrees C: winter 15, 4 +/- 1.8 beats/min.; early spring: 23.9 +/- 2.1 beats/min). Systemic, diastolic and mean arterial pressures decreased slightly but not significantly during aestivation. We conclude that: (1) Bufo paracnemis downregulates metabolic rate during the dry season and (2) heart rate is also downregulated with little change of blood pressure. While the energetics of these responses are probably beneficial for survival during aestivation, the underlying biochemical mechanisms remain obscure.

Effects of anoxia on intracellular free Ca2+ in isolated cardiomyocytes from turtles

One of the most important negative consequences of hypoxic stress in the mammalian myocardium is a breakdown in intracellular calcium homeostasis. This study examines the effects of anoxic stress on intracellular calcium regulation in isolated ventricular myocytes from a hypoxia tolerant vertebrate, the western painted turtle (Chrysemys picta bellii). Isolated calcium tolerant cardiomyocytes from turtle hearts were mounted on a glass cover slip that formed the bottom of a sealed, Plexiglas perfusion chamber. Free [Ca2+]i (determined by FURA2 fluorescence) in isolated turtle cardiomyocytes averaged 31.7 +/- 3.2 nM after 30 min of normoxic perfusion (20 degrees C, pHc = 7.77). This value is on the low end of the published range for mammalian cardiomyocytes. Perfusion with anoxic Ringer equilibrated with 3% CO2, resulted in a significant increase in free [Ca2+]i to 941 +/- 494.6 nM after 60 min. Increasing the CO2 in the perfusion solution to 5% or 6% blunted this rise (peak levels after 60 min of anoxia were 420.5 +/- 176.0 nM and 393.8 +/- 132.8 nM, respectively). A further increase to 8% CO2 increased the maximal value for free [Ca2+]i to 610.9 +/- 297.5 nM. In eight cells from the 5% CO2 protocol in which [Ca2+]i was monitored during recovery, reperfusion with normoxic Ringer rapidly lowered intracellular calcium to 92.8 +/- 9.7 nM within 15 min. Anoxia at relatively high extracellular (and hence intracellular) pH results in an increase in free [Ca2+]i comparable in magnitude and time course to that seen in some mammalian cardiomyocyte preparations. Perfusion of anoxic myocytes with Ringer equilibrated with either 5% or 6% CO2 blunted this increase in intracellular calcium, possibly an example of the pH paradox effect. A more severe combination of respiratory acidosis and anoxia (8% CO2) removed this protective effect.

Anoxia and ischemia tolerance in turtle hearts

It has been known since ancient times that turtle hearts exhibit extraordinary tolerance to anoxia or ischemia. The mechanisms by which they accomplish this remain obscure. The most important adaptation in anoxic turtles is a rapid and dramatic decrease in metabolic rate. Nuclear magnetic resonance measurements indicate that painted turtle (Chrysemys picta) hearts respond to anoxia with a rapid decrease in phosphocreatine (PCr; to 50% of control) after which PCr remains constant for at least 4 h. ATP is defended and does not decrease while intracellular pH (pHi) decreases by 0.2 pH units early in anoxia and is then maintained constant. Softshelled turtles (Trionyx spinifer) have been demonstrated to be far more sensitive than painted turtles to anoxia in vivo. However, isolated hearts from softshelled turtles appear to be as anoxia tolerant as those of Chrysemys. During ischemia there is also little difference in cardic performance, high energy phosphates, or pHi between these two species. A peculiar feature of turtle hearts is an extremely high concentration of phosphodiesters (PDE). The role of cytosolic PDEs remains controversial but they may function as lysophospholipase inhibitors and thereby limit phospholipid turnover (Burt CT and Ribolow H, Comparative Biochemistry and Physiology, 108B: 11-20, 1994). Whether PDEs promote anoxia/ischemia tolerance is unknown but these stresses can result in membrane lipid dysfunction in mammals. Metabolic control, acid-base, and phospholipid homeostasis all play a role in anoxia and ischemia tolerance in turtle hearts. These physiologic processes are interdependent, and how they interact in these animals is unknown, but they are experimentally accessible by modern analytical methods.

