Correlation of immune fitness with response to teclistamab in relapsed/refractory multiple myeloma in MajesTEC-1

Teclistamab, an off-the-shelf B-cell maturation antigen (BCMA) × CD3 bispecific antibody that mediates T-cell activation and subsequent lysis of BCMA-expressing myeloma cells, is approved for the treatment of patients with relapsed/refractory multiple myeloma (RRMM). As a T-cell redirection therapy, clinical outcomes with teclistamab may be influenced by patient immune fitness and tumor antigen expression. We correlated tumor characteristics and baseline immune profiles with clinical response and disease burden in patients with RRMM from the pivotal phase 1/2 MajesTEC-1 study, focusing on patients treated with 1.5 mg/kg of teclistamab (N = 165). Peripheral blood samples were collected at screening and bone marrow samples were collected at screening and cycle 3. Better clinical outcomes to teclistamab correlated with higher baseline total T-cell counts in the periphery. In addition, responders (partial response or better) had a lower proportion of immunosuppressive regulatory T cells, T cells expressing co-inhibitory receptors (CD38, PD-1, PD-1/TIM-3), and soluble BCMA, and a T-cell profile suggestive of a more cytolytic potential, compared with nonresponders. Neither frequency of baseline bone marrow BCMA expression nor BCMA receptor density were associated with clinical response to teclistamab. Improved progression-free survival was observed in patients with a lower frequency of T cells expressing exhaustion markers and immunosuppressive regulatory T cells. Overall, response to teclistamab was associated with baseline immune fitness; nonresponders had immune profiles suggestive of immune suppression and T-cell dysfunction. These findings illustrate the importance of the contribution of the immune landscape to T-cell redirection therapy response. This trial was registered at www.ClinicalTrials.gov, NCT03145181/NCT04557098.

Incidence, timing, and management of infections in patients receiving teclistamab for the treatment of relapsed/refractory multiple myeloma in the MajesTEC-1 study

BACKGROUND

Patients with relapsed/refractory multiple myeloma are at increased risk of infection. Infections during treatment with teclistamab, the first B-cell maturation antigen-directed bispecific antibody approved for triple-class-exposed relapsed/refractory multiple myeloma, was examined in the phase 1/2 MajesTEC-1 study.

METHODS

Patients (N = 165) received subcutaneous teclistamab 1.5 mg/kg weekly after a step-up dosing schedule (0.06 mg/kg and 0.3 mg/kg, each separated by 2-4 days). Patients were monitored frequently for infections; prophylaxis and management were per institutional guidelines.

RESULTS

At a median follow-up of 22.8 months (range, 0.3-33.6), infections were reported in 132 patients (80.0%). Grade 3/4 infections occurred in 91 patients (55.2%), including COVID-19 (21.2%), respiratory infections (19.4%), Pneumocystis jirovecii pneumonia (4.2%), viral infections (4.2%), and gastrointestinal infections (1.2%). Twenty-one patients died from infections (18 from COVID-19). Median time to first onset of any-grade and grade 3 to 5 infections was 1.7 and 4.2 months, respectively. Overall, 70.9% of patients had ≥1 postbaseline immunoglobulin G (IgG) level <400 mg/dL; median time to IgG <400 mg/dL was 1.2 months (range, 0.2-19.8) and 46.1% received ≥1 dose of IgG replacement. Grade 3/4 neutropenia occurred in 65.5% of patients (median time to grade ≥3 neutropenia/febrile neutropenia was 2.3 months [range, 0-18.1]).

CONCLUSION

Based on the infection profile of B-cell maturation antigen-targeted bispecific antibodies such as teclistamab, it is recommended that clinicians and patients remain vigilant for a range of infection types throughout treatment to facilitate prompt intervention. Appropriate screening, prophylaxis, and management of infections, hypogammaglobulinemia, and neutropenia are important.

CLINICAL TRIAL REGISTRATION

NCT03145181/NCT04557098 (ClinicalTrials.gov) PLAIN LANGUAGE SUMMARY: Before starting teclistamab, patients should be up to date with vaccinations (including COVID-19) and screened for hepatitis B and C and HIV. Teclistamab should not be given to patients with any active infections. Prophylactic antimicrobials should be administered per institutional guidelines. Prophylaxis for Pneumocystis jirovecii pneumonia and herpes simplex/varicella zoster virus is recommended during teclistamab treatment. Close monitoring of infections and immunoglobulin G (IgG) levels should continue throughout teclistamab treatment. IgG replacement (administered every 3-6 weeks) should be used to maintain IgG ≥400 mg/dL. Growth factors should be considered for grade ≥3 neutropenia with infection/fever and grade 4 neutropenia.

