Selective STAT3 Degraders Dissect Peripheral T-Cell Lymphomas Vulnerabilities Empowering Personalized Regimens

Introduction: Peripheral T-cell lymphomas (PTCLs) include heterogeneous entities of rare and aggressive neoplasms. The improved understanding of the biological/molecular mechanisms driving T-cell transformation and tumor maintenance has powerfully propelled new therapeutic programs. However, despite this progress, PTCLs remain an unmet medical need. Recurrent aberrations and the deregulated activation of distinct signaling pathways have been mapped and linked to selective subtypes. The JAK/STAT signaling pathway's deregulated activation plays a pathogenetic role in PTCL, including ALCL subtypes. STATs regulate the differentiation/phenotype, survival and cell-growth, metabolism, and drug resistance of T-cell lymphomas as well as host immunosuppressive microenvironments. Although many drugs' discovery programs were launched, a plethora of compounds has failed. Methods: We have discovered heterobifunctional molecules by an iterative medicinal chemistry SAR campaign that potently and selectively degrade STAT3 in a proteasome-dependent manner. Conventional PTCL cell lines and Patient Derived Tumor Xenograft (PDTX) and/or derived cell lines (PDTX-CL), carrying either WT- or mutated-STAT3, were exposed to increasing amounts (50nM⇒5µM) of STAT3-degraders. Proteins and mRNA transcripts (2⇒144hrs) were assessed by deep-proteomics and paired-end RNA sequencing, combined with WB/flow cytometry and qRT-PCR. Cell-titer-glo, cell titer blue, Annexin-V and S-cell cycle analyses were used as readouts. Chromatin accessibility, STAT3 DNA binding, 3D chromosomal architecture reorganization and 5-hmC profiling were assessed by ATACseq, CHIPseq and Hi-C and H3K27ac Hi-CHIP and mass-spectrometry. Drug testing/discovery combinations (96-well-plate) were performed using a semi-automated flow-cytometry. A battery of PTCL PDTX models were tested in pre-clinical trials. Results: Treatment of ALK+ ALCL (SU-DHL1) led to the rapid (~6hrs.) and profound down-regulation of STAT3 followed by the loss of canonical STAT3-regulated proteins (SOCS3, MYC, Granzyme B, GAS1, and IL2RA), without appreciable changes for other STAT family members (STAT1, STAT5b). In vitro, cytoplasmic, nuclear, and mitochondrial STAT3 downregulation was maintained up to 144 hrs. Loss of STAT3 in ALK+/- ALCL and BIA-ALCL cells was associated with major transcriptional changes (7116-10615 and 15114 DEGs in ALK- and ALK+ ALCL, respectively), underscoring public/shared as well as private time-dependent signatures. Main down-regulated pathways included JAK-STAT, MAPK, NF-kB, PI3K, TGFb, and TNFa. Comparison of STAT3 shRNA (ALK+ ALCL) and STAT3 degrader (ALK-/ALK+ ALCL) signatures demonstrated a substantial and concordant gene modulation (24hrs) among all models with the highest overlaps between ALK+ ALCL (Figure 3). To identify direct STAT3 gene targets, we analyzed CHIPseq peaks and predicted bindings sites, demonstrating that canonical genes, i.e., SOCS3, Granzyme B, GAS1, IL2RA, STAT3, and CD30, were significantly downregulated. Conversely, CD58, CD274, and MCH-I/II were upregulated at late time points. By mapping the STAT3 binding sites in ALK+ and ALK- ALCL, we have identified 1077 and 2763 STAT3 peaks within promoter/5'-/3'- and distant intergenic regions, corresponding to both coding and non-coding genes. Therapeutically, in vitro treatments led to cell cycle arrest and profound growth inhibition, and over time increased cell death of PTCL cells, including ALCL. Accordingly, growth inhibition of ALCL xenograft and PDTX tumors was also achieved (Figure 2). To identify drugs that could synergize withSTAT3-degrader activity, we tested a compound library (40) targeting pro-tumorigenic PTCL pathways as well as FDA-approved compounds. Ongoing studies are in progress. Conclusion: We have discovered selective STAT3 degraders which control PTCL growth. STAT3 degraders are powerful tools to define the STAT3 pathogenetic mechanisms