ALBERT

Description: Abstract 2609 Children with relapsed or chemotherapy-refractory ALL have a poor prognosis despite the use of aggressive therapies such as HSCT. Chimeric antigen receptor modified T cells targeting the B-cell antigen CD19 have been reported to be effective in adults with B-cell lymphomas and chronic lymphocytic leukemia. We conducted pre-clinical studies with a CD19-CAR consisting of a CD19-specific scFv and the CD28 and CD3z signaling domains. These cells generated significant levels of IFNg, TNFa, and IL-2 in response to ALL blasts and rapidly eradicated human ALL in murine xenografts. We developed a Phase I clinical trial of CD19-CAR modified autologous T cells for children with CD19+ hematologic malignancies. HSCT-na•ve and post-transplant patients are eligible, and cells are collected directly from patients in both cases. CD19-CAR T cells are manufactured in a semi-closed system over an 11-day period. We report results with the first patient, a 13-year old with chemotherapy-refractory ALL that had relapsed after 2 prior matched related donor HSCTs. Peripheral blood (PB) mononuclear cells were collected from the patient on Day -11 by apheresis. T cells were positively selected and activated by incubation with anti-CD3/anti-CD28 paramagnetic beads in IL-2 for 48 hours then transduced with the CD19-CAR gene via retroviral supernatant for an additional 48 hours. Beads were removed and the expanding CD19-CAR T cells were maintained in culture with IL-2 until harvested for infusion on Day 0. A 59-fold expansion of CAR T cells with 65% transduction efficiency was achieved. The patient was pre-treated with fludarabine (25 mg/m2/day on Days -4, -3, -2) and cyclophosphamide (900 mg/m2 on Day -2) prior to the infusion of 1×106 CAR-transduced T cells/kg. The patient developed signs and symptoms of cytokine release syndrome (CRS) on Day +5 with full resolution by Day +11. Manifestations included fever (maximum 41°C), rigors (Grade 1), and hypotension (Grade 2), the latter of which was responsive to two IV fluid boluses. The patient also developed an erythematous rash (Grade 1) of the extremities from Days +7 to +12 and bilateral scrotal swelling and pain (Grade 1) from Days +8 to +10, which was associated with increased testicular blood flow by ultrasound. Cytokine analysis revealed high levels of IL-6 (53.1 pg/ml; normal

Description: Abstract 1497 Background: Vincristine is active in many pediatric cancers, but cumulative neuromuscular toxicity is often dose limiting and requires a maximum dose cap. Liposomal carriers are capable of increasing the therapeutic index of anticancer agents by altering pharmacokinetic behavior. Vincristine sulfate liposomes injection (VSLI, Marqibo®) is a novel preparation of standard vincristine encapsulated in sphingomyelin/cholesterol liposomes. Clinical trials have demonstrated safety, tolerability and activity in adults with leukemias, lymphomas and solid tumors. Pediatric experience with VSLI is limited. Design: This single center Phase I dose-escalation study is designed to determine the maximum tolerated dose (MTD) and to assess safety, pharmacokinetics and activity of VSLI in pediatric patients with relapsed/refractory cancer. Patients with active central nervous system disease or ≥grade 2 sensory or motor neuropathy are excluded. Dose escalation is per a standard 3 + 3 Phase I trial design with enrollment following a rolling 6 strategy. VSLI is administered IV over 60-minutes every 7 days (± 3 days) for 4 consecutive weeks for a 28-day treatment cycle (4 doses/cycle). Cycles may be delayed by up to 1 week for toxicity. Two dose levels have been tested to date: 1.75 mg/m2 and 2.25 mg/m2(adult MTD). No individual dose cap is employed. A validated HPLC tandem mass spectrometry assay was used to quantitate total (liposomal encapsulated and non-encapsulated) vincristine. Results: 9 patients have been treated (Table): 6 with acute lymphoblastic leukemia (ALL) and 3 with solid tumors. All patients were heavily pre-treated and 2 had prior stem cell transplants. 6 of 9 completed at least 1 cycle of therapy, with 1 each removed early for alternative therapy, complications of ALL, or dose-limiting toxicity (DLT). Most treatment-related adverse events were reversible grade 1 and 2 severity including hepatic transaminase elevation, parasthesia, low white blood cell count, neutropenia and fatigue. 