CAR-mediated targeting of NK cells overcomes tumor immune escape caused by ICAM-1 downregulation

BACKGROUND

The antitumor activity of natural killer (NK) cells can be enhanced by specific targeting with therapeutic antibodies that trigger antibody-dependent cell-mediated cytotoxicity (ADCC) or by genetic engineering to express chimeric antigen receptors (CARs). Despite antibody or CAR targeting, some tumors remain resistant towards NK cell attack. While the importance of ICAM-1/LFA-1 interaction for natural cytotoxicity of NK cells is known, its impact on ADCC induced by the ErbB2 (HER2)-specific antibody trastuzumab and ErbB2-CAR-mediated NK cell cytotoxicity against breast cancer cells has not been investigated.

METHODS

Here we used NK-92 cells expressing high-affinity Fc receptor FcγRIIIa in combination with trastuzumab or ErbB2-CAR engineered NK-92 cells (NK-92/5.28.z) as well as primary human NK cells combined with trastuzumab or modified with the ErbB2-CAR and tested cytotoxicity against cancer cells varying in ICAM-1 expression or alternatively blocked LFA-1 on NK cells. Furthermore, we specifically stimulated Fc receptor, CAR and/or LFA-1 to study their crosstalk at the immunological synapse and their contribution to degranulation and intracellular signaling in antibody-targeted or CAR-targeted NK cells.

RESULTS

Blockade of LFA-1 or absence of ICAM-1 significantly reduced cell killing and cytokine release during trastuzumab-mediated ADCC against ErbB2-positive breast cancer cells, but not so in CAR-targeted NK cells. Pretreatment with 5-aza-2'-deoxycytidine induced ICAM-1 upregulation and reversed NK cell resistance in ADCC. Trastuzumab alone did not sufficiently activate NK cells and required additional LFA-1 co-stimulation, while activation of the ErbB2-CAR in CAR-NK cells induced efficient degranulation independent of LFA-1. Total internal reflection fluorescence single molecule imaging revealed that CAR-NK cells formed an irregular immunological synapse with tumor cells that excluded ICAM-1, while trastuzumab formed typical peripheral supramolecular activation cluster (pSMAC) structures. Mechanistically, the absence of ICAM-1 did not affect cell-cell adhesion during ADCC, but rather resulted in decreased signaling via Pyk2 and ERK1/2, which was intrinsically provided by CAR-mediated targeting. Furthermore, while stimulation of the inhibitory NK cell checkpoint molecule NKG2A markedly reduced FcγRIIIa/LFA-1-mediated degranulation, retargeting by CAR was only marginally affected.

CONCLUSIONS

Downregulation of ICAM-1 on breast cancer cells is a critical escape mechanism from trastuzumab-triggered ADCC. In contrast, CAR-NK cells are able to overcome cancer cell resistance caused by ICAM-1 reduction, highlighting the potential of CAR-NK cells in cancer immunotherapy.

Viscum album (mistletoe) extract for dogs with cancer?

Compared with the options available to human patients with cancer, treatment choices for dogs are often more limited. Chemotherapy is frequently the first-line treatment for many cancers. However, its efficacy can be limited, and its side effects can affect the quality of the remaining life. This paper briefly summarizes the experience with Viscum album L. (mistletoe) extract in human patients as a stipulation to consider treatment with mistletoe extract for canines with cancer. The mistletoe extract contains -among others - lectins and viscotoxins that have documented anti-proliferative effect on cancer cells as well as immune-stimulatory function. Importantly, it also improves the well-being of patients with cancer due to its lectin ML-1 content, which can trigger the release of endorphins. Being cross-reactive with canine cells and having a relatively low side effect profile, it raises the question of whether mistletoe preparations might be considered as part of the treatment approach for dogs with cancer.

The NK-92 cell line-30 years later: its impact on natural killer cell research and treatment of cancer

The NK-92 cell line, established in 1992, mirrors all the characteristics of highly active blood natural killer (NK) cells but with much broader and greater cytotoxicity. The cell line was established from the blood cells of a patient with lymphoma and has been made widely available for research since it was deposited into the American Type Culture Collection in 1998. The worldwide distribution of NK-92 cells has led to a plethora of scientific discoveries that have greatly increased the understanding of NK-cell biology. NK-92 cells also have been developed for clinical use, overcoming the challenges of obtaining and expanding NK cells from donor or patient blood. More than 100 patients with cancer have now been treated all over the world with unmodified or genetically engineered NK-92 cells. Modified cells include high-affinity Fc-receptor expressing NK-92 cells (haNK^R) and various chimeric antigen receptor targeted haNK cells (t-haNK^TM). Infusions of either unmodified or modified NK-92 cells have been reported to be safe and efficacious, leading in some cases to disease remission even in patients who had failed multiple previous lines of therapy. It is the purpose of this review to distill the plethora of scientific data on NK-92 cells and its genetic variants, highlighting relevant experimental findings that have contributed to a better understanding of NK cell biology and summarize the therapeutic potential of these cells for treatment of cancer and infections.

Immunotherapy for Dogs: Still Running Behind Humans

Despite all good intentions, dogs are still running behind humans in effective cancer immunotherapies. The more effective treatments in humans, like infusions of CAR-T and NK-cells are not broadly pursued for canines due to significant costs, the rather complicated logistics and the lack of targetable surface antigens. Monoclonal antibodies are challenging to develop considering the limited knowledge about canine target antigens and about their mode of action. Although immunogenic vaccines could be less costly, this approach is hampered by the fact that cancer by itself is immuno-suppressive and any preceding chemotherapy may suppress any clinically meaningful immune response. This review - rather than providing a comprehensive listing of all available immunotherapies for dogs, aims at pointing out the issues that are holding back this field but which hopefully can be addressed so that dogs can "catch up" with what is available to humans.

