HPV-specific CD8 Research Articles

Neoadjuvant HPV16-specific arenavirus-based immunotherapy HB-200 plus chemotherapy followed by response-stratified de-intensification in HPV16+ oropharyngeal cancer: TARGET-HPV.

6017 Background: The role of immunotherapy in curative viral-mediated oropharyngeal cancer (OPC) remains undefined. Human papillomavirus (HPV) 16 positive (+) OPC constitutively expresses viral epitopes that drive antigen-specific anti-tumor immunity, supporting rationale for evaluating neoadjuvant HPV16 directed therapeutics in non-metastatic OPC. HB-200 is an arenavirus-based vector therapy derived from LCMV (HB-201) and Pichinde virus (HB-202) each expressing a non-oncogenic HPV16 E7E6 fusion protein to induce HPV16 specific CD8+ T-cell responses. Building on our OPTIMA II results demonstrating that neoadjuvant chemotherapy/nivolumab led to deep responses in 71% of patients who went on to receive reduced radiation (RT), we hypothesized that adding HB-200 to chemotherapy to drive HPV16-specific anti-tumor immunity would be safe and effective to further deepen responses and facilitate more de-escalation. Methods: In this Phase 1 dose escalation investigator-initiated study, patients with non-metastatic HPV16+ OPC were treated with escalating doses of HB-201 single vector (Arm A) or HB-202/201 alternating vector (Arm B) x3 with neoadjuvant carboplatin AUC5 on day 1 and paclitaxel 100mg/m2 on days 1/8/15 of a 21-day cycle for 3 cycles. Deep responders (≥50% tumor shrinkage) received transoral robotic surgery (TORS) alone or RT to 50Gy +/- cisplatin, while non-responders (<50% shrinkage) received 50 or 70Gy of RT with cisplatin. Primary objective was safety/tolerability and recommended phase 2 dose of HB-200 with chemotherapy. Additional objectives included deep response rate, circulating tumor (ct) HPV-DNA dynamics, and HPV16-specific T-cell response. Results: Twenty-one patients with HPV16+ OPC were enrolled and treated (Arm A, n=9, 43%; Arm B, n=12, 57%). Median age 57, 91% male, 75% base of tongue, 52% non-smokers, and 33% stage II/III (AJCC 8th edition). ≥Grade 3 treatment-emergent adverse events (AEs) occurred in 13 (62%) of patients overall and 3 (14%) non-hematologic during neoadjuvant. There were no Grade 4 AEs reported. All patients completed neoadjuvant HB-200/chemotherapy and response-stratified locoregional treatment. Deep responses following HB-200/chemotherapy were observed in 17/21 (81%) of patients, and in 14/15 (93%) treated on higher dose levels 1 or 2 ( p=0.05). All three patients who underwent TORS had no viable tumor at time of surgery. Two patients (9%) had persistent disease following CRT and underwent salvage surgery with no evidence of disease at last follow-up. ctHPV-DNA and HPV16-specific T-cell response data will be presented at the meeting. Conclusions: Neoadjuvant HB-200/chemotherapy is safe and feasible with early efficacy signal in this setting warranting further study. Enrollment to the subsequent randomized phase II part is ongoing (NCT05108870). Clinical trial information: NCT05108870 .

A phase 1 dose-escalation and expansion study of CUE-101, given as monotherapy and in combination with pembrolizumab, in patients with recurrent/metastatic HPV16+ head and neck squamous cell cancer (R/M HNSCC).

6004 Background: Immuno-STATs are modular T cell engagers engineered to selectively activate tumor-antigen specific CD8+ T cells via targeted delivery of cytokines. CUE-101, the first Immuno-STAT in clinical trials, is composed of a human leukocyte antigen (HLA) complex, HLA-A*0201, a peptide epitope derived from the HPV16 E7 protein and 4 molecules of attenuated human interleukin-2 (IL-2), to bind, expand, and activate HPV16-specific CD8+ T cells for the treatment of HPV16+ HNSCC. Methods: CUE-101-01 is an ongoing first-in-human study in HLA-A*0201 patients with HPV16+ R/M HNSCC. Escalating doses of CUE-101 monotherapy (0.06 mg/kg to 8 mg/kg) were evaluated in R/M HNSCC refractory to ≥ 1 platinum or checkpoint inhibitor (CPI) based therapy, alone or combined with pembrolizumab (1 mg/kg to 4 mg/kg + 200 mg pembrolizumab) in the first line treatment of PD-L1+ R/M HNSCCs. Enrollment at the recommended phase 2 dose (RP2D) was expanded. Therapy was administered every 3 weeks (Q3W) until disease progression or intolerable toxicity. Safety, PK/PD, and antitumor activity were assessed. Results: Enrollment in both monotherapy and combination cohorts is now completed (N=80 patients, 49 in monotherapy and 31 CUE-101 plus pembrolizumab). Following dose escalation, 4 mg/kg Q3W of CUE-101 was selected for RP2D for both monotherapy and pembrolizumab combination cohorts. At data cut-off, adverse events (AEs) have been manageable and 92% grade ≤2. The most frequent grade 3 AEs reported include lymphocyte count decreased (7.6%), anemia (6.3%), decreased appetite (5.1%) and infusion-related reactions (5.1%). In combination with pembrolizumab no unanticipated significant safety concerns have emerged. Exposure-dependent PD effects of CUE-101 are consistent with IL-2 pharmacology and indicate preferential expansion of CUE-101 on E7-specific T cells. Among the 19 evaluable patients treated with the RP2D of CUE-101 plus pembrolizumab, an ORR of 47% (1 CR, 8 PRs), a Disease Control Rate (ORR + durable SDs) of 74%, and mPFS of 5.8 months [95% CI 2.56; NA] were observed. A median OS has not been reached. Of the 9 patients with confirmed objective responses, all achieved >99% reduction in HPV16 cfDNA in plasma during their treatment course. Among the 19 evaluable monotherapy RP2D patients, 1 PR and 6 durable SD (SD ≥ 12 weeks) and mOS of 20.8 months [95% CI 11.0; NA] were observed. Conclusions: An ORR of 47% and a mPFS of 5.8 months were observed in R/M HNSCC patients treated with CUE-101 4 mg/kg + pembrolizumab as 1L therapy. A median OS of 20.8 was observed in patients treated with CUE-101 monotherapy as post-platinum/CPI therapy. CUE-101 continues to demonstrate safety, tolerability and meaningful clinical benefit in patients with HPV16+ R/M HNSCC. Clinical trial information: NCT03978689 .