The effect of prolonged anoxia at 3 degrees C on tissue high energy phosphates and phosphodiesters in turtles: a 31P-NMR study

Selected tissues (skeletal muscle, heart ventrical, and liver), sampled from turtles (Chrysemys picta bellii) at 3 degrees C either under normoxic conditions or after 12 weeks of anoxic submergence were quantitatively analysed for intracellular pH and phosphorus metabolites using 31P-NMR. Plasma was tested for osmolality and for the concentrations of lactate, calcium, and magnesium to confirm anoxic stress. We hypothesized that, in the anoxic animals, tissue ATP levels would be maintained and that the increased osmolality of the body fluids of anoxic turtles would be accounted for by a corresponding increase in the concentrations of phosphodiesters. The responses observed differed among the three tissues. In muscle, ATP was unchanged by anoxia but phosphocreatine was reduced by 80%; in heart, both ATP and phosphocreatine fell by 35-40%. The reduction in phosphocreatine in heart tissue at 3 degrees C was similar to that observed in isolated, perfused working hearts from turtles maintained at 20 degrees C but no decrease in ATP occurred in the latter tissues. In liver, although analyses of several specimens were confounded by line-broadening, neither ATP nor phosphocreatine was detectable in anoxic samples. Phosphosdiesters were detected in amounts sufficient to account for 30% of normoxic cell osmotic concentration in heart and 11% and 12% in liver and muscle, respectively. The phosphodiester levels did not change in anoxia. Heart ventricular phosphodiester levels in turtles at 3 degrees C were significantly higher than those determined for whole hearts from turtles at 20 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Maintenance of high extracellular pH does not influence cell pH or metabolism in submerged anoxic bullfrogs

We compared extracellular and intracellular acid-base states in paralyzed bullfrogs subjected to 4 h of anoxic submergence at 15 degrees C with or without maintenance of extracellular pH at preanoxic levels by bicarbonate infusion. We also assessed anaerobic metabolism under these conditions by measuring tissue lactate and glycogen concentrations in liver, heart, and skeletal muscle. Although bicarbonate infusion resulted in a significantly higher arterial blood pH (pHe) than saline infusion, intracellular pH (pHi) of heart and skeletal muscle, as determined by the DMO equilibration technique, were not significantly different after 4 h of anoxia. We were also unable to demonstrate any differences in anaerobic metabolic rate, since both tissue lactate accumulation and glycogen depletion were identical in bicarbonate- and saline-infused frogs in the tissues studied. We conclude that (1) alterations in the extracellular acid-base state by bicarbonate infusion are not necessarily reflected in the intracellular compartment, perhaps due to powerful intracellular buffering processes, and (2) maintenance of an alkaline extracellular pH during anoxia in bullfrogs does not influence the anaerobic metabolic rate. We could not, however, rule out a possible role for intracellular pH in regulating anaerobic metabolism during anoxia in frogs.

Metabolic and cardiodynamic responses of isolated turtle hearts to ischemia and reperfusion

