Trends in cord blood enhancement 2013

by Alexey Bersenev on November 10, 2013 · 1 comment

in cord blood

I’m following with a big interest the latest development in technologies for cord blood (CB) enhancement in hematology. “Enhancement” means boosting a therapeutic value of cord blood graft via its stimulation/ modification (homing, migration, engraftment) or increase cell number (expansion, processing optimization). Today, I’m going to overview very recent trends and give update on methodologies and trials with emphasis on cell product.

Myeloid bridge and Hutch technology
Colleen Delaney (Fred Hutchinson Cancer Center) in her recent plenary talk during ISCT North America, said: “Hematopoietic cell expansion here to stay!“. She was talking about “hematopoietic cells” more broadly, rather than “hematopoietic stem cell” (HSC) expansion, since the main goal is rapid neutrophil and platelet recovery. Cord blood has a delayed neutrophil engraftment (in average ~26 days) and, therefore, could be associated with increased transplant-related mortality risk. Myeloid progenitor cells within CD34+ population is the major contributor to rapid neutrophil recovery or so-called “myeloid bridge“. Such “bridge” covers the most critical period of profound neutropenia in early post-transplant course and allows to avoid infectious complications. Delaney said that if we can provide a therapeutic dose of CD34+ hematopoietic cells > 10 million/ kg – we can drive neutrophil recovery speed below 10 days. Because concentration of CD34+ cells in conventional CB unit is about 0.2-0.3 million/ kg., the optimal expansion rate should be >50 times.

I wrote about phase 1 trial in Fred Hutchinson Cancer Center here and here. Phase 2 multicentral trial (with enrollment goal = 160 subjects) has been started and few patients got infusions. It utilizes notch-mediated expansion of CD34+ cells from third party donors. In phase 1 they did a real time expansions of partially HLA-matched units and infuse it right after harvest with the second – fresh unmanipulated unit. Delaney mentioned that it was very difficult logistically and will be not feasible commercially. So, they moved to “universal donor off-the-shelf” concept, where they can utilized non-matched cryopreserved expanded product. However, the big questions remain about possible pooling of CB units and impact of cryopreservation on a product potency. Pooling of few units will allow to increase number of CD34+ cells in starting population, since there is significant cell loss during magnetic sorting. The current IND, however, outlines a single unit processing. Delaney mentioned that they saw better results with fresh products, but it will not be commercially viable.

So, Delaney’s group made a decision in favor of “universal donor off-the-shelf” non-matched product as myeloid bridge. The main goal of “myeloid bridge is rapid generation of temporary engraftable progenitors and facilitation of host marrow recovery. Notch-based expansion allows to make pure (without T-cells and granulocytes) product with therapeutic dose >10 million CD34+ cells/ kg. The trial settings still include second unmanipulated unit to ensure engraftment. Even though, “myeloid bridge” alone will be applicable in some indications, in leukemias with myeloablative conditioning and expectations for complete donor’s chimerism, it will require additional source of HSC.

Going beyond double unit
Few years ago, when many CB expansion trials have been started, every group was doing it only in double unit (DUCB) settings. The reason for using “fresh” unmanipulated CB unit was some kind of insurance from graft failure, since “expanded unit” was not able to engraft long-term and sustain life-long hematopoiesis. But with accumulation of clinical data and optimizing expansion/ conditioning protocols, we start to see long-term engraftment from “expanded” units! Two year ago, French group reported long-term engraftment (>1 year) from single expanded CB unit in 6 out of 8 patients. I didn’t hear any updates from this group since then. But 2 months ago, I’ve heard new data from Gamida Cell about long-term results of their NiCord platform. Mitch Horwitz, who is supervising Gamida’s trial at Duke, in his plenary talk during ISCT North America meeting, showed data of 4 patients with complete neutrophil engraftment > 1 year from NiCord unit. Some patients engrafted from NiCord more than 2 years. Strikingly, in some patients, NiCord unit also sustained T-cell engraftment beyond 1 year. So, NiCord technology allows at least to maintain hematopoietic stem cells after 21 days of expansion. These encouraging data, allowed Gamida to launch single NiCord unit program:

We are witnessing a paradigm shift in transplantation. The first patient was successfully transplanted with a stem cell graft entirely expanded in ex vivo cultures and without the support of a second unit of un-manipulated stem cells. Gamida Cell CEO Dr. Yael Margolin.

