FOXP1 and KLF2 reciprocally regulate checkpoints of stem-like to effector transition in CAR T cells

In cancer and infections, self-renewing stem-like CD8+ T cells mediate the response of immunotherapies and replenish terminally exhausted T cells and effector-like T cells. However, the programs governing the lineage choice in chimeric antigen receptor (CAR) T cells are unclear. Here, by simultaneously profiling single-cell chromatin accessibility and transcriptome in the same CAR T cells, we identified heterogeneous chromatin states within CD8+ T cell subsets that foreshadowed transcriptional changes and were primed for regulation by distinct transcription factors. Transcription factors that controlled each CD8+ T cell subset were regulated by high numbers of enhancers and positioned as hubs of gene networks. FOXP1, a hub in the stem-like network, promoted expansion and stemness of CAR T cells and limited excessive effector differentiation. In the effector network, KLF2 enhanced effector CD8+ T cell differentiation and prevented terminal exhaustion. Thus, we identified gene networks and hub transcription factors that controlled the differentiation of stem-like CD8+ CAR T cells into effector or exhausted CD8+ CAR T cells.

Prospective PTCTC trial of myeloablative haplo-BMT with posttransplant cyclophosphamide for pediatric acute leukemias

Promising results have been reported for adult patients with high-risk hematologic malignancies undergoing haploidentical bone marrow transplant (haploBMT) with posttransplant cyclophosphamide (PTCy). To our knowledge, we report results from the first multicenter trial for pediatric and young adult patients with high-risk acute leukemias and myelodysplastic syndrome (MDS) in the Pediatric Transplantation and Cellular Therapy Consortium. Nine centers performed transplants in 32 patients having acute leukemias or MDS, with myeloablative conditioning (MAC), haploBMT with PTCy, mycophenolate mofetil, and tacrolimus. The median patient age was 12 years. Diagnoses included AML (15), ALL (11), mixed-lineage leukemia (1), and MDS (5). Transplant-related mortality (TRM) at 180 days was 0%. The cumulative incidence (CuI) of grade 2 acute graft-versus-host disease (aGVHD) on day 100 was 13%. No patients developed grades 3-4 aGVHD. The CuI of moderate-to-severe chronic GVHD (cGVHD) at 1 year was 4%. Donor engraftment occurred in 27 patients (84%). Primary graft failures included 3 patients who received suboptimal bone marrow grafts; all successfully engrafted after second transplants. The CuI of relapse at 1 year was 32%, with more relapse among patients MRD positive pre-BMT vs MRD negative. Overall survival rates at 1 and 2 years were 77% and 73%, and event-free survival rate at 1 and 2 years were 68% and 64%. There was no TRM or severe aGVHD, low cGVHD, and favorable relapse and survival rates. This successful pilot trial has led to a phase 3 trial comparing MAC haploBMT vs HLA-matched unrelated donor BMT in the Children's Oncology Group. This trial was registered at www.clinicaltrials.gov as #NCT02120157.

Abstract CT522: Feasibility and safety of a novel CD19 CAR T cell therapy in adults with R/R B-NHL

Genetically engineered chimeric antigen receptor (CAR) T cells have exhibited distinct effectiveness against chemotherapy refractory CD19 expressing B cell malignancies in both adults and children. This phase I clinical trial tests a novel anti-CD19 CAR T cell product in adults with relapsed/refractory (R/R) B-cell Non-Hodgkin’s Lymphoma (B-NHL). The CAR construct is comprised of the short chain variable regions of the anti-CD19 monoclonal antibody FMC63, the TNFRSF19-derived transmembrane domain, the 4-1BB costimulatory domain, and the CD3-zeta signaling domain. CD19 CAR T cells were manufactured utilizing the CliniMACS Prodigy® T Cell Transduction Process (CD3/CD28 TransAct™ reagent) allowing for highly automated production, with IL-7 and IL-15 used for T cell expansion for 8-12 days. To date, 7 patients have been treated with an average dose of 1.2 ± 0.2 x 108 CAR T cells. The histology includes marginal zone lymphoma (n=1), follicular lymphoma Grade IIIA (n=1), transformed lymphoma (n=3), follicular lymphoma low grade (n=2), and diffuse large B-cell lymphoma (n=1). One patient required a second apheresis due to poor cell expansion. Despite heterogeneity in disease subtype and leukapheresis product quality, CAR T production and expansion have been consistent with final transduction efficiencies between 14-45%, cell viability between 88-91%, and an overall average yield of 3.2 ± 0.3 x 109 cells before harvest, allowing for product banking. No safety-related out of specifications (OOS) events have occurred, however, 2 patients had OOS product infused due to low transduction efficiency (both at 14% rather than the ≥ 20% release criteria). Two patients experienced Grade 2 CRS, 1 patient experienced Grade 2 neurotoxicity; otherwise, no new safety signals were detected. Disease response was assessed on Days 90, 180, 270, and 360 post-infusion. The assessments were based on 2014 Lugano criteria. Even with 2 OOS products, Day 90 scans showed a complete metabolic remission (CMR) in 6 evaluable patients to date. Of the 6 patients with CMR, 1 patient progressed at Day 180 and the others remain in remission (median f/u = 12 months). Flow cytometry was utilized to measure CAR T cell peak expansion and persistence in 5 patients. Peak CAR T cell expansion (2.9-44.4% of CD3 cells) ranged from Day 5 to 15. Cell persistence was detected for the 5 patients through at least Day 180. ddPCR is currently in development to perform persistence testing in parallel. Additionally, cytokine concentrations including INFγ, IL-10, IL-12p70, IL-13, IL1β, IL-2, IL-4, IL-6, IL-8, and TNFα were evaluated over the first 30 days. Overall, 7 patients diagnosed with 5 different B-NHL subtypes have been treated with the CD19 CAR T cell product. Manufacturing was successful for all patients with no safety related OOS, and no new post-infusion safety signals detected. To date, 6 out of 7 patients are alive, 5 with CMR and with CD19 CAR T cell persistence through at least 180 days.

Citation Format: Manali Kamdar, Cheri Adams, Steven Bair, Boro Dropulic, Jonathon Gutman, Bradley Haverkos, Kimberly Jordan, Rebecca Mallo, Russell Marians, Felicia Mast, Lindsey Murphy, Andrew Roth, Matthew Seefeldt, Andrew Worden, Mike Kadan, Ying Xiong, Dina Schneider, Rimas Orentas, Terry Fry, Michael Verneris. Feasibility and safety of a novel CD19 CAR T cell therapy in adults with R/R B-NHL [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT522.

