[STUDI] Sangamo: CD4 e staminali resi CCR5- mediante ZFN II

[Leon]

A Phase 1/2 study (SB-728-T-1002) is ongoing to evaluate SB-728-T in HIV-infected individuals who are treatment naive and not yet on HAART

Ottima notizia, che, ai miei occhi, compensa quella del trial sugli eterozigoti!

A proposito di questi eterozigoti, vorrei rimarcare una cosa che, anche tenendo conto dei tuoi commenti, forse non ho messo abbastanza in evidenza: secondo me, tralasciando i fortissimi limiti in termini di praticabilità/utilità, questo degli eterozigoti CCR5-Delta32 resi aviremici, se dura, è un successo ENORME e, anche se non durasse più di tanto, e soprattutto se questi eterozigoti diventati aviremici sono effettivamente 2 su 2, è una PROOF-OF-CONCEPT FOR-MI-DA-BI-LE, proprio senza precedenti (a parte farmaci antiretrovirali e "paziente tedesco", vabbè).

Lalezari cerca pazienti, sia per la fase II dell'SB-728-T, sia per le staminali (cfr. Quest Clinical)

Non direi. Il discorso staminali mi sembra buttato lì solo a titolo di prospettiva futura e per fare colpo e, anche al di là di questa mia impressione, trattandosi di una fase *II* non credo proprio che Lalezari stia reclutando che per la sangamizzazione dei CD4 maturi.

Vediamo questa fino a quando dura (anche se non ritengo a priori un difetto quello di aggiustare il tiro cammin facendo, anzi!).

[Dora]

Vediamo questa fino a quando dura (anche se non ritengo a priori un difetto quello di aggiustare il tiro cammin facendo, anzi!).

Ma certo che non è un difetto, ci mancherebbe! Speriamo solo che non faccia la fine dell'XXX (non lo scrivo per non portare sfortuna).
E comunque a merito di Sangamo ascriverei che sta diversificando i pazienti a 360 gradi.
Quello che però per me è più importante capire è se, aumentando i miliardi di CD4 modificati, altri pazienti si avvicineranno alla viremia irrilevabile in assenza di HAART del paziente di June (quello di Mitzuyasu non è comunque andato sotto la soglia di rilevabilità, sempre se è davvero un altro eterozigote CCR5Delta32). Questo sì che potrebbe rendere l'SB-728-T un'opzione meno di nicchia, per quanto sempre costosa.

Intanto, mi par di capire che i risultati sui naive dovrebbero arrivare entro fine anno.

[Dora]

Curioso come - a tanti anni dalla fine dell'Unione Sovietica - la Pravda continui a fare disinformatjia, a parlare di "scienza americana" e a disonorare il suo stesso nome. Leggete che cosa scrive oggi, nella sua versione inglese, sulle ricerche di Sangamo.
Con tutte le critiche che si possono fare ai CD4 sangamizzati, proprio ai negazionisti si dovevano aggrappare?



english.pravda.ru

[Dora]

Un aggiornamento sui trial dell'SB-728-T.
Si è tenuta ieri sera una conference call, durante la quale Sangamo ha dato conto dei risultati finanziari del III trimestre del 2011 e, per quel che riguarda le sperimentazioni cliniche sui CD4 modificati, Lanphier ha ribadito che, dopo il fallimento dell'SB-509, tutti i loro sforzi si concentreranno sul farmaco che distrugge il CCR5 e ha confermato che stanno arruolando i nuovi pazienti.
Nelle parole di Geoffrey Nichol, vice presidente esecutivo:


The first study is to recapitulate and further explore our visual observation in HIV infected CCR5-delta32 heterozygote. In this study, which is being added as the fifth cohort to our original SB-728-902 trial, we will enroll up to 20 subjects to around HAART and who will undergo a 16-week treatment interruption one-month after SB-728-T treatment.

This study will as previously re-institute HAART if a subjects CD4 count falls below a certain threshold or viral loads rise too high to a too higher level. But importantly, we’ll also have the provision to delay resumption of HAART if patients are aviremic at the end of the treatment interruption period.

Screening of potential CCR5 heterozygote subjects has begun and we will update you after the status of this trial at appropriate medical and scientific meetings as data become available.

The second trial that we plan to initiate takes the observation of enhancing engraftment of biallelically modified cells much further and potentially applies to the entire population of HIV infected patients. The rationale behind the study design is to use what is called a lymphopenic preconditioning regimen that transiently depletes T-cells in the subject and not only makes space from new cells, but sets up a response in the body that signals remaining cells to rapidly multiply to address this depletion [questa è una novità e mi pare assai interessante, perché simula parzialmente un trapianto à la Cannon, anche se poi vengono reinfusi CD4 maturi e non staminali].