Abstract 4103: Novel mRNA-encoded HPV vaccine with APC maturation signal and endolysosomal trafficking domain demonstrates superior T cell-mediated immunogenicity and efficacious tumor clearance in vivo

Abstract Human Papillomavirus (HPV), particularly HPV16, is a known causative agent of cancers in various anatomical sites, notably the anogenital and oropharyngeal regions. Despite the availability of prophylactic HPV vaccines for almost two decades, vaccination rates among young females, who are at a heightened risk for cervical intraepithelial neoplasia (CIN) and subsequent invasive cancer, remain suboptimal. The current standard of care for cervical cancer, involving invasive surgery and chemotherapy-based treatments, underscores the pressing need for safer and more effective therapeutics to enhance patient survival and quality of life. In this context, while several HPV16-E6/E7 targeted therapeutic vaccines are in development and clinical trials, their clinical efficacy has been limited due to inadequate antigen presentation and suboptimal immunogenicity. Addressing this, our team has developed a novel, highly immunogenic mRNA therapeutic cancer vaccine, engineered to activate a robust T cell-mediated adaptive immune response and exhibit strong anti-tumor potential. Our innovative approach includes the design of an HPV16-E6/E7 mRNA vaccine (ABO2101) that incorporates a unique antigen-expressing cassette. This cassette features endolysosomal trafficking domains and antigen presenting cell (APC) activation stimulators, enhancing both Class I and Class II antigen presentation and APC maturation, thereby amplifying antigen-specific T cell responses. In both murine and human-derived experimental models, ABO2101 has demonstrated a significantly more potent adaptive T cell response against HPV16 antigens compared to other HPV16 mRNA therapeutic vaccines. In antitumor efficacy evaluations using TC-1 tumor-bearing mice, ABO2101 single-dose administration successfully eradicated both early-stage (50 mm³) and advanced (500 mm³) tumors. This was accompanied by a marked increase in HPV16-specific CD8+ cytotoxic T lymphocytes within the tumor microenvironment. Moreover, in prophylactic and adjuvant therapy models, ABO2101 prevented tumor growth across various dosages, indicating its robust preventative capabilities. Further, the combination of ABO2101 with immune checkpoint inhibitors, including PD-1 and CTLA-4 antibodies, displayed a synergistic effect in both immune-oncology sensitive and resistant animal models, suggesting a potential for combinational clinical therapy. In conclusion, our development of ABO2101, a mRNA-based HPV16-E6/E7 therapeutic cancer vaccine inclusive of APC maturation signals, represents a groundbreaking advancement in HPV-associated cancer treatment, as supported by our compelling preclinical data. Citation Format: Liang Du, Hongya Han, Jingshu Ma, Zhenxing Yang, Jinjuan Mao, Jijun Yuan, Bo Ying. Novel mRNA-encoded HPV vaccine with APC maturation signal and endolysosomal trafficking domain demonstrates superior T cell-mediated immunogenicity and efficacious tumor clearance in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4103.

Abstract A003: High-throughput TCR sequencing demonstrates induction of long-lasting HPV16-specific T cell responses in VB10.16 vaccinated advanced cervical cancer patients

Abstract Background: Assessment of vaccine-induced T cell responses is a primary pharmacodynamic readout in cancer vaccine clinical trials. High-throughput sequencing of T cell receptors (TCRs) is emerging as a rapid and scalable method, suitable for late-stage clinical trials, and offers sensitive and accurate quantification of the full T cell repertoire. Here we performed ELISpot and TCR sequencing on serial peripheral blood mononuclear cell (PBMC) samples from a clinical phase 2 trial investigating the therapeutic HPV16 cancer vaccine VB10.16 in combination with atezolizumab in advanced cervical cancer patients (NCT04405349). Methods: T cell responses were assessed by ex vivo IFN-g ELISpot (n=36). Immunosequencing of the TCRB locus was performed in 10 patients with available PBMCs, representing clinical response, stable disease, and progressive disease as best overall response. Immunosequencing of PBMC-derived gDNA was performed on up to five timepoints per patient, ranging from week 10 to 52. Novel and expanded clones from baseline to on-treatment timepoints were determined by a differential abundance framework, using binomial models in pair-wise comparisons, enabling longitudinal tracking of significantly expanded T cell clones. The sequences were matched and annotated to HPV16-specific TCRs present in a proprietary database of confirmed HLA class I HPV16-specific T cell clones; the database was constructed from querying the T cell repertoires of 92 healthy donors with 146 peptides derived from HPV16 E6 and E7 in MIRA assay. Results: An increased T cell response was significantly associated with disease control assessed by RECIST1.1 (n=24 patients with disease control vs n=12 patients with progressive disease, p=0.0113) and patients with a >2-fold increase measured by ex vivo IFN-g ELISpot showed a numerically improved progression-free survival (8 vs 3.7 months median PFS). The longitudinal tracking of TCRs provided a detailed insight into the dynamics of the overall TCR repertoire during treatment. Expansion of both pre-existing and newly expanded T cell clones was observed from week 10 and persisted until the end of treatment. Despite the non-exhaustive database, at least one verified HPV16-specific CD8 T cell clone was expanded in 8 out of 10 patients, supporting that the clonotypic expansion is caused by VB10.16. In 5 out of 7 patients with disease control, the breadth of HPV16-specific TCRs increased after vaccination, demonstrating induction of clinically relevant T cell responses. Conclusions: We demonstrate induction of strong and long-lasting HPV16-specific T cell responses after treatment with VB10.16 and atezolizumab in advanced cervical cancer patients. Induction of HPV16-specific T cell responses was significantly correlated with clinical efficacy. Immunosequencing and HPV16-specific annotation allowed longitudinal tracking of expanded TCRs and demonstrated a potential clinical relevance of increased repertoire diversity of HPV16-specific CD8 T cells in patients. Citation Format: Kaja C G Berg, Paula Bousquet, Milena Blaga, Thomas Bello, Mohammad Arabpour, Mikkel W Pedersen, Karoline Schjetne. High-throughput TCR sequencing demonstrates induction of long-lasting HPV16-specific T cell responses in VB10.16 vaccinated advanced cervical cancer patients [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A003.