Gamida’s confidence in “single expanded unit” can lead to real paradigm shift, indeed. Of course, if everything will go smoothly. We should remember that significant part of patients did not sustained long-term engraftment from NiCord unit. These patients will always require unmanipualted CB unit. Both – heterogeneity of the product and heterogeneity of the patient population can contribute to different engraftment outcome. We will watch the progression of this remarkable “single cord” trial. I’m predicting that results of “single cord” (expanded) only will be worse than DUCB (expanded + unmanipulated).

StemEx update
StemEx is another Gamida’s product, which is undergoing Phase 3 trial. This year, Gamida (with Teva) was trying very hard to push StemEx to the market, but it didn’t work. I’m not sure what was a reason for delay in Israel, but FDA asked the company to conduct one more Phase 3 randomized controlled trial. As of now, StemEx trials included only historic controls. You can look at last clinical updates, including evaluation of 101 patients from 25 centers, here and here. Primary end point of trial has been met: 100-day survival 84.2% in StemEx versus 74.6% in control (p=0.035).

Analogously to NiCord, CD133+ cells get expanded for 21 days and CD133- portion of the same unit cryopreserved. Unlike NiCord, StemEx utilizes “single cord” settings. However, in terms of neutrophil recovery, NiCord is doing much better (~11 days versus 21 days). We still don’t know though if it’s because of NiCord or because of unmanipulated unit. Unlike Hutch technique, StemEx and NiCord have some CD3+ T-cells. As a consequence, GVHD rates in StemEx trial, were not different from controls. The key differences between Hutch and Gamida’s CB expansion could be starting population (CD34+ versus CD133+) and major expansion platform (Notch-mediated versus nicotinamide (NiCord) and copper chelation (StemEx)). What struck me most in StemEx was the huge difference in expansion rate from unit-to-unit:

Median NC and CD34 fold expansion were 400 (0-764) and 77 (6-280), respectively. StemEx yielded a median of 14-fold increase in the number of CD34+ infused, in comparison to the number of CD34+ cells the patients could have received from the entire UM CBU.

The possible reasons for such difference could be inherent heterogeneity of CB CD133+ population and/or lack of robustness in expansion protocol. It is also unclear how expanded cells engrafted, since unmanipulated part of the same unit was infused.

Novartis Stem-Regenin 1 first results
Novartis is assessing a small molecule HSC835 (aryl hydrocarbon receptor antagonist; SR1) in University of Minnesota in DUCB settings. CD34+ cells from one unit undergo expansion with SR-1 for 15 days, while CD34- cells from the same unit cryopreserved. John Wagner will report first data next month in ASH 2013. From the abstract:

Culture in the presence of SR1 resulted in a median of 248-fold (range, 66-446) expansion of CD34+ cells.

There were no infusional toxicities noted. Based on a presumed graft-graft interaction, the HSC835 product predominated in 5 of 9 patients and resulted in sustained hematopoiesis for a median follow up of 303 days (range 140-401). The median time to neutrophil recovery (days to absolute neutrophil count of ≥500/uL) was shorter in recipients of HSC835 (i.e., 16 days [range, 6-23] versus 24 days [range, 22-30]) with the speed of neutrophil recovery correlating with the number of CD34+ cells infused…

So, preliminary data are very encouraging! Similar to NiCord, SR-1 can sustain long-term engraftment – means able to maintain (at least) HSC. Clinical outcome (neutrophil recovery) looks close to NiCord. But, 15 days in culture (SR-1) versus 21 day (NiCord) can reduce cost of the product significantly.

