Non-thermal Red Light Research Articles

A phase 1, first-in-human, drug dose-escalation study of RM-1995 photoimmunotherapy, as monotherapy or combined with pembrolizumab, in patients with advanced cutaneous squamous cell carcinoma or with head and neck squamous cell carcinoma.

TPS6103 Background: RM-1995 comprises an antibody against CD25, conjugated with a light-activatable dye (IRDye 700DX), which can subsequently be activated by illumination with 690 nm non-thermal red light for precise, targeted cell killing. Administration of the antibody-dye conjugate followed by local illumination results in target cell membrane disruption, while limiting damage to surrounding tissue. CD25 (lL-2Rα) is highly expressed by regulatory T cells (Tregs), thereby providing an opportunity to specifically target intratumoral Tregs for depletion via photoimmunotherapy. Tregs are critical in promoting immune homeostasis; however, in the context of solid tumors, Treg-mediated suppression detrimentally constrains anticancer T-cell responses, and a low ratio of CD8+ T cells:Tregs in the tumor is negatively correlated with clinical outcomes. Preclinical data suggest that RM-1995 photoimmunotherapy treatment alleviates local Treg-mediated restraint within the tumor microenvironment. Anticancer responses were further improved when combined with anti-PD-1 checkpoint inhibition. Methods: A phase 1 first-in-human dose-escalation study of RM-1995 photoimmunotherapy as monotherapy, or in combination with pembrolizumab, in patients with advanced cutaneous squamous cell carcinoma (cuSCC) and head and neck squamous cell carcinoma (HNSCC) is now enrolling (NCT05220748). The phase 1a portion will evaluate safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of single-agent RM-1995 photoimmunotherapy and determine the maximum tolerated dose or maximum administered dose of RM-1995 with a fixed light dose for tumor illumination. The phase 1b portion will include combination therapy with pembrolizumab. Enrolled patients will receive RM-1995 IV, followed 24±4 hours later by local tumor illumination. Pembrolizumab (200 mg) will be administered 5–7 days prior to RM-1995 infusion, then again 3 weeks later. Patients may be eligible to receive repeated photoimmunotherapy cycles for up to 12 months. Primary outcomes include safety and tolerability, and dose finding. The study will include cuSCC or HNSCC patients with locally advanced or locoregional disease with or without metastases that has recurred or progressed on or after platinum-based chemotherapy, and who are not eligible for further locoregional treatment. Other criteria include ECOG 0–2 and having ≥1 tumor accessible for illumination. Key exclusion criteria are: tumor sites located in sensitive or vital anatomic structures or invading a major blood vessel (unless treated to prevent hemorrhage); and other clinically significant or uncontrolled disease processes. An estimated 18 patients will be enrolled into each portion of the study. Clinical trial information: NCT05220748.

Abstract 1796: PD-L1 photoimmunotherapy kills immunosuppressive myeloid cells to activate local and systemic antitumor immunity in syngeneic mouse models

Abstract Introduction: Photoimmunotherapy is an investigational anticancer treatment platform that combines the cell surface binding of an antibody conjugated to a light activatable dye (IRDye® 700DX, IR700) with non-thermal red light illumination for selective cell killing. PD-L1, the target of anti-PD-L1 inhibitors, is a suppressive checkpoint marker expressed on tumor cells and immunosuppressive myeloid cells in the tumor microenvironment. Here we examined the anticancer activity and immune activation elicited by anti-PD-L1-IR700 photoimmunotherapy (PD-L1 photoimmunotherapy). Methods: CT26 or LL/2 tumors were used to assess antitumor immune response following PD-L1 photoimmunotherapy. CT26PD-L1-/- tumors were generated by CRISPR/Cas9. Tumor volume was determined by caliper measurements in illuminated and non-illuminated tumors. Intratumoral immune responses were assessed by flow cytometry. Complete responder (CR) mice were challenged with either CT26 or 4T1 tumors to evaluate immune memory. Results: Mice bearing CT26 or LL/2 tumors treated with PD-L1 photoimmunotherapy exhibited a notable reduction of tumor growth compared to mice that received control treatments (saline, anti-PD-L1-IR700 conjugate alone without illumination, or multi-dosing with anti-PD-L1 antibody). Pre-treatment depletion of CD8+ T cells in the mice abrogated the antitumor activity of PD-L1 photoimmunotherapy, demonstrating a key role of CD8+ T-cell effector activity in the responses. PD-L1 photoimmunotherapy induced CRs in 7/15 mice, and all CR mice rejected CT26 tumor growth after re-challenge, indicating the generation of immunological memory. Furthermore, 6/8 mice rejected inoculation of 4T1 tumors, suggesting an enhanced ability to prime new T cells with tumor neoantigens. Intratumoral immune cell analysis showed a reduction of myeloid cells 2 hours following illumination, an increase of CD103+ dendritic cells 2 days following illumination, and an increase of non-exhausted PD-1-CD8+ T effector cells 8 days after illumination. In a bilateral tumor model, PD-L1 photoimmunotherapy resulted in tumor reduction in the non-illuminated tumor. Mice bearing CT26PD-L1-/- tumor cells similarly exhibited tumor reduction after PD-L1 photoimmunotherapy, suggesting that antitumor activity resulted from the elimination of PD-L1+ non-tumor cells. Conclusions: PD-L1photoimmunotherapy induces anticancer responses by killing PD-L1+ myeloid cells and possibly PD-L1+ cancer cells within the tumor, resulting in augmentation of local and systemic antitumor immunity. These results indicate that PD-L1 photoimmunotherapy can elicit anticancer immune responses in target and distal tumors, including syngeneic mouse models refractory to checkpoint inhibition. Citation Format: Amy H. Thorne, Michelle H. Hsu, Daniel Mendoza, Jason Lapetoda, Christopher M. Parry, Jerry J. Fong, Miguel Garcia-Guzman. PD-L1 photoimmunotherapy kills immunosuppressive myeloid cells to activate local and systemic antitumor immunity in syngeneic mouse models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1796.