MRNA-LNP vaccination-based immunotherapy augments CD8+ T cell responses against HPV-positive oropharyngeal cancer

Although mRNA vaccines are known as potent activators of antigen-specific immune responses against infectious diseases, limited understanding of how they drive the functional commitment of CD8+ T cells in tumor microenvironment (TME) and secondary lymphoid organs hinders their broader application in cancer immunotherapy. Here, we systematically evaluated the immunological effects of a lipid nanoparticle (LNP)-encapsulated mRNA vaccine that encodes human papillomavirus E7 protein (HPV mRNA-LNP), a tumor-specific antigen of HPV-positive oropharyngeal squamous cell carcinoma (OPSCC). HPV mRNA-LNP vaccination activated overall and HPV-specific CD8+ T cells, as well as differentially drove the functional commitment of CD8+ T cells through distinct IFN-response and exhaustion trajectories in the spleen and TME, respectively. Combination therapies of HPV mRNA-LNP vaccination with immune checkpoint blockades boosted HPV-specific CD8+ T cells while maintaining their anti-tumor function, thus further promoting tumor regression. Our results showed that the HPV mRNA-LNP vaccination combined with immune checkpoint blockade is a promising approach for immunotherapy of HPV-positive OPSCC.

A phase 1 dose-escalation and expansion study of CUE-101, a novel HPV16 E7-pHLA-IL2-Fc fusion protein, given as monotherapy and in combination with pembrolizumab in patients with recurrent/metastatic HPV16+ head and neck cancer.

6013 Background: Immuno-STATs are modular T cell engagers engineered to selectively activate tumor-antigen specific CD8+ T cells via targeted delivery of cytokines. CUE-101, the first Immuno-STAT in clinical trials, is composed of a human leukocyte antigen (HLA) complex, HLA-A*0201, a peptide epitope derived from the HPV16 E7 protein, and 4 molecules of attenuated human interleukin-2 (IL-2) designed to bind, expand, and activate HPV16-specific CD8+ T cells for the treatment of HPV16+ cancers. Methods: CUE-101-01 is an ongoing first-in-human study in HLA-A*0201 patients with HPV16+ recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC). Escalating doses of CUE-101 monotherapy (0.06 mg/kg to 8 mg/kg) and in combination with pembrolizumab (1 mg/kg to 4 mg/kg + 200 mg pembrolizumab) were evaluated, followed by expanded enrollment at the recommended phase 2 dose (RP2D). Patients with R/M HNSCC refractory to ≥ 1 platinum-based or checkpoint inhibitor therapy received CUE-101 monotherapy. Patients with previously untreated PD-L1+ R/M HNSCC received CUE-101 + pembrolizumab as first-line treatment. Therapy was administered every 3 weeks until disease progression or intolerable toxicity. Safety, pharmacokinetics (PK), pharmacodynamics (PD), and antitumor activity were assessed. Results: As of January 12, 2023, 67 patients were enrolled. A MTD was not established in monotherapy or combination-treated patients; 4 mg/kg of CUE-101, alone or in combination with pembrolizumab, was chosen as the RP2D dose in both cohorts. Monotherapy RP2D enrollment is complete and combination RP2D enrollment is ongoing. Frequent adverse events include fatigue (45%), anemia (34%), chills (27%), infusion related reactions (25%), constipation (22%), lymphopenia (22%) and nausea (22%). CUE-101 PK data demonstrate dose-dependent increases in drug exposure sustained with repeat dosing. PD data demonstrate selective expansion of HPV-16 E711-20-specific CD8+ T cells, sustained increase in NK cells and transient increase in Treg cells. Among 19 evaluable monotherapy RP2D patients, 1 PR and 6 durable SD (SD ≥ 12 weeks) were observed, with mOS of 24.4 months (9.1, NA). Among 12 evaluable RP2D combination patients to date, 5 PRs, and 2 durable SDs have been observed, with 71% (5/7) of patients expressing PD-L1 CPS ≤ 20. Conclusions: CUE-101 facilitates the targeted delivery of high concentrations of IL-2 to relevant tumor-specific CD8+ T cells. We demonstrate safety and tolerability with encouraging PD signals and antitumor activity with monotherapy and in combination with pembrolizumab in HPV+ R/M HNSCC patients. Enrollment continues in the CUE-101 and pembrolizumab combination cohort. Clinical trial information: Clinical trial information: NCT03978689 .