GPRC5D as a novel target for the treatment of multiple myeloma: a narrative review

Multiple myeloma is a genetically complex and heterogenous malignancy with a 5-year survival rate of approximately 60%. Despite advances in therapy, patients experience cycles of remission and relapse, with each successive line of therapy associated with poorer outcomes; therefore, therapies with different mechanisms of action against new myeloma antigens are needed. G protein-coupled receptor class C group 5 member D (GPRC5D) has emerged as a novel therapeutic target for the treatment of multiple myeloma. We review the biology and target validation of GPRC5D, and clinical data from early phase trials of GPRC5D-targeting bispecific antibodies, talquetamab and forimtamig, and chimeric antigen receptor T cell (CAR-T) therapies, MCARH109, OriCAR-017, and BMS-986393. In addition to adverse events (AEs) associated with T-cell-redirection therapies irrespective of target, a consistent pattern of dermatologic and oral AEs has been reported across several trials of GPRC5D-targeting bispecific antibodies, as well as rare cerebellar events with CAR-T therapy. Additional studies are needed to understand the underlying mechanisms involved in the development of skin- and oral-related toxicities. We review the strategies that have been used to manage these GPRC5D-related toxicities. Preliminary efficacy data showed overall response rates for GPRC5D-targeting T-cell-redirecting therapies were ≥64%; most responders achieved a very good partial response or better. Pharmacokinetics/pharmacodynamics showed that these therapies led to cytokine release and T-cell activation. In conclusion, results from early phase trials of GPRC5D-targeting T-cell-redirecting agents have shown promising efficacy and manageable safety profiles, including lower infection rates compared with B-cell maturation antigen- and Fc receptor-like protein 5-targeting bispecific antibodies. Further clinical trials, including those investigating GPRC5D-targeting T-cell-redirecting agents in combination with other anti-myeloma therapies and with different treatment modalities, may help to elucidate the future optimal treatment regimen and sequence for patients with multiple myeloma and improve survival outcomes. Video Summary.

Teclistamab: Mechanism of action, clinical, and translational science

Multiple myeloma (MM) remains incurable despite improvements in treatment options. B-cell maturation antigen (BCMA) is predominantly expressed in B-lineage cells and represents a promising new target for MM. Teclistamab (TECVAYLITM ) is the first T-cell redirecting bispecific antibody approved for patients with MM. Targeting both CD3 receptor complex on T cells and BCMA on myeloma cells, teclistamab leads to T-cell activation and subsequent lysis of BCMA+ cells. The recommended dose of teclistamab is 1.5 mg/kg subcutaneous weekly after two step-up doses of 0.06 and 0.3 mg/kg, which was selected after review of safety, efficacy, pharmacokinetic, and pharmacodynamic data. Exposure-response analyses of efficacy and safety data were also used to confirm the teclistamab dose. Teclistamab resulted in a high rate of deep and durable responses (63% overall response, 45.5% complete response or better, with 22 months median duration of response) in patients with triple-exposed relapsed/refractory MM. Common adverse reactions included cytokine release syndrome, hematologic abnormalities, and infections. Teclistamab is currently being investigated as monotherapy as well as combination therapy across different MM indications.

Population Pharmacokinetics and Exposure-Response with Teclistamab in Patients With Relapsed/Refractory Multiple Myeloma: Results From MajesTEC-1

BACKGROUND

Teclistamab, a B-cell maturation antigen × CD3 bispecific antibody, is approved in patients with relapsed/refractory multiple myeloma (RRMM) who have previously received an immunomodulatory agent, a proteasome inhibitor, and an anti-CD38 antibody.

OBJECTIVE

We report the population pharmacokinetics of teclistamab administered intravenously and subcutaneously (SC) and exposure-response relationships from the phase I/II, first-in-human, open-label, multicenter MajesTEC-1 study.