An NK cell line (haNK) expressing high levels of granzyme and engineered to express the high affinity CD16 allele

Natural killer (NK) cells are known to play a role in mediating innate immunity, in enhancing adaptive immune responses, and have been implicated in mediating anti-tumor responses via antibody-dependent cell-mediated cytotoxicity (ADCC) by reactivity of CD16 with the Fc region of human IgG1 antibodies. The NK-92 cell line, derived from a lymphoma patient, has previously been well characterized and adoptive transfer of irradiated NK-92 cells has demonstrated safety and shown preliminary evidence of clinical benefit in cancer patients. The NK-92 cell line, devoid of CD16, has now been engineered to express the high affinity (ha) CD16 V158 FcγRIIIa receptor, as well as engineered to express IL-2; IL-2 has been shown to replenish the granular stock of NK cells, leading to enhanced perforin- and granzyme-mediated lysis of tumor cells. The studies reported here show high levels of granzyme in haNK cells, and demonstrate the effects of irradiation of haNK cells on multiple phenotypic markers, viability, IL-2 production, and lysis of a spectrum of human tumor cells. Studies also compare endogenous irradiated haNK lysis of tumor cells with that of irradiated haNK-mediated ADCC using cetuximab, trastuzumab and pertuzumab monoclonal antibodies. These studies thus provide the rationale for the potential use of irradiated haNK cells in adoptive transfer studies for a range of human tumor types. Moreover, since only approximately 10% of humans are homozygous for the high affinity V CD16 allele, these studies also provide the rationale for the use of irradiated haNK cells in combination with IgG1 anti-tumor monoclonal antibodies.

Glypican-1 as a novel immunotherapeutic target in prostate cancer

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Background: New effective therapies for men with prostate cancer are desperately needed. Recently, cancer immunotherapy has emerged as an important new treatment strategy for prostate cancer and for castrate resistant prostate cancer (CRPC). Multiple studies have identified the heparan sulfate proteoglycan-1 Glypican 1 (GPC-1) as being overexpressed in different cancers, and also as being a possible marker of poor prognosis in several solid tumor cancers. GPC-1 has been recently identified as a potential marker for prostate cancer. The MIL-38 monoclonal antibody detects GPC-1 and an IgG1 chimeric version of this antibody has been developed for preclinical studies. Here we sought to examine MIL-38 binding to a panel of prostate cancer cell lines and examine its feasibility as a novel immunotherapeutic agent targeting GPC-1 in prostate cancer Methods: Expression of GPC-1 in CRPC cell lines was examined by Flow cytometry and Western Blotting using MIL-38 as the detector antibody. The competency of GPC-1 as an immunotherapeutic target was assessed via chimeric MIL-38 induced Antibody Dependent Cell Cytotoxicity (ADCC) using high affinity Natural Killer cells (haNKs) in vitro . Results: Flow cytometry and Western blot assessments of normal prostatic epithelial cells (i.e. RWPE-1) and cells from prostate cancer cell lines (i.e. PC-3, 22RV1, DU-145, VCaP, LNCaP, CWR-R1, and LAPC-4) revealed that only cancer cells expressed GPC-1. Enzalutamide resistant cell lines demonstrated higher expression of GPC-1 than their respective parental line. ADCC assays demonstrated enhanced haNK – prostate cancer cell cytotoxicity in the presence of chimeric MIL-38 anti-GPC-1 antibody, while the IgG1 isotype control had no effect. Conclusions: GPC-1 protein was expressed by most prostate cancer cell lines, including enhanced expression by enzalutamide resistant cells. Preliminary in vitro ADCC assay results revealed the potential utility of GPC-1 as an immunotherapeutic target in prostate cancer.

Immunotherapy for Dogs: Running Behind Humans

A number of excellent reviews on the potential of canine cancer immunotherapy are available, but many extrapolate from observations in humans when in fact only very few immunotherapies have been developed for canines that have shown efficacy in well-designed studies. Pharmaceutical and biotech companies are aware that the market for more expensive immunotherapies in canines is limited resulting in limited funding for clinical trials. However, dogs and other pets deserve access to this new form of cancer therapy. The purpose of this brief review is to summarize the current status of available immunotherapies for dogs and their near-term prospects, provided we can effectively translate discoveries and progress in humans to canines.

Abstract P2-04-10: High-affinity activated natural killer (haNK) cells augment trastuzumab efficacy in a mouse model of HER2-positive human metastatic breast cancer

Background. The ability of NK cells to kill cancer cells makes them an attractive choice for clinical immunotherapy. Early phase clinical trials in patients (pts) with advanced cancers have demonstrated the safety of activated NK (aNK [NK-92]) cells, an investigational cell line that was established from the peripheral blood mononuclear cells of a pt with non-Hodgkin lymphoma. NK cells can participate in antibody-dependent cellular cytotoxicity (ADCC) mediated by recognition of the Fc fragment of the target-bound antibody (IgG1) via the CD16 Fc receptor. Among pts with HER2-positive breast cancer treated with trastuzumab (IgG1) the high-affinity CD16 V/V genotype was significantly correlated with better clinical outcomes (Musolino. JCO. 2008;26:1789-96). To enhance the killing activity of aNK cells, we modified aNK cells to stably express high-affinity CD16 and evaluated the resulting haNK cells in combination with trastuzumab in a mouse xenograft model of HER2-positive human breast cancer.