IMMU-23. Novel gene-edited CAR-T cell therapy against Diffuse Intrinsic Pontine Glioma

BACKGROUND: We identified high expression of CD99 in DIPG tumors and developed a CAR using our newly identified single chain variable fragment (scFv) targeting CD99 incorporating a 4-1BB co-stimulatory domain. This CD99 CAR demonstrated the ability to dramatically shrink the established orthotopic DIPG tumor, however tumor recurrence remains an obstacle to cure, due to a loss of the CAR-T cells as they also express the target antigen, CD99 (fratricide). To overcome this obstacle, we modified these CAR-T by editing out CD99. METHODS: CD99 was knocked-out from the human T cells using CRISPR-cas9 gene-editing and subsequently transduced with our CD99 CAR-encoding virus, and isolated the pure population of CD99KO T-cells. These novel, gene-edited T-cells expressing CD99 CAR (“CD99KO CARs”) and the un-edited ones (“CD99 CAR”) were tested for tumor-lysis function when co-cultured with DIPG cells. DIPG tumor-bearing mice infused with a one-time dose of CD99KO CAR-T cells or CD99 CAR- or CD19 control CAR-T cells and were monitored for changes in the tumor burden. At the endpoint spleen and bone marrow were isolated to test for CAR+ cell persistence. RESULTS: The CD99KO CAR-T cells demonstrated effective tumor-lysis when co-cultured with DIPG cells. CD99KO CAR-T cells targeting CD99 showed complete clearance of DIPG tumor in orthotopic DIPG mouse models, and no tumor recurrence was seen well-beyond the time frame of expected tumor recurrence after treatment with un-edited CD99 CAR-T cells. There was an un-precedented increase in the xenograft survival, > 200 days, in mice treated with CD99KO CARs and at which time point sustained persistence of CAR+ cells were evident in the animal spleen and bone marrow. CONCLUSIONS: We have generated a new and promising CAR-T cell therapy that is effective against DIPG with enhanced persistence in animal models which is critical for clinical translation.

Precision killing of T cells via targeting of T cell receptors using two novel chimeric antigen receptor designs

Pathologic T cells drive T cell leukemia, solid organ transplant rejection, and many autoimmune diseases. Currently approved treatments have limited ability to target pathogenic vs non-pathogenic T cells. While pan-T cell treatments can be effective, they have significant risks such as infection and malignancy. Chimeric antigen receptors (CAR) are synthetic constructs that retarget T cells to a specific antigen of interest; we hypothesized that we could use this technology for targeted killing of T cells.

We developed two novel CAR designs which target T cells via their T cell receptor (TCR). We opted to target OT1 T cells, a model system with a known antigenic epitope. The anti-Vβ5 CAR is a second-generation CAR with a traditional extracellular scFv domain that targets Vβ5 of the OT1 TCR. The H2Kb bait CAR instead has an extracellular H2Kb complex loaded with the SIINFEKL cognate epitope. Both anti-Vβ5 and H2Kb bait CAR T cells demonstrate degranulation, activation, and proliferation upon binding OT1 T cells. In vitro co-culture with OT1 T cells results in internalization of the OT1 TCR and specific killing of OT1 T cells. Interestingly, the changes induced by the H2Kb bait CAR were delayed relative to the anti-Vβ5 CAR. In vivo experiments show both CAR designs kill adoptively transferred OT1 T cells without significant effect on the other T cell populations.

In conclusion, we report the development of two novel CAR designs which allow for the targeted killing of T cells via their T cell receptor. While the anti-Vβ5 CAR T cells generated a more rapid response, the H2Kb bait CAR offers the promise of more precisely targeting T cells. This work has the potential to transform the treatment of conditions where removal of pathogenic T cells is critical for cure.

Supported by NIH HL152756

Does lineage plasticity enable escape from CAR-T cell therapy? Lessons from MLL-r leukemia

The clinical success of engineered, CD19-directed chimeric antigen receptor (CAR) T cells in relapsed, refractory B-cell acute lymphoblastic leukemia (B-ALL) has generated great enthusiasm for the use of CAR T cells in patients with cytogenetics that portend a poor prognosis with conventional cytotoxic therapies. One such group includes infants and children with mixed lineage leukemia (MLL1, KMT2A) rearrangements (MLL-r), who fare much worse than patients with low- or standard-risk B-ALL. Although early clinical trials using CD19 CAR T cells for MLL-r B-ALL produced complete remission in most patients, relapse with CD19-negative disease was a common mechanism of treatment failure. Whereas CD19neg relapse has been observed across a broad spectrum of B-ALL patients treated with CD19-directed therapy, patients with MLL-r have manifested the emergence of AML, often clonally related to the B-ALL, suggesting that the inherent heterogeneity or lineage plasticity of MLL-r B-ALL may predispose patients to a myeloid relapse. Understanding the factors that enable and drive myeloid relapse may be important to devise strategies to improve durability of remissions. In this review, we summarize clinical observations to date with MLL-r B-ALL and generally discuss lineage plasticity as a mechanism of escape from immunotherapy.

Abstract LB105: In vivo CAR T therapy: targeted in vivo gene delivery of a CAR using a CD8-specific fusogen results in tumor eradication

CAR T cells are highly effective at inducing remissions in patients with refractory B cell malignancies. The ex vivo process used to manufacture these therapies limits patient access and exposes T cells to non-physiologic conditions in culture. Viral vectors are efficient at genetically modifying T cells and are used in the ex vivo manufacture of most CAR T cell products but lack target-cell specificity. Here we describe how viral envelope glycoproteins, termed fusogens, engineered to target the CD8 co-receptor can efficiently and specifically deliver a chimeric antigen receptor (CAR) to human T cells in vivo that support target cell killing and tumor eradication. Modification of viral envelope proteins to include antibody-based binding domains (CD8 binders) can produce fusogen-viral vector compositions that deliver genetic payloads to CD8 T cells with therapeutic effect (1, 2). Screening CD8-targeted binders identified fusogens with a range of on-target cell transduction efficiencies and off-target cell line specificities. CD8-targeted fusogens with the highest efficiency were comparable to VSVg-pseudotyped lentiviruses at transducing CD8 T cells, but unlike VSVg showed CD8 T cell specific transduction. Interestingly, CD8-targeted fusogens were superior to VSVg-pseudotyped lentivirus at transducing non-activated human T cells. In vivo fusogen-mediated delivery showed efficient and specific CD8 T cell transduction and expression of a GFP reporter gene. Second-generation CARs containing a CD19 binding domain and a 41BB costimulatory domain delivered by targeted fusogen demonstrated CD8 specific expression and functional activity against non-malignant B cells and CD19+ Nalm6 leukemia cells. To demonstrate targeted fusogen-mediated in vivo CAR delivery and activity, we established Nalm6 xenografts in mice into which unmodified activated human PBMCs were infused. Activated human PBMCs alone were unable to control tumor growth. A single intravenous delivery of a CD8 fusogen containing a second-generation CD19 CAR transgene across a range of functional titer doses resulted in the generation of CD8 CAR Ts that eradicated the CD19+ tumor xenografts. A high percentage of T cells demonstrated CAR expression after fusogen delivery with clear specificity for the CD8+ cells. Importantly, the fusogen was able to generate a functional CAR response regardless of prior activation status of the T cells. Targeted in vivo delivery of CAR into T cell subsets may represent a novel therapeutic approach for human B cell malignancies. The ability to specifically deliver a CAR gene to a T cell in vivo would be transformative in terms of patient access and is likely to generate a qualitatively superior therapeutic T cell. References: 1) Bender, R. R. et al. PLOS Pathogens 12, e1005641 (2016). 2) Agarwal, S. et al. OncoImmunology 8, 1-8 (2019).