METHODS

Phase I of MajesTEC-1 consisted of dose escalation and expansion at the recommended phase II dose (RP2D; 1.5 mg/kg SC weekly, preceded by step-up doses of 0.06 and 0.3 mg/kg); phase II investigated the efficacy of teclistamab RP2D in patients with RRMM. Population pharmacokinetics and the impact of covariates on teclistamab systemic exposure were assessed using a 2-compartment model with first-order absorption for SC and parallel time-independent and time-dependent elimination pathways. Exposure-response analyses were conducted, including overall response rate (ORR), duration of response (DoR), progression-free survival (PFS), overall survival (OS), and the incidence of grade ≥ 3 anemia, neutropenia, lymphopenia, leukopenia, thrombocytopenia, and infection.

RESULTS

In total, 4840 measurable serum concentration samples from 338 pharmacokinetics-evaluable patients who received teclistamab were analyzed. The typical population value of time-independent and time-dependent clearance were 0.449 L/day and 0.547 L/day, respectively. The time-dependent clearance decreased rapidly to < 10% after 8 weeks of teclistamab treatment. Patients who discontinue teclistamab after the 13th dose are expected to have a 50% reduction from Cmax in teclistamab concentration at a median (5th to 95th percentile) time of 15 days (7-33 days) after Tmax and a 97% reduction from Cmax in teclistamab concentration at a median time of 69 days (32-163 days) after Tmax. Body weight, multiple myeloma type (immunoglobulin G vs non-immunoglobulin G), and International Staging System (ISS) stage (II vs I and III vs I) were statistically significant covariates on teclistamab pharmacokinetics; however, these covariates had no clinically relevant effect on the efficacy of teclistamab at the RP2D. Across all doses, ORR approached a plateau at the concentration range associated with RP2D, and in patients who received the RP2D, a flat exposure-response curve was observed. No apparent relationship was observed between DoR, PFS, OS, and the incidence of grade ≥3 adverse events across the predicted exposure quartiles.

CONCLUSION

Body weight, myeloma type, and ISS stage impacted systemic teclistamab exposure without any clinically relevant effect on efficacy. The exposure-response analyses for ORR showed a positive trend with increasing teclistamab systemic exposure, with a plateau at the RP2D, and there was no apparent exposure-response trend for safety or other efficacy endpoints. These analyses support the RP2D of teclistamab in patients with RRMM.

CLINICAL TRIAL REGISTRATION

NCT03145181 (phase I, 09 May 2017); NCT04557098 (phase II, 21 September 2020).

Detailed overview of incidence and management of cytokine release syndrome observed with teclistamab in the MajesTEC-1 study of patients with relapsed/refractory multiple myeloma

BACKGROUND

Teclistamab, a B-cell maturation antigen × CD3 bispecific antibody, demonstrated an overall response rate of 63.0% in 165 heavily pretreated patients with relapsed or refractory multiple myeloma in the phase 1/2 MajesTEC-1 study. Cytokine release syndrome (CRS), a known manifestation of T-cell redirection, was observed in 119 of 165 patients (72.1%).

METHODS

Patients received once-weekly teclistamab 1.5 mg/kg subcutaneously after two step-up doses (0.06 and 0.3 mg/kg). CRS was graded according to American Society for Transplantation and Cellular Therapy criteria and managed according to the study protocol, including use of tocilizumab and/or steroids.

RESULTS

Most cases of CRS occurred during the step-up dosing schedule of teclistamab and were grade 1 (50.3% of patients) or grade 2 (21.2% of patients); a single case of grade 3 CRS was reported in a patient with concurrent grade 3 pneumonia. All CRS cases resolved and none led to treatment discontinuation. Overall, 33.3% of patients had >1 CRS event; CRS recurrence was reduced when tocilizumab was administered for the first CRS event compared with when it was not (20.0% vs. 62.2%, respectively). Baseline characteristics such as tumor burden and cytokine levels did not appear to predict CRS incidence or severity.

CONCLUSIONS

Findings of this study support the need for preemptive planning and prompt management of CRS in patients treated with T-cell-engaging bispecific antibodies. Intervention with tocilizumab for CRS appears to decrease the likelihood of patients experiencing subsequent CRS events without compromising response to teclistamab.

PLAIN LANGUAGE SUMMARY

Cytokine release syndrome (CRS), observed in 72.1% of patients treated with teclistamab in the MajesTEC-1 study, was mostly grade 1 or 2 and manageable, without requiring treatment discontinuation. Most CRS occurred during the step-up schedule, requiring vigilance during treatment initiation. Ensure fever is resolved and patients have no signs of infection before initiating the teclistamab step-up schedule or administering the next teclistamab dose, to avoid exacerbating CRS. Tocilizumab reduced the risk of subsequent CRS in patients receiving it for their first CRS event (20.0% vs. 62.2% in those not receiving it), without affecting response to teclistamab. No baseline characteristics, including tumor burden or cytokine levels, appeared to clearly predict for CRS occurrence or severity.