2 patients evaluable for hematologic toxicity developed grade 4 neutropenia that spontaneously and rapidly resolved. No DLT occurred on dose level 1. Grade 4 aspartate aminotransferase elevation was observed in one patient at the second dose level and this dose level is being expanded. 1 patient treated at dose level 1 had dose de-escalation starting with Cycle 2 Dose 3 due to neuropathy. No patient was taken off study due to neurotoxicity. 7 of 9 patients received a VSLI dose that exceeded the 2 mg dose limit set for standard vincristine. 6 patients were evaluable for response: 1 had a complete remission (CR) (minimal residual disease negative by flow cytometry); 3 had stable disease (SD); and 2 had progressive disease (PD). First-dose pharmacokinetic analysis revealed wide interpatient variation (Table). The median (range) maximum concentrations (Cmax) of total vincristine (ng/ml) were 1,485 (845-2,120) and 2,450 (1,690-3,690) at dose levels 1 and 2 respectively. The median plasma half-life (T½) was 8.5 and 13.5 hours at dose levels 1 and 2 respectively (range 1.8 to 40.4 hours). Conclusions: VSLI appears to be safe, tolerable and demonstrates preliminary activity in pediatric patients with refractory ALL and solid tumors. The toxicity spectrum appears to be similar in children and adults. Clearance of total vincristine in our study is approximately 100-fold lower in comparison to administration of standard vincristine. VSLI allows for intensification of vincristine therapy in children with cancer. Accrual to the Phase I component at the adult recommended dose is ongoing and an expanded Phase II cohort in pediatric patients with ALL is planned. This study was sponsored by Talon Therapeutics and is supported by the Intramural Research Program of the NIH, National Cancer Institute, Center for Cancer Research. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 3013 Background: Allogeneic Hematopoietic Stem Cell Transplant (alloHSCT) is effective in some hematologic malignancies and studies of alloHSCT for ultra high-risk pediatric solid tumors have shown some promise. Preclinical data demonstrates that activated NK cells readily kill pediatric solid tumors and leukemias, large numbers of activated NK cells can be generated ex vivo using artificial APCs (aAPCs) and the post-transplant period may be favorable for expansion and survival of adoptively transferred NK cells. Methods: We initiated a Phase I trial to assess feasibility and toxicity of escalating doses of donor-derived activated NK cell donor lymphocyte infusions (NK-DLI) on days 7 and 35 days following HLA-matched T cell depleted PBSCT in children and young adults with ultra-high risk solid tumors and leukemias. Donors underwent a single apheresis for filgrastim mobilized PBSC. The product was T cell depleted and CD34 and CD56 selected prior to cryopreservation, and the CD56+ fraction was cultured for 9–11 days with a K562 based aAPC expressing 4-1BBL and IL-15Ra plus rhIL-15 to generate the NK-DLI. NK-DLI consistently expressed high levels of natural cytotoxicity receptors NKp44 and NKp46 and mediated potent cytotoxicity ex vivo. T cell addback to the CD34 selected graft was performed to administer a T cell dose of 0.8–1.4 × 10e4 T cells/kg. Except for two pilot patients where NK-DLI was infused following engraftment, NK-DLI were administered ∼Day 7 and 35 post-transplant. Patients received a reduced intensity preparative regimen (fludarabine 30 mg/m2 and cyclophosphamide, 1200 mg/m2 on days –6 to -3; and melphalan 100 mg/m2 on day -2), and no prophylactic immunosuppression. Results: Seven patients with sarcomas were transplanted with NK-DLI infusion (1×10e5 CD56+ cells/kg/dose). Engraftment was brisk (median platelet recovery at 8d and neutrophil recovery at 9d). Patients had full donor myeloid chimerism by day 14 and all but one had 〉80% lymphoid chimerism by day 28. Patient #1 received NK-DLI on day +24 following alloHSCT and experienced aGVHD within 24 hours of NK-DLI with bullous skin rash and voluminous diarrhea. Prior to infusion the patient had what appeared to be a viral rash and fevers (skin biopsy negative for GVHD), but in retrospect likely GVHD, which was exacerbated by NK-DLI. Patient #2 received NK-DLI on Day +15 with no adverse effects. Subsequent patients enrolled onto cohort 1 with planned NK-DLI at days 7 and 35 (+7). Two patients developed aGVHD (rash and diarrhea), one with a cytokine-type reaction (fevers, hypotension) within 48 hours of NK-DLI infusion and one with aGVHD starting 21 days post NK-DLI. All 3 patients with matched unrelated donors experienced aGVHD after NK-DLI, whereas the 5 patients with matched sibling donors had no apparent adverse reactions nor GVHD. Persistence/engraftment of infused NK-DLI cannot be definitively determined, however, mean NK cell counts measured pre-alloHSCT and day +28 are 165/mm3 and 668/mm3 in the present cohort (n=6) compared to 149/mm3 and 395/mm3 in a historical alloHSCT population that did not receive NK-DLI (n=24). Antitumor effects via PET imaging were observed in patients with measurable disease and those without disease at the time of transplant have remained NED. Conclusions: Ex-vivo, aAPC expanded NK-DLIs do not interfere with stem cell engraftment but may contribute to or induce aGVHD, particularly in patients with matched, unrelated donors. Preliminary results suggest that aAPC NK-DLI expand in vivo and mediate antitumor effects following allogeneic PBSCT. Disclosures: No relevant conflicts of interest to declare.

Description: Survival after relapsed and refractory pediatric pre-B ALL and non-Hodgkin lymphoma (NHL) is poor despite intensive chemotherapy and HSCT. CAR T cells combine the specificity and MHC independence of antibodies with the cytotoxic capacity of T cells. By genetically engineering them with a CAR that links an scFv for CD19, present on most NHL and ALL blasts, with the CD3zeta activation domain of the T cell receptor and the CD28 co-stimulatory domain, cytotoxicity can be specifically and fully activated with a single interaction. We undertook a Phase I clinical trial (NCT01593696) of anti-CD19-CD28-zeta CAR T cells in children with relapsed and refractory ALL and NHL with the aim of assessing 1) feasibility of generating adequate numbers of CAR T cells from a high risk population including post-HSCT patients 2) response rate 3) CAR T cell persistence and trafficking to extramedullary sites and 4) toxicities including acute toxicity related to cytokine release syndrome (CRS) and chronic B-cell aplasia related to long-term persistence of CAR T cells. Patients were enrolled on study, then PBMCs were collected by apheresis then immediately enriched for T cells using activating anti-CD3/CD28 beads before retroviral transduction of the CAR gene. After an 11-day manufacturing process, CAR T cells were infused fresh to patients who have received fludarabine (25 mg/m2/day Days -4, -3, -2) and cyclophosphamide (900 mg/m2/day Day -2). We have enrolled and treated 8 patients (7 ALL, 1 NHL; 4 pre-HSCT, 4 post-HSCT) aged 10-23 years. Regarding feasibility, 6 of 8 patients had successful expansion of CAR T cells that met the assigned dose level, with transduction efficiencies of 18-87%. Expansion was insufficient to meet the target dose for 2 patients, but each still received products that were 3% and 14% of the target dose. Response rate The overall complete response (CR) rate is 5 of 8 (62.5%; 95% CI 29-96%) or 5 of 7 ALL patients (71.4%; 95% CI 38-105%) with 3 of these being MRD-negative, including 1 patient who was primarily refractory to chemotherapy, and who proceeded to HSCT following CD19 CAR therapy. Both patients who received cells below the target dose experienced anti-leukemic effects, one with a transient CR and the other with an MRD-negative CR. CAR T cell expansion, persistence and trafficking: CAR T cells have been identified in blood (0.1-38%) and marrow (0.1-5%) in all responding patients. They have also been found in the CSF of 3 patients (0.3-17%), in the pleural fluid (13%) of an NHL patient with pre-existing malignant pleural effusions, and are suspected to have caused Gr 1 scrotal edema in a patient with a remote history of testicular disease. One patient with CNS2 disease at the time of enrollment cleared all CSF blasts as detected by flow cytometry without additional intrathecal chemotherapy after CAR T cells were administered (max 17% CAR T cells in CSF). The mean time to undetectable CAR T cells in any tissue in responding patients was 55 days (± 22.6; 95% CI 35-72). Toxicity Treatment was well tolerated. Two patients had Gr 2 CRS (Gr 3 fever, Gr 2 hypotension) that resolved with IV fluids and correlated with high IL6, GM-CSF, IFNg, TNFa, and C-reactive protein. One DLT (Gr 4 CRS) occurred (3 x 10^6 CAR+ T cells/kg) and required vasopressors for hypotension. After identifying