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Caring Cross Shows Proof of Concept for Place-of-Care Anti-CD19 CAR T-Cell Manufacturing


NEW YORK – Caring Cross demonstrated the feasibility of manufacturing autologous anti-CD19 CAR T-cell therapies at a patient's place of care in a recently published paper describing two proof-of-concept Phase I clinical trials.

Manufacturing CAR T-cell therapies where patients receive treatment using only fresh cells can improve turnaround time, avoid complications associated with cryopreserved patient samples, and potentially lower the cost of care.

Following the publication of its proof-of-concept studies in Nature Communications last month, Caring Cross is now planning further studies to refine an automated method of manufacturing its CAR T-cell therapies, which it hopes will eventually support biologics license applications, or BLAs, for its products. Once its place-of-care CAR T-cell manufacturing processes are fully established, Caring Cross aims to launch a commercial model, in which it contracts with hospital-based sites that can reliably and consistently manufacture its CAR T-cell products themselves for the patients treated at these facilities.

In its proof-of-concept studies, Caring Cross demonstrated its ability to manufacture autologous CD19-targeting CAR T cells using Miltenyi Biotec's CliniMACS Prodigy automated cell processing platform at sites in Cleveland and Moscow. To conduct the studies, Caring Cross collaborated with Miltenyi Biotec subsidiary Lentigen, which provides solutions for cell and gene therapy development.

Patients in the two studies had either relapsed or refractory pediatric B-cell acute lymphocytic leukemia or adult B-cell non-Hodgkin's lymphoma. Out of 31 ALL patients, 89 percent had a complete response to the CD19 CAR T-cell therapy, while 73 percent of 23 NHL patients saw their tumors completely disappear on treatment. At a median follow-up of 17 months, the one-year survival rate among ALL complete responders was around 79 percent and the median response duration of responses was 10.2 months. Among NHL complete responders, the one-year survival rate was nearly 93 percent and the median duration of response had not yet been reached.

According to Caring Cross, response rates to its therapies at both the Moscow and Cleveland sites were comparable to what has been reported for other CD19 CAR T-cell therapies in the published literature, indicating that the firm's automated manufacturing technique was at least as good as other techniques (see here and here), where the cell therapies are developed at centralized facilities far away from where patients are ultimately infused with the treatment.

Current autologous CAR T-cell manufacture begins with the isolation of a patient's peripheral blood mononuclear cells, or PBMCs, either through whole-blood phlebotomy or, more commonly, leukapheresis. Cryopreserved PBMCs are then typically sent to a centralized manufacturing facility, where they undergo selection or depletion of specific T-cell types, as needed. The selected cell population is then expanded before being once again cryopreserved and returned to patients' place of care.

Overall, Caring Cross sees these proof-of-concept trials as providing evidence that its place-of-care manufacturing process yields a consistent and efficacious therapeutic product, which will be necessary to show regulators when it seeks marketing approval for its CAR T-cell therapies down the road.

"Place-of-care manufacturing offers several advantages," Boro Dropulic, executive director and cofounder of Caring Cross, said in an interview. "The first advantage is reduced vein-to-vein time, due to lack of transport to a centralized facility. We were able to manufacture the product in eight days, compared to 12, 14, and even [longer]."

A second advantage is the ability to infuse patients with fresh cells, eliminating the need for cryopreservation. Because it takes time for cells to activate following cryopreservation, "we found that fresh CAR19 T cells reduced the tumor burden faster in vivo in an [immunodeficient] mouse model, than cryopreserved T cells," Dropulic said.

These simplified logistics give physicians more flexibility when tailoring care decisions for a patient whose disease status may be rapidly changing. With fresh cells available, for example, a doctor can administer partial doses based on a patient's actual tumor burden and signs of cytokine release syndrome.

"You can tailor the actual dose depending upon the response of the patient, when you have place-of-care manufacturing, [which] you can't do with the frozen product," Dropulic said.

Finally, Dropulic expects that by removing the need for transportation and multiple layers of quality and custodial assurance needed for centralized manufacturing, CAR T-cell therapy could fall to a fraction of its current cost.

Before Caring Cross can achieve this though, it will have to navigate the US Food and Drug Administration's review process amid regulatory uncertainties.