A phase 1 study of intravenous mitazalimab, a CD40 agonistic monoclonal antibody, in patients with advanced solid tumors

Mitazalimab is an agonistic human monoclonal antibody targeting CD40, a target for anti-tumor immunotherapy. This phase 1, dose-escalation study evaluated the safety, dose-limiting toxicities (DLTs), pharmacokinetic and pharmacodynamic profile of mitazalimab. Adults with advanced solid malignancies received mitazalimab intravenously once every-2-weeks. Dose-escalation was pursued with and without pre-infusion corticosteroids for mitigation of infusion-related reactions (IRRs). In all, 95 patients were enrolled in 7 cohorts (n = 50, 75-2000 µg/kg) with corticosteroids and in 5 cohorts (n = 45, 75-1200 µg/kg) without corticosteroids. Two patients experienced DLTs (transient Grade-3 headache; Grade-3 drug-induced liver injury [Hy's law]). The most frequently reported (≥ 25%) treatment-emergent adverse events were fatigue (44.2%), pyrexia (38.9%), pruritus (38.9%), chills (27.4%), and headache (26.3%). IRRs were reported in 51.6% of patients; pruritus (30.5%; with corticosteroids [36.0%], without corticosteroids [24.4%]) was the most frequent. Following the first infusions of 600 μg/kg and 2000 μg/kg, mitazalimab was rapidly cleared from the systemic circulation with mean terminal half-life of 11.9 and 24.1 h, respectively. Pharmacokinetics appeared to exhibit target-mediated drug disposition at the tested doses. Mitazalimab treatment induced higher levels of selected chemokines and transient reduction of B-cells, T-cells, and NK cells. One patient (renal cell carcinoma) displayed partial response lasting 5.6 months. Stable disease was reported by 35 (36.8%) patients, persisting for ≥ 6 months in 9 patients. Mitazalimab has a manageable safety profile with acceptable pharmacokinetic and pharmacodynamic properties. Future clinical development will evaluate combination with existing treatment options. Trial registration NCT02829099 (ClinicalTrials.gov; July 7, 2016).

Talquetamab, a T-Cell-Redirecting GPRC5D Bispecific Antibody for Multiple Myeloma

BACKGROUND

G protein-coupled receptor, family C, group 5, member D (GPRC5D) is an orphan receptor expressed in malignant plasma cells. Talquetamab, a bispecific antibody against CD3 and GPRC5D, redirects T cells to mediate killing of GPRC5D-expressing myeloma cells.

METHODS

In a phase 1 study, we evaluated talquetamab administered intravenously weekly or every other week (in doses from 0.5 to 180 μg per kilogram of body weight) or subcutaneously weekly, every other week, or monthly (5 to 1600 μg per kilogram) in patients who had heavily pretreated relapsed or refractory multiple myeloma that had progressed with established therapies (a median of six previous lines of therapy) or who could not receive these therapies without unacceptable side effects. The primary end points - the frequency and type of dose-limiting toxic effects (study part 1 only), adverse events, and laboratory abnormalities - were assessed in order to select the recommended doses for a phase 2 study.

RESULTS

At the data-cutoff date, 232 patients had received talquetamab (102 intravenously and 130 subcutaneously). At the two subcutaneous doses recommended for a phase 2 study (405 μg per kilogram weekly [30 patients] and 800 μg per kilogram every other week [44 patients]), common adverse events were cytokine release syndrome (in 77% and 80% of the patients, respectively), skin-related events (in 67% and 70%), and dysgeusia (in 63% and 57%); all but one cytokine release syndrome event were of grade 1 or 2. One dose-limiting toxic effect of grade 3 rash was reported in a patient who had received talquetamab at the 800-μg dose level. At median follow-ups of 11.7 months (in patients who had received talquetamab at the 405-μg dose level) and 4.2 months (in those who had received it at the 800-μg dose level), the percentages of patients with a response were 70% (95% confidence interval [CI], 51 to 85) and 64% (95% CI, 48 to 78), respectively. The median duration of response was 10.2 months and 7.8 months, respectively.