Citation Format: Akinola Emmanuel, Patty Cruite, Hanane Ennajdaoui, Carmela Passaro, Paige Baldwin, Victoria Duback, Anna Liang, Jess Elman, Samantha Crocker, Shirisha Amatya, Caspian Harding, Allyse Mazarelli, Sergey Lyubinetsky, Vidur Patel, Avani Parikh, Kelan Hlavaty, Jason Rodriguez, Lauren Pepper, Albert Ruzo, Salvatore Iovino, Kutlu Elpek, Michael Laska, Trevor McGill, Donna Dambach, Terry Fry, Jagesh Shah. In vivo CAR T therapy: targeted in vivo gene delivery of a CAR using a CD8-specific fusogen results in tumor eradication [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB105.

IMMU-20. EVALUATION OF CAR T CELLS IN EPENDYMOMA

BACKGROUND

Ependymoma is the third most common pediatric brain tumor and current treatment still results in a 10-year relapse rate of over 70% in the highest risk groups. The treatment refractory nature of ependymoma to standard therapies strongly supports the development of novel interventions. Ependymoma tumor cells express HER2 and there are active clinical trials treating children with ependymoma using local delivery of second-generation HER2 CAR T cells.

METHODS

Two high-risk patient-derived ependymoma cell lines, MAF811 and MAF928, that display HER2 surface expression are used for testing. We tested second-generation HER2-BBz CAR T cells in vitro and in vivo.

RESULTS

HER2 CAR T cells effectively kill ependymoma tumor cells in culture, but this strategy cannot eradicate the same tumor cells in mice when implanted in the fourth ventricle of the brain. HER2 CAR T cells proliferate and traffic into the tumor, but this causes a dramatic influx of immune cells, tumor swelling and lethal toxicity in a subset of mice. Mice that survive this initial tumor swelling, display significant tumor shrinkage but all tumors eventually start growing again. Ependymoma tumor cells release high amounts of inflammatory chemokines that strongly attract neutrophils and monocytes to the tumor, compared to other brain tumors, and can downregulate HER2 expression to escape recognition by CAR T cells.

CONCLUSION

The immunosuppressive microenvironment as well as tumor heterogeneity make HER2 CAR T cells ineffective in ependymoma. Studying these two hurdles in CAR T cell therapy is critical to effectively treat brain tumors with CAR T cells.

Abstract 3234: Multi-antigen targeting of CD19, CD22 and TSLPR to prevent Ph-like ALL resistance

Background: Despite high remission induction rates after CD19 chimeric antigen receptor T cell (CART) therapy in patients with B-acute lymphoblastic leukemia (ALL), many patients eventually relapse with loss of CD19 antigen. Strategies to overcome antigen-loss relapse include co-targeting of multiple antigens and selection of alternative functionally important surface targets. The thymic stromal lymphopoietin receptor (TSLPR), encoded by CRLF2 (cytokine receptor-like factor 2), is overexpressed in >50% of patients with Ph-like ALL and is associated with constitutively active JAK/STAT signaling targetable by ruxolitinib. Our groups previously demonstrated potent activity of TSLPRCART against TSLPR+ ALL (Qin Blood 2015). Our current study aims to develop (1) multi-specific CAR T cells targeting TSLPR and CD19 or CD22 and (2) TSLPRCART and ruxolitinib combinatorial approaches to decrease antigen-negative relapse potential after CART therapy.

Methods: Lentiviral transduction of activated healthy donor T cells was used to introduce monovalent TSLPR or CD19 CARs and bivalent CD19xTSLPR or CD22xTSLPR CARs. CAR expression was quantified via flow cytometry. CRISPR/Cas9-modified Nalm-6 (human B-ALL) cells were transduced with a TSLPR expression vector to generate cell lines expressing combinations of CD19, CD22, and TSLPR antigens. In vitro functionality was assessed using enzyme linked immunosorbent assays to detect IL-2 and IFN-γ production following CART co-culture with Nalm-6. In vivo evaluation was performed against luciferase-transduced Nalm-6 murine xenograft models treated with 5e6 CART and monitored by bioluminescent imaging. TSLPRCART was also tested against MUTZ5 (TSLPR-overexpressing Ph-like ALL) cells in vitro and in vivo in combination with ruxolitinib to determine effects on CAR T cells.

Results: TSLPRCART and CD19xTSLPRCART induced in vitro cytokine production when co-cultured with CD19+/TSLPR+ Nalm-6 cells with higher levels than those produced by CD19CART. Greater cytokine production was observed with co-incubation of TSLPR+ Nalm-6 cells with CD22xTSLPRCART vs TSLPRCART. In vivo studies demonstrated equivalent leukemia eradication by TSLPRCART and CD19CART compared to CD19xTSLPRCART in CD19+/TSLPR+ Nalm-6 xenograft models. Additional in vivo studies in MUTZ5 xenograft models co-treated with TSLPRCART and ruxolitinib demonstrated impaired T cell expansion and cytokine production, which could be overcome via higher CART cell dose or delayed ruxolitinib administration.