Human papilloma virus-16-specific CD8+ T-cell expansions characterize different clinical forms of lichen planus and not lichen sclerosus et atrophicus.

Lichen planus (LP) is a cutaneomucosal chronic inflammatory disease characterized by a CD8+ cytotoxic T-lymphocytes (CTL) infiltrate. In erosive oral LP, we found HPV16-specific activated CTL in lesions, supporting a pathogenic contribution of HPV16. Here, we investigated whether a similar scenario occurs in other clinical forms of LP and in lichen sclerosus et atrophicus (LSA), another chronic disease also affecting the mucosa and/or the skin. Blood CTL from LP and LSA patients expressed significant higher levels of granzyme B, perforin and CD107a proteins than healthy donors. Expansions of TCRVß3+ CTL, with presence of TCR clonotypes identical to those previously detected in erosive oral LP, were found both in blood and mucosal/skin lesions of LP, and not of LSA patients. These expansions were enriched with HPV16-specific CD8+ T-cells as shown by their recognition of the E711-20 immunodominant epitope. In LSA patients, the peripheral repertoire of CTL was oligoclonal for TCRVß6+ CTL. Finally, although patients with LP and LSA have developed antibodies against HPV16 capsid L1, antibodies against HPV16 E6 were only observed in patients with LP. Overall, our data collectively suggest an involvement of HPV16-specific CTL in different clinical forms of LP, not only in erosive oral LP, while a different scenario operates in LSA.

44P HPV16-specific CD4 and CD8 T-cell activation and functionality in patients receiving combination PDS0101 immunotherapy

44P HPV16-specific CD4 and CD8 T-cell activation and functionality in patients receiving combination PDS0101 immunotherapy

Safety and feasibility of an HPV therapeutic vaccine (TA-CIN) in patients with HPV16 associated cervical cancer (458)

<b>Objectives:</b> Therapeutic vaccines against the Human Papilloma Virus (HPV), the causative agent of cervical cancer, have the potential to stimulate HPV-specific CD8 T cell immune responses. TA-CIN is a single fusion protein comprised of HPV16 E6, E7, and L2 proteins linked in tandem. In preclinical studies, vaccination with TA-CIN induces immunity to HPV16 E6/E7-specific T cell-mediated immune responses and L2-specific neutralizing antibodies in mice. Administration of the vaccine following chemotherapy with cisplatin or radiation was able to improve the therapeutic antitumor effect in a preclinical model compared to vaccination, chemotherapy, or chemoradiation alone (Tseng et al. <i>Cancer Immunol Immunother.</i> 58:737, 2009). This suggests that a therapeutic HPV vaccine may have value in improving the therapeutic effect of the standard care of chemoradiation for patients with cervical cancer. Furthermore, preclinical studies demonstrated that site of administration in the mice influenced the extent of antitumor immunity with vaccination in the hind leg resulting in improved efficacy compared to front leg vaccination (Qiu et al. <i>Virology.</i> 525:205, 2018). This randomized, multi-center study is designed to evaluate the safety and feasibility of administering TA-CIN to patients with HPV-16 associated cervical cancer after completion of definitive primary therapy and assess the immune response when the vaccine is administered in the thigh versus the arm. <b>Methods:</b> Eligible patients for this study have HPV16-related stage IB1-IVA cervical cancer and have completed definitive treatment within the past 12 months. HPV16 nucleic acid within the cervical tumor specimen must be documented by in situ hybridization. Patients must not have evidence of disease recurrence based on prevaccination imaging and clinical assessments within eight weeks of enrollment. Other key eligibility criteria include ECOG performance status ≤1 and absolute lymphocyte count > 500/cu mm. Patients with autoimmune conditions or on immunosuppressive therapy are excluded. Fourteen patients will be randomized to receive up to 3 doses of 100ug TA-CIN vaccine three times to either the arm or the thigh. Immune and clinical responses in patients receiving vaccines will be assessed, and the injection site that elicits more potent immune responses will be selected for future studies.

A phase II study of pembrolizumab for HPV-associated papilloma patients with laryngeal, tracheal, and/or pulmonary involvement.

2590 Background: Recurrent respiratory papillomatosis (RRP) is caused by human papillomavirus (HPV) types 6 &amp; 11. RRP proliferates in the squamous epithelium lining the respiratory tract impacting breathing, swallowing, and voice and carries a 3-5% risk of malignant transformation. Given the multi-focality of the disease and tolerized host immune response against HPV, in part through upregulation of the PD1:PDL1 axis, the safety and efficacy of systemic pembrolizumab (pembro) as a novel treatment for this benign tumor patient (pt) population was evaluated in a phase II clinical trial. Methods: RRP pts &gt; 12 years of age were treated with pembro 200mg every 3 weeks. Primary endpoints were best overall response (ORR) (measured by endoscopic lesional burden) and safety. Greater than 5 pts with disease response out of 21 (assuming &gt; 1 of first n = 11 with disease in response) provided 86% power to distinguish between a 15% and a 38% ORR (one-sided 8% binomial test). HPV-specific CD8+ T cell frequency and functional states and biomarkers of response and immune resistance are being evaluated in serial tissue and liquid biopsies (up to 8 biopsies/patient over the 24 months of treatment). Results: The Simon two-stage, stage 1 criteria was met. A total of 21 patients were enrolled and all are now off treatment. Median age (range) was 45 (19-68), 57% (12/21) were male and 67% (14/21) were white. 48% (10/21) had Juvenile-onset (Jo)-RRP, 57% (12/21) had pulmonary RRP involvement, and 19% (4/21) had SCC derived from their RRP. 62% (13/21) completed 24 months of treatment. Reasons for discontinuation included disease progression (14%, 3/21), treatment related adverse event (TRAEs) (14%, 3/21), and study withdrawal (10%, 2/21). A partial response (≥25% reduction in endoscopic tumor burden score) was observed in 57% (12/21) (95% CI: 34%-78.2%) of pts (7 of 10 with Jo-RRP and 5 of 11 with Adult-onset (Ao)-RRP disease responded). Stable disease was observed in 33% (7/21). No complete responses were observed. Fatigue was the most frequent TRAEs; Grade 3 TRAEs included uveitis and hypophysitis, both of which were reversible upon pembro discontinuation and steroid use. At a median follow-up: 25.6 (6.2-38.1 months), the mean number of surgical interventions was reduced by 7 surgeries/year (p = 0.004) in pts treated on the trial for &gt; 12 months, and, upon treatment completion, durable clinical benefit was observed with no additional treatment needed for the duration of the clinical trial follow-up for some pts. Conclusions: Pembro reduces the need for routine surgical interventions based on the durable response rates being achieved. Further study of pembro +/- other agents is warranted to achieve and sustain complete responses in this population. Clinical trial information: NCT02632344.