and dissect genes/pathways to be targeted for T-cell lymphoma eradication. These data provide additional rationale for testing STAT3 degraders in the clinic for the treatment of aggressive malignancies including PTCL/ALCL. Figure 1 Figure 1. Disclosures Yang: Kymera Therapeutics: Current Employment, Current equity holder in publicly-traded company. Sharma: Kymera Therapeutics: Current Employment, Current equity holder in publicly-traded company. Dey: Kymera Therapeutics: Current Employment, Current equity holder in publicly-traded company. Karnik: Kymera Therapeutics: Current Employment, Current equity holder in publicly-traded company. Elemento: Owkin: Consultancy, Other: Current equity holder; Volastra Therapeutics: Consultancy, Other: Current equity holder, Research Funding; Johnson and Johnson: Research Funding; Eli Lilly: Research Funding; Janssen: Research Funding; Champions Oncology: Consultancy; Freenome: Consultancy, Other: Current equity holder in a privately-held company; One Three Biotech: Consultancy, Other: Current equity holder; AstraZeneca: Research Funding. Horwitz: Affimed: Research Funding; Aileron: Research Funding; ADC Therapeutics, Affimed, Aileron, Celgene, Daiichi Sankyo, Forty Seven, Inc., Kyowa Hakko Kirin, Millennium /Takeda, Seattle Genetics, Trillium Therapeutics, and Verastem/SecuraBio.: Consultancy, Research Funding; Acrotech Biopharma, Affimed, ADC Therapeutics, Astex, Merck, Portola Pharma, C4 Therapeutics, Celgene, Janssen, Kura Oncology, Kyowa Hakko Kirin, Myeloid Therapeutics, ONO Pharmaceuticals, Seattle Genetics, Shoreline Biosciences, Inc, Takeda, Trillium Th: Consultancy; Celgene: Research Funding; C4 Therapeutics: Consultancy; Crispr Therapeutics: Research Funding; Daiichi Sankyo: Research Funding; Forty Seven, Inc.: Research Funding; Kura Oncology: Consultancy; Kyowa Hakko Kirin: Consultancy, Research Funding; Millennium/Takeda: Research Funding; Myeloid Therapeutics: Consultancy; ONO Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy, Research Funding; Secura Bio: Consultancy; Shoreline Biosciences, Inc.: Consultancy; Takeda: Consultancy; Trillium Therapeutics: Consultancy, Research Funding; Tubulis: Consultancy; Verastem/Securabio: Research Funding. DeSavi: Kymera Therapeutics: Current Employment, Current equity holder in publicly-traded company. Liu: Kymera Therapeutics: Current Employment, Current equity holder in publicly-traded company.

A Pilot Study Using Nivolumab in Combination with Standard of Care Chemotherapy in Newly Diagnosed Peripheral T-Cell Lymphomas

Introduction: The chemotherapy regimen dose adjusted (DA)-EPOCH (etoposide, prednisone, vincristine, doxorubicin, and cyclophosphamide) is a first line option for peripheral T-cell lymphomas (PTCLs), but for most subtypes relapses are common and long-term outcomes are poor. Checkpoint blockade is an immunotherapeutic approach that has shown efficacy as a single agent in relapsed PTCLs. The combination of checkpoint blockade and cytotoxic chemotherapy can have additive or synergistic activity by increasing the expression of neoantigens and overcoming mechanisms of resistance to immunotherapy such as weak tumor immunogenicity and an immune suppressive tumor microenvironment. Methods: We conducted a single arm, open-label clinical trial evaluating the efficacy and safety of the anti-PD1 antibody nivolumab (Nivo) in combination with DA-EPOCH in newly diagnosed PTCLs with ≥Stage II disease by Ann Arbor criteria. Pts were allowed to receive one cycle of chemotherapy prior to enrollment. Pts received Nivo (360 mg) followed by DA-EPOCH every 21 days for a planned six cycles unless treatment was stopped early for progression. For any immune related adverse event (irAE), Nivo was held until resolution to grade 1 and on ≤10mg prednisone. For serious grade 3-4 irAEs, Nivo was omitted with remaining DA-EPOCH cycles. DA-EPOCH was dose adjusted according to CALGB 50303 with the exception that pts could begin treatment at dose level -1 (i.e. 600 mg/m2 cyclophosphamide), at