Conclusions: TSLPRCART is a robust immunotherapeutic strategy for CRLF2-rearranged Ph-like ALL. We demonstrate potent in vitro and in vivo functionality of novel bivalent CD19xTSLPRCART and CD22xTSLPRCART. Ongoing studies are also evaluating bicistronic CD19xTSLPR CAR constructs. We further demonstrate that combining TSLPRCART with ruxolitinib moderately blunts T cell expansion and cytokine production, which could be an attractive strategy for management of CAR T cell-associated toxicities such as cytokine release syndrome.

Citation Format: Savannah Ross, Asen Bagashev, Dina Schneider, Peirong Hu, Sarah Tasian, Terry Fry. Multi-antigen targeting of CD19, CD22 and TSLPR to prevent Ph-like ALL resistance [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3234.

Abstract 1440: Evolution of CD19 expression in pediatric B-cell malignancies in the era of targeted therapy

Introduction: Ubiquitous expression of CD19 renders it an ideal target for immunotherapy in B-cell neoplasms. As such, loss or decrease in CD19 is emerging as a means of cancer resistance. As a referral center for CD22-based approaches, an alternative target in B-cells, we had the opportunity to serially evaluate CD19 changes following targeted therapy.

Methods: In this retrospective chart review, we assessed for evolution of CD19 expression in patients referred for CD22 immunotherapies. Data collection included demographics, prior therapies, and serial CD19 expression as assessed by flow cytometry (% positivity and site density), response to prior CD19 targeted therapy, and change from baseline.

Results: 56 unique patients were analyzed. The median age was 19 years (range 4-30). At the time of referral (baseline), 23 (41%) subjects were CD19 negative, all following > 1 forms of CD19-targeted therapy. 8 (14%) were CD19 partial positive including 2 patients who were 28% and 81% CD19 positive but CD19-immunotherapy naïve. 25 (43%) were CD19 positive, 2 were CD19 dim following blinatumomab, and 7 were CD19-immunotherapy naïve. In 40 of 56 subjects (71%), there was no change in CD19 expression. 16 (29%) patients had either gain or loss of CD19. In those with CD19 re-expression, the median time for this occurrence was 91 days from baseline.

Conclusions: In this heterogenous population, we document evolution in CD19 expression following CD19-immunotherapy and identified unique patients with inherent CD19 alterations. Some patients retain or regain CD19 expression, conferring new susceptibility to CD19 targeting, while others permanently lose CD19, rendering further CD19-targeted approaches futile. The development of this latter population raises the concern for the outgrowth of subclinical CD19 negative clones. Pairing these findings with genomics will be important to understand the mechanism behind these changes in expression in the search to optimize treatment for B-cell cancers.

Table 1Baseline DemographicsFirst Change from Baselinen=56 (%)# with CR to prior therapyChangen (%)Days to ↑ CD19 expression (Median, IQR)Age (median, range in years)19 (4-30)Male38 (68%)At study baseline*CD19 negative23 (41%)Baseline CD19 Negative (n=23)Remains CD19 neg17 (74%)NAPrior CD19 CAR1614Prior blinatumomab32Becomes CD19 Partial4 (17%)133 (351)Both33**Other CD19 targeted (SGN19a)10Becomes CD19 Positive2 (9%)416 (39)No prior targeted therapy0–CD19 partial#8 (14%)Baseline CD19 Partial (n=8)Becomes CD19 neg0NAPrior CD19 CAR10Prior blinatumomab62Remains CD19 partial4 (50%)NABoth00Becomes CD19 positive4 (50%)53 (66)No prior targeted therapy2–CD19 positive23 (41%)Baseline CD19 positive (n=25)Becomes CD19 neg##2 (8%)NAPrior CD19 CAR55Prior blinatumomab74Becomes CD19 partial3 (12%)NABoth42**No prior targeted therapy7–CD19 dim^ (uniformly positive)2 (4%)CD19 dim to positive1 (4%)21 (NA)Prior CD19 CAR00Prior blinatumomab21Remains CD19 positive19 (76%)NABoth00No prior targeted therapy00CR: Complete remissionIQR: interquartile range*Baseline represents first sample that subject had at the time of referral to the NIH with detectable disease^Indicates CD19 expression < 2000 sites/cells#Partial positivity defined by < 95% antigen positive**Complete response to CD19 CAR, no response to blinatumomab##Following interval CD19 targeted-therapy

Citation Format: Diane Libert, Constance M. Yuan, Haneen Shalabi, Dalia Salem, Bonnie Yates, Cindy Delbrook, Terry Fry, John Shern, Maryalice Stetler-Stevenson, Nirali Shah. Evolution of CD19 expression in pediatric B-cell malignancies in the era of targeted therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1440.

Abstract 603: Evaluation of CD19 targeted T cells in relapsed or refractory ALL patients unable to afford allogenic bone marrow transplant in India

CAR-T cell therapy has demonstrated remarkable success in long-term remission of relapsed or refractory B-ALL. Unlike western countries, most of the relapsed/refractory B-ALL patients in India are unable to afford allogeneic stem cell transplant (allo-SCT), and simply choose palliation. To assess the potential use of CAR-T cells as a first line therapy, it is critical to evaluate CAR-T cell efficacy in patients unable to undergo allo-SCT. As a first step, a novel anti-CD19 CAR was designed and CD19-vector was produced using lentiviral mediated gene delivery system. To generate CD19+CAR T cells, T cells from healthy subjects were transduced and expanded either with rIL-2 or rIL-15. Almost 20-50% transduced T cells express CD19-CAR on their surface as analysed by flow cytometry. Next, efficacy of CD19-CAR-T cells was examined by cytotoxicity assay using CD19+ malignant B cell lines (Raji cells) and autologous B cells. CAR-T cells were able to kill majority of CD19+B cells effectively (100% killing). In addition, CAR-T cells secreted high levels of IFNΓ and IL-2. The CAR-T cells expanded in presence of rIL-15 showed fewer Treg compared to CAR-T cells expanded using rIL-2, however, there were no differences in numbers of T stem cells (TSC) and central memory T cells (TCM). In addition to data on healthy volunteers reflected above, results of above tests in relapsed/ refractory B-ALL patients is ongoing and being collated for inclusion in the final analysis. In conclusion, our data demonstrate the successful development of an indigenous CAR-T cell platform for subsequent use in clinical trials of CD19+B cell malignancies.