Abstract 949: Anti-cancer activity by photoimmunotherapy is driven by adaptive immune responses and vaccinates the host against the tumor

Abstract INTRODUCTION: Photoimmunotherapy (PIT) is an investigational anti-cancer treatment platform utilizing cell-targeted antibodies conjugated to the IR700 (IRDye 700DX®) light-excitable dye. Upon illumination with non-thermal red light, target cells bound with antibody-conjugates undergo rapid necrosis. Previous work demonstrated that PIT induces features of immunogenic cell death of tumor cells and ignites an immune response against the tumor. In these preclinical studies, we investigated the extent to which the immune response contributes to the in vivo anti-cancer activity using syngeneic cancer models. METHODS: PIT treatment was applied to a panel of mouse and human cancer cell lines targeted by their respective antigen-binding conjugate in vitro, and the release of damage-associated molecular patterns (DAMPs) was measured from the cell supernatant. To determine the contribution of the immune response to PIT anti-cancer activity, PIT treatment was applied to immunocompetent animals with antibody-mediated CD8 T cell depletion, or blockade of CD40-CD40L axis concurrent with tumor implant or PIT treatment. To determine whether the immunogenic properties of PIT treatment induce vaccinal effects, immunocompetent animals were inoculated with in vitro PIT-treated cancer cells, and then challenged with live tumor cells in the contralateral flank one week later. RESULTS: Cancer cells treated with PIT released significant amounts of immunogenic cell death markers including DAMPs such as ATP and Annexin A1. The anti-cancer activity of PIT treatment in immunocompetent animals was inhibited when 1) pre-existing immunity was abrogated by blockade of the CD40-CD40L interaction at time of tumor implant, and 2) CD8 T cells were depleted from the animals. Applying CD40-CD40L blockade concurrent with PIT treatment partially abrogated anti-cancer activity. When animals were inoculated with cancer cells treated by PIT ex vivo, tumor rejection was achieved in 8 out of 9 animals when challenged with live tumor cells on the contralateral flank. CONCLUSIONS: Cancer treatment by PIT induces necrotic and immunogenic cell death resulting in local and systemic immune response. These preclinical data indicate that adaptive immune responses induced by PIT treatment drive the anti-cancer effects and can also provide vaccinal effects due to the release of DAMPs and cancer antigens. Citation Format: C. Daniel De Magalhaes Filho, Michelle A. Hsu, Stephanie M. Okamura, Dany Gitnick, Estela Solis, Jerry J. Fong, Miguel Garcia-Guzman. Anti-cancer activity by photoimmunotherapy is driven by adaptive immune responses and vaccinates the host against the tumor [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 949.

Abstract 480: Molecular mechanism of action of photoimmunotherapy with antibody-IR700 dye conjugates