CONCLUSIONS

Cytokine release syndrome, skin-related events, and dysgeusia were common with talquetamab treatment but were primarily low-grade. Talquetamab induced a substantial response among patients with heavily pretreated relapsed or refractory multiple myeloma. (Funded by Janssen Research and Development; MonumenTAL-1 ClinicalTrials.gov number, NCT03399799.).

Teclistamab in Relapsed or Refractory Multiple Myeloma

BACKGROUND

Teclistamab is a T-cell-redirecting bispecific antibody that targets both CD3 expressed on the surface of T cells and B-cell maturation antigen expressed on the surface of myeloma cells. In the phase 1 dose-defining portion of the study, teclistamab showed promising efficacy in patients with relapsed or refractory multiple myeloma.

METHODS

In this phase 1-2 study, we enrolled patients who had relapsed or refractory myeloma after at least three therapy lines, including triple-class exposure to an immunomodulatory drug, a proteasome inhibitor, and an anti-CD38 antibody. Patients received a weekly subcutaneous injection of teclistamab (at a dose of 1.5 mg per kilogram of body weight) after receiving step-up doses of 0.06 mg and 0.3 mg per kilogram. The primary end point was the overall response (partial response or better).

RESULTS

Among 165 patients who received teclistamab, 77.6% had triple-class refractory disease (median, five previous therapy lines). With a median follow-up of 14.1 months, the overall response rate was 63.0%, with 65 patients (39.4%) having a complete response or better. A total of 44 patients (26.7%) were found to have no minimal residual disease (MRD); the MRD-negativity rate among the patients with a complete response or better was 46%. The median duration of response was 18.4 months (95% confidence interval [CI], 14.9 to not estimable). The median duration of progression-free survival was 11.3 months (95% CI, 8.8 to 17.1). Common adverse events included cytokine release syndrome (in 72.1% of the patients; grade 3, 0.6%; no grade 4), neutropenia (in 70.9%; grade 3 or 4, 64.2%), anemia (in 52.1%; grade 3 or 4, 37.0%), and thrombocytopenia (in 40.0%; grade 3 or 4, 21.2%). Infections were frequent (in 76.4%; grade 3 or 4, 44.8%). Neurotoxic events occurred in 24 patients (14.5%), including immune effector cell-associated neurotoxicity syndrome in 5 patients (3.0%; all grade 1 or 2).

CONCLUSIONS

Teclistamab resulted in a high rate of deep and durable response in patients with triple-class-exposed relapsed or refractory multiple myeloma. Cytopenias and infections were common; toxic effects that were consistent with T-cell redirection were mostly grade 1 or 2. (Funded by Janssen Research and Development; MajesTEC-1 ClinicalTrials.gov numbers, NCT03145181 and NCT04557098.).

Proceedings from the Blood and Marrow Transplant Clinical Trials Network Myeloma Intergroup Workshop on Immune and Cellular Therapy in Multiple Myeloma

The Blood and Marrow Transplant Clinical Trials Network (BMT CTN) Myeloma Intergroup conducted a workshop on Immune and Cellular Therapy in Multiple Myeloma on January 7, 2022. This workshop included presentations by basic, translational, and clinical researchers with expertise in plasma cell dyscrasias. Four main topics were discussed: platforms for myeloma disease evaluation, insights into pathophysiology, therapeutic target and resistance mechanisms, and cellular therapy for multiple myeloma. Here we provide a comprehensive summary of these workshop presentations.

Genetic subtypes of smoldering multiple myeloma are associated with distinct pathogenic phenotypes and clinical outcomes

Smoldering multiple myeloma (SMM) is a precursor condition of multiple myeloma (MM) with significant heterogeneity in disease progression. Existing clinical models of progression risk do not fully capture this heterogeneity. Here we integrate 42 genetic alterations from 214 SMM patients using unsupervised binary matrix factorization (BMF) clustering and identify six distinct genetic subtypes. These subtypes are differentially associated with established MM-related RNA signatures, oncogenic and immune transcriptional profiles, and evolving clinical biomarkers. Three genetic subtypes are associated with increased risk of progression to active MM in both the primary and validation cohorts, indicating they can be used to better predict high and low-risk patients within the currently used clinical risk stratification models.