Immune correlates of clinical parameters in patients with HPV-associated malignancies treated with bintrafusp alfa

PurposeBintrafusp alfa is a bifunctional agent consisting of an anti-human PD-L1 antibody linked to two TGFβRII. It is designed to act both as a checkpoint inhibitor and to ‘trap’ TGFβ...

Preliminary Safety of PDS0101 (Versamune +HPVmix) and Pembrolizumab Combination Therapy in Subjects with Recurrent/Metastatic Human Papillomavirus-16 Positive Oropharyngeal Squamous Cell Carcinoma (OPSCC)

Purpose/Objective(s) Persistent HPV16 DNA infection is associated with up to 70% of OPSCC and recurrent/metastatic disease is often incurable and poorly palliated by standard therapies. Despite significant advances documented with checkpoint inhibitor (CPI) immunotherapy, clinical benefit and efficacy remains limited in most patients due to a lack of meaningful tumor-directed T cell responses. Major barriers to effective cancer vaccine delivery include a relative absence of shared neo-antigens between tumors and weak T-cell activation. PDS0101 is a T-cell activating immunotherapy directed against preserved HPV neoantigens E6/7 that is based on a cationic lipid nanoparticle platform that promotes antigen processing and cross presentation. It has been shown to specifically upregulate type I interferons, allowing generation of high levels of polyfunctional HPV16-specific CD8 and CD4 T cells in vivo as well as immune memory. VERSATILE-002 (NCT04260126) is a phase 2 study of the combination of PDS0101 and pembrolizumab in first line treatment (CPI naïve) and CPI refractory patients with recurrent or metastatic HPV16-related OPSCC. Herein, we report preliminary safety data for CPI naïve patients. Materials/Methods Subjects are treated with pembrolizumab 200mg IV every three weeks plus SC PDS0101 following pembrolizumab on days one of C1-4 and C12. An initial safety cohort was assessed during Cycle 1 and 21 days following, for dose limiting toxicity (DLT) and thereafter for safety and tolerability of the combination. Results Fifteen CPI naïve subjects, median age 60 yrs (range 46-68), all male, 14 (93%) of whom were White and not Hispanic or Latino, received at least one cycle of combination therapy. All were confirmed HPV16 postive and to have a CPS score >=1 (8 with CPS >=20); 8 (53%) were ECOG 0 and 93% had received prior curative intent HNSCC therapy. At the time of safety review, subjects had received a median of 4 doses (range 1-4) of PDS0101 and pembrolizumab. Treatment-emergent adverse events (TEAEs) were documented in 9 (60%) subjects: self-limited, Grade 1 local inject site reactions predominated (7 subjects, 47%), with occasional ≤ Gr2 fatigue, nausea or diarrhea (13% of subjects or fewer). Five subjects had serious adverse events (SAEs), all unrelated to PDS0101 and pembrolizumab. No DLTs, drug discontinuation related to toxicity or immune-related AEs have been documented to date. Conclusion The combination of PDS0101 and pembrolizumab is safe and well tolerated without evidence of enhanced or significant toxicity. Persistent HPV16 DNA infection is associated with up to 70% of OPSCC and recurrent/metastatic disease is often incurable and poorly palliated by standard therapies. Despite significant advances documented with checkpoint inhibitor (CPI) immunotherapy, clinical benefit and efficacy remains limited in most patients due to a lack of meaningful tumor-directed T cell responses. Major barriers to effective cancer vaccine delivery include a relative absence of shared neo-antigens between tumors and weak T-cell activation. PDS0101 is a T-cell activating immunotherapy directed against preserved HPV neoantigens E6/7 that is based on a cationic lipid nanoparticle platform that promotes antigen processing and cross presentation. It has been shown to specifically upregulate type I interferons, allowing generation of high levels of polyfunctional HPV16-specific CD8 and CD4 T cells in vivo as well as immune memory. VERSATILE-002 (NCT04260126) is a phase 2 study of the combination of PDS0101 and pembrolizumab in first line treatment (CPI naïve) and CPI refractory patients with recurrent or metastatic HPV16-related OPSCC. Herein, we report preliminary safety data for CPI naïve patients. Subjects are treated with pembrolizumab 200mg IV every three weeks plus SC PDS0101 following pembrolizumab on days one of C1-4 and C12. An initial safety cohort was assessed during Cycle 1 and 21 days following, for dose limiting toxicity (DLT) and thereafter for safety and tolerability of the combination. Fifteen CPI naïve subjects, median age 60 yrs (range 46-68), all male, 14 (93%) of whom were White and not Hispanic or Latino, received at least one cycle of combination therapy. All were confirmed HPV16 postive and to have a CPS score >=1 (8 with CPS >=20); 8 (53%) were ECOG 0 and 93% had received prior curative intent HNSCC therapy. At the time of safety review, subjects had received a median of 4 doses (range 1-4) of PDS0101 and pembrolizumab. Treatment-emergent adverse events (TEAEs) were documented in 9 (60%) subjects: self-limited, Grade 1 local inject site reactions predominated (7 subjects, 47%), with occasional ≤ Gr2 fatigue, nausea or diarrhea (13% of subjects or fewer). Five subjects had serious adverse events (SAEs), all unrelated to PDS0101 and pembrolizumab. No DLTs, drug discontinuation related to toxicity or immune-related AEs have been documented to date. The combination of PDS0101 and pembrolizumab is safe and well tolerated without evidence of enhanced or significant toxicity.