Abstract INTRODUCTION: Cancer cell-targeted photoimmunotherapy (PIT) is a platform technology under development for the treatment of various cancers. PIT is a drug and device combination that utilizes an antibody conjugated to the IR700 (IRDye 700DX®) light-excitable dye, which upon antigen binding and illumination with non-thermal red light, leads to necrotic cell death. The objective of these studies was to characterize the molecular pharmacology and the underlying mechanism of action of PIT. METHODS: In vitro PIT studies using human and mouse cancer cells were performed to evaluate conjugate (antibody + dye) binding, dose response and light dosimetry response. Mouse xenograft experiments assessed necrotic markers in tumor tissue and surrounding normal tissue post-PIT treatment. Oxidative damage to lipids was detected with a reporter dye. Mass spectrometry analysis was performed to assess protein oxidation, crosslinking and axial ligand dissociation from the dye. RESULTS: Binding of the conjugate to the target cancer cells was required for PIT treatment to induce cell death as measured by antibody competition studies, however, internalization of the conjugate was not required for cytotoxic effects. Administration of non-thermal red light to the target cells bound with the conjugate led to morphologic changes and membrane disruption within minutes, and necrotic cell death was observed in a conjugate- and light-dose dependent manner. Requirement of conjugate binding to the cancer antigen provided high level of tumor specificity as demonstrated by lack of damage to normal surrounding tissue after PIT treatment. Light excitation of the conjugate generated 1O2 with high quantum yield. In vitro PIT treatment led to cell membrane lipid peroxidation, mediated by 1O2 as shown by abrogation with sodium azide, a selective 1O2 quencher. In addition, protein oxidation, cross-linking and aggregation of the conjugate was observed. In low oxygen concentrations and in the presence of ascorbate, photo-induced dissociation of axial ligands from the dye was detected. CONCLUSIONS: These studies suggest the molecular mechanism of action of PIT includes generation of 1O2 that leads to lipid peroxidation and cell membrane disruption. Additional mechanisms may include protein oxidation and non-oxygen dependent mechanisms such as axial ligand loss of the IR700 dye. These results describe a biophysical process that damages and disrupts the cell membrane integrity resulting in necrotic cell death and immunogenic cell death. Citation Format: Roger Heim, Lew Makings, Torsten Wiemann, Anthony Manibusan, Miguel Garcia-Guzman. Molecular mechanism of action of photoimmunotherapy with antibody-IR700 dye conjugates [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 480.

Phase 1 study of RM-1929 photoimmunotherapy in Japanese patients with recurrent head and neck squamous cell carcinoma

Abstract INTRODUCTION Photoimmunotherapy (PIT) is a novel cancer-targeted platform technology that utilizes monoclonal antibodies conjugated to a dye that can be activated with 690 nm nonthermal red light. PIT using RM-1929, consisting of the EGFR-directed monoclonal antibody cetuximab conjugated to a dye (IRDye 700DX), demonstrated promising clinical activity with overall response rate of 44.8%, median PFS of 5.7 months and median OS of 9.5 months in patients with recurrent head and neck squamous cell carcinoma (rHNSCC) in a phase 2a study with 30 patients (Gillenwater, ASCO 2018). METHODS The objectives of this phase 1 single-center, open-label, study were to evaluate the safety and objective response with RM-1929 PIT in Japanese patients with rHNSCC, who in the opinion of their physician, could not be satisfactorily treated with surgery, radiation, or platinum-based chemotherapy. Patients received a single fixed dose of RM-1929 (640 mg/m2) followed by tumor illumination with nonthermal red light, 24 hours after RM-1929 administration. Primary endpoint was safety of a single treatment of RM-1929 PIT. RESULTS Three female patients were enrolled in the study and received RM-1929 PIT. Median age was 68 (53-74). All patients failed more than 3 lines of prior therapy. Tumor sites included gums, temporal and cervical lymph nodes. All patients experienced edema and pain at the light application site. A Grade 3 application site pain treatment-emergent adverse event occurred in one patient. There were no serious adverse events, treatment discontinuation, or treatment-related deaths. Objective response based on modified RECIST 1.1 by central leader was observed in 2 patients. CONCLUSION RM-1929 PIT was well tolerated in 3 Japanese patients with rHNSCC. Preliminary efficacy data showed promising activity, and further investigation of this novel therapeutic strategy is warranted in an ongoing phase 3 clinical trial (NCT02422979).

1137P - Integrated data review evaluating safety, pharmacokinetics (PK) and immunogenicity of RM-1929 photoimmunotherapy (PIT) in subjects with locoregional, recurrent head and neck squamous cell carcinoma (rHNSCC)