high plasma IL6, the anti-IL6 receptor antibody, tocilizumab, was administered, and quickly reversed most toxicity from CRS. At the time of Day 28 restaging, CD19+ hematogones were detected by flow cytometry in four of five responding patients (mean 81.4% of all CD19+ cells; 95% CI 51-112%), indicating that significant antileukemic effects can be induced by CD19 CAR T cells without chronic depletion of B cell precursors. None of the patients with prior HSCT developed graft versus host (GVH) disease despite administering donor-derived activated T cells harvested from the recipient. Conclusions Anti-CD19-CD28-zeta CAR T cells that mediate potent antileukemic effects can be reliably generated, even from very advanced patients with or without a history of allogeneic HSCT. Using intent-to-treat reporting, CR rates are high (62.5%) in this refractory population. CD19 CAR T cells traffic to extramedullary sites and can mediate anti-tumor effects in CSF. Acute toxicity is manageable and because the anti-CD19-CD28-zeta CAR T cells do not persist at high levels for prolonged periods of time, rapid resumption of B cell lymphopoiesis occurs following therapy. Disclosures: Off Label Use: Anti-CD19 CAR T cells for the treatment of ALL and NHL.

Description: Abstract 3055 Background: Treatment of relapse after allogeneic hematopoietic stem cell transplantation (alloHSCT) remains challenging. The Wilms' tumor 1 (WT1) gene product is a tumor-associated antigen that is expressed in acute leukemia and other hematologic malignancies with limited expression in normal tissues. This pilot trial incorporates antigen-specific immunotherapy and allogeneic adoptive cell transfer for pediatric and adult patients with relapsed hematologic malignancies after alloHSCT. The primary objectives are to assess safety and feasibility of a peptide-loaded donor-derived dendritic cell (DC) vaccine and donor lymphocyte infusion (DLI) designed to enhance the graft-vs -leukemia effect. Secondary objectives are to determine if immunologic and clinical responses to WT1 specific peptides can be generated by this novel vaccine strategy after alloHSCT. Design: HLA-A2+ patients with WT1-expressing hematologic malignancies that have relapsed after alloHSCT are eligible. Donor-derived DC vaccines are given every 2 weeks for 6 doses and DLI every 4 weeks for 3 doses. Peripheral blood monocyte-derived DCs are loaded with a combination of three HLA-A2 binding WT1 peptides (WT1 37–45; WT1 126–134; WT1 187–195) linked to the 11-mer HIV TAT protein transduction domain peptide (47–57) designed to enhance antigen presentation. The DCs are generated from donor peripheral blood monocytes that are separated from DLI collected by apheresis. Monocytes are incubated with GM-CSF and IL-4 followed by maturation with LPS and IFN-g. WT1 expression is assessed using immunohistochemistry and/or quantative RT-PCR. Study endpoints included toxicity, feasibility, and antigen-specific immune and clinical responses. Results: 4 patients, aged 9–19 years have been treated to date, 3 with acute lymphoblastic leukemia (ALL) and one with Hodgkin lymphoma (HL). Donors were matched siblings in 3 cases and a 10/10 HLA matched father in one case. Vaccines were successfully produced from all donors. All patients tolerated vaccine and DLI administrations well. The most common adverse events were mild, reversible pain and pruritus at vaccine administration and delayed type hypersensitivity (DTH) skin test sites. One patient developed Grade I skin GVHD that did not require treatment. Immune responses were observed in all 3 patients with ALL. ELISPOT was considered positive when it was at least two times greater than and had at least 10 spots more than background. 3 of 4 (75%) patients had positive ELISPOT responses to WT1 peptides. 3 of 4 (75%) patients had positive DTH responses to the keyhole limpet hemocyanin (KLH) control and 2 of 4 (50%) to the WT1 peptides. Median overall survival was 12 months. 1 patient remains in remission 12 months after initiation of therapy and 3 have died of disease. All donors tolerated apheresis well and there were no complications from donor procedures. Conclusions: This novel allogeneic immunotherapy regimen is feasible, well-tolerated and can induce immune responses in the allogeneic setting. Accrual is ongoing. Disclosures: Off Label Use: This is a pilot clinical trial of an investigational cancer vaccine.