Citation Format: Alka Dwivedi, Sushant Kumar, Terry Fry, Gaurav Narula, Rahul Purwar. Evaluation of CD19 targeted T cells in relapsed or refractory ALL patients unable to afford allogenic bone marrow transplant in India [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 603. doi:10.1158/1538-7445.AM2017-603

Research involving pediatric stem cell donors: A way forward

The most suitable donor for younger patients who undergo hematopoietic stem cell transplantation in the research setting is frequently a minor sibling. These cases raise the question of whether minors who serve as stem cell donors for research subjects should be regarded as research subjects themselves. Regarding pediatric donors as research subjects ensures that an Institutional Review Boards reviews their involvement and determines whether it is appropriate. Yet, Institutional Review Boards must follow the US regulations for pediatric research, which were designed for patients and healthy volunteers, not for healthy donors. As a result, regarding pediatric donors as research subjects also can pose unnecessary obstacles to appropriate and potentially life-saving research. This article considers a new way to address this dilemma. The federal research regulations allow for waiver of some or all of the included requirements when they are unnecessary for a study or a class of studies. We argue that this option offers a way to ensure that the involvement of pediatric donors receives sufficient review and approval without inadvertently undermining valuable and potentially life-saving research.

Convergence of Acquired Mutations and Alternative Splicing of CD19 Enables Resistance to CART-19 Immunotherapy

The CD19 antigen, expressed on most B-cell acute lymphoblastic leukemias (B-ALL), can be targeted with chimeric antigen receptor-armed T cells (CART-19), but relapses with epitope loss occur in 10% to 20% of pediatric responders. We detected hemizygous deletions spanning the CD19 locus and de novo frameshift and missense mutations in exon 2 of CD19 in some relapse samples. However, we also discovered alternatively spliced CD19 mRNA species, including one lacking exon 2. Pull-down/siRNA experiments identified SRSF3 as a splicing factor involved in exon 2 retention, and its levels were lower in relapsed B-ALL. Using genome editing, we demonstrated that exon 2 skipping bypasses exon 2 mutations in B-ALL cells and allows expression of the N-terminally truncated CD19 variant, which fails to trigger killing by CART-19 but partly rescues defects associated with CD19 loss. Thus, this mechanism of resistance is based on a combination of deleterious mutations and ensuing selection for alternatively spliced RNA isoforms.

SIGNIFICANCE

CART-19 yield 70% response rates in patients with B-ALL, but also produce escape variants. We discovered that the underlying mechanism is the selection for preexisting alternatively spliced CD19 isoforms with the compromised CART-19 epitope. This mechanism suggests a possibility of targeting alternative CD19 ectodomains, which could improve survival of patients with B-cell neoplasms.

Abstract 3309: T cell lymphoblastic leukemia in survivin TCR transgenic mice

Survivin has been considered a potential tumor antigen due to high expression in most cancers and limited expression in normal tissues. To explore whether survivin reactive TCRs mediate antitumor effects in mice, we generated TCR transgenic (Tg) mice with specificity for the H-2b restricted immunodominant epitope of survivin. Survivin reactive T cells were CD8+ and mediated immune reactivity toward survivin peptide pulsed targets. Some antitumor reactivity was observed, but it was not potent, and the survivin TCR Tg+ cells did not mediate objective tumor regression of survivin bearing tumors. Surprisingly, spontaneous T cell acute lymphoblastic leukemia (T-ALL) was observed beginning at 4-6 months of age in Tg+Rag+/- and Tg+Rag-/- mice. By one year of age, all survivin Tg+ mice succumbed to T-cell ALL. The leukemic cells were CD3+, survivin TCR+, and CD8+ or CD4-/CD8-Occurrence in 3 founders suggests that the transgene itself, rather than insertional mutagenesis, is causative. Given that survivin is expressed in the thymus, we postulated that the TCR-Tg serves as an oncogene via recognition of survivin peptides, which expands early thymic progenitors. In support of this, premalignant survivin TCR Tg+ thymi show expanded CD4-CD8-CD44-CD25- thymocytes and increased BrdU incorporation and leukemia incidence was significantly diminished TCR-Tg+β2m-/- mice. Subsequent to expansion of early thymic progenitors in response to TCR triggering, survivin TCR Tg+ cells acquire NOTCH mutations and upregulate CD25, implicating NOTCH signaling as a 2nd hit in this oncogenic process. At least one NOTCH1 mutation was found in all leukemias, with PEST (8/8), 5’ deletions (19/25) and heterodimerization mutations observed. T-ALL with NOTCH mutations was also observed at reduced frequencies, in TCR Tg mice with specificity to WT1 and gp100. We conclude that genetic engineering aimed at endowing hematopoietic or T lymphoid progenitors with the capacity to recognize tumor antigens expressed in the thymus could pose a risk for neoplasia, independent of insertional mutagenesis.

Citation Format: Yongzhi Cui, Masahiro Onozawa, Haiying Qin, Terry Fry, Peter Aplan, Crystal L. Mackall. T cell lymphoblastic leukemia in survivin TCR transgenic mice. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3309. doi:10.1158/1538-7445.AM2013-3309

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

Graft versus host disease impairs vaccine responses via decreased CD4+ and CD8+ T cell proliferation and increased CD8+ T cell apoptosis through the perforin pathway (126.27)

Graft versus leukemia (GVL) responses contribute to the curative potential of allogeneic blood or marrow transplantation (alloBMT) but can be associated with graft versus host disease (GVHD). Tumor-targeted vaccines have the potential to enhance the potency and specificity of GVL, but we have shown that GVHD can limit responses. Using a minor histocompatibility-mismatched BMT (B6 ->C3H.SW) with donor lymphocyte infusions (DLI), we examined the mechanism of reduced vaccine responses. The proliferative capacity, persistence and survival of vaccine-responding T cells were monitored following adoptive transfer of HY-specific T cells and HY-expressing dendritic cells in mice with GVHD. Both CD4+ and CD8+ HY specific T cells undergo less vaccine-driven proliferation in recipients with GVHD. Furthermore, HY-specific CD8+ T cells demonstrated increased apoptosis, whereas HY-specific CD4+ T cells did not. To determine a mechanism of apoptosis, we used a Fas Ligand-, TRAIL-, or perforin-deficient DLI to induce GVHD. Fas ligand- and TRAIL-deficient DLI did not affect apoptosis of the CD8+ HY-specific T cell population. However, a perforin-deficient DLI resulted in significantly less apoptosis. Finally, perforin-deficient DLI allowed for enhanced HY-expressing tumor protection. Thus, diminished vaccine responses seen during GVHD result from reduced proliferation and perforin-mediated CD8+ T cell apoptosis, factors to be considered when optimizing vaccine strategies following alloBMT.