BackgroundRM-1929 photoimmunotherapy (PIT) consists of the EGFR-directed antibody cetuximab conjugated to a dye (IRDye® 700DX). Binding of the antibody-dye conjugate to cancer cells followed by photoactivation with non-thermal red light induces selective and rapid tumour cell death. MethodsAn integrated analysis of safety, PK, and immunogenicity was conducted in subjects with rHNSCC who received RM-1929 PIT in Phase 1 and Phase 1/2a trials. ResultsForty-one subjects were treated with RM-1929 PIT. There were no dose-limiting toxicities or clinically significant shifts in chemistry, hematology, or ECGs. The observed TEAEs by grade were: Grade 1 – 97.6% (40/41); Grade 2 – 85.4% (35/41); Grade 3 – 58.5% (24/41); Grade 4 – 12.2% (5/41); and Grade 5 – 7.3% (3/41). The most frequent TEAEs (>15% incidence) included fatigue, application site pain, dysphagia, constipation, cough, erythema, and face edema. Three photosensitivity reactions were observed. All Grade 4 TEAEs (anemia, myocardial infarction, sepsis, hypoglycemia, tumor hemorrhage, obstructive airway and pneumothorax) resolved. 41.5% (17/41) of subjects experienced SAEs, while 12.2% (5/41) were considered treatment related SAEs (oral pain, tumor pain, obstructive airways disorder, and tumor hemorrhage-non fatal). Three subjects experienced SAEs that led to death (pneumonia, tumor hemorrhage, and arterial hemorrhage) that were considered unrelated to treatment due to the late onset of the events. PK analysis showed that RM-1929 exposure (AUC) increased with escalating doses in a dose proportional manner. At 640mg/m2 RM-1929 dose, AUC reaches a range expected to achieve full saturation of EGFR binding in tissues when compared to a single 250mg/m2 dose of Erbitux. In subsequent cycles, the mean CL, Vss and T1/2 estimates appeared comparable to those in Cycle 1. Immunogenicity (anti-drug antibody) was detected in 9.5% (4/42) of subjects, 3 of which emerged post-treatment. ConclusionsThe integrated clinical safety data indicated that RM-1929 PIT treatment had a favorable safety profile with no unexpected safety concerns. Clinical trial identificationNCT02422979. Legal entity responsible for the studyRakuten Medical, Inc. FundingRakuten Medical, Inc. DisclosureJ.M. Johnson: Advisory / Consultancy: Foundation Medicine; Research grant / Funding (institution): BMS; Research grant / Funding (institution): Merck; Research grant / Funding (institution): AstraZeneca. J.M. Curry: Research grant / Funding (institution): AstraZeneca. S.T. Kochuparambil: Shareholder / Stockholder / Stock options, Full / Part-time employment: Minnesota Hematology Oncology; Advisory / Consultancy: BMS. D.R. McDonald: Travel / Accommodation / Expenses, Formerly Rakuten Aspyrian: Rakuten Medical, Inc. M.J. Fidler: Advisory / Consultancy, Speaker Bureau / Expert testimony: Genentech; Advisory / Consultancy: AbbVie; Advisory / Consultancy: Guardant Health; Honoraria (self), Advisory / Consultancy: AstraZeneca; Speaker Bureau / Expert testimony: Merck; Research grant / Funding (self): Biodesix. N.R. Vasan: Leadership role, Travel / Accommodation / Expenses, Shareholder / Stockholder / Stock options, Licensing / Royalties: Adroit Surgical, LLC. M.A. Razaq: Shareholder / Stockholder / Stock options: AbbVie; Honoraria (self), Speaker Bureau / Expert testimony, Travel / Accommodation / Expenses: Merck; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses, previously Rakuten Aspyrian: Rakuten Medical. M. Tahara: Honoraria (self): Merck Serono; Honoraria (self), Advisory / Consultancy, Research grant / Funding (self): BMS; Honoraria (self): Eisai; Honoraria (self), Advisory / Consultancy, Research grant / Funding (self): Ono Pharmaceuticals; Advisory / Consultancy, Research grant / Funding (self): MSD; Advisory / Consultancy: Pfizer; Advisory / Consultancy, (previously Rakuten Aspyrian): Rakuten Medical; Research grant / Funding (self): Loxo; Research grant / Funding (self): Novartis. M.A. Biel: Leadership role, Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc. M. Tello: Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc. M. Garcia-Guzman: Leadership role, Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc. E. Sun: Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc. A.M. Gillenwater: Advisory / Consultancy: Sanofi; Advisory / Consultancy: Masimo; Advisory / Consultancy: Novartis; Travel / Accommodation / Expenses, Previously Rakuten Aspyrian: Rakuten Medical, Inc.; Travel / Accommodation / Expenses: IAOO Conference. All other authors have declared no conflicts of interest.

1161P - Intratumoral and peripheral exploratory biomarker analysis in patients with locoregional, recurrent head and neck squamous cell carcinoma (rHNSCC) treated with RM-1929 photoimmunotherapy