Drugmakers have begun developing autologous CAR T-cell products where patients are receiving care but have encountered regulatory obstacles in their attempts to advance scalable manufacturing processes. The problem revolves around the need to show that each separate manufacturing location can reliably produce the same product with equivalent degrees of safety and potency.

The FDA to date has largely overseen cell therapy applications on a case-by-case basis, whereas industry players would prefer clearer and more broadly applicable guidance from the agency.

A fully automated manufacturing process may help overcome or minimize the variability in cell therapies developed using manual techniques. Automated manufacturing could also help improve access to CAR T-cell therapies for patients located in places where shipping samples can be logistically complicated.

"We are looking at many of these different kinds of [manufacturing] workflows and devices because we're trying to balance between full automation cost," Dropulic said. "What could we do to lower the costs, but still have a robust [manufacturing] process to make this possible in a low- or middle-income country?"

Caring Cross selected the CliniMACS Prodigy for the nonprofit's place-of-care CAR T-cell platform because it provides a closed system with proven use in CAR T-cell manufacturing. Other groups using this platform include the German Red Cross Blood Service, the German Centre for Infection Research, and Milan-based biotech MolMed.

The platform's maker, Miltenyi Biotec, acquired Lentigen, which was cofounded by Dropulic, in 2014, although he no longer has any affiliation with either company. Dropulic pointed out that no business relationship exists between Caring Cross and Lentigen/Miltenyi outside of Lentigen providing instruments for its proof-of-concept studies.

Although Caring Cross' CAR19 T-cell production process involves some manual steps, Dropulic explained that these are "minimal."

"On the Prodigy," he said, "you could put the apheresis product on and [get] the final product, and all you have to do is add the bags to the device to wash the cells and things like that."

For consistency, Caring Cross did require that each clinical site use the same tests and reagents in analyzing their products.

Since its proof-of-concept studies are aimed at validating its automated manufacturing process, Caring Cross used monospecific CD19-targeting CAR T cells. Future studies, however, will likely incorporate bispecific and multispecific CARs.

"We used CAR19 because it was standard," said Dropulic. "The data was out there [and] we could compare the manufacturing data and clinical outcomes. But … we already know that having a bispecific is better for patients in terms of antigen loss-related relapse, than a single mono product."

As Caring Cross further develops its place-of-care manufacturing processes, the nonprofit plans to file for BLAs for CAR T-cell therapies advanced using these methods and launch an open commercial model, wherein networks of hospital-based sites under contract with Caring Cross develop these cell therapies for patients treated at the facilities. Caring Cross will work with each hospital partner on developing the best platform for their needs.

Caring Cross plans to continue using the CliniMACS Prodigy platform but the nonprofit also intends to evaluate other devices for future CAR T-cell offerings. "As a nonprofit we are agnostic to the actual platform used as long as it is robust and allows for the place-of-care manufacture in an affordable and accessible manner," Dropulic said. "As we finalize which platform is the most robust and cost effective, and once we show safety and efficacy with our candidates, we intend to initiate pivotal trials with our partners with the goal of attaining BLA approval."

As an example of how place-of-care CAR T-cell therapy manufacturing might play out, a major hospital chain interested in offering Caring Cross' products could designate one of its centers as a reference center and ensure that each site within the hospital's network manufactures CAR T-cell products to the same specifications as that reference center. All sites in the network might then be able to make CAR T-cell products under reference center supervision.

Companies developing CAR T-cell therapies could also use this distributed model in the clinical trial phase. Hospital chains wanting to adopt place-of-care manufacturing could partner with organizations developing CAR T-cell therapy candidates so that each is aligned with respect to vectors, devices, materials, reagents, and protocols used during development. These sites would then need to work collaboratively with all BLA-applicant partners and the FDA and other regulatory agencies in seeking approval.

"This is the first study that definitively demonstrates the feasibility of place-of-care manufacturing of gene-modified cell products," Dropulic said. "The next step will be to expand CAR T-cell clinical trials to include more clinical centers and support the development of regulatory pathways for the approval of CAR T cell and other gene-modified cellular products that are manufactured at the place-of-care."