Progression of acute lymphoblastic leukemia (ALL) results in compartment-restricted T cell expression of PD-1 and T cell dysfunction (46.22)

ALL is the most common cause of cancer related mortality in children. Although immune-based therapies for B cell malignancies have recently demonstrated promising results, the limited efficacy of donor lymphocyte infusions after allogeneic transplantation suggest that ALL may compromise immune responses. Using a murine model of pre-B-cell ALL, we have shown that leukemia progression is associated with PD-1 and TIM3 expression on CD4+ and CD8+ T cells evident at early infiltration of ALL with eventual expression on 80% of T cells with advanced disease. This was apparent in all leukemia-containing compartments including bone marrow, spleen and lymph nodes. PD-1 expressing CD8+ cells in leukemia compartments are predominantly CD44+CD62L- consistent with effector memory phenotype and a subset also express KLRG1 and LAG3. Finally, we assessed functionality of T cells from ALL mice including expression of the degranulation marker CD107a as well as production of TNFα, IFNγ, and IL-2 cytokines. Preliminary data suggests global impairments of functionality in the presence of leukemia. Currently, we are investigating the antigen-specificity of PD-1 acquisition, the translatability of our findings to clinical samples, and the effects of anti-PD-1 blockade on tumor progression. Given the pervasiveness of PD-1 and evidence for T cell dysfunction with ALL progression, elucidating the mechanism by which this process occurs could provide therapeutic targets for advancing ALL immunotherapy.

Inhibition of STAT1 modulates GVHD after allogeneic BMT through induction of S100A8/A9 (169.38)

T cell depletion (TCD) of donor bone marrow (BM) reduces graft-versus-host-disease (GVHD) after allogeneic blood and marrow transplantation (alloBMT), but can result in poor T cell reconstitution and relapse. We have shown that transplantation of TCD BM deficient in the gamma interferon (IFNγ) receptor allows delayed donor lymphocyte infusions (DLI) without GVHD. We have replicated these results with TCD BM deficient in STAT1, which mediates IFNα and IFNγ signals, and demonstrated expanded plasmacytoid dendritic cells (pDCs). In this study, we further characterized the mechanism of GVHD resistance. After MHC-matched, minor histocompatibility antigen-mismatched alloBMT, TCD STAT1-deficient BM prevents DLI-induced GVHD. Treatment of wild type BM donors and recipients with the glucagon-like peptide-1 analog, Exenatide, which mediates off-target inhibition of STAT1, attenuates GVHD and increases splenic B220+ cell recovery. TCD IRF9-deficient BM, which lacks IFNα signaling, does not prevent GVHD, confirming that IFNγ signaling via STAT1 is the primary pathway of GVHD resistance. Selective deletion of STAT1 using CD11c cre/STAT1flox BM is sufficient to attenuate GVHD-associated weight loss, further implicating a DC subset. Although S100 proteins are not typically found in pDCs, pDCs from TCD STAT1-deficient BM recipients express increased S100A8. Finally, TCD S100A8/A9-deficient BM causes more severe weight loss after DLI, confirming the relevance of S100 proteins in GVHD.

Eradication of disseminated adenovirus infection in a pediatric hematopoietic stem cell transplantation recipient using the novel antiviral agent CMX001

Adenovirus infection is a serious and often fatal complication in hematopoietic stem cell transplant patients. There are currently no FDA-approved therapies for adenovirus infection, with only anecdotal, off-label uses described for a variety of anti-viral agents or immune therapies. We report the first case of successful eradication of disseminated adenovirus infection by the novel antiviral agent CMX001 in a severely immunocompromised pediatric stem cell transplant recipient following failure to respond to intravenous cidofovir. Complete clinical and virologic response was documented; virologic and pharmacokinetic data are reported. CMX001 is a promising new oral antiviral agent under development for the prophylaxis and treatment of severe infections caused by double-stranded DNA viruses including adenovirus in immunocompromised patients.

STAT1-deficient bone marrow prevents GVHD by modulating plasmacytoid DCs while preserving vaccine-mediated responses to tumor (145.40)

A barrier to using donor lymphocyte infusions (DLI) after allogeneic blood and marrow transplantation (alloBMT) is induction of graft versus host disease (GVHD). We have previously demonstrated that gamma interferon (IFNg) receptor-/- bone marrow abrogates GVHD after T cell depleted (TCD) alloBMT, however the mechanism remains elusive. Since the IFNg receptor signals through STAT1, we hypothesized that STAT1-/- bone marrow could also prevent GVHD. Using TCD minor histocompatibility antigen-mismatched alloBMT with delayed DLI and tumor vaccines, we demonstrate that STAT1-/- whole bone marrow protects against a leukemic and solid tumor challenge as efficiently as wild type marrow, but STAT1-/- marrow prevents GVHD-associated weight loss. Using a Cre-Flox system, we generated mice that had STAT1 selectively deleted in either CD11c+ (Dendritic cells, DCs) or lysozyme+ (macrophage/neutrophils) cells, but as marrow donors neither prevented GVHD, implying other STAT1-/- cell subsets are critical. Prior to DLI administration, an increase in splenic plasmacytoid DCs in recipients of STAT1-/- marrow is observed. Microarray analysis of pDCs from recipients of STAT1-/- marrow shows marked upregulation of S100A8 and S100A9, molecules typically associated with myeloid-derived suppressor cells. Taken together, STAT1-/- marrow replicates the effects of IFNg receptor-/- marrow in terms of preventing GVHD and improved efficacy of DLI and vaccines, but also has immunomodulatory effects on pDCs.

Association of serum interleukin-7 levels with the development of acute graft-versus-host disease

PURPOSE

Morbidity from acute graft-versus-host disease (GVHD) limits the success of allogeneic hematopoietic stem-cell transplantation (HSCT) to treat malignancy. Interleukin-7 (IL-7), the principal homeostatic cytokine for T cells, is required for acute GVHD in murine models. In contrast to inflammatory cytokines (eg, IL-2, tumor necrosis factor alpha), IL-7 has not been studied extensively in the clinical transplant setting relative to its relationship with acute GVHD.

PATIENTS AND METHODS

We evaluated the association of serum IL-7 levels with acute GVHD in 31 patients who were uniformly treated in a prospective clinical trial with reduced-intensity allogeneic HSCT from human leukocyte antigen-identical siblings. GVHD prophylaxis consisted of cyclosporine and methotrexate. Serum IL-7 levels and lymphocyte populations were determined at enrollment, the day of transplantation before the allograft infusion, and at specified intervals through 12 months post-transplantation.