We used 31P and 1H nuclear magnetic resonance spectroscopy to measure intracellular pH, high energy phosphates, and lactate levels in hearts of turtles (Chrysemys picta bellii) subjected to 1.5 h of global ischemia followed by reperfusion. We simultaneously monitored maximum ventricular developed pressure (Pmax), maximal rate of pressure development (dP/dtmax), rate-pressure product (RPP), cardiac output, and heart rate and also measured lactate efflux from the hearts during reperfusion. Our goal was to test the hypothesis that turtle hearts would prove tolerant of prolonged global ischemia at 20 degrees C and would recover completely on reperfusion without any indication of ischemia-or reperfusion-related injury. The 1.5 h of ischemia resulted in decreases in phosphocreatine and ATP to 31.4 +/- 2.8 and 87.3 +/- 6.3% of control, respectively, while Pi rose to 236.6 +/- 26.3%. Intracellular pH decreased during this period from 7.38 +/- 0.02 to 6.87 +/- 0.04. Most of these changes occurred during the first 30 min. Tissue lactate rose during 1.5 h of ischemia from approximately 1.5 to 22.3 mumol/g wet tissue wt. However, the rate of lactate production was much higher during the first 21 min of ischemia (0.41 mumol.g-1.min-1) than during the remaining 70 min (0.10 mumol.g-1.min-1). With the onset of ischemia, Pmax, dP/dtmax, RPP, and heart rate all decreased dramatically with roughly the same time course as the changes in high-energy phosphates and intracellular pH. On reperfusion, turtle hearts rapidly restored high-energy phosphates, intracellular pH, lactate, and cardiodynamics to control levels, usually within 15-30 min, with no evidence of reperfusion injury.(ABSTRACT TRUNCATED AT 250 WORDS)

31P-NMR study of normoxic and anoxic perfused turtle heart during graded CO2 and lactic acidosis

We studied the effects of graded acidosis (both CO2 and lactic acid) and anoxia on intracellular pH (pHi) regulation, high-energy phosphates, and mechanical function of isolated perfused hearts of the turtle (Chrysemys picta bellii) at 20 degrees C using 31P-nuclear magnetic resonance (NMR) spectroscopy. During CO2 acidosis, anoxia had no effect on apparent nonbicarbonate buffer value (d[HCO3-]/dpHi = 71 and 89 mM/pH in normoxia and anoxia, respectively) or on pHi regulation (dpHi/dpHe = 0.52 and 0.43 in normoxia and anoxia, respectively, where pHe is extracellular pH). During normoxic lactic acidosis, dpHi/dpHe was similar to the values observed in CO2 acidosis and averaged 0.55 overall. During anoxic lactic acidosis, however, similar regulation occurred over only a narrow range of pHe, and then dpHi/dpHe increased to greater than 1.0 at pHe less than 7.1. Creatine phosphate (CP), calculated as the area of the NMR peak, fell more in response to normoxic CO2 acidosis than to normoxic lactic acidosis; in anoxia, the fall in CP was further increased but to similar extreme levels (10-20% of control) in both acid perfusions. Cardiac output and maximum rate of pressure development each fell during acidosis in similar fashion in all protocols, and the responses were similar in normoxic and anoxic hearts. Heart rate, in contrast, decreased during acidosis, but this effect was more pronounced when hearts were anoxic. We conclude that the effect of acidosis on cardiac function can depend on the type of acidosis imposed. Based on the heart's insensitivity to anoxia alone, we suggest that anoxia may normally depress function indirectly via its effect on intracellular acid-base state.

Effects of anoxia and graded acidosis on the levels of circulating catecholamines in turtles

We measured circulating levels of catecholamines in painted turtles subjected to anoxia with different degrees of concomitant acidosis at 20 degrees C and in turtles subjected to long-term submergence at 3 and 10 degrees C. Blood levels of both epinephrine (E) and norepinephrine (NE) increased during N2-breathing, N2/CO2 breathing and submergence, with NE generally being present in higher concentrations than E. During submergence at 20 degrees C, anoxic turtles experienced an extreme acidosis and NE levels exceeded 18,000 pg/ml. The greater the degree of acidosis in anoxic turtles the higher were the levels of plasma NE (log [NE; pg/ml] = 1.640 x pHa + 15.776, r = -0.826). Elevation of plasma E under anoxic conditions was more modest and the correlation between plasma E and pHa was less pronounced (log [E; pg/ml] = -0.329 x pHa + 6.069, r = -0.285). Submergence at lower temperatures also resulted in increases in plasma levels of NE, but while plasma E generally increased during anoxia, this elevation was less dramatic than that observed for NE. Exposure of turtles to either mild (6.5% CO2) or severe (14.5% CO2) normoxic hypercapnia resulted in no increase in E and only modest increases in NE. Upon resumption of air-breathing in all of the 20 degrees C protocols, turtles rapidly restored E and NE to control levels. The function of elevated plasma catecholamines during anoxia and acidemia in turtles is unknown but may be important in stimulating respiratory and cardiovascular recovery once air-breathing is resumed. Catecholamines may also play a role in mediating the rise in blood glucose we observed in this study, which may be an important factor in maintaining tissue viability during anoxic stress.