BackgroundPhotoimmunotherapy (PIT) is a platform technology that utilizes a photoactivatable dye conjugated to a cancer-targeting antibody. RM-1929 is composed of anti-EGFR antibody cetuximab and IRDye® 700DX. Binding of RM-1929 to EGFR followed by tumor illumination with non-thermal red light elicits rapid necrosis of EGFR-expressing cancer cells. RM-1929 PIT treatment was evaluated in a Phase 1/2a trial in patients with rHNSCC who failed multiple standard of care therapies, and demonstrated a favorable safety profile and resulted in positive response rates (Cognetti et al. ASCO 2019). Here we report preliminary data from exploratory biomarker studies from this study. MethodsPhase 1 included 9 patients and Phase 2a cohort 30 patients. Pre-treatment biopsies and blood were collected within 12 months and 2 weeks prior to treatment, respectively. Post-treatment biopsies and blood samples were collected after cycle 1 and multiple time points during treatment cycles, respectively. EGFR and PD-L1 IHC expression and plasma cytokines levels were measured. PBMCs were phenotyped using innate and adaptive immune-marker panels. ResultsIn 25 patients with pre-treatment biopsies, no trend was observed between EGFR expression and best target tumour response. In 12 patients for which pre- and post-treatment biopsies were available, EGFR expression was maintained in residual tumour after RM-1929 PIT treatment. Additionally, treatment was associated with induction of PD-L1 expression in tumour and immune cells in 10 out of 12 cases. In 13 samples tested, elevated baseline plasma cytokine levels were observed in 4 of 7 responders (3 of 4 CR and 1 of 3 PR) and 1 of 6 non-responders (1 of 5 SD and 0 of 1 PD). Immunophenotyping of whole blood showed systemic induction of innate and adaptive immunity (e.g. NK cells, cytokines, lymphocytes, monocytes, CD4 and CD8 T-cells) after treatment in 15 of 18 patients. ConclusionsBiomarker analysis in this limited data set provided evidence of potential activation of innate and adaptive immunity following RM-1929 PIT treatment. Further evaluation of these biomarkers will be conducted in a Phase 3 trial (NCT03769506). Clinical trial identificationNCT02422979. Legal entity responsible for the studyRakuten Medical, Inc. FundingRakuten Medical, Inc. DisclosureJ.D. Bui: Advisory / Consultancy: Rakuten Medical, Inc.; Advisory / Consultancy, Research grant / Funding (self): Ignyta, Inc.; Shareholder / Stockholder / Stock options: Paramita Therapeutics. N. Suslov: Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc. D. Yadav: Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc. J. Fong: Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc. E. Sun: Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc. M. Haedo: Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc. M. Garcia-Guzman: Leadership role, Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc.

Abstract 3734: Cancer cell-targeted photoimmunotherapy elicits immunogenic cell death and activates the innate and adaptive immune response in the tumor microenvironment

Abstract INTRODUCTION: Cancer cell-targeted photoimmunotherapy (PIT) is a platform technology under development for the treatment of various cancers. PIT is a drug + device combination that utilizes monoclonal antibodies conjugated to a dye (IRDye 700DX) that are activated with nonthermal red light illumination to induce rapid cell death by necrosis. Binding of the antibody-dye conjugate to cancer cells followed by photoactivation with nonthermal red light elicits rapid necrosis of the cancer cells bound to the antibody conjugate, providing very high cancer cell specificity. Given the rapid cell necrosis induced by PIT treatment, we hypothesized that PIT also induces immunogenic cell death (ICD) as a step to activate immune cells in the tumor microenvironment. The objective of this study was to evaluate, through in vitro and in vivo experiments, whether PIT results in ICD of targeted cancer cells and activation of the innate and adaptive immune response. METHODS: Human cancer cells (A431 and FaDu cells) were targeted by PIT, and evaluated for ICD markers in vitro. Human dendritic cells exposed to supernatants of PIT-killed cancer cells were evaluated for activation markers and cytokine production. An immunocompetent mouse model for PIT was also developed to determine intratumoral immune activation after treatment with PIT. RESULTS: After photoactivation, PIT-targeted human cancer cells upregulated cell surface ICD markers Hsp70, Hsp90, and calreticulin, as well as release of intracellular HMGB1. Human dendritic cells exposed to PIT-killed cell supernatants exhibited markers of immune activation (CD86 and MHCII), and secreted proinflammatory cytokines including TNF, IP-10, IL-1β, MIP-1a, MIP-1b, and IL-8. In an immunocompetent mouse model, tumors treated by PIT displayed increased percentage of intratumoral CD11c+ dendritic cells with activation markers MHCIIhigh, CD80, and PD-L1. In addition, intratumoral natural killer cells from PIT treated tumors displayed increased cytotoxic activity (CD3-DX5+CD69+ and CD3-DX5+CD107a+), as well as an increased population of total CD3+ CD8+ T cells, compared to non-PIT treated tumors. CONCLUSION: Cancer cells killed by PIT undergo ICD, which results in the activation of intratumoral innate and adaptive immune response in a preclinical mouse model. Combination studies with PIT and immune modulators are warranted to explore potential synergistic anticancer effects. Citation Format: Michelle A. Hsu, Stephanie M. Okamura, Daniele M. Bergeron, Deepak Yadav, Jerry J. Fong, Roger Heim, Miguel Garcia-Guzman. Cancer cell-targeted photoimmunotherapy elicits immunogenic cell death and activates the innate and adaptive immune response in the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3734.