Methods. haNK cells were generated by transfection of aNK cells with a bicistronic plasmid coding for CD16 (158V) and an intracellular form of IL-2, which enables haNK cells to grow in the absence of exogenous IL-2. Female, 7 to 8-week-old NOD-scid IL2Rgammanull (NSG) mice were inoculated subcutaneously in the left and right flank area with 0.1mL of 1x108/mL MDA-MB-453 human breast cancer cells in 50% Matrigel. When tumors reached ≥100mm3, mice were randomly assigned to 10 groups of 4 mice per group and dosed (IV) with PBS, 1 or 3mg/kg IgG1 isotype control, 1 or 3mg/kg trastuzumab (determined from a dose range finding study), 1x107 non-irradiated haNK cells, or non-irradiated haNK cells in combination with IgG1 or trastuzumab. The dosing schedules were: PBS/haNK cells twice weekly for 4 weeks; IgG1/trastuzumab once weekly for 4 weeks. For the combination treatments, mice received antibodies at least 3h prior to the injection of haNK cells. Tumor growth and animal weights were measured twice weekly.

Results: Results obtained after 4 weeks of treatment are shown in the table. haNK alone and both doses of trastuzumab alone significantly inhibited the growth of human MDA-MB-453 breast tumors. The combination of haNK plus 1mg/kg trastuzumab was synergistic with a T/C value of -60.1%.

Conclusions: The combination of haNK cells and trastuzumab was synergistic at 1mg/kg trastuzumab resulting in tumor regressions and significantly better efficacy vs each agent alone. Trastuzumab monotherapy at 3mg/kg was very effective and likely masked any synergistic effect of haNK. This study illustrates the potential for combining haNK cells with trastuzumab in a clinical trial of pts with HER2-positive metastatic breast cancer.

ResultsGroupTreatmentT/C (%)BWC (%)APBS--0.6BIgG1 (1mg/kg)40.8-4.7CTrastuzumab (1mg/kg)-34.5-2.8DhaNK (1x107)-20.3-15.9EIgG1 (1mg/kg) + haNK (1x107)-10.7-16.0FTrastuzumab (1mg/kg) + haNK (1x107)-60.1-16.6GIgG1 (3mg/kg)39.1-0.4HTrastuzumab (3mg/kg)-95.2-1.8IIgG1 (3mg/kg)+ haNK (1x107)-26.4-16.7JTrastuzumab (3mg/kg) + haNK (1x107)-93.8-18.3%T/C, percent treated/control; BWC, body weight change.

Citation Format: Rabizadeh S, Zhou L, Toneguzzo F, Boissel L, Soon-Shiong P, Niazi K, Klingemann H. High-affinity activated natural killer (haNK) cells augment trastuzumab efficacy in a mouse model of HER2-positive human metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-04-10.

Continuously expanding CAR NK-92 cells display selective cytotoxicity against B-cell leukemia and lymphoma

BACKGROUND AIMS

Natural killer (NK) cells can rapidly respond to transformed and stressed cells and represent an important effector cell type for adoptive immunotherapy. In addition to donor-derived primary NK cells, continuously expanding cytotoxic cell lines such as NK-92 are being developed for clinical applications.

METHODS

To enhance their therapeutic utility for the treatment of B-cell malignancies, we engineered NK-92 cells by lentiviral gene transfer to express chimeric antigen receptors (CARs) that target CD19 and contain human CD3ζ (CAR 63.z), composite CD28-CD3ζ or CD137-CD3ζ signaling domains (CARs 63.28.z and 63.137.z).

RESULTS

Exposure of CD19-positive targets to CAR NK-92 cells resulted in formation of conjugates between NK and cancer cells, NK-cell degranulation and selective cytotoxicity toward established B-cell leukemia and lymphoma cells. Likewise, the CAR NK cells displayed targeted cell killing of primary pre-B-ALL blasts that were resistant to parental NK-92. Although all three CAR NK-92 cell variants were functionally active, NK-92/63.137.z cells were less effective than NK-92/63.z and NK-92/63.28.z in cell killing and cytokine production, pointing to differential effects of the costimulatory CD28 and CD137 domains. In a Raji B-cell lymphoma model in NOD-SCID IL2R γ^null mice, treatment with NK-92/63.z cells, but not parental NK-92 cells, inhibited disease progression, indicating that selective cytotoxicity was retained in vivo.

CONCLUSIONS

Our data demonstrate that it is feasible to generate CAR-engineered NK-92 cells with potent and selective antitumor activity. These cells may become clinically useful as a continuously expandable off-the-shelf cell therapeutic agent.

CD19-CAR engineered NK-92 cells are sufficient to overcome NK cell resistance in B-cell malignancies

Many B‐cell acute and chronic leukaemias tend to be resistant to killing by natural killer (NK) cells. The introduction of chimeric antigen receptors (CAR) into T cells or NK cells could potentially overcome this resistance. Here, we extend our previous observations on the resistance of malignant lymphoblasts to NK‐92 cells, a continuously growing NK cell line, showing that anti‐CD19‐CAR (αCD19‐CAR) engineered NK‐92 cells can regain significant cytotoxicity against CD19 positive leukaemic cell lines and primary leukaemia cells that are resistant to cytolytic activity of parental NK‐92 cells. The ‘first generation’ CAR was generated from a scFv (CD19) antibody fragment, coupled to a flexible hinge region, the CD3ζ chain and a Myc‐tag and cloned into a retrovirus backbone. No difference in cytotoxic activity of NK‐92 and transduced αCD19‐CAR NK‐92 cells towards CD19 negative targets was found. However, αCD19‐CAR NK‐92 cells specifically and efficiently lysed CD19 expressing B‐precursor leukaemia cell lines as well as lymphoblasts from leukaemia patients. Since NK‐92 cells can be easily expanded to clinical grade numbers under current Good Manufactoring Practice (cGMP) conditions and its safety has been documented in several phase I clinical studies, treatment with CAR modified NK‐92 should be considered a treatment option for patients with lymphoid malignancies.