Microfluidic Squeezing Enables MHC Class I Antigen Presentation by Diverse Immune Cells to Elicit CD8+ T Cell Responses with Antitumor Activity.

CD8+ T cell responses are the foundation of the recent clinical success of immunotherapy in oncologic indications. Although checkpoint inhibitors have enhanced the activity of existing CD8+ T cell responses, therapeutic approaches to generate Ag-specific CD8+ T cell responses have had limited success. Here, we demonstrate that cytosolic delivery of Ag through microfluidic squeezing enables MHC class I presentation to CD8+ T cells by diverse cell types. In murine dendritic cells (DCs), squeezed DCs were ∼1000-fold more potent at eliciting CD8+ T cell responses than DCs cross-presenting the same amount of protein Ag. The approach also enabled engineering of less conventional APCs, such as T cells, for effective priming of CD8+ T cells in vitro and in vivo. Mixtures of immune cells, such as murine splenocytes, also elicited CD8+ T cell responses in vivo when squeezed with Ag. We demonstrate that squeezing enables effective MHC class I presentation by human DCs, T cells, B cells, and PBMCs and that, in clinical scale formats, the system can squeeze up to 2 billion cells per minute. Using the human papillomavirus 16 (HPV16) murine model, TC-1, we demonstrate that squeezed B cells, T cells, and unfractionated splenocytes elicit antitumor immunity and correlate with an influx of HPV-specific CD8+ T cells such that >80% of CD8s in the tumor were HPV specific. Together, these findings demonstrate the potential of cytosolic Ag delivery to drive robust CD8+ T cell responses and illustrate the potential for an autologous cell-based vaccine with minimal turnaround time for patients.

Functional HPV-specific PD-1+ stem-like CD8 T cells in head and neck cancer.

T cells are important in tumour immunity but a better understanding is needed of the differentiation of antigen-specific T cells in human cancer1,2. Here we studied CD8 T cells in patients with human papillomavirus (HPV)-positive head and neck cancer and identified several epitopes derived from HPV E2, E5 and E6 proteins that allowed us to analyse virus-specific CD8 T cells using major histocompatibility complex (MHC) class I tetramers. HPV-specific CD8 T cells expressed PD-1 and were detectable in the tumour at levels that ranged from 0.1% to 10% of tumour-infiltrating CD8 T lymphocytes (TILs) for a given epitope. Single-cell RNA-sequencing analyses of tetramer-sorted HPV-specific PD-1+ CD8 TILs revealed three transcriptionally distinct subsets. One subset expressed TCF7 and other genes associated with PD-1+ stem-like CD8 T cells that are critical for maintaining T cell responses in conditions of antigen persistence. The second subset expressed more effector molecules, representing a transitory cell population, and the third subset was characterized by a terminally differentiated gene signature. T cell receptor clonotypes were shared between the three subsets and pseudotime analysis suggested a hypothetical differentiation trajectory from stem-like to transitory to terminally differentiated cells. More notably, HPV-specific PD-1+TCF-1+ stem-like TILs proliferated and differentiated into more effector-like cells after in vitro stimulation with the cognate HPV peptide, whereas the more terminally differentiated cells did not proliferate. The presence of functional HPV-specific PD-1+TCF-1+CD45RO+ stem-like CD8 T cells with proliferative capacity shows that the cellular machinery to respond to PD-1 blockade exists in HPV-positive head and neck cancer, supporting the further investigation of PD-1 targeted therapies in this malignancy. Furthermore, HPV therapeutic vaccination efforts have focused on E6 and E7 proteins; our results suggest that E2 and E5 should also be considered for inclusion as vaccine antigens to elicit tumour-reactive CD8 T cell responses of maximal breadth.

Profiling HPV-16-specific T cell responses reveals broad antigen reactivities in oropharyngeal cancer patients.

Cellular immunotherapeutics targeting the human papillomavirus (HPV)-16 E6 and E7 proteins have achieved limited success in HPV-positive oropharyngeal cancer (OPC). Here we have conducted proteome-wide profiling of HPV-16-specific T cell responses in a cohort of 66 patients with HPV-associated OPC and 22 healthy individuals. Unexpectedly, HPV-specific T cell responses from OPC patients were not constrained to the E6 and E7 antigens; they also recognized E1, E2, E4, E5, and L1 proteins as dominant targets for virus-specific CD8+ and CD4+ T cells. Multivariate analysis incorporating tumor staging, treatment status, and smoking history revealed that treatment status had the most significant impact on HPV-specific CD8+ and CD4+ T cell immunity. Specifically, the breadth and overall strength of HPV-specific T cell responses were significantly higher before the commencement of curative therapy than after therapy. These data provide the first glimpse of the overall human T cell response to HPV in a clinical setting and offer groundbreaking insight into future development of cellular immunotherapies for HPV-associated OPC patients.