Abstract 2255: Combination treatment of cancer cell-targeted photoimmunotherapy plus anti-PD1 leads to synergistic anticancer activity in an immunocompetent mouse model

Abstract INTRODUCTION: Photoimmunotherapy (PIT) is a new cancer-targeted platform technology that utilizes a photoactivatable dye (IRDye 700DX) conjugated to a cancer-targeting antibody. Binding of the antibody- dye conjugate to cancer cells followed by photoactivation with nonthermal red light elicits rapid necrosis of the cancer cells bound to the antibody conjugate. In previous studies using immunocompetent mouse models, intratumoral innate and adaptive immune cell activation was observed after PIT treatment. We hypothesized that combination therapy with PIT plus anti-PD1 may enhance the activity of anticancer immune activation elicited by PIT treatments and in this study we evaluated the effects of the combination treatment in an immunocompetent mouse model. METHODS: Immunocompetent mice implanted with CT26 tumor cells engineered to overexpress specific recombinant mouse antigens, received PIT treatment alone, anti-PD1, or combination therapy and were assessed for tumor growth inhibition and complete response rate. In animals achieving a complete response, the specificity of the response was evaluated by tumor re-challenge experiments. Animals with residual disease had their tumors excised and assessed for intratumoral immune activation. Splenocytes from treated animals were harvested and evaluated for cytotoxic activity against the cancer cells. RESULTS: Of the mice that received combination treatment, 7 of 14 achieved complete response compared to 0 of 14 and 1 of 14 when treated with anti-PD1 monotherapy and PIT monotherapy, respectively. All tumor-free animals from combination treatment also rejected formation of new tumors following inoculation with the same tumor type (CT26), but not tumors from a different cancer cell type (4T1). Splenocytes derived from animals that received combination treatment had the greatest cytotoxic activity against CT26 cells when compared to single agent controls. In addition, splenocytes derived from animals that received combination treatment had increased total CD3+ CD8+ cells, as well as increased CD62L-CD44+ effector memory CD8+ cells, in comparison to splenocytes derived from animals that received single agent therapies. CONCLUSION: In this study, combination cancer-targeted PIT plus anti-PD1 treatment in immunocompetent mice resulted in synergistic anticancer activity due to enhanced adaptive immune activation, as demonstrated by tumor rejection and increased systemic, tumor-specific cytotoxic T cells, and effector memory CD8+ cells. The results of this study warrant the clinical evaluation of combination treatment of cancer-targeted PIT plus anti-PD1 therapies. Citation Format: Stephanie M. Okamura, Michelle A. Hsu, Daniele M. Bergeron, Estela Solis, Deepak Yadav, Jerry J. Fong, Roger Heim, Miguel Garcia-Guzman. Combination treatment of cancer cell-targeted photoimmunotherapy plus anti-PD1 leads to synergistic anticancer activity in an immunocompetent mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2255.

Results of a phase 2a, multicenter, open-label, study of RM-1929 photoimmunotherapy (PIT) in patients with locoregional, recurrent head and neck squamous cell carcinoma (rHNSCC).

6014 Background: Patients with rHNSCC who have failed standard of care have poor prognoses and limited therapeutic options. In this study, final results are reported of a phase 2a trial of photoimmunotherapy (PIT) with a targeted drug RM-1929, consisting of the EGFR-directed antibody cetuximab conjugated to a photoactivatable dye (IRDye 700DX). Binding of the antibody-dye conjugate to cancer cells followed by photoactivation with nonthermal red light induces selective and rapid necrosis of the cancer cells, with minimal damage to surrounding tissue. Methods: A phase 2a, multicenter, open-label, study of RM-1929 PIT in patients with locoregional, rHNSCC who could not be satisfactorily treated with surgery, radiation, or platinum chemotherapy was conducted to evaluate the safety and efficacy of the drug, RM-1929. For each treatment, nonthermal red light (690 nm) was applied to the tumors 24 hours post IV infusion of the drug. Surface illumination was administered for superficial tumors and interstitial illumination via intratumoral placement of fiber optic diffusers for deep tumors. Therapeutic response was assessed using CT RECIST 1.1 by an independent blinded radiologist. Results: Thirty rHNSCC patients were enrolled. There were no dose-limiting toxicities and one Grade 1 photosensitivity reaction. Most reported AEs were mild to moderate in severity with 96.7% (29/30) of patients with Grade 1 and 83.3% (25/30) with Grade 2, respectively. There were 13 (43.3%) patients who had at least one SAE. 86% (19/22) of SAEs were deemed unlikely related to treatment, including all 3 fatal SAEs. Three SAEs were reported to be possibly/probably related to treatment (site/oral pain, tumor hemorrhage, and airway obstruction). ORR was 50% (15/30) with 16.7% (5/30) CR and 86.7% (26/30) DCR. Median PFS and OS results will be forthcoming. Conclusions: These data indicate that RM-1929 PIT treatment was generally well tolerated with majority of AEs as mild to moderate in severity. Preliminary data showed favorable response rates in a heavily pre-treated population. A global phase 3 clinical trial is currently underway. Clinical trial information: NCT02422979.