ProHema
Fate Therapeutics is developing very interesting CB enhancement product. CB unit incubated for short time with PGE2 (ProHema), washed and infused in DUCB settings. Since the first cohort (CB incubated for 1 hour in cold) did not result in any improvements, the company invest some time for process optimization. The second cohort was treated in optimized protocol (CB incubated for 2 hours at +37) and redesigned trial. The results of Phase 1 trial were published few months ago:

We observed encouraging trends in efficacy, with accelerated neutrophil recovery (17.5 vs 21 days, P= .045), coupled withpreferential, long-term engraftment of the dmPGE2-treated UCB unit in 10 of 12 treated participants.

The mechanism of action, mainly based on increase of hematopoietic cells homing to host bone marrow. However, the authors also emphasized:

We also demonstrated that dmPGE2 functions as a modifier pathway for Wnt signaling via cAMP, which could lead to enhanced self-renewal of the HSCs.16 Rather than increasing the number of HSCs, this pharmacologic ex vivo modulation increases the “effective stem cell dose” for use in transplantation.

I think, such statement could be speculative for human, especially in the light of recent findings:

Treatment with PGE2 did not result in a long-term increase in HSC competitiveness, lineage bias, or enhanced proliferative potential, demonstrating that pulse exposure to PGE2 results in transient increases in HSC homing and engraftment potential.

Fucosylation
America Stem Cell Inc is assessing CB fucosylation (ASC-101; Engraftin) technique in MD Anderson Cancer Center. Fucosylation enhances binding of E-selectin ligands and leads to increased homing to bone marrow. Elizabeth Shpall group will report first preliminary results of this trial next month in ASH 2013 meeting. Analysis of the first 7 patients:

Median time to absolute neutrophil count ≥ 0.5 X 109 /L was 14 (range 12-28) days. Median time to platelet count ≥ 20 X 109/L was 33 (range 18-100) days. One patient had secondary graft failure and was rescued with backup autologous stem cells. Four patients had engraftment of the fucosylated unit and 2 of the unfucosylated unit. Two patients developed grade 2 acute graft versus host disease. No infusion related toxicities were seen.

Only 30 min of incubation at room temperature! It could definitely beat “expansion” techniques in DUCB settings. Interestingly, fucosylation can positively affect other than hematopoietic cells in CB. For example, NK or other immune cells. Impact on multiple cell types could also be a mechanism of PGE2 action. So, short pulse by PGE2 or ASC-101 can increase “competitive fitness” of the whole CB unit. The big question for ProHema and Egraftin will be a possibility to go beyond DUCB settings.

Conclusions:

  1. For the first time we have evidence that ex vivo CB expansion can result in at least HSC maintenance and maube expansion.
  2. Switching from conventional DUCB to “single manipulated unit” is real paradigm shift in CB transplantation.
  3. Multiple techniques and companies with quite similar clinical results will compete for relatively small market.

Some future outstanding questions:

  • Will cost of one unit expansion be lower than DUCB transplant?
  • How can we predict “expandability” and ID CB units for better CD34+ cell yield?
  • What is the best business model and the best technology for commercial success?
  • How impact on T-cell recovery will affect competition between different products?
  • Will point-of-care techniques (ProHema, Engraftin) beat “expanded products”?

{ 1 comment… read it below or add one }

David March 7, 2014 at 9:41 am

Dear Alexey,

A more accurate accounting of our NiCord trial is in order.
There were ten engrafted pts in this trial of NiCord, using one fully manipulated and one unmanipulated unit.
Chimerism has remained stable from day 14 post transplant: Eight patients who engrafted with NiCord, (starting over 3 years ago) remain to this day engrafted with NiCord and two patients who engrafted with the unmanipulated unit remain engrafted with the unmanipulated cord. Thus your conclusion that there shall always be a need for an unmanipulated unit is not substantiated.
The conclusion is the NiCord graft is capable of out-competing an unmanipulated graft for short- and long-term engraftment. With median patient follow up of 22 months, the expanded graft remains stable in all 8 patients initially engrafted with NiCord.

As far as your prediction goes, time will tell, but so far in our single unit trial we are seeing the same time to early engraftment and durability of the graft.

David Snyder
Gamida Cell

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