Natural Killer Cells for Immunotherapy - Advantages of the NK-92 Cell Line over Blood NK Cells

Natural killer (NK) cells are potent cytotoxic effector cells for cancer therapy and potentially for severe viral infections. However, there are technical challenges to obtain sufficient numbers of functionally active NK cells from a patient’s blood since they represent only 10% of the lymphocytes and are often dysfunctional. The alternative is to obtain cells from a healthy donor, which requires depletion of the allogeneic T cells to prevent graft-versus-host reactions. Cytotoxic cell lines have been established from patients with clonal NK-cell lymphoma. Those cells can be expanded in culture in the presence of IL-2. Except for the NK-92 cell line, though, none of the other six known NK cell lines has consistently and reproducibly shown high antitumor cytotoxicity. Only NK-92 cells can easily be genetically manipulated to recognize specific tumor antigens or to augment monoclonal antibody activity through antibody-dependent cellular cytotoxicity. NK-92 is also the only cell line product that has been infused into patients with advanced cancer with clinical benefit and minimal side effects.

Abstract P2-11-12: Novel protocol combining metronomic nant-paclitaxel with HER2-targeted natural killer cells (innate immunotherapy) for HER2-positive metastatic breast cancer

Background. Natural killer (NK) cells are an important effector cell type for adoptive cancer immunotherapy. Phase 1 clinical trials in patients with advanced cancers demonstrated the safety of unmodified, activated NK-92 cells (aNK), with no evidence of cytokine storm from 18 infusions delivered over 6 months; clinical responses were observed in a subset of patients. Like T cells, NK cells can be engineered to express chimeric antigen receptors (CARs) to enhance their antitumor activity. A stable clonal HER2-specific NK-92 cell line (HER2.taNK) mediated selective and sequential killing of HER2-expressing MDA-MB-453 cells in vitro (Schönfeld. MolTher. 2015;23:330-338). In addition, HER2.taNK cells were enriched in MDA-MB-453/EGFP xenografts and reduced the number of pulmonary metastasis in a renal cell carcinoma model, suggesting that HER2.taNK cells are a promising clinical candidate for use in adoptive cancer immunotherapy. Metronomic (low-dose, continuous) chemotherapy can be more effective than high-dose therapy in patients with advanced breast cancer (Montagna. Canc. Treat. Rev. 2014;40:922-950). Here we evaluate HER2.taNK cells in combination with metronomic nant-paclitaxel (lyophilized polymeric micellar formulation of paclitaxel) in a mouse model of HER2-positive breast cancer to determine the feasibility of a human clinical trial of HER2.taNK in combination with metronomic nant-paclitaxel.

Methods. HER2.taNK cells were generated as described previously (Schönfeld. MolTher. 2015;23:330-338). MDA-MB-453 cells were implanted into the mammary fat pads of female nude mice. When tumors reached 100 mm3, mice were divided into 6 groups of 5 mice and dosed (IV) with saline (10 mL/kg, qd x 15), nant-paclitaxel (2.5-4 mg/kg q2d x 15), γ-irradiated (5 Gy) HER2.taNK cells (1 x 107 cells, days 1, 3, 5, and 8), or nant-paclitaxel + γ-irradiated (5 Gy) HER2.taNK cells–γ-irradiation is a potential safety measure for clinical application and prevents HER2.taNK cell replication while preserving antitumor activity. Tumor size and animal weights were measured every other day post-implantation.

Results: Results obtained 20 days post-treatment are shown in the table. Nant-paclitaxel alone and HER2.taNK alone significantly inhibited tumor growth. The combination of nant-paclitaxel + HER2.taNK led to significant tumor regressions (p<0.05).

Treatment Dose T/C (%) P-ValueSalinenant-paclitaxel5 mg/kg-26.7 P < 0.05 (vs saline) HER2.taNK1 x 107 cells-22.2 P < 0.05 (vs saline)nant-paclitaxel +5 mg/kg +-60.0P < 0.05 (vs nant-paclitaxel)HER2.taNK1 x 107 cellsP < 0.05 (vs HER2.taNK)

Conclusions: Single agent nant-paclitaxel and HER2.taNK were similarly effective at inhibiting tumor growth in this mouse model of HER2+ breast cancer. The combination of nant-paclitaxel + HER2.taNK appeared to be synergistic resulting in tumor regressions and significantly better efficacy vs each agent alone. This study illustrates the potential for combining metronomic low-dose chemotherapy with NK-based immunotherapy in a clinical trial of patients with metastatic breast cancer.

Citation Format: Rabizadeh S, Simon B, Klingemann H, Sims D, Weiss R, Soon-Shiong P. Novel protocol combining metronomic nant-paclitaxel with HER2-targeted natural killer cells (innate immunotherapy) for HER2-positive metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-11-12.