A global phase III multicenter, randomized, double-arm, open label trial of ASP-1929 photoimmunotherapy versus physician’s choice standard of care for the treatment of patients with locoregional, recurrent head and neck squamous cell carcinoma (rHNSCC).

TPS6094 Background: rHNSCC commonly affects local or regional sites and is associated with considerable morbidity and mortality. Outcomes of these patients remain poor with limited curative treatment options and low response rates. New modalities that are targeted, minimally invasive, and provide improved tumor response and control while having limited systemic side effects are needed. Photoimmunotherapy (PIT) is a new cancer-targeted platform technology. It is a combination drug and device treatment that utilizes monoclonal antibodies conjugated to a dye (IRDye 700DX) that is photoactivated using nonthermal red light to induce rapid and selective tumor cell death. The objective of this phase 3 study is to evaluate the efficacy and safety of ASP-1929 (EGFR-directed antibody cetuximab-IR700 conjugate) PIT treatment as a monotherapy in patients with locoregional rHNSCC. Methods: A global, multicenter phase 3, randomized, double-arm, open-label, controlled trial of ASP-1929 PIT vs physician’s choice standard of care (SOC) for the treatment of locoregional, rHNSCC in patients who have failed or progressed on or after at least two lines of therapy, of which at least one line must be systemic therapy, is currently underway. Primary endpoints of the study are PFS and OS and the key secondary endpoint is ORR. Key inclusion criteria include: disease not amenable to curative therapy; tumor(s) accessible for PIT light treatment and measurable by CT or MRI; male or female ≥ 18 yrs old with life expectancy > 6 months; ECOG score of 0 to 1. Key exclusion criteria include: history of ≥ Grade 3 cetuximab infusion reaction; distant metastatic disease; tumors invading a major blood vessel unless embolized. The study will include ~275 subjects in a 2:1 randomization (ASP-1929 PIT: Physician’s choice SOC). The physician’s choice SOC arm includes cetuximab, methotrexate, or docetaxel. Tumor(s) are illuminated with 690 nm PIT light treatment 24 hrs following completion of ASP-1929 infusion (640 mg/m²). Clinical trial sites will be in the USA, EU and Asia. Clinical trial information: NCT03769506.

A Phase 2a, Multicenter, Open-Label Study of RM-1929 Photoimmunotherapy in Patients With Recurrent Head And Neck Cancer

Patients with recurrent head and neck squamous cell cancer (rHNSCC) have poor prognoses and limited treatment options after they have failed standard therapies. We are investigating photoimmunotherapy (PIT) for the treatment of rHNSCC using a novel targeted light-activated drug conjugate RM1929, consisting of the EGFR-directed monoclonal antibody cetuximab conjugated to the phthalocyanine dye, IRDye 700DX. This is a multi-institutional open-label Phase 2a study of rHNSCC patients who cannot be satisfactorily treated with surgery, radiation, or platinum chemotherapy. PIT, using a previously determined optimal drug dose and light treatment dose, was performed to evaluate the safety and efficacy associated with repeat dosing of up to 4 treatment cycles, 4-8 weeks apart, in patients with persistence of disease. For each treatment, nonthermal red light was applied to the tumors 24 hours after intravenous infusion of the photoactivated conjugate. The light was applied on the surface for superficial mucosal/cutaneous disease or within the tumor (via fiber optic diffusers placed by ultrasound guidance) for submucosal/subcutaneous or nodal disease. Responses and Progression-Free Survival (PFS) were calculated using CT RECIST 1.1. All CT RECIST 1.1 measurements were determined by an independent blinded radiologist. Nineteen patients with rHNSCC who were treated with RM-1929 PIT and have been followed for at least 3 months were included in the outcome analysis. There were no dose-limiting toxicities or skin photosensitivity reactions observed. No toxicity was noted for normal tissues exposed to therapeutic light treatment. Two reported SAEs, tumor hemorrhage and tumor pain, were assessed as possibly or probably related to treatment. CT RECIST 1.1 demonstrated a PFS of 153 days (5.1 months). Objective response rate (ORR), complete response (CR) and disease control rate (DCR) by CT RECIST 1.1 were 42% (8/19), 26% (5/19) and 84% (16/19) respectively. Photoimmunotherapy with RM1929 in patients with rHNSCC is safe and well-tolerated. CT RECIST 1.1 PFS, ORR, and CR response rates are improved over those of standard of care therapies and encouraging in these patients who have failed standard therapies and have typically recalcitrant disease. Further investigation of this novel therapeutic strategy is warranted and a Phase 3 clinical trial is planned.