Efficacy and safety of teclistamab (tec), a B-cell maturation antigen (BCMA) x CD3 bispecific antibody, in patients (pts) with relapsed/refractory multiple myeloma (RRMM) after exposure to other BCMA-targeted agents

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Background: Tec (JNJ-64007957) is a BCMA x CD3 bispecific antibody (Ab) that redirects CD3+ T cells to mediate T-cell activation and subsequent lysis of BCMA-expressing myeloma cells. MajesTEC-1 is a multicohort, open-label phase 1/2 study of tec in pts with RRMM who previously received ≥3 prior lines of therapy (LOT). Results from a pooled analysis of phase 1 and phase 2 cohort A (median follow-up 7.8 mo) demonstrated an overall response rate (ORR) of 62.0% in pts with no prior anti-BCMA treatment (tx). We present initial results from cohort C, in which pts had prior exposure to an anti-BCMA tx. Methods: Eligible pts (age ≥18 y) had documented MM per IMWG criteria and had received ≥3 prior LOT including a PI, an IMiD, an anti-CD38 Ab, and an anti-BCMA tx (chimeric antigen receptor T [CAR-T] or Ab drug conjugate [ADC]). Pts were enrolled into a Simon’s stage design, receiving weekly subcutaneous tec 1.5 mg/kg preceded by step-up doses of 0.06 and 0.3 mg/kg. Primary endpoint was ORR (per IMWG 2016 criteria). AEs were graded per CTCAE v4.03; cytokine release syndrome (CRS) and immune effector cell–associated neurotoxicity syndrome (ICANS) were graded per ASTCT guidelines. Results: As of Sep 7, 2021, 38 pts in cohort C received tec (63% male; median age 63.5 y [range 32–82]; median prior LOT 6 [range 3–14]). 32 (84%) pts were refractory to last LOT; 25 (66%) were refractory to an anti-BCMA tx. Of 25 pts evaluated for efficacy, 16 (64%) had prior ADC, 11 (44%) prior CAR-T (2 pts received both). With median follow-up of 6.9 mo (range 0.7–8.7), ORR was 40% (95% CI 21–61). 5 pts (20%) achieved a complete response or better. The ORR (95% CI) was 38% (15–65) in ADC-exposed pts and 45% (17–77) in CAR-T–exposed pts. Most responses occurred rapidly; 7/25 pts had responses that deepened over time. Median time (range) to first and best response was 1.2 mo (0.2–4.9) and 2.1 mo (1.1–5.7), respectively. Median duration of response was not reached. The safety profile was comparable with that observed in BMCA tx-naive pts, with no new safety concerns. 16 pts (42%; grade 3/4 26%) had infections. Most common AEs (n = 38) were CRS (63%; all grade 1/2; median [range] time to CRS onset: 3 d [2–6], duration of CRS: 2 d [1–4]), neutropenia (55%; grade 3/4 50%), thrombocytopenia (42%; grade 3/4 29%), anemia (39%; grade 3/4 29%), and lymphopenia (40%; grade 3/4 37%). One pt had grade 3 ICANS that resolved with supportive care; pt remains on tx. No pts developed anti-tec Abs. Baseline BCMA expression was comparable with that observed in BCMA tx-naive pts. Updated efficacy and safety data will be presented for 40 pts. Conclusions: Initial results of serial targeting of BCMA with tec following ADC or CAR-T tx suggest a promising ORR with responses occurring early and deepening over time. A well-tolerated safety profile was observed in pts previously treated with anti-BCMA tx. Clinical trial information: NCT04557098.

Teclistamab, a B-cell maturation antigen (BCMA) x CD3 bispecific antibody, in patients with relapsed/refractory multiple myeloma (RRMM): Updated efficacy and safety results from MajesTEC-1

