Cell, Tissue, and Gene Therapies

Elizabeth Read, MDAdjunct Professor, Lab Medicine, UCSF

May 13, 2010

My backgroundMD, Internal Medicine with Hematology/Oncology

subspecialties

Immediately after fellowship, worked at NCI managing extramural cancer cooperative group clinical trials

Fellowship in Blood Banking/Immunohematology

On staff at NIH Clinical Center for 15 yrs – clinical lab support and product development/GMP manufacturing for hematopoietic transplantation, cellular gene therapies, immunotherapies, islet transplantation

3 years ago, came to BSRI/UCSF to work with investigators on CIRM and NIH supported stem cell therapy development projects

CBER regulatesBlood, blood products, and plasma derivatives

Human cells, tissues, and cellular and tissue-based products (HCT/Ps)

Other biological products Allergenics, vaccines Antitoxins/antivenins/venomsGene therapy products Xenotransplantation products

Devices related to licensed blood & cellular products for processing & administration In vitro diagnostic kits for testing

Some combination products

These products have the same general development/regulatory

framework as drugs & other biologics….

Preclinical,CMC IND

Clinical Studies

BLA

But there are differencesHistory

Regulatory

CMC – product development & characterization

Preclinical studies

Clinical trials & safety issues

Cell & Tissue Therapies

Cell-based therapies originated with hematopoietic transplantation in 1970s

Bone marrow harvested, filtered, and transferred to blood bags in operating room

BM product carried directly to patient unit for infusion

Minimal donor & product testing, graft manipulation, quality systems

FDA still considers conventional autologous and allogeneic related BMT as “Practice of Medicine”

1980s – 2000s• Advances in science & technology spurred novel

approaches for development of cell-based therapiesHematopoietic transplants with “engineered” grafts

ImmunotherapiesT cells & subpopulationsDendritic cell tumor vaccinesNK cells

Cellular gene therapiesCells isolated from organs & tissues (e.g.

pancreatic islets)

Advances were facilitated by development of large scale cell collection, separation &

isolation technologies

… and use of closed systems (often with single-use disposables) for collecting &

handling cells

2000s – Stem Cells & Regenerative Medicine

Explosion in stem cell science has led to interest in use of stem cells for therapy of many diseases and conditions, from life-threatening to cosmeticMultipotent

Adult stem cells from bone marrow, fat & other tissues

Fetal stem cells & placental stem cells are usually considered “adult”

PluripotentEmbryonic stem (ES) cellsInduced pluripotent stem (iPS) cells

Published by the Repair Stem Cell Institute (RSCI) -- a Dallas- and Bangkok-based public affairs company that provides interested patients

with contact information for stem cell treatment centers around the world.

Expert Commentary on “Super Stemmys”

" [The book]… was completely focused on bone marrow [stem cells] -- a very small subset of the whole stem cell field. Indeed, there is no mention of induced pluripotent stem cells or embryonic stem cells… All stem cells are not the same."

"It's just not a complete story. [The book] is also a bit unclear with regard to the science behind Doris's mission. It was very nebulous about how that cell would fix the heart...”

FDA definitionHuman cells, tissues, and cellular and

tissue-based products

• HCT/Ps are “articles containing human cells or tissues that are intended for implantation, transplantation, infusion, or transfer into a human recipient”

HCT/Ps includeMusculoskeletal tissue and skin

Ocular tissue

Cellular therapies

Hematopoietic stem/progenitor cells

Therapeutic cells (DLI)

Somatic cells (regardless of source)

Reproductive tissue

Combination tissue/device, tissue/drug

Human heart valve allografts

Human dura mater

HCT/Ps do not include

Vascularized whole organs HRSA regulates

Bone marrow, minimally manipulated, homologous use - AUTO or FAMILY DONOR

Practice of medicine (not regulated by FDA)

Bone marrow, minimally manipulated, homologous use – UNRELATED DONOR

HRSA regulates

Xenografts FDA separate regs

Blood & blood products FDA separate regs

Secreted or extracted products (e.g., human milk, collagen, cell factors)

FDA separate regs

In vitro diagnostic products FDA separate regs

FDA’s Risk-Based Approach forHCT/Ps

Lower risk “361”Autologous or family related donors and minimally

manipulated and homologous useRegulated under section 361 of Public Health

Service Act

Higher risk “351”Allogeneic unrelated donors and/or more than

minimally manipulated and/or non-homologous use

Regulated under section 351 of Public Health Service Act, and subject to same rules as drugs & other biologics for IND and premarket approval