Extracellular and intracellular acid-base effects of submergence anoxia and nitrogen breathing in turtles

We compared extracellular and intracellular acid-base state in turtles (Chrysemys picta bellii) subjected to anoxic submergence to turtles made anoxic by N2-breathing. Measurements made on control animals and on animals after 1, 2, 4, or 6 h of anoxia included blood pH, PO2, PCO2, and lactate as well as liver, heart, skeletal muscle, and brain pHi (using DMO equilibration), lactate, and glycogen concentrations. We hypothesized that the anaerobic metabolic rate of submerged turtles would be depressed by the more severe extra- and intracellular acidosis, and that this would be indicated by reduced lactate accumulation and glycogen depletion. Submerged turtles became extremely acidemic due to a combined metabolic and respiratory acidosis and had significantly lower arterial pH than N2-breathing animals (6.98 and 7.34, respectively, after 6 h). In spite of this disparity in pHa, 6 h pHi values for liver, heart, and brain were similar. Likewise, our data on glycogen depletion and lactate accumulation at h 6 in these tissues suggest no dramatic differences in anaerobic metabolic rate. While skeletal muscle pHi was somewhat lower at h 6 in the submerged group (6.73 vs 6.91 for N2-breathers), we observed no differences in either glycogen depletion or lactate accumulation in this tissue between our two treatments. Thus, at h 6, in spite of a 0.37 pH unit difference in pHa and a nearly 70 mm Hg difference in arterial and presumably cytosolic PCO2, pHi and tissue lactate and glycogen concentrations were similar. These results can be explained if the in vivo intracellular buffer values (beta) of turtle tissues are very high. We conclude that extracellular acid-base state is not necessarily reflected intracellularly in vivo in turtles and care must be taken in extrapolating from one compartment to another when attempting to make inferences about metabolic depression or acid-base regulation in this species.

31P-NMR measurements of pHi and high-energy phosphates in isolated turtle hearts during anoxia and acidosis

We used 31P-nuclear magnetic resonance (NMR) spectroscopy to measure intracellular pH (pHi) and high-energy phosphate levels in hearts of turtles (Chrysemys picta bellii) during either 4 h of anoxia [extracellular pH (pHo) 7.8, 97% N2-3% CO2], 4 h of lactic acidosis (pHo 7.0, 97% O2-3% CO2), or 1.5 h of combined anoxia + lactic acidosis (pHo 7.0, 97% N2-3% CO2) followed by 2 h of oxygenated recovery (pHo 7.8) at 20 degrees C. We also measured heart rate, maximum ventricular-developed pressure, and rate of pressure development (dP/dtmax). 31P-NMR spectra were characterized by the seven peaks typical of mammalian hearts, although turtle spectra were dominated by a large phosphodiester peak. Anoxia caused an increase in Pi to 165% and a decrease in creatine phosphate (CP) to 42% of control, whereas ATP levels remained unchanged. pHi declined from 7.37 +/- 0.01 to 7.22 +/- 0.03 at 1 h of anoxia and remained unchanged through hour 4. Lactic acidosis caused a 59% decrease in Pi, whereas CP and ATP levels remained unchanged. pHi fell to 6.88 +/- 0.04 by hour 1 and then climbed steadily to 7.14 +/- 0.05 at hour 4. During recovery from acidosis, pHi exceeded control values and returned to control by 2 h. Combined anoxia + acidosis caused profound decreases in CP to 14% and pHi to 6.56 +/- 0.03. In anoxic hearts, cardiodynamic variables remained at control levels through hour 3, after which cardiac output, heart rate, and dP/dtmax declined. Cardiodynamic variables were essentially unchanged from control throughout 4 h of acidosis except for dP/dtmax, which declined rapidly. In the combined protocol, all measures of cardiac function decreased. Recovery in all three cases was complete by approximately 2 h. We conclude that turtle hearts were relatively resistant to the stresses imposed in all three protocols compared with mammalian hearts, although anoxia + acidosis depressed the measured cardiac variables more profoundly than predicted from responses to the conditions imposed separately. Our results from the anoxia protocol suggest no direct causal relationship between myocardial CP (or ATP) levels and cardiac function.