We plan to enroll subject in this engraftment enhancement study that are on HAART. Immediately prior to administration SB-728-T, we will precondition our immune systems to reduce the lymphopenics state, stimulating the transfused ZFN-modified cells to undergo significant growth and expansion. This is expected to enhance engraftment of the modified cells and as a consequence, the engraftment of biallelically modified cells.

As I mentioned, lymphopenic preconditioning has been effectively used in other reductive T-cell settings and has resulted in significantly enhanced engraftment of the transplanted autologous T-cell. For example, me and Dr. Carl June’s work on chronic lymphocytic leukemia that was recently published in the New England Journal of Medicine, he observed up to a 1,000 fold expansion of the modified T-cells infused after conditioning [ecco perché aveva senso seguire il lavoro sulla CLL e intervistare il professor Lambertenghi!!].

The agent that we plan to use is routinely used to treat autoimmune conditions with acceptable safety and tolerability and has also been previously used in subjects with HIV resulting in the induction of temporary lymphopenia with no long-term effect on the CD4 count. The proposed clinical trial design will involve aviremic subject on HAART.

We will conduct a dose escalation phase to establish safety and efficacy of the engraftment enhancement and will subsequently expand enrollment at a well tolerated lymphopenic dose to evaluate effects on viral load.

All subjects will undergo a treatment interruption following the expansion of SB-728-T, again with a provision for HAART resumption if there are aviremic at the end of the TI.

We are currently consulting with our clinical advisors on the details of the design of the trial. Subject to a new regulatory filing, we anticipate enrollment in the dose escalation cohorts to begin in the first half of 2012.

Again, we will update you on the status of this trial at appropriate medical and scientific meetings as data become available.

Finally, I’d like to update you on our SB-728-1002 trial. As we have discussed, the recent ICAAC data suggest that subject that have higher biallelic engraftment of CCR5 modified cells, experience better reduction in viral loads and the patients with the best reconstitution of their immune system are those most likely to make best use of the modified CD4 cells.

As a result, we believe that the best proof of concept population is subject on HAART with maximal immune reconstitution where biallelic modification can be greatly enhanced, whether by treating heterozygotes or using a preconditioning regimen. The time for implementing this enhanced strategy is opportune.

We are just completing accrual of the 1002 study having enrolled 21 subjects. We will present data from the study at an appropriate meeting in 2012 when we have more prolonged follow up data on the entire cohort.



Da seekingalpha.com

[Eilan]

Sempre più raffinati insomma.

[Dora]

Niente di davvero nuovo, sul fronte Sangamo.
Ma oggi si è tenuta la Lazard Capital Markets 8th Annual Healthcare Conference Call e Lanphier ha confermato che hanno dato inizio alla ricerca dei pazienti eterozigoti delta-32 e contano di far partire il trial nella prima metà del 2012. Sempre nel 2012, arriveranno i dati sui pazienti naive.

• (...) actually we have begun screening on the first one, the delta-32 population and we expect to initiate the engraftment enhancement study in the first half of next year. We also expect to present data from our recently completed accrued study the 1002 trial in treatment naïve subjects in 2012 as well. So that gives you a sense of where we are in the HIV program, very exciting opportunity and one that we are working very hard to move forward quickly. We will have more data in 2012 on that program.

[Dora]

Non ho - purtroppo! - nessuna novità sul fronte SB-728 (aspetto di leggere gli abstract delle presentazioni fatte da June e dalla Cannon a St Martin, ma non credo ci siano aggiornamenti di rilievo).
Mi ha però colpito un lavoro portato da Sangamo all'ASH, l'incontro annuale della American Society for Hematology, che è uno dei principali congressi di ematologia (ha partecipato anche Hütter, ma non per cose che abbiano attinenza ai trapianti di staminali difettive in HIV+).
Si tratta, infatti, di una ricerca che si propone di creare un'immunoterapia contro il cancro - e segnatamente la leucemia - rinforzando geneticamente la capacità dei CD8 di uccidere le cellule cancerose (ricordate il successo di June l'estate scorsa? Cfr. http://www.hivforum.info/forum/viewtopi ... 1695#p1695). Per modificare i linfociti T, anche in questo caso Sangamo utilizza le nucleasi a dita di zinco.
In particolare, questo abstract mi ha colpito perché la ricerca si è svolta a Milano, al San Raffaele.


