Intratumoral pan-ErbB targeted CAR-T for head and neck squamous cell carcinoma: interim analysis of the T4 immunotherapy study

BACKGROUND

Locally advanced/recurrent head and neck squamous cell carcinoma (HNSCC) is associated with significant morbidity and mortality. To target upregulated ErbB dimer expression in this cancer, we developed an autologous CD28-based chimeric antigen receptor T-cell (CAR-T) approach named T4 immunotherapy. Patient-derived T-cells are engineered by retroviral transduction to coexpress a panErbB-specific CAR called T1E28ζ and an IL-4-responsive chimeric cytokine receptor, 4αβ, which allows IL-4-mediated enrichment of transduced cells during manufacture. These cells elicit preclinical antitumor activity against HNSCC and other carcinomas. In this trial, we used intratumoral delivery to mitigate significant clinical risk of on-target off-tumor toxicity owing to low-level ErbB expression in healthy tissues.

METHODS

We undertook a phase 1 dose-escalation 3+3 trial of intratumoral T4 immunotherapy in HNSCC (NCT01818323). CAR T-cell batches were manufactured from 40 to 130 mL of whole blood using a 2-week semiclosed process. A single CAR T-cell treatment, formulated as a fresh product in 1-4 mL of medium, was injected into one or more target lesions. Dose of CAR T-cells was escalated in 5 cohorts from 1×107-1×109 T4+ T-cells, administered without prior lymphodepletion.

RESULTS

Despite baseline lymphopenia in most enrolled subjects, the target cell dose was successfully manufactured in all cases, yielding up to 7.5 billion T-cells (67.5±11.8% transduced), without any batch failures. Treatment-related adverse events were all grade 2 or less, with no dose-limiting toxicities (Common Terminology Criteria for Adverse Events V.4.0). Frequent treatment-related adverse events were tumor swelling, pain, pyrexias, chills, and fatigue. There was no evidence of leakage of T4+ T-cells into the circulation following intratumoral delivery, and injection of radiolabeled cells demonstrated intratumoral persistence. Despite rapid progression at trial entry, stabilization of disease (Response Evaluation Criteria in Solid Tumors V.1.1) was observed in 9 of 15 subjects (60%) at 6 weeks post-CAR T-cell administration. Subsequent treatment with pembrolizumab and T-VEC oncolytic virus achieved a rapid complete clinical response in one subject, which was durable for over 3 years. Median overall survival was greater than for historical controls. Disease stabilization was associated with the administration of an immunophenotypically fitter, less exhausted, T4 CAR T-cell product.

CONCLUSIONS

These data demonstrate the safe intratumoral administration of T4 immunotherapy in advanced HNSCC.

Unveiling the epigenomic mechanisms of acquired platinum-resistance in high-grade serous ovarian cancer

Resistance to platinum-based chemotherapy is the major cause of death from high-grade serous ovarian cancer (HGSOC). We hypothesise that detection of specific DNA methylation changes may predict platinum resistance in HGSOC. Using a publicly available "discovery" dataset we examined epigenomic and transcriptomic alterations between primary platinum-sensitive (n = 32) and recurrent acquired drug resistant HGSOC (n = 28) and identified several genes involved in immune and chemoresistance-related pathways. Validation via high-resolution melt analysis of these findings, in cell lines and HGSOC tumours, demonstrated the most consistent changes were observed in three of the genes: APOBEC3A, NKAPL and PDCD1. Plasma samples from an independent HGSOC cohort (n = 17) were analysed using droplet digital PCR. Hypermethylation of NKAPL was detected in 46% and hypomethylation of APOBEC3A in 69% of plasma samples taken from women with relapsed HGSOC (n = 13), with no alterations identified in disease-free patients (n = 4). Following these results, and using a CRISPR-Cas9 approach, we were also able to demonstrate that in vitro NKAPL promoter demethylation increased platinum sensitivity by 15%. Overall, this study demonstrates the importance of aberrant methylation, especially of the NKAPL gene, in acquired platinum resistance in HGSOC.

Abstract CT118: T4 immunotherapy of head and neck squamous cell carcinoma using pan-ErbB targeted CAR T-cells

Striking progress has been achieved in CD19+ hematologic malignancies using chimeric antigen receptor (CAR) T-cells following lymphodepletion. Nonetheless, toxicity remains significant, due to cytokine release syndrome (CRS) and neurologic dysfunction. The frequent emergence of resistance due to antigen loss provides a strong rationale for engagement of multiple targets. Solid tumors impose additional challenges. Foremost, a paucity of targets that are tumor-specific, or restricted to dispensable tissues. Moreover, active CAR T-cells need to home to, penetrate and persist within profoundly immunosuppressive tumors. Cognizant of these obstacles, we designed T4 immunotherapy. T4+ T-cells are retroviral transduced to co-express (i) T1E28ζ, a CAR coupling a promiscuous ErbB ligand derived from EGF and TGFα to a fused CD28+CD3ζ endodomain; and (ii) 4αβ, a chimeric cytokine receptor containing the IL-4Rα ectodomain coupled to the IL-2Rβ endodomain. T1E28ζ engages 8/9 possible ErbB dimers, providing broad anti-tumor activity while minimizing risk of antigen escape. 4αβ enables IL-4-driven selective enrichment and expansion of CAR T-cells during manufacture. Pre-clinical data demonstrate potent anti-tumor activity in head and neck squamous cell carcinoma (HNSCC), mesothelioma, ovarian and breast cancer. However, risk of on-target off-tumor toxicity is significant, due to low-level ErbB expression in normal tissues. Indeed, CRS can be modeled when human T4+ T-cells are administered to the peritoneal cavity of SCID Beige mice. To de-risk T4 immunotherapy in man, a dose-escalation intra-tumoral Phase I trial was commenced, without lymphodepletion. HNSCC was selected due to the unmet need presented by locally advanced or recurrent disease. Ninety percent of patients were lymphopenic yet T4 immunotherapy was successfully generated from a 130mL blood draw, in a closed manufacturing process. Batches contained up to 7.5 x 109 cells, of which 63.8+ 12.1% were T4+, comprising a variable mixture of central and effector memory CD4+ and CD8+ T-cells. Cohorts of 1, 3 and 10 x 107 T4+ T-cells were treated. Patient 5 died of advanced HNSCC, prior to treatment. Intra-tumoral 1-2mL injections of T4 immunotherapy were administered as a single dose. Treatment-related AEs were < grade 2, with no dose-limiting toxicities (CTCAE v4.0). Common AEs were tumor swelling/ pain and fatigue. All patients experienced a self-limited rise in CRP. Grade 1 chills occurred in cohort 3 within 24h. Circulating T4+ T-cells were not seen. Disease control rate was 44% with all three patients in cohort 3 achieving stable disease (RECIST 1.1 at 6 weeks). These data demonstrate the safe intra-tumoral administration of T4-immunotherapy in patients with advanced HNSCC, with disease control observed at the highest dose tested. Further dose escalation and combination with immune-modulating agents is warranted.

Citation Format: Sophie Papa, Antonella Adami, Michael Metoudi, Daniela Achkova, May van Schalkwyk, Ana Parente Pereira, Leticia Bosshard-Carter, Lynsey Whilding, Sjoukje van der Stegen, David M. Davies, Teresa Guerrero-Urbano, Jean Pierre Jeannon, James Spicer, John Maher. T4 immunotherapy of head and neck squamous cell carcinoma using pan-ErbB targeted CAR T-cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT118. doi:10.1158/1538-7445.AM2017-CT118