Force and acid-base state of turtle cardiac tissue exposed to combined anoxia and acidosis

We measured contractile force of ventricular strips form the turtle Chrysemys picta bellii exposed to 1 h of combined anoxia and acidosis (pH 7.0) at 20 degrees C. Strips either beat spontaneously (self-paced) or in response to electrical stimulation (paced at 12, 24, or 36 beats/min). Tissue [lactate] and intracellular pH (pHi) were measured in control strips and at the end of anoxia-acidosis. In self-paced strips, at normal extracellular Ca2+ concentration ([Ca2+]o) (1 mM), both rate and force fell significantly after 1 h of anoxia-acidosis to 54 and 17.1%, respectively, of control values. Increased [Ca2+]o to 10 mM at 30 min had a small but significant positive effect on both rate and force. Contractile force of paced strips also fell progressively during anoxia-acidosis, but the decrease varied directly with pacing frequency. Under all cases of anoxia-acidosis, pHi fell significantly from the control value of 7.53; in paced strips, acidosis was most severe at 36 beats/min (pHi 6.75), and in self-paced strips, pHi (approximately 6.85) was independent of [Ca2+]o. Based on this and previous work, we conclude that combined anoxia-acidosis, similar to that observed in vivo after prolonged anoxic submergence, profoundly depresses cardiac function. Both hypercalcemia and bradycardia improve performance in this extreme state, but these effects are not as great as when anoxia and acidosis occur alone.

Cardiovascular and metabolic responses during anoxic submergence in the bullfrog with and without maintained extracellular pH

We studied metabolic, cardiovascular, and electrolyte responses of paralyzed bullfrogs to 6 hours of submerged anoxia at 15 degrees C, either with or without maintenance of extracellular pH at preanoxic values by NaHCO3 infusion. There were no differences in arterial PCO2 between acidemic and nonacidemic groups. Lactate appearance in arterial blood, as an indicator of anaerobic metabolic rate, was not significantly different between the anoxic groups, although both were significantly elevated over control. Heart rate in both anoxic groups was similar and significantly lower than in control. During anoxia, both systolic and diastolic pressures fell, and the group with maintained pH fell further. Plasma calcium concentration decreased in both anoxic groups, but the fall was more severe in the group in which pH was controlled. Survival was lower in this group, with a rapid decline in survival after 4 hours of anoxia. We conclude that the fall in extracellular pH seen during anoxia has a protective effect on cardiovascular function that may be partially due to maintenance of relatively high extracellular calcium levels.

