In our two part ‘Ask the Experts’ series, we shine a light on CAR-T cell therapy; providing perspectives from a panel that includes both researchers in the field and a patient who underwent this treatment modality. What are the biggest challenges surrounding the production of CAR-T cells? What was it like receiving CAR-T cell therapy? Where will CAR-T cell therapy be in the next 5 years? With CAR-T cell therapy becoming a rapidly emerging platform for cancer treatment, our experts address these questions and more.
Bringing together insights from a patients experience to research and clinical perspectives, our experts are Robyn Stacy-Humphries MD (Carolina Healthcare System University Medical Center, NC, USA), Prasad Adusumilli MD (Memorial Sloan Kettering Centre, NY, USA) and Bruce Levine Ph.D. (University of Pennsylvania, PA, USA). Take a look at the first installment of this discussion below which looks at the challenges in producing and administering CAR-T cells and a patient’s perspective on receiving CAR-T cell therapy.
Keep an eye out for Part II of the discussion, which delves into the potential of CAR-T cell therapy against solid tumors and what the future holds for this type of treatment.
Could you tell us about your experience with CAR-T cell therapy?
Robyn Stacy-Humphries: I was diagnosed with diffuse large B-cell lymphoma in 2011 at the age of 48. I diagnosed myself when I felt a supraclavicular lymph node and then reviewed my CT scans the next day. At that time, I was super healthy, running races, enjoying my life as a mother of three with a supportive husband. Six years later, after fourteen rounds of chemotherapy with sixteen different types of agents, multiple biopsies, three indwelling ports, intrathecal chemotherapy, head and neck radiation and finally an autologous bone marrow transplant with septic shock, I relapsed with lymphoma for a third time.
I did not have a bone marrow match for an allogenic transplant but had already been researching CAR-T therapy, which had shown success in Phase I trials. Getting a spot in the Phase II, JULIET trial of Novartis’s Kymriah® (tisagenlecleucel) was like winning the lottery. I had hope.
My T cells were collected with peripheral apheresis and sent to the lab for processing. Unfortunately, there were lab delays but luckily, bridging chemotherapy with ibrutinib (Imbruvica®) was successful.
The day of CAR-T cells infusion was very anti-climactic. My entire hospital room was filled with staff watching the infusion of a tiny bag of 6 million cells, which occurred in minutes. Then, waited. We didn’t wait long and within 24 hours I had a low-grade fever, but my palpable lymph nodes began to melt like ice cubes. At day five, I experienced grade II cytokine-release syndrome with a high fever, 104F, shaking chills and hypotension. Luckily, this resolved in 3 days with just fluid, Tylenol® and eventually ibruprofen.
When I was discharged, I was extremely fatigued and had some low-grade nausea which gradually subsided over a few weeks. I was able to return to work, with a reduced schedule, in 4 weeks versus the bone marrow transplant where I was out of work for 3 months. At 3 months, complete remission was confirmed and I also became open water dive certified.
Subsequently, I have been able to return to a very normal life and work full time. I am beyond grateful for the chance to live and even more importantly, live life to the fullest because of Kymriah CD-19 CAR-T. Given a second chance, I relish my current life and have been fulfilling my bucket list—hiking Chilean Patagonia, diving in Tahiti, climbing up Skellig Michael in Ireland and I plan to return to the Galapagos next month. LIFE IS GREAT!
Bruce Levine: Our experience with CAR-T cell therapy began in the late 1990’s. Carl June (Perelman School of Medicine of the University of Pennsylvania, PA, USA) and I had developed a new way to expand T cells using anti-CD3 and anti-CD28 coated beads (Dynabeads). Cell Genesys (CA, USA) was a small company that conducted the first ever CAR T cells trials, both in HIV and in cancer. Cell Genesys (CA, USA) had started their trial with manufacturing using a standard method of T cell stimulation, however, the in vivo engraftment was very poor. They approached Carl and I as they knew about the bead method for growing T cells we had developed and wished to incorporate it into their trial to try to improve T cell persistence. The CAR they were testing in HIV was CD4zeta, a first-generation CAR with native CD4 in the extracellular domain that binds gp120 on HIV infected cells. Subsequently, subjects who were infused with bead-activated cells, though the anti-viral effect was modest, demonstrated long term engraftment. In fact, these cells persisted in some subjects for a decade.
When we moved to the University of Pennsylvania, we started our own clinical trial testing CD4zeta in subjects in a clinical trial at the Walter Reed Army Medical Center in the early 2000’s. This was a randomized trial testing CAR T cells with and without IL-2 infusion, though again the anti-viral effects we could observe were very modest. The logical next step was in cancer. We received funding from a philanthropy, the Alliance for Cancer Gene Therapy, in 2004 to begin pre-clinical studies of a “second generation” CAR in cancer targeting CD19. The first three subjects were treated in 2010 and remarkable things happened – in the first three patients between 2.9 and 7.8 pounds of leukemia was destroyed in the several weeks after infusion, the cells persisted long term, and were demonstrated to be functional several months later. These results were published in 2011 [1,2]. Our feeling was that it was a responsibility to develop this therapy by the fastest road possible to get it to people in dire need, and we signed an alliance with Novartis (Basel, Switzerland) in 2012 to do just that.