Advances in clinical NK cell studies: Donor selection, manufacturing and quality control

Natural killer (NK) cells are increasingly used in clinical studies in order to treat patients with various malignancies. The following review summarizes platform lectures and 2013–2015 consortium meetings on manufacturing and clinical use of NK cells in Europe and United States. A broad overview of recent pre-clinical and clinical results in NK cell therapies is provided based on unstimulated, cytokine-activated, as well as genetically engineered NK cells using chimeric antigen receptors (CAR). Differences in donor selection, manufacturing and quality control of NK cells for cancer immunotherapies are described and basic recommendations are outlined for harmonization in future NK cell studies.

Are natural killer cells superior CAR drivers?

T lymphocytes engineered to express a chimeric antigen receptor (CAR) are being celebrated as a major breakthrough of anticancer immunotherapy. Natural killer cells have not received similar attention as CAR effectors, although the use of these relatively short-lived cytotoxic cells is associated with several advantages.

Retargeting NK-92 cells by means of CD19- and CD20-specific chimeric antigen receptors compares favorably with antibody-dependent cellular cytotoxicity

Multiple natural killer (NK) cell-based anticancer therapies are currently under development. Here, we compare the efficiency of genetically modified NK-92 cells expressing chimeric antigen receptors (CARs) at killing NK cell-resistant B-lymphoid leukemia cells to the antibody-dependent cell-mediated cytotoxicity (ADCC) of NK-92 cells expressing a high affinity variant of the IgG Fc receptor (FcγRIII). First, we compared in vitro the abilities of NK-92 cells expressing CD20-targeting CARs to kill primary chronic lymphocytic leukemia (CLL) cells derived from 9 patients with active, untreated disease to the cytotoxicity of NK-92 cells expressing FcγRIII combined with either of the anti-CD20 monoclonal antibodies (mAbs) rituximab or ofatumumab. We found that CAR-expressing NK-92 cells effectively kill NK cell-resistant primary CLL cells and that such a cytotoxic response is significantly stronger than that resulting from ADCC. For studying CAR-expressing NK cell-based immunotherapy in vivo, we established xenograft mouse models of residual leukemia using the human BCR-ABL1+ cell lines SUP-B15 (CD19+CD20-) and TMD-5 (CD19+CD20+), two acute lymphoblastic leukemia (ALL) lines that are resistant to parental NK-92 cells. Intravenous injection of NK-92 cells expressing CD19-targeting CARs eliminated SUP-B15 cells, whereas they had no such effect on TMD-5 cells. However, the intrafemoral injection of NK-92 cells expressing CD19-targeting CAR resulted in the depletion of TMD-5 cells from the bone marrow environment. Comparative studies in which NK-92 cells expressing either CD19- or CD20-targeting CARs were directly injected into subcutaneous CD19+CD20+ Daudi lymphoma xenografts revealed that CD20-targeting CAR is superior to its CD19-specific counterpart in controlling local tumor growth. In summary, we show here that CAR-expressing NK-92 cells can be functionally superior to ADCC (as mediated by anti-CD20 mAbs) in the elimination of primary CLL cells. Moreover, we provide data demonstrating that the systemic administration of CAR-expressing NK-92 cells can control lymphoblastic leukemia in immunocompromised mice. Our results also suggest that the direct injection of CAR-expressing NK-92 cells to neoplastic lesions could be an effective treatment modality against lymphoma.

Autologous stem cell transplant recipients tolerate haploidentical related-donor natural killer cell-enriched infusions

BACKGROUND

In the setting of allogeneic stem cell transplantation (SCT), infusing natural killer (NK) cells from a major histocompatibility complex (MHC)-mismatched donor can mediate an antileukemic effect. The graft-versus-tumor effect after autologous stem cell transplantation (ASCT) may result in less disease relapse.

STUDY DESIGN AND METHODS

We performed a Phase I clinical trial to assess the safety and feasibility of infusing distantly processed donor NK-enriched mononuclear cell (NK-MNC) infusions from a MHC haplotype-mismatched (haploidentical) donor to patients who recently underwent ASCT for a hematologic malignancy. On Day 1, peripheral blood MNCs were obtained by steady-state leukapheresis and sent from Boston to the Production Assistance for Cellular Therapies (PACT) facility at the University of Minnesota, where immunomagnetic depletion of CD3 cells was performed on Day 2. NK-MNC products were then returned to Boston on Day 2 for infusion on Day 3. Toxicity, cellular product characteristics, and logistic events were monitored.

RESULTS

At a median of 90 days (range, 49-191 days) after ASCT, 13 patients were treated with escalating doses of NK-MNCs per kilogram from 10(5) to 2 × 10(7) . Adverse effects included Grade 2 rigors and muscle aches, but no Grade 3 or 4 events and no graft-versus-host disease or marrow suppression. One air courier delay occurred. NK-MNC products were viable with cytotoxic activity after transport.

CONCLUSION

CD3-depleted, MHC-mismatched allogeneic NK-MNC infusions can be safely and feasibly administered to patients after ASCT after distant processing and transport, justifying further development of this approach.

Successful "in-flight" activation of natural killer cells during long-distance shipping

BACKGROUND

Natural killer (NK) cells have shown promise in the treatment of malignancy. However, the widespread use of these cells may be limited by both the lack of resources and the expertise needed to manufacture them and the apparent need to use only fresh cells. The NHLBI-sponsored Production Assistance for Cellular Therapies group was established to provide the resources and expertise to carry out cell therapy research, including support of clinical trials. Here we describe the qualification of in transit activation of an NK-cell therapy product in preparation for a Phase I clinical trial at a distant medical center.