FDA framework for HCT/Ps361

HCT/Ps

351

HCT/Ps

(Tissue) Establishment registration √ √

(Tissue) Donor eligibility √ √

(Tissue) CGTP manufacturing √ √

CGMP regulations √

IND / IDE regulations √

Premarket approval (BLA) √

Tissue RulesApply to ALL cell and tissue-based products (but

for 351 products can be superseded by more stringent CGMP regulations)

Focus is on preventing communicable disease transmission, and ensuring 2-way tracking/traceability between donor & recipient

HCT/P Development Issues

CMCInteresting but erroneous statements I’ve

heard

CMC is good to go if I have described a small scale method

I’ll do all the development in my research lab

I’ve done most of the real work-- product development should take only month or two

My research reagents are the only ones that will work

We won’t worry about the product until we finish the preclinical animal studies

CMC development for all HCT/Ps Donor qualification

Protocol/product-specific donor requirements (biologic variability) Donor eligibility (DE) rule – effective May 2005

Manufacturing methods Cell source qualification – bioburden issues Closed systems and/or aseptic methods in classified environment

(terminal sterilization is not possible) Scale up for cell collection, culture, selection, harvest Containers – interaction with cells Ancillary reagents (availability & qualification)

Product stability in relationship to timing of administration is especially critical, because most HCT/Ps consist of live cells

Delivery methods/devices/structural components result in combination product issues

Product assays (in-process and final release) must be appropriately developed and validated

CMC concerns for HCT/Ps derived from pluripotent and fetal stem cells

Donor source Documentation of donor consent? Donor eligibility – prospective, full screening and testing usually

not done for ES and fetal cells

Product consistency (requires assays) Source variability Consistency through differentiation process

Product stability (requires assays)

What are most appropriate assays for master cell bank, working cell bank, and final product? Phenotype of desired & other cell populations Detection of residual pluripotent cells Karyotype, genetic and epigenetic profiles Potency assays?

Preclinical animal studies for HCT/PsCBER’s Office of Cellular, Tissue, and Gene Therapies

(OCTGT) has a Pharm/Tox group that Encourages informal pre-pre-IND meetings for planning

and review of preclinical studies Uses a case-by-case approach Often recommends “hybrid” efficacy/safety studies

using animal model of human disease, with concurrent evaluation of both efficacy and safety endpoints

Is always concerned with comparability of products used for POC studies, pivotal

safety studies, and clinical trialappropriate modeling of product delivery

Preclinical animal studySafety endpoints – stem cell therapies Implant site reaction

Inflammatory response in target & non-target tissue

Host immune response

Morphologic alterations in target & non-target tissues

Cell survival post transplantation

Cell migration/homing

Cellular fate-plasticity: differentiation, transdifferentiation, fusion

Integration into host tissue

Tumorigenicity

Clinical Protocol:CDER & CBER Guidance

CDER has numerous disease-specific and other clinical trial guidances focused on study design, patient population, endpoints

CBER product/disease-specific guidances for cellular therapiesTherapeutic Cancer Vaccines (2009 – draft)Pancreatic Islet Cell Products (2009)Somatic Cell Therapy for Cardiac Disease (2009 –

draft)Products to Repair or Replace Knee Cartilage

(2007)

Clinical Protocol: How are stem cell trials different?

For novel stem cell products, risk : benefit assessment is difficultRationale for clinical trial must be justified by

especially strong proof of conceptGreater emphasis placed on product

characterization and preclinical testing

Gene Therapies

Gene therapy: history1974: NIH established Recombinant DNA Advisory

Committee (RAC) NIH Guidelines on recombinant DNA research

1980s: New subcommittee of RAC to oversee clinical gene therapy Appendix M to NIH Guidelines – covered design of

preclinical & clinical research, consent issues, AE reporting

PUBLIC review of gene transfer protocols

1989: First clinical gene transfer study (gene marking) using retroviral vector

1990: First clinical gene transfer study (therapeutic intent) using retroviral vector

Gene therapy: history1995: No real clinical efficacy demonstrated, and

NIH report concluded that enthusiasm had outstripped knowledge Back to the bench for research on improved gene

delivery methods (e.g., higher titer vectors, use of stromal feeder layer or fibronectin for HSC transductions)

By 1995, NIH RAC Had approved 149 GT clinical protocols No dire consequences Policy change: public review & approval only for GT

protocols that presented novel or unresolved issues

1997: Role of NIH RAC modified – still required public review, but not “approval” of novel GT protocols