Effect of induced hypercapnia on anaerobic metabolic rate of anoxic musk turtles

To evaluate the possible effect of induced hypercapnia on anaerobic metabolic rate during anoxia, musk turtles (Sternotherus odoratus) were submerged in N2-equilibrated water at 10 degrees C for 3 days either with (anoxic hypercapnic) or without (anoxic normocapnic) elevated aquatic PCO2 (30-40 Torr). Control animals had access to air at 10 degrees C. Plasma [lactate] was significantly higher (P less than 0.01) in the normocapnic [59.4 +/- 7.4 (SD) mM; n = 22] than in the hypercapnic (47.4 +/- 8.5 mM; n = 19) anoxic turtles, although the hypercapnic turtles had lower blood pH (P less than 0.05). Plasma ion concentrations (Na, K, Cl, Ca, and Mg), however, were no different in the two groups, although all values other than Na were different from control. In some of the animals, [lactate] and [glycogen] (per g wet wt) of skeletal muscle, heart, and liver were measured in addition to blood acid-base values and lactate. Tissue lactates, although significantly elevated from control, and glycogens, although (with the exception of skeletal muscle) significantly reduced from control, were no different in the two anoxic groups. We suggest that these tissue data are more valid indicators of anaerobic metabolic rate than is plasma lactate and therefore conclude that induced hypercapnia does not significantly depress anaerobiosis in musk turtles at 10 degrees C.

Acid-base balance and the control of respiration during anoxic and anoxic-hypercapnic gas breathing in turtles

We studied the ventilatory and blood acid-base response of turtles to 6 h of breathing either 100% N2 (anoxic) or 95% N2-5% CO2 (anoxic-hypercapnic). In both groups, minute ventilation (VE) increased promptly with anoxia, with peak ventilation occurring between 1 and 3 h. VE then decreased but was still significantly above control at 6 h. The increase in VE resulted from increases in both respiratory frequency (f) and tidal volume (VT) but after ventilation peaked, f declined to control while VT remained elevated. We observed no significant differences in VE between the two groups in spite of significantly lower arterial pH and higher arterial PCO2 in the anoxic-hypercapnic turtles. During normoxic recovery, VE quickly increased to the peak anoxic values due primarily to a greatly increased f. In both groups, plasma [lactate-] increased during anoxia. Plasma cation concentrations also increased, partially compensating for the elevated blood lactate. We conclude that the anoxic hyperventilation did not depend on arterial pH and central chemoreceptor control but rather on peripheral hypoxic chemoreceptor control. We believe that the decline in VE during prolonged anoxic breathing results from a metabolic arrest response and/or a depression in central nervous function.

Respiratory responses to acute heat stress in cranes (Gruidae): the effects of tracheal coiling

Some species of cranes have extensive coiling of their trachea that substantially increases their anatomical dead space. We subjected individuals of four species of cranes (Anthropoides virgo, Balearica regulorum, Grus grus and Grus japonensis) to acute heat stress to investigate the effectiveness of this trait as a thermoregulatory adaptation. We measured cloacal temperature, respiratory flow and frequency and arterial pH during normothermic breathing and thermal panting. Extra tracheal length appears to be a helpful but nonessential adaptation to prevent cranes from becoming alkalotic while panting. Cranes in our study had relatively lower panting frequencies and greater tidal volumes than have been reported for other birds subjected to heat stress. Tracheal coiling is probably more important to vocalization than to respiration or thermoregulation.

Congenital hypoplastic anemia (Diamond-Blackfan syndrome) terminating in acute myelogenous leukemia

A 31-yr-old female with congenital hypoplastic anemia (Diamond-Blackfan syndrome) whose long course terminated in acute myelogenous leukemia is described. In contrast to Fanconi anemia, malignant transformation rarely occurs in congenital hypoplastic anemia. This patient's diagnosis of congenital hypoplastic anemia is supported by her clinical course, absence of renal abnormalities, a negative family history for hematologic disorders, normal chromosome studies, failure of her skin fibroblasts to transform in culture with SV-40 virus, macrocytic erythrocyte indices, erythrocyte enzyme studies, and bone marrow findings. Only two other cases of malignancy have been reported in patients with congenital hypoplastic anemia. The development of malignancy in these patients suggests that malignant transformation may be a concern in the long-term progression of congenital hypoplastic anemia.