STUDY DESIGN AND METHODS

Nonmobilized apheresis mononuclear cell collections were CD3+ cell depleted, placed into culture bags with interleukin (IL)-2, and shipped from Minneapolis/Saint Paul, Minnesota, to Columbus, Ohio, and back to Minneapolis/Saint Paul, under warm, monitored temperatures. Products underwent quality control (QC) testing including cell count, immunophenotyping, viability, endotoxin, sterility culture, and cytotoxicity assays. One product tested the relative importance of IL-2 and controlled incubation.

RESULTS

The length of shipment ranged from 14 to 16 hours, and temperatures were well controlled. QC testing was acceptable based upon previous in-house experience. Controlled incubation was not necessary for successful activation of NK cells, but IL-2 appeared essential.

CONCLUSION

The need for novel cell therapies to be infused as fresh products may be a limitation for various cell types. However, we have shown that NK cells can be successfully shipped in the fresh state (allowing 48 hr from apheresis to product infusion) for use at clinical centers. Although IL-2 is critical for NK-cell activation, a 37 °C, 5% CO2 incubator is not.

Comparison of mRNA and lentiviral based transfection of natural killer cells with chimeric antigen receptors recognizing lymphoid antigens

Natural killer (NK) cells can be engineered to kill resistant B-lymphoid cell lines and primary B-cell chronic lymphocytic leukemia (B-CLL) cells after transfection with chimeric antigen receptors (CARs) recognizing CD19 or CD20. Here we compared mRNA electroporation with lentiviral vector (LV) transduction for both CARs. Transfection efficiency and cytotoxicity of previously NK-92 resistant CLL cells were significantly higher after mRNA electroporation than after LV transduction. Further cell sorting of LV-transduced NK-92 cells resulted in a highly enriched population of transduced cells with significant target cell lysis. Compared to NK-92 cells, peripheral blood and cord blood cells consistently showed < 10% transfection efficiency with mRNA, while LV transduction varied between 8 and 16% for peripheral blood and 12 and 73% for cord blood. These results suggest that LV should be used to achieve sufficient transgene expression if blood NK cells are considered for CAR transduction. Transfection with mRNA results in clinically relevant levels of transfection only in NK-92 cells.

Variable contribution of monoclonal antibodies to ADCC in patients with chronic lymphocytic leukemia

Monoclonal antibodies (mAbs) are increasingly used in treatment protocols for chronic lymphocytic leukemia (CLL). Here we determined (i) the extent of antibody-dependent cellular cytotoxicity (ADCC) of four different mAbs against primary CLL cells, (ii) whether ADCC correlates with antigen density on CLL cells, and (iii) whether allogeneic natural killer (NK) cells display superior ADCC than autologous. Effector cells for ADCC were (i) NK-92 cells not expressing FcR, (ii) NK-92 cells transfected with a high-affinity Fc receptor, (iii) autologous NK cells from patients with CLL, (iv) allogeneic NK cells. Results suggest that ADCC contributes to killing of CLL cells by anti-CD20 antibodies (rituximab and veltuzumab), whereas mAbs against CD22 (epratuzumab) and CD23 (lumiliximab) showed minimal ADCC. The magnitude of anti-CD20 mediated ADCC did not correlate with antigen density of CD20. ADCC was not influenced by the FcR genotype expressed by autologous NK cells. Allogeneic NK cells were superior to autologous NK cells in killing primary CLL cells.

Infusion of the allogeneic cell line NK-92 in patients with advanced renal cell cancer or melanoma: a phase I trial

BACKGROUND

Renal cell cancer and malignant melanoma are two types of cancer that are responsive to immunotherapy. In this phase I dose-escalation study, the feasibility of large-scale expansion and safety of administering ex vivo-expanded NK-92 cells as allogeneic cellular immunotherapy in patients with refractory renal cell cancer and melanoma were determined.

METHODS

Twelve patients (aged 31-74 years) were enrolled, three per cohort at cell dose levels of 1x10(8)/m(2), 3x10(8)/m(2), 1x10(9)/m(2) and 3x10(9)/m(2). One treatment course consisted of three infusions. Eleven patients had refractory metastatic renal cell cancer; one patient had refractory metastatic melanoma.

RESULTS

The NK-92 cells were expanded in X-Vivo 10 serum-free media supplemented with 500 U/mL Proleukin recombinant human interleukin-2 (rhIL-2), amino acids and 2.5% human AB plasma. Final yields of approximately 1x10(9) cells/culture bag (218-250xexpansion) over 15-17 days were achievable with >or=80% viability. Infusional toxicities of NK-92 were generally mild, with only one grade 3 fever and one grade 4 hypoglycemic episode. All toxicities were transient, resolved and did not require discontinuation of treatment. One patient was alive with disease at 4 years post-NK-92 infusion. The one metastatic melanoma patient had a minor response during the study period. One other patient exhibited a mixed response.

DISCUSSION

This study establishes the feasibility of large-scale expansion and safety of administering NK-92 cells as allogeneic cellular immunotherapy in advanced cancer patients and serves as a platform for future study of this novel natural killer (NK)-cell based therapy.