R-DOTAP (Versamune): A novel enantiospecific cationic lipid nanoparticle that induces CD4 and CD8 cellular immune responses to whole protein and tumor-specific peptide antigens.

e15211 Background: Immunotherapy approaches are limited in their ability to induce antigen-specific CD8+ T cells in vivo able to recognize and kill tumor cells. We developed a novel immunotherapy approach using enantiomerically pure, R-DOTAP cationic lipid nanoparticles and tumor-derived T cell antigens, and previously demonstrated that R-DOTAP formulations efficiently prime cytotoxic T cells through enhanced cross presentation and induction of type I interferons.[1] A phase I clinical trial of a R-DOTAP HPV16 peptide formulation confirmed induction of strong in vivo HPV-specific CD8+ cytolytic T-cells without associated systemic toxicities. In this study, we assessed R-DOTAP nanoparticle formulations containing whole protein (ovalbumin) or long multi-epitope peptides from the tumor antigen TARP (T-cell alternate reading frame protein): a 58-residue protein overexpressed in prostate and breast cancers, documented to be immunogenic in humans. Methods: R-DOTAP formulations were prepared containing ovalbumin (OVA) or TARP peptides. C57BL/6K mice were immunized with 10 μg/mouse of OVA plus R-DOTAP, CFA or sucrose on Days 0, 15 and 30. OVA-specific cellular and humoral responses following vaccination were assessed by measuring splenic CD4 and CD8 T cell IFN-γ production and circulating OVA-specific antibodies in serum. HLA-A2 transgenic mice (AAD mice) were vaccinated with long, multi-epitope TARP peptides delivered as an R-DOTAP admixture or with CFA or sucrose on Days 0 and 7. Antigen-specific T cell responses were measured by IFN-γ ELISpot assay. Results: OVA R-DOTAP formulations induced strong antigen-specific effector CD4 and CD8 immune and memory responses detected 7 and 30 days, respectively, following vaccination as well as OVA-specific antibody responses. In TARP peptide vaccinated mice, R-DOTAP formulations were able to present multiple CD8 T cell epitopes and stimulate responses that were superior to CFA. Conclusions: Our results suggest that R-DOTAP is a versatile immune activating therapy that can be formulated with long, multi-epitope tumor-derived peptides or whole proteins. R-DOTAP formulations induce quantitatively robust antigen-specific CD4 and CD8 T cells in vivo compared to well-established immune stimulants. Reference: 1.Gandhapudi SK, Ward M, Bush JP et al. Antigen Priming with Enantiospecific Cationic Lipid Nanoparticles Induces Potent Antitumor CTL Responses through Novel Induction of a Type I IFN Response. J Immunol 2019;202:3524-3536

Novel HPV-E7 immune modulators to activate HPV-specific T cells to eliminate cervical cancer.

e18027 Background: Human papilloma virus (HPV) infection can lead to several types of cancers in both men and women. HPV+ tumor cells constitutively express the HPV-E7 antigen which can act as an oncogene to promote tumor growth and malignant transformation. Here, we report the application of novel Tavo Immune Modulator (TIM) biologics molecules which are consisted of a pMHC complex with an epitope peptide derived from HPV-E7 and co-stimulatory modulators of T cell activity. The HPV-E7 TIM molecules can specifically recognize and activate HPV-E7-specific T cells for the elimination of HPV affected cells. Methods: HPV-E7 TIM molecules were engineered as fusion molecules with HLA-A*02:01 MHC complexed with an HPV-E7 (11-20) epitope peptide at the N-termini, and various T cell costimulatory modulators at the C-termini of IgG heavy and light chains. TIM molecules were expressed in Expi293 cells and purified by Protein A affinity chromatography. Specific binding of TIM with HPV-E7 specific T cells was confirmed by immunostaining and flow cytometry. The activation and expansion of antigen specific CD8+ T cells were elucidated in T cell activation and recall assays. Results: HPV-E7 TIM molecules with various T cell co-stimulator molecules were engineered to specifically recognize HPV-specific T cells. Activation of T cells was antigen-specific and depended on the presence of an engineered T cell modulatory component on the TIM framework. The effects of various costimulatory molecules in different combinations on T cell activation were explored and an optimal combination was identified which facilitated high potency antigen-specific T cell activation. Such molecular combinations could facilitate T cell expansion and activation in T cell recall assays. Efficacy of HPV-E7 TIM molecules by inhibiting tumor growth in a syngeneic tumor model is ongoing. Conclusions: This study demonstrates that HPV-E7 TIM molecules selectively recognize and activate HPV-specific CD8+ T cells in the presence of a combination of two T cell costimulatory factors. Such novel biologics provide distinctive approaches in the treatment of HPV-related cancers and warrant further investigation. Additional in vitro and in vivo studies are ongoing to demonstrate the utility in eliminating HPV-infected tumor cells. Full data will be presented at the meeting.