Gene therapy: history 1999: Jessie Gelsinger case – first

human gene therapy death. All gene therapy trials placed on hold. 18 year old with a clinically mild form of

ornithine transcarbamylase deficiency volunteered for a clinical trial of gene therapy at the University of Pennsylvania

Adenoviral vector caused massive immune response, multi-organ failure, and death within 4 days

Ethical issues Adverse events in primate studies Adverse events in 2 previous human

subjects Informed consent Principal investigator conflict of

interest

Gene therapy: history2000-2007: X-linked SCID trials, using gamma

retroviral vectors to deliver the corrective gene (IL2RG) to autologous hematopoietic progenitor cells5 of 20 pts developed T cell leukemia-like

proliferative disorder, caused by INSERTIONAL ONCOGENESISRetroviral vector integrated adjacent to one or more

cellular proto-oncogenes (LMO-2 in 4 of the cases), which increased their expression, leading to malignant transformation and outgrowth of clonal population of T cells

Gene therapy approaches IN VIVO: Vector administered directly to patient, and

transfers genetic information to patient cells in vivo Intravenously administered vector delivers gene for

factor IX to patient with hemophilia B

EX VIVO: Vector used to transfer genetic information to cells ex vivo, then cells are administered to patient Vector that delivers gene for enzyme adenosine

deaminase is incubated ex vivo with autologous lymphocytes of patient with ADA-deficient form of SCID (severe combined immunodeficiency), and genetically modified cells are infused to patient

Gene delivery methodsVector = an agent used to introduce genetic

material into cells

Vectors can beViralNon-viral

Plasmid DNALiposomes or other agents that facilitate entry into

cell

Viral vectorsRetrovirus and lentivirus (developed to

overcome inability of retroviral vectors to infect non-dividing cells)

Adenovirus

Parvovirus (Adeno-associated virus or AAV)

Herpes simplex virus

Poxvirus

Togavirus

Vector selection depends on… Disease state

Route of administration

Size of payload genetic sequences, regulatory elements

Cell cycling Lentivirus, adenovirus, AAV do not require cycling cells

Intended duration of expression Retrovirus and lentivirus give stable integration Plasmid used for transient expression

Target cells Poor expression of adenoviral CAR receptor on hematopoietic

cells

More advanced vector design featuresConditional replication-competence

Control of gene expressionTissue-specific promotersDrug-responsive promoters

Suicide genesGanciclovir administered to patient will kill cells

with thymidine kinase gene

Safety issuesObserved to date

Insertional mutagenesis/oncogenesis Immunogenicity

VectorTransgeneFBS (bovine protein used to manufacture vector)

Potential Inadvertent transmission & expression in non-

target cells (including germline, transplacental)

FDA regulations & guidance for gene therapies

Overall similar to biotechnology products ICH guidances

Gene therapy CMC guidance 2008Vector description, map, sequence analysisCell banks, viral banks, cell lines (packaging,

producer, feeder) Vector production/purificationDocumentation of RAC reviewFor ex vivo gene therapy, cell requirements same

as HCT/Ps (i.e. CMC guidance, tissue rules)

FDA guidance for gene therapy clinical trials

2006 – Guidance on long-term follow up for delayed adverse events Recommends preclinical study designs to assess

clinical risk Requires long term clinical follow up, based on

preclinical studies, forIn vivo gene therapy with persistence of vector

sequences, when sequences are integratedEx vivo gene therapy with sequences integrated, or not

integrated but have potential for latency & reactivation Specific follow up observations yearly for at least 10

years, and reporting to FDA Informed consent for long term follow up, and for use of

retroviral vectors

FDA guidance for gene therapy clinical trials

2006 – Supplemental guidance on testing for replication-competent retrovirus (RCR) Product testing

Master cell bankWorking cell bankEnd of production cellsVector-containing supernatantEx vivo transduced cells

Patient testingPre-treatment3 months, 6 months, 1 year, and yearly thereafterIf negative through 1 year, archive samples

How many cell, tissue, and gene therapy products have been approved

by FDA?Carticel (Genzyme) – autologous chondrocytes for

knee repair

Provenge (Dendreon) – autologous tumor vaccine for prostate cancer

Skin replacement products for wounds or burns (regulated as devices) Epicel Dermagraft Transcyte Apligraf

Gene therapies – NONE approved yet

But there’s a lot in the pipeline

CIRMGrant Funding by Disease Categories

as of Dec 2009