investigator's discretion. Pts who received one cycle of chemotherapy prior to enrollment received five cycles of Nivo + DA-EPOCH. After completing six cycles of chemotherapy, pts had the option to proceed with consolidative autologous stem cell transplant (ASCT) versus surveillance, according to patient/physician preference. Responses were assessed by PET/CT after 2 cycles of Nivo + DA-EPOCH and after the last cycle, using RECIL criteria. PFS events were defined as start of new treatment, progression, or death. Targeted next generation sequencing and multiplex immunohistochemistry of diagnostic tumor tissue are being performed. Results: We enrolled 18 pts: 4 angioimmunoblastic TCLs, 2 nodal PTCLs with T-follicular helper phenotype, 7 PTCL-NOS (not otherwise specified), 2 primary cutaneous gamma delta TCLs, 2 ALK negative anaplastic large cell lymphomas, and 1 subcutaneous panniculitis-like TCL who had progressed on methotrexate. Median age was 66 (range 43-77). International Prognostic Index (IPI) was high (4-5) in 50% (N=9), intermediate (2-3) in 33% (N=6), and low in 17% (N=3) of pts. Immune related AEs of all grades occurred in 78% (N=14) of pts and 39% (N=7) of pts experienced ≥grade 3 irAEs. 44% (N=8) of pts required discontinuation of Nivo due to irAEs. In the 8 pts whose irAEs resulted in discontinuation of Nivo, the irAE occurred prior to the second or third cycle of Nivo + DA-EPOCH. None of the 6 pts who received a cycle of anthracycline based chemotherapy prior to enrolling on trial experienced an irAE resulting in dose hold or discontinuation of Nivo, whereas 8 of 12 pts who did not receive a prior cycle of anthracycline based chemotherapy experienced an irAE requiring a dose hold or discontinuation of Nivo. The most common non-hematologic non-immune related ≥grade 2 AEs were related to infectious complications. Interim and end of induction overall response rates were 100% and 83%, respectively. We observed 10 CR, 5 PR, and 3 PD at the end of induction. There were 2 pts who received consolidation with ASCT. With a median follow up of 375 days (range 207-422), median modified PFS was 333 days (range 138-666) and median OS was not reached. The three pts with PD during induction were 2 PTCL-NOS (with a cytotoxic phenotype) and 1 AITL (with PD1+ tumor cells). Further correlative studies are ongoing to identify predictors of response. Discussion: In this pilot study using Nivo + DA-EPOCH for newly diagnosed PTCLs, we observed early immune related dose limiting AEs. Pts who received a cycle of anthracycline based chemotherapy prior to enrollment did not experience any dose limiting irAEs. We postulate that T-cell lymphoma pts are immunologically primed for irAEs, which can be mitigated by pre-treatment with chemotherapy. In a study in which half of pts were high risk by IPI, Nivo + DA-EPOCH led to encouraging high initial responses and lengthy responses in 2 PCGDTCL pts, thus warranting further investigation of this chemoimmunotherapeutic strategy. Figure 1 Figure 1. Disclosures Haverkos: Viracta Therapeutics: Consultancy. Zain: Secura Bio, DaichiSankyo, Abbvie: Research Funding; Secura Bio, Ono , Legend, Kiyowa Kirin, Myeloid Therapeutics Verastem Daichi Sankyo: Consultancy; Kiyoaw Kirin, Secura Bio, Seattle Genetics: Honoraria. Kamdar: KaryoPharm: Consultancy; Kite: Consultancy; AstraZeneca: Consultancy; Celgene (BMS): Consultancy; Adaptive Biotechnologies: Consultancy; ADC Therapeutics: Consultancy; SeaGen: Speakers Bureau; Celgene: Other; AbbVie: Consultancy; TG Therapeutics: Research Funding; Genentech: Research Funding; Genetech: Other. Smith: Syros: Research Funding; Kura: Research Funding; Argenx: Research Funding. Porcu: Viracta: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Innate Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BeiGene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Research Funding; Daiichi: Honoraria, Research Funding; Kiowa: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Spectrum: Consultancy; DrenBio: Consultancy.