Following transfer of our CAR-T cell technology to Novartis, they conducted two global pivotal clinical trials- one in pediatric Acute Lymphoid Leukemia (ALL), and one in Diffuse Large B Cell Lymphoma (DLBCL) [3, 4, 5, 6]. The results from the ALL trial were submitted to the FDA in early 2017 as part of a Biologics License Application that led to the first approval by the FDA of a gene therapy. DLBCL is now also approved by the FDA. Approvals have followed in Europe (EMA), Switzerland, Canada and most recently in Australia. I believe Novartis has shipped CAR-T cell product to more than 700 patients around the world by now, including both clinical trials and commercial product. At Penn and the Children’s Hospital of Philadelphia (PN, USA), we have treated well over 500 patients in ped ALL, DLBCL, Hodgkin Lymphoma, and with other targets in myeloma, mesothelioma, pancreatic cancer, ovarian cancer, glioblastoma, and breast cancer. We have also spun a company out of Penn, Tmunity Therapeutics to develop advanced engineered T cells and currently have trials in myeloma and prostate cancer with more to come.
What are some of the challenges associated with manufacturing CAR-T cell therapies?
Prasad Adusumilli: The first challenge that both patients and clinicians face is the length of time required to manufacture CAR-T cells. The longer the CAR-T cell manufacturing process takes, the more likely the need for a bridging therapy. The second challenge is that the use of autologous cells requires harvesting an individual patient’s cells and then manufacturing them. As above the challenges are being addressed and improved. The quality and phenotypic composition of manufactured cells matters, as it influences anti-tumor efficacy. This will become even more important as we start incorporating multiple elements of immune targeting within one product such as CAR-T cells that are capable of overcoming immuno-suppression, for example, checkpoint blockade.
BL: For CAR-T cell therapies, as with other autologous therapies, the raw material varies every time. As different as healthy humans are, those with cancer vary even more. We can adapt manufacturing to deal with the challenge of variable yield and growth in T cells, yet there are always outliers, and a decision algorithm needs to be in place to maximize the chances of successfully producing a cell product. In a perfect world of drug development, the allogeneic “off the shelf” CAR therapies would have demonstrated equivalent potency to autologous therapies, but they have not yet. However, allogeneic CAR-T cells in combination with other therapies like stem cell transplantation are an option for patients who do not have sufficient cells from which to generate an autologous CAR product.
We are constantly evaluating manufacturing improvements, from T-cell culture methods to gene delivery methods to analytics methods. A key challenge is in deciding when to bring improvements in to the clinic, as part of an existing clinical trial, or to wait for a new trial. Additional challenges including recruiting, training, and retaining staff. This is the most limiting factor in being able to treat more patients and creates an ethical quandary when the schedule is limited, but patients are queuing up for clinical trials and for the commercially approved products Kymriah® and Yescarta®.
What are some of the challenges associated with manufacturing CAR-T cell therapies?
PA: The hurdles differ by cancer type and the stage of cancer. For example, in solid tumors, since CAR-T cell therapy is investigational, patients typically undergo standard-of-care therapy first, and then reach out for experimental therapy when the standard-of-care has failed. Then we must wait to see if they are eligible for the trial and for cell manufacturing. Coordination of standard-of-care, screening for eligibility for CAR-T cell trials, and manufacturing cells is crucial.
Unlike CD19 that is uniformly and strongly expressed on target cells, majority of target antigens expressed on tumor cells are of heterogenous expression. Selection of site and time of biopsy combined with serum tumor markers, both for screening for eligibility and tumor progression / regression monitoring, is another hurdle that needs more research and insight.
BL: There was, and still is, great skepticism on the feasibility of CAR-T cells becoming more widely available due to very complex logistics. The obvious place to start is that the raw material patient cells must be sourced separately, the lot size is one, and the product is patient specific. Thus, scheduling with robust chain of custody is the most important consideration. Along that chain of custody is the transport logistics and maintenance of temperature and package integrity across countries and in fact across continents. While allogeneic CAR-T and natural killer cells products can be sourced in advance of patient need, both autologous and allogeneic CAR products are manufactured with hundreds of complex components, many of them sole source. Even those components have complex components and manufacturing themselves. Take for example the viral vector, which is produced following transfection of multiple plasmids into a qualified producer cell line, undergoes downstream processing and formulation prior to analytics for release. The manufacturing and quality control testing of CAR products must be scheduled to account for collection of the cells from the patient, and availability of qualified staff, rooms and equipment. We are beginning to see the development of electronic manufacturing execution systems to track all this activity. Some have said the process is the product, I prefer to think of this therapy as a remotely engineered organ (immune system) transplant. The complexity is daunting, however, we have seen rapid development in manufacturing technologies, reagents, materials, equipment, and electronic systems that leaves me optimistic on the continuing deployment of more CAR therapies for patients in need.
In your opinion, what is required for the successful commercial translation of CAR-T cell therapies in oncology?