Abst. No. 667 - TCR Gene Editing Results in Effective Immunotherapy of Leukemia without the Development of GvHD (Oral Session: 801)

Cancer immunotherapy uses CD8 T-cells that have been engineered to express high avidity T-cell receptor (TCR) genes isolated from tumor-specific lymphocytes. The engineered CD8 T-cells are then able to attack the tumor. Problems can arise with this approach because the expression of the CD8 T-cell's own TCR gene interferes with expression of the inserted tumor-specific TCR gene. This interaction limits the potency of this cellular therapy but, more importantly, it can also make the cells "self-reactive" leading to graft versus host disease (GvHD).

In this study, ZFNs were used to disrupt the native TCR genes in these tumor-directed CD8 T-cells resulting in an enhanced immunotherapeutic product with potent cancer cell-killing activity and the elimination of GvHD in a mouse model. These studies were performed in the laboratory of Chiara Bonini, M.D., Head of the Experimental Hematology Unit, San Raffaele Hospital, Milan, in collaboration with Luigi Naldini, Head of TIGET, San Raffaele Hospital, and Sangamo scientists.

Transfer of high-avidity T-cell receptor (TCR) genes isolated from rare tumor-specific lymphocytes into polyclonal CD8+ T cells is an attractive strategy for targeted cancer immunotherapy. However, the successful implementation of this approach is limited by technical and safety issues, including inefficient gene transfer, unstable transgene expression, exhaustion of gene-modified cells and most importantly, the unpredictable results of mispairing between the endogenous and exogenous TCR chains. Indeed, co-expression of the endogenous and exogenous TCR in the same cell not only reduces cell-surface expression of the introduced tumor-specific TCR, but also drives the potential for these gene-modified T cells to acquire autoreactive specificities. Such TCR mispairing has been shown to result in autoreactive T cells in animal models [Bendle et al., Nat Med. 2010]. To partially overcome these limitations, we have developed a novel strategy based on zinc finger nucleases (ZFNs) that permits editing of T cell specificity at the DNA level, combining the disruption of the endogenous TCR chain genes with the transfer of a tumor-specific TCR. Two sets of ZFNs were designed targeting the constant regions of the α (TRAC-ZFN) and β (TRBC-ZFN) TCR chain genes, respectively. We transiently delivered these ZFNs into primary T lymphocytes activated with anti-CD3 and anti-CD28 antibody-conjugated beads and cultured with low doses of IL-7 and IL-15, to promote the survival and expansion of the ZFN-modified cells. ZFN delivery into activated T lymphocytes abrogated expression of the CD3/TCR complex on the cell surface (% of CD3neg cells with TRAC-ZFN: 34%±11 and with TRBC-ZFN: 30%±9). No phenotypic differences were observed in CD3pos and CD3neg lymphocytes, which displayed a similar CD4/CD8 ratio while displaying an early T-cell differentiation phenotype, as evidenced by high expression of CD62L, CD27, CD28 and IL-7Rα markers. Sorted CD3neg cells proved stable in culture (demonstrating that ZFN exposure was well tolerated), and did not respond to TCR-dependent stimulation with the mitogen PHA, as expected for cells carrying a disrupted TCR gene. CD3neg cells were efficiently transduced with a lentiviral vector encoding a tumor-specific exogenous TCR chain, resulting in the restoration of cell surface translocation of CD3, thus facilitating the selective expansion of TCR-transduced cells by polyclonal stimulation. To demonstrate the antitumor activity of these modified cells we selected an HLA-A2 restricted, codon-optimized cysteine-modified TCR specific for the Wilms’ tumor antigen 1 (WT1). To achieve complete editing of T cell specificity, we established a protocol that sequentially disrupted the endogenous TCR α and β chains with high efficiency (averages: 36% and 18%), followed by lentiviral transfer of the tumor-specific TCR α and β chains (average efficiencies: 65% and 25%). This procedure resulted in a population of TCR-edited lymphocytes encoding only the tumor-specific TCR that, in the absence of competition from the endogenous receptor, was expressed at high physiological levels. Accordingly, TCR-edited lymphocytes were superior to conventional TCR-transferred cells in promoting specific recognition of WT1-expressing targets, including primary leukemias, and most importantly, were devoid of residual endogenous TCR reactivity including alloreactivity. Finally, in a humanized GvHD model, we showed that, at a variance with 100% of mice infused with unmanipulated T cells, and 80% of mice receiving TCR-transferred lymphocytes developing lethal GvHD, no GvHD was observed upon infusion of matched TCR-edited cells, despite robust T cell engraftment rates across all groups. These data demonstrate that the successful genetic re-programming of T cell specificity in primary lymphocytes results in a functionally superior target specific killing activity and thus has the potential to greatly improve the safety and therapeutic benefit of cancer immunotherapy, without triggering its potentially negative effects. (Provasi and Genovese: equal contribution).