Transfection with mRNA for CD19 specific chimeric antigen receptor restores NK cell mediated killing of CLL cells

An emerging treatment option for chronic lymphocytic leukemia (CLL) is to make cytotoxic immune cells express a chimeric antigen receptor (CAR) that recognizes specific surface molecules on CLL cells. Here an mRNA coding for an anti-CD19 CAR was transfected into the NK-92 cell line by electroporation. In contrast to cDNA, mRNA resulted in high transfection efficiency (47.2 +/- 8% versus <5% for cDNA) with minimal effect on cell viability. NK-92 cells expressing anti-CD19 CAR killed previously resistant CD19+ B-ALL cell lines, as well as primary CLL cells and therefore may present a safe, cell-based, targeted treatment for patients with CLL.

Mesenchymal Stem Cells - Sources and Clinical Applications

SUMMARY: Although mesenchymal stem cells (MSC) from different tissue sources share many characteristics and generally fulfill accepted criteria for MSC (plastic adherence, certain surface marker expression, and ability to differentiate into mesenchymal tissues), we are increasingly learning that they can be distinguished at the level of cytokine production and gene expression profiles. Their ability to differentiate into different tissues including endodermal and ectodermal lineages, also varies according to tissue origin. Importantly, MSC from fetal sources can undergo more cell divisions before they reach senescence than MSC from adult tissue such as bone marrow or adipose tissue. As we learn more about the differentiation and plasticity of MSC from different sources, health care providers in the future will use them tailored to different medical indications.

Targeted cellular therapy with natural killer cells

Natural killer (NK) cells are believed to be important contributors to a patient's immune armamentarium to fight cancer. However, cancer patients have reportedly defective NK cells and the malignant target frequently has developed mechanisms to escape detection of NK cells. Our research is aimed at overcoming this NK cell paralysis through three different approaches: instead of using autologous NK cells for adoptive immunotherapy, allogeneic NK cells are used that are not inhibited by self histocompatibility antigens. Further, NK cells, selected for a high affinity Fc receptor can, together with monoclonal antibodies, kill targets through ADCC irrespective of any inhibitory receptors. Finally, the genetic engineering of NK cells to express chimeric antigen receptors recognizing antigens on tumor target can overcome inhibitory mechanism and effectively lyse tumor cells.

Discarded stem cells with a future?

Although embryonic stem cells hold the promise for tissue and organ generation, stem cells with early mesenchymal character, which can be obtained at the time of birth from extra-embryonic tissue, may have similar capabilities if manipulated appropriately. These 'perinatal' tissues, such as the umbilical cord or the placenta, which are generally discarded after delivery, contain early mesenchymal stem cells that are believed to have a greater potential for plasticity than postnatal mesenchymal cells, such as those from bone marrow. They express early transcriptional genes, and emerging technologies, such as nuclear reprogramming, could direct their development into tissues of embryonic origin. Hence, these cells, generally discarded after birth, could become a valuable source for future tissue generation.

Characterization of functional heparan sulfate motifs overexpressed on multiple myeloma cells using single chain antibody variable fragments generated by phage display

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Background: Multiple myeloma (MM) is the most prevalent plasma cell neoplasm and is characterized by the infiltration of the bone marrow by terminally differentiated B lymphocytes. Although novel drugs have recently been introduced, the disease remains incurable. No therapeutic antibody is as yet available for treatment of MM. One of the key molecules involved in multiple myeloma (MM) tumor progression is syndecan-1, a cell surface heparan sulfate (HS) proteoglycan expressed on both MM cells and normal plasma cells. Syndecan-1 regulates cell interactions with soluble molecules and the extracellular matrix through its heparan sulfate chains. These chains allow it to bind multiple growth factors such as Fibroblast Growth Factor type 2 (FGF-2), WNT, Hepatocyte Growth Factor (HGF), midkine, all of which promote survival and metastasis of MM cells. In addition, syndecan-1 on MM cells binds and internalizes osteoprotegerin, the RANKL antagonist, through its HS chains and depletes it from the bone marrow milieu, which triggers osteoclastogenesis. Methods: Using the phage display technique, we have generated a panel of MM-specific human antibody variable fragments (scFvs) against the MM cell line RPMI-8226. These scFvs were tested against a variety of cell lines and primary normal bone marrow or myeloma cells. The biochemical identity of the targeted antigens was determined. Results: Two of the selected scFvs, D4A4 and D6B10, reacted against heparan sulfate motifs that were highly expressed in MM cell lines and patient MM cells but absent (scFv D6B10) or poorly expressed (scFv D4A4) in normal plasma cells. Binding of scFv D6B10 to MM heparan sulfate chains required NS sulfation, 6-O-sulfation and, to a lesser extent, 2-O-sulfation. Additional experiments indicated that FGF-2, midkine and osteoprotegerin competed with scFv D6B10 for binding to HS. Conclusions: This study indicates that the structure of syndecan-1-associated HS is altered in MM cells and may influence its capacity to bind to growth factors and promote tumor progression. Human therapeutic antibodies derived from scFvs D4A4 and D6B10 may be useful for immune targeting of MM cells and interfering with pro-survival signaling pathways.

No significant financial relationships to disclose.