Description: Abstract 3246 Although most children and adolescents with ALL are cured, treatment-associated side effects are significant and outcome after relapse is poor. New therapies are needed to overcome drug resistance and reduce toxicities of chemotherapy. CD22 is a B-lymphoid differentiation antigen expressed on most B-lineage ALL blasts. We recently conducted a Phase I trial of the anti-CD22 immunotoxin RFB4(dsFv)-PE38 (CAT-3888 or BL22) in children with ALL or non-Hodgkin lymphoma (NHL). The safety profile was acceptable and transient clinical activity was seen; however, no objective responses were observed (Clin Cancer Res 2010;16:1894). We are conducting a Phase I trial of a modified agent with higher CD22 binding affinity (moxetumomab pasudotox, also known as CAT-8015 or HA22). Methods: Patients 6 months to 24 years of age with relapsed or refractory CD22+ B-lineage ALL or NHL are eligible for enrollment. Moxetumomab pasudotox is being administered at doses of 5, 10, 20, or 30 μg/kg every other day for 6 doses, every 21 days for up to 6 cycles. All patients receive pre-medication with acetaminophen, ranitidine, and diphenhydramine and prophylaxis for central-nervous-system leukemia with intrathecal hydrocortisone, cytarabine, and methotrexate. An initial completed cohort (A) consisted of one patient each treated at the first 3 dose levels (5, 10, 20 μg/kg) followed by standard 3+3 dose escalation commencing at 30 μg/kg. In attempt to reduce the incidence of vascular leak syndrome (VLS), a second ongoing cohort (B) is also receiving dexamethasone 2.5 mg/m2 every 12 hours around doses of moxetumomab pasudotox during cycle 1 with standard 3+3 dose escalation commencing at 20 μg/kg. Results: At the time of reporting, 14 patients 5 to 22 years of age (median, 11) with ALL (13 precursor-B, 1 mature B-cell) have been treated in the clinical trial. Patients had received a median of 4 prior regimens (range, 2–8), 12 were chemotherapy refractory, and 7 had received prior stem cell transplantation. Thirteen had leukemia-associated baseline cytopenias and thus were not evaluable for hematologic toxicities. The most common adverse events observed to date have been hyperbilirubinemia, transaminase elevations, hypoalbuminemia, elevated creatinine, febrile neutropenia, hypertension, microscopic proteinuria, hemoglobinuria, hypoxia, and pleural effusion. Two of 7 patients in Cohort A treated at 30 μg/kg experienced Grade 3 and Grade 4 VLS. None of 7 patients treated in Cohort B developed VLS. All toxicities attributed to moxetumomab pasudotox were reversible. Twelve patients were evaluable for response: 3 (25%) achieved complete remission by morphology and flow cytometry after 1, 1, and 2 cycles, respectively; 5 (42%) had hematologic activity (blood count improvement, blast reduction); and 3 (25%) had stable disease. One patient treated at the lowest dose level had progressive disease. Two patients developed high-titer neutralizing antibodies. Conclusions: Moxetumomab pasudotox has shown clinical activity against chemotherapy-refractory pediatric ALL, with complete remissions achieved in 3 of 12 patients. The demonstration of clinical activity and the safety profile exhibited by this agent to date support further study in ALL. ClinicalTrials.gov Identifier: NCT00659425 This study was sponsored by MedImmune, LLC. Disclosures: Off Label Use: Moxetumomab pasudotox is an investigational agent. Bhojwani:MedImmune: Research Funding. Silverman:Enzon: Consultancy, Honoraria; EUSA: Consultancy, Honoraria. Jeha:Genzyme: Honoraria, Research Funding. Pui:EUSA Pharma: Honoraria; Enzon: Honoraria; Sanofi-Aventis: Honoraria. McDevitt:MedImmune, LLC: Employment. FitzGerald:NCI: Co-inventor on patents assigned to the NIH for the investigational product., Patents & Royalties. Kreitman:NCI: Co-inventor on patents assigned to the NIH for the investigational product., Patents & Royalties. Lechleider:MedImmune, LLC: Employment. Pastan:NCI: Co-inventor on patents assigned to the NIH for the investigational product., Patents & Royalties.