Queste le conclusioni di Lanphier, nel comunicato stampa:

• "We continue to develop our ZFP Therapeutic pipeline and, on the strength of our success in mouse models, have advanced our hemophilia B program into preclinical studies in a large animal model of the disease," stated Edward Lanphier, Sangamo's president and chief executive officer. "As these presentations demonstrate, our ZFN gene-editing platform has broad applicability in that it can be applied to any disease-relevant gene enabling permanent gene modification and has the potential to provide a valuable therapeutic approach to a variety of unmet medical needs."

[Dora]

Ecco i due lavori presentati da Sangamo a St Martin: uno di Tebas - June sul trial clinico di somministrazione di CD4 resi CCR5 negativi e uno di Wylen - June sulla distruzione in vitro del CXCR4 e sulla prova in vivo - su topi - dei CD4 così modificati.


Abstract 45
A Single Infusion of Zinc Finger Nuclease (ZFN) CCR5 Modified Autologous CD4 T-cells Correlates with Increases CD4 Counts and Effects on Viral Load in Aviremic HIV-infected Subjects

P Tebas1, D Stein2, S Wang3, G Lee3, M Giedlin3, W Tang5 ,D Ando3 and C June1

1 PENN, Philadelphia, PA; 2 Albert Einstein College of Medicine, Bronx, NY; and 3 Sangamo BioSciences Inc,
Richmond, CA

CCR5 is an important coreceptor for HIV entry and modification of this receptor in CD4 T-cells with ZFN may render a survival advantage. Here, we report interim results of enrollment and data relating to safety, increases in CD4, persistence and trafficking of SB-728-T, and effect on HIV. In the study, 12 subjects were infused with 10^10 cells; 6 in a well controlled cohort (CD4 >450/uL, cohort 1) and 6 in immunological non responders (<500/uL, cohort 2)). Subjects in Cohort 1 underwent a 12-week HAART Treatment Interruption (TI) at Wk 4 after infusion. The median duration of follow-up is in excess of 230 days (range 86-591). CD4 and SB-728-T count increased by 1533/μL (range 216-3025) and 83/μL, respectively on D7 in Cohort 1 and by 820/μL (range 133-4467) and 19/μL, respectively in cohort 2. Increases in CD4 over time correlated with SB-728-T engraftment (г=0.78, p<0.0001). Homing to the gut mucosa was detected in all 18 subjects biopsied (median 6%). During TI, HIV-RNA dropped ~0.8-2.1 log from their peak levels in 3 subjects. In 1 subject, heterozygous for the Δ32 mutation, with a viral setpoint of 165K copies/ml, VL peaked at 6247 during Wk 6 of TI and was undetectable by Wk 12. We conclude that SB-728-T infusion increases CD4 counts that persist over time. CCR5 modified CD4 cells expand rapidly and home to the gut. Preliminary data suggest that SB-728-T may decrease proviral DNA. In one subject with the highest level of CCR5 modification, VL was controlled (< limit of detection) without HAART during TI.
These data suggest that in addition to the increases in CD4 cells, CCR5 modified CD4 cells may also suppress HIV replication.


Abstract 46
Targeted Disruption of CXCR4 in Human CD4+ T Cells with Zincfinger Nucleases

C Wilen1, J Wang2, CA Didigu1, JC Tilton1, JC Miller2,SA Sherill-Mix1, FD Bushman1, PD Gregory2, CH June1, MC Holmes2, and RW Doms1

1 University of Pennsylvania, PA, USA, 2 Sangamo BioSciences, CA, USA

BACKGROUND: The Berlin patient highlights the potential therapeutic benefit of CCR5 disruption in the treatment and possible eradication of HIV infection.
We have previously shown that CCR5 can be genetically disrupted in human CD4+ T cells conferring protection to HIV challenge in vitro. Several phase I clinical trials are currently underway to assess the safety and efficacy of this approach in vivo. Given that there is also a set of patients afflicted with CXCR4-tropic HIV, we have designed zincfinger nucleases to specifically disrupt the CXCR4 gene.
Our long-term goal is to simultaneously and permanently disrupt both CCR5 and CXCR4 in CD4+ T cells for the long-term control of HIV in the absence of anti-retroviral therapy.