RESULTS

As expected, IL-7 levels were inversely correlated with T-cell populations (P < .00001). Acute GVHD was significantly associated with higher IL-7 levels at day +7 (P = .01) and day +14 (P = .00003) post-transplantation as well as with the allograft CD34(+) cell dose (P = .01). IL-7 levels at day +14 also correlated with the severity of acute GVHD (P < .0001). In logistic regression models, these factors were highly sensitive (up to 86%) and specific (100%) for classifying whether patients developed acute GVHD.

CONCLUSION

These data support preclinical observations that IL-7 plays a critical role in inducing acute GVHD and provide a rational basis for novel approaches to prevent and treat acute GVHD through modulation of the IL-7 pathway.

Sibling stem cell donor experiences at a single institution

Allogeneic bone marrow (BM) and cytokine mobilized peripheral blood stem cell (PBSC) transplantation can be curative for patients with malignant and nonmalignant hematologic diseases. Siblings are most often selected as a donor match; however, research on sibling donors is limited and has focused primarily on conventional BM donors. This exploratory study describes the experiences of PBSC sibling donors at a single institution. Through retrospective interviews, 14 sibling donors shared their perceived needs and concerns before and after their stem cell collection. Donors identified fears about the donation procedure, and expressed the need for more information about transplant outcome and complications. The inclusion of the sibling donors themselves, rather than the report of their parents or health-care providers and the qualitative nature of the structured design allowed sibling donors to describe their concerns and thoughts without being restrained by the beliefs of the participant's parents, researcher or sibling's medical team. Suggestions for visual educational tools, psychosocial interventions and future research are provided.

Association of serum interleukin-7 and interleukin-15 levels with immune reconstitution (IR), graft-versus-host disease (GVHD), and survival after reduced-intensity allogeneic stem cell transplantation (RIST)

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Background: In laboratory models, interleukin-7 (IL-7) and IL-15 significantly influence IR after allogeneic stem cell transplantation (SCT), thereby affecting immunity, graft-versus-malignancy (GVM) effects, and GVHD. Interleukin-7 (IL-7) is the main homeostatic regulator of naïve CD4+ and CD8+ T cells, and IL-15 is homeostatic for CD8+ memory and effector T cells and NK cells. The contributions of these cytokines to IR after allogeneic SCT are not well characterized in a clinical setting. Methods: We studied serum IL-7 and IL-15 levels in 31 pts with hematologic malignancies undergoing RIST from HLA-matched siblings in a prospective trial. Pts received identical transplant conditioning (fludarabine/cyclophosphamide) and GVHD prophylaxis (CSA/MTX). IL-7 and IL-15 levels and peripheral blood lymphocyte subpopulations (ALC, CD3, CD4, CD8, B, NK, and NKT) were measured before RIST, and post RIST at 1 and 2 weeks; 1, 2, 3, 6, 9, and 12 months. Results: Consistent with their homeostatic effects, IL-7 and IL-15 levels rose from baseline as transplant conditioning induced lymphopenia, and then decreased with lymphocyte recovery. These inverse correlations were strongest within 1 month post RIST. In an exploratory analysis, IL-15 levels at day 0 were correlated with baseline age (r=0.49; p=0.0058) and were higher among patients with CMV reactivation after RIST (p=0.048). At 2 weeks post RIST, higher IL-7 levels were strongly associated with subsequent acute GVHD (p=0.000033), and higher IL-15 levels were associated with inferior survival (p=0.007), mainly from relapse. At 3 months post RIST, superior survival was associated with higher NK cell counts (p=0.0008), and to a lesser extent with higher CD4 counts (p=0.036). Conclusions: These data support preclinical observations that IL-7 promotes GVHD after allogeneic SCT. The association of higher post-RIST IL-15 levels with death from relapse may identify pts with impaired IR leading to inadequate GVM effects. This hypothesis is consistent with the finding that higher NK cell counts after RIST were associated with better survival. Further studies must confirm the hypotheses generated in this setting.

No significant financial relationships to disclose.

Hematopoietic stem cell donation in children: a review of the sibling donor experience

Hematopoietic Stem Cell Transplant (HSCT) represents the second most frequent major organ transplant in the United States. Compared with other family members, siblings are more likely to be immunologically matched with the recipient and therefore are often the most suitable donors. Due to a dearth of information on the positive and adverse effects of HSCT on pediatric sibling donors, we sought to examine available data. Eight published reports assessing the pediatric sibling donor experience were identified in the literature. Studies were predominately small (n < 44) and cross-sectional. Results suggest a range of psychological distress responses with higher distress in pediatric donor than non-donor siblings. Recommendations include future longitudinal research on sibling donor psychosocial adjustment, identification of sibling donors at high risk for maladaptive responses, and development of educational and psychosocial interventions for this overlooked pediatric population.

Body fat reference curves for children

OBJECTIVE

To refine the diagnosis of childhood obesity by creating new sex-specific centile curves for body fat and to base these references on a simple and affordable method that could be widely adopted in clinical practice and surveys.

DESIGN

Body fat was measured by bio-impedance in 1985 Caucasian children aged 5-18 years from schools in Southern England. Smoothed centile charts were derived using the LMS method.

RESULTS

The new body fat curves reflect the known differences in the development of adiposity between boys and girls. The curves are similar by sex until puberty but then diverge markedly, with males proportionately decreasing body fat and females continuing to gain. These sex differences are not revealed by existing curves based on body mass index. We present charts in which cutoffs to define regions of 'underfat', 'normal', 'overfat' and 'obese' are set at the 2nd, 85th and 95th centiles. These have been designed to yield similar proportions of overweight/overfat and obese children to the IOTF body mass index cutoffs.

CONCLUSIONS

Direct assessment of adiposity, the component of overweight that leads to pathology, represents a significant advance over body mass index. Our new charts will be published by the Child Growth Foundation for clinical monitoring of body fat, along with the software to convert individual measurements to Z-scores.

Recombinant interleukin-7 induces proliferation of naive macaque CD4+ and CD8+ T cells in vivo

Interleukin-7 (IL-7) regulates T-cell homeostasis, and its availability is augmented in lymphopenic hosts. Naive CD8+ T cells transferred to lymphopenic mice acquire a memory-like phenotype, raising the possibility that IL-7 is the biological mediator of this effect. Here, we provide direct evidence that IL-7 induces the acquisition of memory-cell markers not only in CD8+ T cells but also in CD4+ T-cell subsets in immune-competent Indian rhesus macaques. The increase of these memory-like populations was dependent on the dose of the cytokine, and these cells were found in the blood as well as secondary lymphoid organs. Memory-like CD4+ and CD8+ T cells acquired the ability to secrete tumor necrosis factor alpha and, to a lesser extent, gamma interferon following stimulation with a cognate antigen. The phenotypic change observed in naive T cells was promptly reversed after discontinuation of IL-7. Importantly, IL-7 induced cycling of both CD4+ and CD8+ central memory and effector memory T cells, demonstrating its contribution to the maintenance of the entire T-cell pool. Thus, IL-7 may be of benefit in the treatment of iatrogenic or virus-induced T-cell depletion.