Description: Abstract 248 Background: Most pediatric patients with acute lymphoblastic leukemia (ALL) are cured. For the 10 to 20% of patients with relapsed or refractory ALL, novel therapies are needed to overcome chemotherapy resistance. CD22 is an antigen commonly expressed on B-lineage ALL blasts. Moxetumomab pasudotox (previously known as CAT-8015 or HA22) is a recombinant immunotoxin composed of the variable domain of an anti-CD22 monoclonal antibody fused to a 38 Kda truncated form of Pseudomonas exotoxin A. Methods: We are conducting a multicenter, open-label, Phase I, dose-escalation study to determine the maximum tolerated dose and to assess the safety profile, activity, and immunogenicity of moxetumomab pasudotox in pediatric patients with relapsed/refractory hematologic malignancies. Eligibility criteria include age 6 months to 24 years, CD22+ B-lineage ALL or non-Hodgkin lymphoma, ≥1 prior salvage therapy, and no isolated testicular or central nervous system (CNS) disease. Moxetumomab pasudotox is administered as a 30-minute intravenous (IV) infusion at doses of 5, 10, 20, 30, or 40 mcg/kg, every other day for 6 doses, every 21 days. Patients receive concomitant IV hydration, pre-medication with acetaminophen, ranitidine, and diphenhydramine, and CNS prophylaxis with intrathecal hydrocortisone, cytarabine, and methotrexate. An initial cohort (A) consisting of an accelerated dose-escalation phase (one patient each treated at 5, 10, and 20 mcg/kg dose levels) followed by standard 3+3 dose-escalation at 30 mcg/kg dose has been completed. To reduce the incidence of capillary leak syndrome (CLS), a second ongoing cohort (B) was added to the study in which dexamethasone (2.5 mg/m2 every 12 hours) is coadministered during treatment cycle 1 around moxetumomab pasudotox doses. Standard 3+3 dose-escalation is being followed starting at the 20 mcg/kg dose level. Results: 21 patients 4 – 21 years of age (median, 11) with ALL have been treated; 7 in Cohort A and 14 in Cohort B (Table). They had received 2 – 8 prior regimens (median 4) and 17 were refractory to chemotherapy and 10 had undergone stem cell transplant. 1 – 4 treatment cycles (median, 1) of moxetumomab pasudotox were administered. The most common adverse events (regardless of attribution) reported to date are decreased hemoglobin, decreased platelets, increased aspartate aminotransferase (AST), pyrexia, decreased neutrophils, tachycardia, increased alanine aminotransferase (ALT), hypokalemia, increased weight, and decreased white blood cells. The most common treatment-related adverse events were increased weight, increased AST, increased ALT, and hypoalbuminemia. Most (70%) of the treatment-related toxicities have been mild and reversible. CLS that was dose-limiting was observed in 2 of 7 patients in Cohort A (30 mcg/kg dose level) and in none of 14 patients in Cohort B. One patient treated at 40 mcg/kg developed refractory hypercalcemia and died of a cardiac arrhythmia during attempted central venous catheter placement. That dose level (5B) was expanded and is currently accruing. Of the 17 (81%) patients evaluable for response (Table), objective responses were achieved in 5 (29%), including 4 (24%) complete responses (CR) and 1 (6%) partial response (PR). Hematological activity (HA) (〉50% reduction in blasts and/or improvement in neutrophil and/or platelet counts) was observed