METHODS: A zinc-finger nuclease pair specific to the CXCR4 gene (CXCR4-ZFNs) was generated by combining the catalytic domain of a modified Fok1 endonuclease with a pair of zinc-finger proteins that recognize a specific 24 base pair region in the CXCR4 gene. The CXCR4-ZFNs were delivered in vitro to human CD4+ T cells using an Ad5/F35 vector and then gene-modified cells were challenged with diverse HIV strains in vitro and in a humanized NSG mouse model.

RESULTS: The CXCR4-ZFNs specifically and stably disrupted 20-40% of CXCR4 genes in human CD4+ T cells in vitro. Upon in vitro challenge with CXCR4-tropic HIV, CXCR4 disruption reduced viral titers and conferred a profound survival advantage resulting in a population of up to 98% CXCR4 negative cells. Consistent with our in vitro results CXCR4 disruption was well tolerated in a humanized mouse model in vivo. In the presence of CXCR4-tropic HIV challenge, CXCR4-ZFN treatment preserved CD4+ T cell counts, and CXCR4 -/- cells preferentially survived.

CONCLUSION: Our data suggest that genome editing with CXCR4-ZFNs may provide therapeutic benefit to HIV-infected individuals. Further, this supports our longterm goal of engineering CD4+ T cells resistant to both CCR5- and CXCR4-tropic HIV.

[Dora]

Come aveva promesso a fine ottobre (http://www.hivforum.info/forum/viewtopi ... 4673#p4673), oggi Sangamo ha comunicato di aver dato inizio a due nuovi trial dedicati ai CD4 resi CCR5 negativi mediante ZFN: si tratta di due studi di fase II - SB-728-1101 e SB-728-902, Coorte 5 - il primo dei quali mi pare presenti non poche novità.
Ha anche aggiunto di contare di presentare i dati sui trial clinici sull'SB-728-T nel 2012 (forse già a inizio marzo al CROI?).


Studies Advance Development of a 'Functional Cure' for HIV/AIDS

RICHMOND, Calif., Jan. 9, 2012

Sangamo BioSciences, Inc. (Nasdaq: SGMO) announced today the initiation of two new Phase 2 clinical studies (SB-728-1101 and SB-728-902, Cohort 5) in its program to develop a "functional cure" for HIV/AIDS. Sangamo's ZFP Therapeutic® approach (SB-728-T) generates T-cells that are resistant to HIV infection using its zinc finger nuclease (ZFN) technology to permanently disrupt the DNA sequence encoding CCR5, a co-receptor used by HIV to enter cells. The company expects to present data from its SB-728-T HIV clinical trials at appropriate medical meetings in 2012.

"We are delighted to be able to open these two important clinical studies ahead of schedule," said Geoff Nichol, M.B. Ch.B., Sangamo's executive vice president, research and development. "Data from earlier Phase 1 trials demonstrated a statistically significant relationship between the number of circulating T-cells in which both CCR5 genes are modified and the reduction in HIV viral load in infected subjects during an interruption of anti-retroviral therapy. Both of these new Phase 2 clinical trials are specifically designed to confirm and further investigate these findings."

The new studies employ two approaches to increase the number of engrafted T-cells in which both CCR5 gene copies are modified (biallelically modified) in SB-728-T-treated, HIV-infected subjects. The first, an extension of an ongoing trial (SB-728-902, Cohort 5), is designed to further investigate the effect of SB-728-T treatment on HIV viral load in subjects that are naturally heterozygous for the CCR5 delta-32 gene mutation (i.e. one of their two CCR5 gene copies has the mutation and one is normal). The second study (SB-728-1101), in HIV-infected subjects without the CCR5 delta-32 mutation, employs a conditioning pretreatment designed to significantly enhance the number of engrafted biallelically modified T-cells.

The rationale for the Phase 2 studies is based on data obtained in a Phase 1 trial of SB-728-T that demonstrated a statistically significant relationship between the number of engrafted biallelically modified T-cells and the reduction in HIV viral load in treated subjects. In this earlier trial, the viral load of an SB-728-T treated-subject decreased to undetectable levels during a scheduled treatment interruption (TI). This subject was heterozygous for the CCR5 delta-32 gene mutation, thus doubling the number of biallelically modified T-cells after SB-728-T treatment.