Relapse to prior autograft and chronic graft-versus-host disease are the strongest prognostic factors for outcome of melphalan/fludarabine-based dose-reduced allogeneic stem cell transplantation in patients with multiple myeloma

We evaluated prognostic factors of melphalan/fludarabine-based dose-reduced allografts in patients with multiple myeloma. From 1998 to 2002, 120 patients with multiple myeloma were treated with melphalan/fludarabine followed by allogeneic stem cell transplantation. The cumulative risk at 1 year for treatment-related mortality (TRM) was 18% (95% confidence interval [CI], 12%-28%). In a multivariate analysis, relapse after prior high-dose chemotherapy was the most significant risk factor for TRM (hazard ratio [HR], 2.80; 95% CI, 1.16-6.74; P =.02), relapse (HR, 4.14; 95% CI, 2.04-8.38; P <.001), event-free survival (HR, 3.11; 95% CI, 1.77-5.46; P <.001), and overall survival (HR, 2.69; 95% CI, 1.35-5.35; P =.005). In addition, relapse was also significantly diminished by chronic graft-versus-host disease (GVHD) in a time-dependent Cox model (HR, 0.37; 95% CI, 0.16-0.87; P =.02). At transplantation, 8% of the patients were in complete remission, whereas 27% had progressive disease. After allografting, 49% achieved complete remission, and 38% achieved partial remission. In a subgroup of patients with chemosensitivity at transplantation and no relapse after prior high-dose chemotherapy who underwent transplantation with peripheral blood stem cells (n = 46), the cumulative risk of TRM at 1 year was only 8% (95% CI, 1%-54%). The 2-year estimated event-free and overall survival was 60% (95% CI, 42%-78%) and 75% (95% CI, 59%-91%), respectively, for related donors (n = 34) and was 81% (95% CI, 59%-100%) and 92% (95% CI, 76%-100%), respectively, for unrelated donors (n = 12).

Deletion of chromosome band 13q14 as detected by fluorescence in situ hybridization is a prognostic factor in patients with multiple myeloma who are receiving allogeneic dose-reduced stem cell transplantation

We investigated in a retrospective multicenter study the impact of chromosome arm 13q deletion (13q-) as detected by fluorescence in situ hybridization (FISH) on outcome after dose-reduced allografting in patients with multiple myeloma. In 68 of 140 patients, data on chromosome 13q status were available. Most patients included had advanced myeloma. At 2 years, patients with 13q deletion (n = 31) had a shorter event-free (18% vs 42%; P =.05) and overall survival (18% vs 67%; P =.03) than patients without 13q- (n = 37). Patients with 13q- experienced a higher relapse rate (77% vs 44%; P <.001) but a similar incidence of transplantation-related mortality at one year (24% vs 18%). In a multivariate analysis, 13q- remained a significant risk factor for a higher relapse rate (hazard ratio [HR], 3.28; 95% confidence interval [CI], 1.31-8.24; P =.01) and a shorter event-free survival (HR, 1.94; 95% CI, 1.03-3.67; P =.04). Concerning overall survival, 2 or more cycles of prior high-dose chemotherapy were associated with a significantly higher probability of death (HR, 2.48; 95% CI, 1.19-5.17; P =.02), while patients with deletion 13q had a nearly 2 times higher risk of death (HR, 1.94; 95% CI, 0.95-3.98; P =.07) after dose-reduced allogeneic stem cell transplantation.

"To every thing there is a season"--social time and clock time in addiction treatment

Research on therapeutic interventions and the development or efficacy of treatment services consider 'time' only as a technical, 'objective' condition. Time series analysis and cohort studies describe changes in addiction careers over time, but fail to take into account the role of 'subjective' or 'social time', e.g. the functions of organisational and individual patterns of time use and time budgets. This paper reviews the notion of 'time' in addiction treatment systems. More specifically, the explicit or implicit role played by 'the time factor' in specific types of treatment such as '12-step programs', in-patient, out-patient care and individual treatment plans differs considerably and implies a re-definition and interpretation of 'Past', 'Present' and 'Future'. Temporal conceptions and time estimations of patients and therapists may influence the access to treatment and treatment outcomes. Societal values--lack of time in affluent societies--and a general acceleration in the fields of communication, consumption, work and leisure are mirrored in the treatment system. Recovery as a long-lasting learning process stands in sharp contrast to the 'quick fix'. The question is raised whether a post-modern concept of time is gaining importance as a counter movement, promoting a more individualised and differentiated treatment response and not any longer based on assumingly objective, technical criteria such as cost-efficiency. More research is needed on group-specific time concepts in treatment programs and the acceleration hypothesis in treatment systems.

Intravesicular instillation of E-aminocaproic acid for patients with adenovirus-induced hemorrhagic cystitis

Hemorrhagic cystitis (HC) is a known complication of allogenic BMT. We report a case of a 28-year-old female with CML in chronic phase, which was treated with a matched unrelated donor (MUD) transplant, complicated by hemorrhagic cystitis on day +42 after the transplant. Adenovirus was isolated from the urine and she was treated with ribavirin, 1 g twice a day for 8 days. We report the use of Amicar (E-aminocaproic acid), 2.5 g solution as bladder instillation to treat the intractable hematuria.

National treatment systems in global perspective

Drug policy development is mostly viewed as emerging within the nation state. Processes of diffusion of innovative policies have been neglected to a large extent. The comparative study of public policy has demonstrated, however, that diffusion is an important predictor of early policy adaptation. Thus, the analysis asks the general question of the relative importance of endogenous and exogenous effects on the development of drug policies in various countries. Specifically it describes the Swiss debate leading to the popular initiative on 'Youth Without Drugs' as well as the international reactions regarding its liberal outcome. Results of an expert survey show two broad types of reactions. There is one set of countries where chances for the introduction of limited heroin-prescription trials during the next 5 years are considered probable and a second set of countries which seems to be strictly status quo oriented. In the concluding section a model is suggested which systematically considers endogenous as well as exogenous predictors of 'soft' or 'hard' drug policy adoption. Results of a first tentative test of the model are encouraging for future empirical research on diffusion processes of drug policies.