Novel approach for the detection of antigen-specific CD8 T cell responses corresponding to treatment outcome in HPV+ cancer patients

Abstract HPV cancer treatment outcome has been positively correlated to the presence of patient immunity against the virus. Six HPV strains account for over 75% of cervical cancer cases worldwide with HPVE6 &amp; E7 protein integration into the host’s DNA being the driving factor in these cancers. However, the sequence of these proteins vary between strains resulting in high diversity in epitope presentation in patients with different HLA haplotypes. Therefore, using one tetramer gives an inaccurate read of a patient’s immunity to the virus. In this study, we set out to develop a method to obtain a more complete read-out of patient immunity to HPV by creating a more comprehensive tetramer staining panel. We first selected 29 in-silico predicted epitopes of both E6 and E7 oncogenic proteins in the 6 most common HPV strains for 3 HLA haplotypes (HLA-A*02:01, HLA-A*11:01 and *24:02). We then utilized a non-UV “peptide exchange MHC tetramer platform” to assess the binding of these peptides to corresponding MHC groove. Since the peptide exchange and affinity of peptides to the cleft of MHC are correlated, we used an algorithm to calculate the measure of the peptide exchange rate. We found that 3 of the 29 peptides showed poor or no binding to the matched MHC, while all others had rates over 81.78%. The MHC tetramers generated by this peptide exchange platform were then used alone or as part of a pool to stain HPV specific CD8+ T cell enriched PBMCs from an HPV positive host. Our results showed no significant difference in the detection of HPV+ CD8 T cells between our generated HPV16 E7 tetramer and the commercially available tetramer. This implies that the use of this peptide exchange tetramer platform can serve as an accurate tool for measuring HPV immunity in cancer patients.

Live-attenuated lymphocytic choriomeningitis virus-based vaccines for active immunotherapy of HPV16-positive cancer

ABSTRACT Infection with human papillomavirus (HPV) is associated with a variety of cancer types and limited therapy options. Therapeutic cancer vaccines targeting the HPV16 oncoproteins E6 and E7 have recently been extensively explored as a promising immunotherapy approach to drive durable antitumor T cell immunity and induce effective tumor control. With the goal to achieve potent and lasting antitumor T cell responses, we generated a novel lymphocytic choriomeningitis virus (LCMV)-based vaccine, TT1-E7E6, targeting HPV16 E6 and E7. This replication-competent vector was stably attenuated using a three-segmented viral genome packaging strategy. Compared to wild-type LCMV, TT1-E7E6 demonstrated significantly reduced viremia and CNS immunopathology. Intravenous vaccination of mice with TT1-E7E6 induced robust expansion of HPV16-specific CD8+ T cells producing IFN-γ, TNF-α and IL-2. In the HPV16 E6 and E7-expressing TC-1 tumor model, mice immunized with TT1-E7E6 showed significantly delayed tumor growth or complete tumor clearance accompanied with prolonged survival. Tumor control by TT1-E7E6 was also achieved in established large-sized tumors in this model. Furthermore, a combination of TT1-E7E6 with anti-PD-1 therapy led to enhanced antitumor efficacy with complete tumor regression in the majority of tumor-bearing mice that were resistant to anti-PD-1 treatment alone. TT1-E7E6 vector itself did not exhibit oncolytic properties in TC-1 cells, while the antitumor effect was associated with the accumulation of HPV16-specific CD8+ T cells with reduced PD-1 expression in the tumor tissues. Together, our results suggest that TT1-E7E6 is a promising therapeutic vaccine for HPV-positive cancers.

Phase I Clinical Study for Validation of Fimaporfin-Based Photochemical Internalisation: A Novel Technology for Enhancing Cellular Immune Responses Important for Therapeutic Effect of Peptide-and Protein-Based Vaccines

Abstract Background FimaVacc is a vaccine formulated by the photosensitising compound fimaporfin and a toll-like receptor (TLR) agonist, and is administered intradermally followed by illumination of the vaccination site. In preclinical studies, fimaVacc has been shown to improve MHC class I antigen presentation, resulting in strongly enhanced cytotoxic and helper T-cell responses to various types of peptide and protein vaccines. Methods A phase I clinical study with fimaVacc has been performed in healthy volunteers to study the safety and immunogenicity of this novel vaccine. The subjects were vaccinated with HPV16 E7 peptides and Keyhole Limpet Hemocyanin (KLH) protein, serving as model antigens for peptide- and protein-based vaccines. Both antigens were formulated with fimaporfin and the TLR3 agonist poly-ICLC (Hiltonol) and administered in up to three vaccinations. Local and systemic adverse effects were assessed for safety, and cellular and humoral immune responses were analysed by ELISPOT, flow cytometry and ELISA assays to determine the immunogenicity of fimaVacc. Results The principle of the fimaVacc technology will be presented, together with preclinical results showing that fimaVacc strongly enhances both cellular and humoral immune responses and improves anti-tumour effects in mouse models. The clinical study showed that intradermal vaccination with fimaVacc was well tolerated, with no systemic side effects and generally only mild local reactions. Elispot analysis showed that fimaVacc can significantly increase the number of healthy donors displaying a T-cell response to HPV peptide vaccination. Furthermore, Elispot and flow cytometry analyses demonstrated an enhancement of both HPV-specific CD4+ and CD8+ T cells upon fimaVacc treatment. Conclusion The photochemically based fimaVacc vaccination technology can be applied safely in humans, and enhances T-cell responses to an HPV peptide vaccine over what is achieved in a control group which received antigen + adjuvant without fimaVacc. Clinical trial identification NCT02947854. Legal entity responsible for the study PCI Biotech AS. Funding PCI Biotech AS. Disclosure S. Janetzki: Advisory / Consultancy: PCI Biotech AS. V.T. Edwards: Full / Part-time employment: PCI Biotech AS. H. Olivecrona: Leadership role, Shareholder / Stockholder / Stock options, Full / Part-time employment: PCI Biotech AS. S.H. van der Burg: Advisory / Consultancy: PCI Biotech AS. T. Otterhaug: Shareholder / Stockholder / Stock options, Full / Part-time employment: PCI Biotech AS. A. Hogset: Leadership role, Shareholder / Stockholder / Stock options, Full / Part-time employment: PCI Biotech AS. All other authors have declared no conflicts of interest.