"We are focused on applying our ZFP Technology platform to develop novel therapeutics to address unmet medical needs," stated Edward Lanphier, Sangamo's president and CEO. "In addition to the rapid progress that we are making in our clinical program to develop a "functional cure" for HIV/AIDS, we are advancing our preclinical ZFP Therapeutic programs to engineer genetic cures for monogenic diseases including hemophilias and hemoglobinopathies such as sickle cell anemia. Sangamo enters 2012 with a solid cash position which allows us to aggressively pursue our goals while maintaining our historic control on cash burn. As such, we plan to end 2012 with at least $60 million in cash. We look forward to providing further financial guidance for 2012 as well as an update on our clinical and preclinical programs and our corporate partnering activities on our fourth quarter and end of year 2011 call in early February."
Mr. Lanphier will also provide an update on Sangamo's ZFP Therapeutic pipeline and an overview of the Company's business strategy and objectives for 2012 during his presentation at the 30th Annual J.P. Morgan Healthcare Conference at 7:30 am PT, on Thursday, January 12, 2012. The presentation will be webcast and available at http://investor.sangamo.com/events.cfm.
(...)

About SB-728-902 Cohort 5 – Phase 2 Study

Up to 20 HIV-infected subjects heterozygous for the CCR5 delta-32 mutation (i.e. with one CCR5 gene that is naturally modified) who are currently on Highly Active Anti-retroviral Therapy (HAART) will be enrolled and will receive a single intravenous infusion of SB-728-T (5 to 30 billion modified cells). Two months after SB-728-T treatment, subjects will undergo a 16 week TI during which time their anti-retroviral therapy will be discontinued. HAART will be reinstituted in subjects whose CD4 T-cell counts drop to <350 cells/mm3 and/or whose HIV-RNA increases to >100,000 /mL for three consecutive weekly measurements. At the end of the TI, subjects with a sustained detectable HIV viral load will be reinstituted on HAART. Subjects with an undetectable viral load will remain off HAART until HIV RNA levels are detectable or their CD4 T-cell count drops below 350 cell/mm3 for three consecutive weekly measurements.

About SB-728-1101 – Phase 1/2 Study

SB-728-1101 is an open-label, dose escalation, multi-center study designed primarily to evaluate the safety and tolerability of escalating doses of cyclophosphamide (Cytoxan®) administered one day prior to SB-728-T infusion. Cytoxan is a drug that is used to transiently reduce the numbers of T-cells in the body which then rapidly repopulate once the drug is discontinued. Such lymphodepletive treatment has been used to enhance engraftment of adoptively transferred T-cells in the treatment of cancer and as therapy for numerous autoimmune diseases. The drug has been previously used in HIV-infected individuals and studies demonstrate that, while the drug was transiently lymphodepleting, it did not significantly reduce total CD4 T-cell counts over the long term and was adequately tolerated.
In addition to safety, the study will evaluate the effect of escalating doses of Cytoxan on SB-728-T engraftment, the effect of SB-728-T treatment on viral load following HAART interruption, the change in CD4+ T-cell counts in peripheral blood and the long-term persistence of SB-728-T.
At least 9 HIV-infected subjects on HAART will be enrolled into 3 dose-escalating cohorts (3 subjects/cohort), and will receive intravenous Cytoxan (200 mg, 500 mg or 1000 mg). Within each cohort, treatment will be staggered so that each subsequent subject cannot be infused with Cytoxan until at least 2 weeks after the preceding subject. One day after receiving Cytoxan, subjects will be infused with SB-728-T (5 to 30 billion cells). Six weeks after SB-728-T infusion, subjects with CD4 cell counts >500 cells/mm3 will undergo a 16 week TI during which time their anti-retroviral therapy will be discontinued. HAART will be reinstituted in subjects whose CD4 T-cell counts drop to <500 cells/ mm3 and/or whose HIV-RNA increases to >100,000 copies/ mL for three consecutive weekly measurements. At the end of the TI, subjects with a sustained detectable viral load or CD4 T-cell count <500 cells/mm3 will be reinstituted on HAART. Subjects with an undetectable viral load will remain off HAART until HIV RNA levels are detectable or their CD4 T-cell count drops below 500 cells/ mm3 for three consecutive weekly measurements. (...)

[Eilan]

Cioe? fatemi capire bene, usano il ciclofosfamide per fare prima tabula rasa delle cellule o quasi, per poi infondere a spron battuto i Sangamizzati per vedere se attecchiscono e per quanto tempo?