Tandem CD20–CD19 CAR T-cell therapy for relapsed B-cell malignancies

The novel chimeric antigen receptor (CAR) T-cell therapies targeting CD19 achieved unprecedented survival outcomes in heavily pretreated patients with advanced B-cell malignancies. However, some patients still relapse, mostly with CD19-negative disease, reducing considerably their treatment options left at this stage.

Tandem CAR T cells aim to target two essential antigens widely presented in B-cell non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL): CD19 and CD20. Dual targeting might improve the clinical outcomes and overcome antigen-loss relapses seen so far with singly targeted CD19 CAR T-cell therapies.

Nirav N. Shah and colleagues published recently in Nature Medicine the first experience with an onsite manufactured tandem CD19–CD20 CAR T cell for patients with relapsed B-cell malignancies.¹ Below there is a summary of the study results.

Study design

• This is a first-in-human phase I trial to evaluate the safety and feasibility of tandem CD20–CD19 4-1BB–CD3ζ lentiviral (LV20.19) CAR T-cell therapy for patients with relapsed/refractory B-cell malignancies (NCT03019055).
• A total of 26 patients were enrolled, of which 22 achieved the target dose. The key selection criteria were:
  • Measurable B-cell NHL or CLL, treated with at least two prior lines of therapy.
  • CD19 or CD20 positive disease (≥ 5% by immunohistochemistry or flow cytometry) in the most recent biopsy.
  • CD3-positive T-cell count of at least 50/mm³.
  • Karnofsky performance score ≥ 70.
  • No active central nervous system involvement.
  • Prior CAR T-cell therapy was permitted if patients remained positive for CD19 or CD20.
• After apheresis and lymphodepletion (30 mg/m² fludarabine for 3 days and 500 mg/m² cyclophosphamide for 1 day), patients were divided into three cohorts:
  • Cohort 1: dose escalation at dose levels 2.5 × 10⁵ cells/kg, 7.5 × 10⁵ cells/kg, and a target dose of 2.5 × 10⁶ cells/kg, administered over 2 days (30–70%).
  • Cohort 2: expansion cohort with dose selected from cohort 1, split into a 2-day infusion.
  • Cohort 3: expansion cohort with selected dose, single infusion.

LV20.19 CAR T-cell manufacturing

• The CliniMACS Prodigy is a new closed-system device that enables the production of CAR T cells locally.² Tandem LV20.19 CAR T cells were manufactured onsite at the Medical College of Wisconsin.
• Once adjusted and tested appropriately, it can reduce manufacturing timelines (14 days), and patients can receive fresh CAR T cells (non-cryopreserved).
• In the cell cultures, a mean of 17.4% were CAR T cells (range, 7.4–28.0%), with a mean CD4:CD8 ratio of 3:1 at the time of cell collection.
• The final product reached an average of 5.76 × 10⁸ LV20.19 CAR T cells (range, 2.22–12.8 × 10⁸).

Results

• Patients' baseline characteristics are summarized in Table 1.

Table 1. Patient characteristics at the time of CAR T-cell infusion¹

• Tandem LV20.19 CAR T cells achieved an overall response rate (ORR) of 82% after 28 days from infusion, including high complete response (CR) rates across all subtypes (Figure 1).
• Higher rates and better responses were achieved in the target dose level cohort and in patients infused with fresh cells; although the difference is not statistically significant (p = 0.08), it is important to note that these patients also presented a higher expansion of the CAR T-cell product.
• After a median follow-up of 10.1 months, the median duration of response in patients achieving a CR was not reached.
• To date, nine (40.9%) patients progressed after initial response to LV20.19 CAR T cells; four of them were late relapses (≥ 6 months after infusion). Three patients progressed again after retreatment with the cryopreserved product.

Figure 1. Response rates at Day 28 after infusion of LV20.19 CAR T cells by type of B-cell NHL¹

CAR, chimeric antigen receptor; CLL, chronic lymphocytic leukemia; CR, complete response; DLBCL, diffuse-large B-cell lymphoma; FL, follicular lymphoma; MCL, mantle cell lymphoma; NHL, non-Hodgkin lymphoma; ORR, overall response rate; PR, partial response; TDL, target dose level.
*2.5 × 10⁶ cells/kg.

• Patients who were previously exposed to an anti-CD19 CAR T-cell therapy (n = 5) presented lower manufacturing success. Three were infused with the tandem CAR T cells but progressed by Day 28.
• Split and single infusion cohorts did not differ in response rates or adverse event incidence.
• Median overall survival was 20.3 months.

Predicting response to LV20.19 CAR T cells

• Baseline CD19 and CD20 expression was not associated with response to LV20.19 CAR T cells.
• Responders presented a peak of CAR T-cell expansion in peripheral blood at 7–12 days and were undetectable by Day 90 post-infusion.
• Higher levels of naïve and central memory T cells in the apheresis product were detected in patients later achieving a partial response or CR at the higher dose level.
• Five patients with progressive disease were infused with a lower dose level than 2.5 × 10⁶ cells/kg.
• Biopsies after progression to LV20.19 CAR T cells show persistence of CD19 expression.

Safety

• There were no dose-limiting toxicities reported in the dose-escalation cohorts, although one patient in the expansion cohort experienced a dose-limiting toxicity at 2.5 × 10⁶ cells/kg, requiring urgent hospitalization due to Grade 4 cytokine release syndrome (CRS) and neurotoxicity.

• The most frequent Grade ≥ 3 adverse events (AEs) with the higher CAR T-cell dose were cytopenia, hypoxia, and neurotoxicity. See Table 2 for a detailed list.
• Considering all dose levels, a total of 14 patients (64%) experienced CRS, and seven patients (32%) reported a neurotoxic event of any grade at a median time of 5 and 6 days from infusion, respectively.
• There were no deaths associated with LV20.19 CAR T-cell therapy.

Table 2. Most frequently reported AEs with LV20.19 CAR T cells at dose 2.5 × 10⁶ cells/kg (n = 16)¹

Conclusion

This first-in-human study reported the feasibility and safety of dual-targeting CD19 and CD20 with the tandem CAR T-cell therapy LV20.19 for patients with relapsed or refractory B-cell malignancies. With the possibility of onsite manufacturing, timelines were optimized, and it was possible to infuse non-cryopreserved product at 2.5 × 10⁶ cells/kg, which led to a potentially better expansion of the CAR T cells, hence, a possibility to improve the clinical outcomes. This local procedure had an 85% success rate, including the 100% of patients naïve to CAR T cells, but needs to be further investigated.

In light of the promising response rates, the phase I/II trial with LV20.19 in B-cell NHL and mantle cell lymphoma has already started to recruit participants (NCT04186520), including patients previously treated with CD20-directed therapy and anti-CD19 CAR T-cell therapy.

A similar strategy with the same device has been tested in the University Hospital Cologne, Germany, by Peter Borchmann and colleagues. The initial results of the MB-CART2019.1 tandem CAR T-cell therapy in relapsed/refractory B-cell NHL were presented recently at the 62nd American Society of Hematology (ASH) Annual Meeting and Exposition. Watch below a summary of the phase I trial results, which, so far, are consistent with the ones reported with LV20.19.