PA: In my opinion, translational research is addressing some of the issues mentioned above and when combined with correlative science from ongoing CAR-T cell trials it will act as the key to move the field forward rather than simply betting on the best CAR-T cell construct.
1. Porter DL, Levine BL, Kalos M et al. Chimeric antigen receptor–modified t cells in chronic lymphoid leukemia N. Eng. J. Med. 365:725–733 (2011).
2. Kalos M, Levine BL, Porter DL et al. T cells with chimeric antigen receptors have potent antitumor effects and can establish memory in patients with advanced leukemia Sci. Transl. Med. 3(95) (2011).
3. Determine Efficacy and Safety of CTL019 in Pediatric Patients With Relapsed and Refractory B-cell ALL (ELIANA) https://clinicaltrials.gov/ct2/show/NCT02435849
4. Maude SL, Laetsch TW, Buechner J et al. Tisagenlecleucel in children and young adults with b-cell lymphoblastic leukemia N. Eng. J. Med. 378:439–448 (2018).
5. Study of Efficacy and Safety of CTL019 in Adult DLBCL Patients (JULIET) https://clinicaltrials.gov/ct2/show/NCT02445248
6. Schuster SJ, Bishop MR, Tam CS et al. Tisagenlecleucel in adult relapsed or refractory diffuse large b-cell lymphoma N. Eng. J. Med. 380:45–56 (2019).
Prasad S. Adusumilli
Deputy Chief and Attending, Thoracic Surgery, MD, FACS, FCCP
Head, Solid Tumors Cell Therapy, Cellular Therapeutics Center
Director, Mesothelioma Program
Memorial Sloan-Kettering Cancer Center, (NY, USA).
My research focuses on tumor immunology, chimeric antigen receptor CAR-T cell therapy, and combination immunotherapy for thoracic cancers. Over the years, we have developed clinically-relevant mouse models and modeled biological therapies in these models. This research has yielded mechanistic data that has been translated and is now in CAR-T cell and combination immunotherapy clinical trials for patients with lung cancer, pleural mesothelioma, and breast cancer. Our ongoing research focuses on investigating immuno-oncology agents’ efficacy in human ex vivo translational culture systems.
Our laboratory research has been funded by federal agencies and foundations resulting in >60 grant awards to date totaling >$30MM over the past decade. My research has progressed to clinical trials and >200 publications including in Cancer Discov, FASEB, J Clin Invest, J Clin Oncol, J Natl Cancer Inst, Nat Med, and Sci Transl Med. In addition to serving on medical journal editorial boards, I am the Deputy Editor for Molecular Therapy Oncolytics. I serve as a member of national peer-review committees including NCI, DoD, PCORI, National Health Institutions of Austria, Belgium, Ireland, Italy, Poland, Netherlands, Switzerland and the United Kingdom.
I am a member of the Fleischner Society and American Society of Clinical Investigation. I serve on international committees including the American
Society of Cell and Gene Therapy, NCI thoracic cancers steering committee, International Association for the Study of Lung Cancer, and the American Association for Thoracic Surgery. In my laboratory, I mentor MDs, MD/PhDs, and PhDs in thoracic oncology research, including visiting scholars from international institutions.
B.A. (Major-Biology, Minor-History)
The University of Pennsylvania , 1984.
Ph.D. (Immunology and Infectious Diseases)
The Johns Hopkins University, 1992.
Bruce Levine, Barbara and Edward Netter Professor in Cancer Gene Therapy, is the Founding Director of the Clinical Cell and Vaccine Production Facility (CVPF) in the Department of Pathology and Laboratory Medicine and the Abramson Cancer Center, Perelman School of Medicine, University of Pennsylvania (PA, USA). He received a B.A. (Biology) from Penn and a Ph.D. in Immunology and Infectious Diseases from Johns Hopkins (MD, USA). First-in-human adoptive immunotherapy trials include the first use of a lentiviral vector, the first infusions of gene-edited cells, and the first use of lentivirally-modified cells to treat cancer. Levine has overseen the production, testing and release of 3000 cellular products administered to >1200 patients in clinical trials since 1996. T lymphocytes from HIV+ subjects have been rendered resistant to HIV infection and reinfused. T lymphocytes from cancer patients have been redirected with chimeric antigen receptors (CAR’s) to hunt and destroy their malignancies. This therapy, developed by the CVPF and licensed by Novartis, recently became the first FDA approved gene therapy (Kymriah). Levine is co-inventor on 25 issued US patents and co-author of 160 publications with a Google Scholar citation h-index of 79. He is a Co-Founder of Tmunity Therapeutics, a spinout of the University of Pennsylvania. He has been interviewed by the NY Times, Wall Street Journal, Time Magazine, National Geographic, Forbes, BBC, and other international media outlets.
Robyn Stacy-Humphries, MD is a radiologist with Charlotte Radiology, Atrium Health Care System (NC, USA) – body imaging, mammography and nuclear medicine. BS – Wake Forest University , MD – University of NC at Chapel Hill. Residency and Fellowship- Georgetown University Hospital. In remission from DLBCL after Novartis Phase II Juliet clinical trial of CD -19 CAR-T. Follow on Instagram: drrobynforlls.woty2020