in 7 patients (41%). Anti-moxetumomab pasudotox neutralizing antibodies (titer ≥50% neutralization) developed in 3 of 21 (14%) patients. Conclusions: Moxetumomab pasudotox is active in pediatric patients with relapsed and chemotherapy-refractory ALL. The current observed anti-leukemic activity and safety profile at doses up to 40 mcg/kg warrant further development of moxetumomab pasudotox in pediatric ALL. ClinicalTrials.gov Identifier: NCT00659425 This study was sponsored by MedImmune, LLC, and supported in part by the Intramural Research Program of the NIH, National Cancer Institute, Center for Cancer Research. Disclosures: Wayne: NCI: Co-inventor on patents assigned to the NIH for the investigational product. Off Label Use: This is a Phase I trial of an investigational agent. Bhojwani:MedImmune, LLC: Research Funding. Silverman:Enzon: Consultancy, Honoraria; EUSA: Consultancy, Honoraria. Jeha:Genzyme: Honoraria, Research Funding. Pui:EUSA: Honoraria; Enzon: Honoraria; Sanofi: Honoraria. Buzoianu:MedImmune, LLC: Employment. FitzGerald:NCI: Co-inventor on patents assigned to the NIH for the investigational product. Kreitman:NCI: Co-inventor on patents assigned to the NIH for the investigational product. Ibrahim:MedImmune, LLC: Employment.

Description: Despite considerable advances in knowledge of the anatomy, ecology and evolution of early mammals, far less is known about their physiology. Evidence is contradictory concerning the timing and fossil groups in which mammalian endothermy arose. To determine the state of metabolic evolution in two of the earliest stem-mammals, the Early Jurassic Morganucodon and Kuehneotherium, we use separate proxies for basal and maximum metabolic rate. Here we report, using synchrotron X-ray tomographic imaging of incremental tooth cementum, that they had maximum lifespans considerably longer than comparably sized living mammals, but similar to those of reptiles, and so they likely had reptilian-level basal metabolic rates. Measurements of femoral nutrient foramina show Morganucodon had blood flow rates intermediate between living mammals and reptiles, suggesting maximum metabolic rates increased evolutionarily before basal metabolic rates. Stem mammals lacked the elevated endothermic metabolism of living mammals, highlighting the mosaic nature of mammalian physiological evolution.

Description: Chondrichthyan teeth from a new locality in the Scottish Borders supply additional evidence of Early Carboniferous chondrichthyans in the UK. The interbedded dolostones and siltstones of the Ballagan Formation exposed along Whitrope Burn are interpreted as representing a restricted lagoonal environment that received significant amounts of land-derived sediment. This site is palynologically dated to the latest Tournaisian–early Viséan. The diverse dental fauna documented here is dominated by large crushing holocephalan toothplates, with very few, small non-crushing chondrichthyan teeth. Two new taxa are named and described. Our samples are consistent with worldwide evidence that chondrichthyan crushing faunas are common following the Hangenberg extinction event. The lagoonal habitat represented by Whitrope Burn may represent a temporary refugium that was host to a near-relict fauna dominated by large holocephalan chondrichthyans with crushing dentitions. Many of these had already become scarce in other localities by the Viséan and become extinct later in the Carboniferous. This fauna provides evidence of early endemism or niche separation within European chondrichthyan faunas at this time. This evidence points to a complex picture in which the diversity of durophagous chondrichthyans is controlled by narrow spatial shifts in niche availability over time.