A role for thymic stromal lymphopoietin in CD4(+) T cell development

Thymic stromal lymphopoietin (TSLP) signals via a receptor comprising the interleukin (IL)-7 receptor α chain and a distinctive subunit, TSLP receptor (TSLPR), which is most related to the common cytokine receptor γ chain, γ_c. We have generated TSLPR knockout (KO) mice and found that although these mice had normal lymphocyte numbers, γ_c/TSLPR double KO mice had a greater lymphoid defect than γ_c KO mice. This indicates that TSLP contributes to lymphoid development and accounts for some of the residual lymphoid development in γ_c KO mice and presumably in patients with X-linked severe combined immunodeficiency. Injection of TSLP into γ_c KO mice induced the expansion of T and B cells. Moreover, sublethally irradiated TSLPR KO mice showed weaker recovery of lymphocyte populations than wild-type (WT) littermates, even when neutralizing anti–IL-7 antibodies were injected. Interestingly, TSLP preferentially stimulated the proliferation and survival of CD4⁺ single positive thymocytes and peripheral T cells in vitro. Additionally, CD4⁺ T cells from TSLPR KO mice expanded less efficiently than WT CD4⁺ T cells in irradiated hosts, and TSLP preferentially expanded CD4⁺ T cells both in vitro and in vivo. Thus, as compared with other known cytokines, TSLP is distinctive in exhibiting a lineage preference for the expansion and survival of CD4⁺ T cells.

Highly efficient blue-light generation from a compact, diode-pumped femtosecond laser by use of a periodically poled KTP waveguide crystal

We present a simplified, potentially portable, and highly efficient blue-light source from a periodically poled KTP waveguide crystal with a compact femtosecond Cr:LiSAF laser. This light source generates 5.6 mW of blue average output power at 424 nm with 27 mW of incident fundamental in a single-pass extracavity arrangement at room temperature. The overall system efficiency of electrical power to blue light is 0.5%, and the internal second-harmonic generation conversion efficiency is as high as 37%. The slope efficiency of 5.5% pJ(-1) at low pulse energies is, to our knowledge, the highest slope efficiency yet reported for frequency conversion into the blue spectral region.

Efficient frequency doubling of a pulsed laser diode by use of a periodically poled KTP waveguide crystal with Bragg gratings

Blue light with an average power of as much as 7.5 mW in picosecond pulses has been generated at 486, 488, and 491 nm from a frequency-doubled, nonresonant injection seeded, gain-switched InGaAs/GaAs diode laser by use of a periodically poled KTP waveguide crystal that incorporates a Bragg grating section.

Propagation of intercellular calcium waves in C6 glioma cells transfected with connexins 43 or 32

In this study, gap junction-deficient C6 glioma cells, transfected with either connexin 43 (Cx43) or 32 (Cx32), have been used to evaluate the ability of these connexins to pass intercellular Ca2+ waves. Ca2+ waves, observed with fluorescence imaging using fura-2 or fluo-3, were initiated by mechanical stimulation in the presence of a supra-perfusion of the extracellular fluid or by the non-contact technique of flash photolysis of intracellular caged-IP3. Following manual mechanical stimulation, the parental C6 glioma cells and cells expressing Cx43 and Cx32 gap junctions all propagated intercellular Ca2+ waves. Ca2+ waves in cells expressing Cx43 traveled approximately twice the distance as compared to waves in cells expressing Cx32 or parental cells. The cells expressing Cx43 were also about twice as sensitive to ATP as cells expressing Cx32. In the presence of a supra-perfusion of extracellular fluid, the Ca2+ waves in parental cells were almost abolished while the mechanically induced Ca2+ waves in the cells expressing Cx43 and Cx32 propagate similar but limited distances of several cells in a direction opposite to the fluid flow. The photolytic release of IP3, but not Ca2+, in cells expressing Cx43 or Cx32 resulted in the propagation of Ca2+ waves that traveled distances similar to those observed in the presence of supra-perfusion. Parental C6 glioma cells did not initiate intercellular Ca2+ waves when stimulated by photolysis. From these studies we conclude that (1) both Cx43 and Cx32 based gap junctions are permeable to IP3 and can serve to communicate Ca2+ waves, (2) that Ca2+ wave propagation via gap junctions was dependent on the diffusion of IP3 but not Ca2+, (3) that an extracellular messenger capable of communicating waves is released from only the stimulated cell, and (4) that simultaneous intracellular and extracellular signaling can occur to enhance the propagation of intercellular Ca2+ waves.

Monitoring children's growth: how are we doing?

This month the Chief Medical Officer's National Screening Committee held its first conference on systematic reviews of screening in child health. It was managed by the Child Growth Foundation, included an interim report on growth screening and posed the question whether children needed more of the same. Tam Fry, Honorary Chairman of the Foundation, believes that, as far as growth is concerned, they do despite the improvements that have been made since the "new" centile charts were introduced four years ago and reported in Professional Care of Mother & Child.

Introducing the new Child Growth Standards

All children should have their length and weight regularly measured at birth and throughout childhood Growth is a major indicator of child health; deviation from the normal is an important pointer to disease or distress. Measurements must be plotted on a centile chart so that any deviation from the normal pattern of growth can be detected and action taken. The new Child Growth Standards supersede the old Tanner/Whitehouse Standards of the 1950s. The new Standards are compiled from measurements of approximately 30,000 children taken from two national surveys. They are more up-to-date and representative than the old data and should be introduced as soon as possible. Midwives have an important part to play by measuring the baby accurately at birth and measuring both parents' heights. Health visitors, school nurses and practice nurses should ensure growth is regularly measured throughout childhood and deviations promptly referred.

Metastatic laryngeal carcinoma as a cause of progressive ophthalmoplegia

We have described a patient with primary laryngeal carcinoma who had bilateral progressive ophthalmoplegia. Repeated studies of cerebrospinal fluid and initial radiologic examinations failed to provide a diagnosis. Sphenoidal sinusotomy and biopsy were necessary to confirm the diagnosis of metastatic laryngeal carcinoma--a previously unreported phenomenon.