Mono- and tri-cationic porphyrin-monoclonal antibody conjugates: photodynamic activity and mechanism of action

Two cationic porphyrins bearing an isothiocyanate group for conjugation to monocolonal antibodies have been synthesized. The two porphyrins conjugated efficiently to three monoclonal antibodies (anti-CD104, anti-CD146 and anti-CD326), which recognize antigens commonly over-expressed on a range of tumour cells. In vitro, all conjugates retained the phototoxicity of the porphyrin and the immunoreactivity of the antibody. Mechanistic studies showed that conjugates formed from the mono- and tri-cationic porphyrin and anti-CD104 antibody mediated apoptosis following irradiation with non-thermal red light of 630 ± 15 nm wavelength. In vivo antibody conjugates caused suppression of human LoVo tumour growth in immunodeficient NIH III mice, similar to the commercial photodynamic therapy (PDT) agent Photofrin®, but at administered photosensitizer doses that were more than two orders of magnitude lower. Positron emission tomography (PET) following PDT showed a large, early increase in uptake of 18fluorodeoxyglucose (FDG) by tumours treated with the anti-CD104 conjugates. This effect was not observed with Photofrin® or with conjugates formed from the same photosensitizers conjugated to an irrelevant antibody.

Lack of Effect of Sex and Disease State on the Pharmacokinetics of Porfimer Sodium

Porfimer sodium is an agent used for photodynamic therapy (PDT) of cancer and other pre-malignant conditions such as high grade dysplasia in Barrett's oesophagus. Since it is activated by non-thermal red light after a 2-day time interval to allow distribution in the target tissues, its pharmacokinetic properties are relevant to the timing of light treatment and to the period of protection against photosensitivity reactions. With the recent availability of a reliable assay overcoming the limitations of previous assays, two definitive pharmacokinetic studies were undertaken. To determine if sex or a target disease state (cancer) have an effect on porfimer sodium pharmacokinetic parameters. Twenty-four healthy volunteers (12 men and 12 women) and five male patients with oesophageal cancer undergoing palliative PDT for their obstructive lesions were enrolled. All received an intravenous injection of porfimer sodium (Photofrin) 2 mg/kg over 3-5 minutes and underwent serial blood samplings over 35 days postdose. Porfimer sodium was quantified in serum by a validated spectrofluorometry assay and low-level pre-existing interference was subtracted from postdose concentrations. The two sexes had comparable maximum serum concentrations with a ratio of 0.95. Women tended to have higher areas under the serum concentration-time curve from time zero to the last sampling time, and from time zero to infinity than men, but the difference did not reach significance (ratios of means of 1.18 and 1.20, respectively). Elimination parameters also showed no sex-related differences with a mean distribution half-life of 9.5 hours, clearance of 0.88 mL/h/kg and a terminal elimination half-life of 415 hours (17.3 days). The sexes only differed significantly for the time to reach maximum serum concentration (means of 1.54 and 0.165 hours, for women and men, respectively; p = 0.0239). This is probably because of the sparse sampling schedule and the plateau behaviour of the initial concentrations. The pharmacokinetic parameters in cancer patients were generally comparable to healthy volunteers. However, the mean terminal elimination half-life was 30% shorter (283 hours or 11.8 days) in cancer patients. Sex does not have an effect on porfimer sodium pharmacokinetics. The presence of advanced oesophageal cancer does not seem to have any influence either. These findings confirm that there is no need for sex-specific label recommendations. Also, the elimination phase of porfimer sodium starting progressively from 24 hours postdose supports the recommended time interval for laser light application, the window for PDT debridement and the skin protection period of at least 30 days.

Verteporfin for age-related macular degeneration.

To review the pharmacology, pharmacokinetics, clinical efficacy, adverse effects, drug-drug interactions, and the therapeutic issues concerning the use of verteporfin in patients with age-related macular degeneration (AMD). Published articles and abstracts in English were identified by MEDLINE (1990-August 2000) searches using the search terms verteporfin, treatment of age-related macular degeneration, and photodynamic therapy (PDT). Additional references were identified from the bibliographies of the retrieved articles. Data were also obtained from approved product labeling. The literature was assessed for adequate description of patients, methodology, and outcomes. Verteporfin is a synthetic benzoporphyrin derivative and a cytotoxic photosensitizing agent, which is one component of PDT. PDT involves administration of verteporfin for injection and nonthermal red light at a wavelength of 689 nm. It is metabolized, to a small extent, to its diacid metabolite by liver and plasma esterases. Information concerning drug interactions is limited. In clinical trials, verteporfin was effective in patients with wet AMD as demonstrated in standard visual acuity scores. Adverse events were related to injection site reactions and visual disturbances. Verteporfin is a welcome alternative to laser photocoagulation, which can result in damage to the retina and lead to visual loss. Although long-term trials have not been performed in humans, results from monkeys indicate possible improvement in vision following PDT with verteporfin.