Real Life Experience of Brentuximab Vedotin Plus CHP As First-Line Treatment in CD30 + Peripheral T-Cell Lymphomas

INTRODUCTION: Peripheral T-cell lymphomas (PTCL) are a heterogeneous group of lymphomas classically treated with CHOP or CHOP-like regimens, with poor outcomes. CD30 is universally expressed and is pathognomonic in systemic anaplastic large cell lymphoma (sALCL), with variable expression among non-sALCL PTCL subtypes (40-60%). Recent data of frontline treatment with Brentuximab Vedotin (BV), an anti-CD30 monoclonal antibody, plus CHOP has demonstrated significant improvement in survival (ECHELON-2 clinical trial), becoming the new standard of care for sALCL in Europe. PATIENT AND METHODS: From February 2019 to April 2021, 21 patients with de novo newly diagnosed CD30+ PTCL have been treated with the combination of BV-CHP, in the centers of the Catalan Institute of Oncology in Spain. Survival curves were plotted by the Kaplan-Meier method. RESULTS: Clinical characteristics at diagnosis are shown in the table. Of interest, 5 of the 11 ALK negative ALCL patients were diagnosed of breast implant associated ALCL (BIA-ALCL) with extracapsular involvement. The number of cycles administrated were 108, with a median of 6 cycles per patient (range 1-6), all of them with G-CSF primary prophylaxis. At the time of this report, 1 patient was still on treatment and 2 patients without the final evaluation. Seven cycles (6%) were delayed (3 due to infection, 2 due to neutropenia grade 2, and 2 due to causes not related with chemotherapy).An adverse event was reported in 45 (44%) cycles, being the most frequent peripheral neuropathy in 14, nausea/vomiting in 9 and anemia in 8; all of them grade 1-2. Treatment was discontinued after 1 cycle in 1 patient due to progression. Of the 18 evaluable patients, the overall response rate (ORR) was of 83%, with 72% complete responses and 11% partial responses. Consolidative autologous stem cell transplant (ASCT) was performed in 5 patients. With a median follow-up of 14 months (limits: 1-24), 1-year progression-free survival (PFS) and overall survival (OS) was 68.2% (95% CI 44.6-91.7) and 82.2% (95% CI 63.9-100), respectively. CONCLUSIONS: Brentuximab Vedotin plus CHP is an effective regimen for CD30 positive PTCL, with a high rate of response. This combination presents a manageable safety profile, with the majority of patients completing the planned treatment. The incidence and severity of side effects are low, being peripheral neuropathy and neutropenia the most frequent. Figure 1 Figure 1. Disclosures Eva: Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Sancho: Roche, Janssen, Celgene-BMS, Gilead, Novartis, Takeda: Honoraria, Speakers Bureau; Roche, Janssen, Celgene-BMS, Gilead, Novartis, Incyte, Beigene: Speakers Bureau. González-Barca: Janssen: Consultancy, Honoraria, Other: Travel; EUSA Pharma: Consultancy, Honoraria; Kyowa Kirin: Consultancy; Roche: Honoraria, Other: Travel; Takeda. Abbvie: Honoraria. Ribera: ARIAD: Consultancy, Research Funding, Speakers Bureau; SHIRE: Consultancy, Speakers Bureau; AMGEN: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy, Research Funding, Speakers Bureau; TAKEDA: Consultancy, Research Funding, Speakers Bureau; NOVARTIS: Consultancy, Speakers Bureau. Sureda: Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; MSD: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kite, a Gilead Company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bluebird: Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy, Honoraria, Speakers Bureau; Roche: Other: Support for attending meetings and/or travel; BMS/Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel, Speakers Bureau; Mundipharma: Consultancy; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel, Research Funding, Speakers Bureau; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.