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Background: The BCMA × CD3 bispecific antibody teclistamab (tec; JNJ-64007957) redirects CD3+ T cells to mediate T-cell activation and subsequent lysis of BCMA-expressing myeloma cells. The multicohort, open-label, phase 1/2 MajesTEC-1 study is investigating safety/efficacy of tec in patients (pts) with RRMM who previously received ≥3 lines of therapy (LOT). In phase 1, the recommended phase 2 dose (RP2D) of tec was identified as a weekly subcutaneous dose of 1.5 mg/kg preceded by step-up doses of 0.06 and 0.3 mg/kg. Initial results from pts treated with the tec RP2D in phase 1/2 (no prior exposure to an anti–BCMA-targeted treatment), demonstrated that tec was well tolerated with encouraging efficacy. Here we present updated results from pts treated at the RP2D, including additional pts and longer follow-up. Methods: Eligible pts were aged ≥18 years, had documented MM (per IMWG criteria), and had received ≥3 prior LOT including a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 antibody. Prior BCMA-targeted therapy was not permitted in Phase 1. Pts received tec at the RP2D. The primary endpoint was overall response rate (assessed per IMWG 2016 criteria). Adverse events (AEs) were graded per CTCAE v4.03 (cytokine release syndrome [CRS] and ICANS graded per ASTCT guidelines). Data cutoffs for safety and efficacy (N = 165) were Sep 7 and Nov 9, 2021, respectively. Results: Median pt age was 64 y (range 33–84); 58% were male, and median prior LOT was 5 (range 2–14); 100% were triple-class exposed, 70% were penta-drug exposed, 78% were triple-class refractory, and 30% were penta-drug refractory. ORR was 64% (95% CI 56–72), with a complete response or better achieved in 30% of pts. Responses were durable and deepened over time; median duration of response (DOR) was not reached. The 12-mo DOR rate was 66% (95% CI 49–79). The majority of pts who responded to treatment in the first cycle had a reduction in soluble BCMA. The most common hematologic AEs were neutropenia (65%; grade 3/4: 57%), anemia (50%; grade 3/4: 35%), thrombocytopenia (38%; grade 3/4: 21%), and lymphopenia (34%; grade 3/4: 32%). Infections occurred in 104 pts (63%; grade 3/4: 35%). The most common nonhematologic AE was CRS (72%; grade 3: 0.6%; no grade 4/5); median time to CRS onset (range) was 2 days (1–6) and median duration was 2 days (1–9). Five pts (3%) reported a total of 9 ICANS events (all grade 1/2; 7 were concurrent with CRS; all resolved). There were no treatment-related deaths. No pts required a teclistamab dose reduction due to AEs. Conclusions: Current data with ̃9 months of follow-up reaffirm the deep and durable responses that have been observed with tec in pts with highly refractory MM, with no new safety signals. Additional data with longer follow-up, including subgroup analyses and PFS, will be presented. Clinical trial information: NCT04557098.

Redirecting T-cell Activity with Anti-BCMA/Anti-CD3 Bispecific Antibodies in Chronic Lymphocytic Leukemia and Other B-cell Lymphomas

T-cell redirecting bispecific antibodies hold high promise for treatment of B-cell malignancies. B-cell maturation antigen (BCMA) exhibits high expression on normal and malignant mature B cells including plasma cells, which can be enhanced by inhibition of γ-secretase. BCMA is considered a validated target in multiple myeloma but whether mature B-cell lymphomas can be targeted by the BCMAxCD3 T-cell redirector teclistamab is currently unknown. BCMA expression on B-cell non-Hodgkin lymphoma and primary chronic lymphocytic leukemia (CLL) cells was assessed by flow cytometry and/or IHC. To assess teclistamab efficacy, cells were treated with teclistamab in presence of effector cells with/without γ-secretase inhibition. BCMA could be detected on all tested mature B-cell malignancy cell lines, while expression levels varied per tumor type. γ-secretase inhibition universally increased BCMA surface expression. These data were corroborated in primary samples from patients with Waldenstrom's macroglobulinemia, CLL, and diffuse large B-cell lymphoma. Functional studies with the B-cell lymphoma cell lines revealed teclistamab-mediated T-cell activation, proliferation, and cytotoxicity. This was independent of the level of BCMA expression, but generally lower in mature B-cell malignancies compared with multiple myeloma. Despite low BCMA levels, healthy donor T cells and CLL-derived T cells induced lysis of (autologous) CLL cells upon addition of teclistamab. These data show that BCMA is expressed on various B-cell malignancies and that lymphoma cell lines and primary CLL can be targeted using teclistamab. Further studies to understand the determinants of response to teclistamab are required to identify which other diseases might be suitable for teclistamab targeting.

Significance

Besides reported BCMA expression on multiple myeloma, we demonstrate BCMA can be detected and enhanced using γ-secretase inhibition on cell lines and primary material of various B-cell malignancies. Furthermore, using CLL we demonstrate that low BCMA-expressing tumors can be targeted efficiently using the BCMAxCD3 DuoBody teclistamab.

Teclistamab, a B-cell maturation antigen × CD3 bispecific antibody, in patients with relapsed or refractory multiple myeloma (MajesTEC-1): a multicentre, open-label, single-arm, phase 1 study

BACKGROUND

There is a need for novel therapies for relapsed or refractory multiple myeloma, and B-cell maturation antigen (BCMA) is a validated target. Teclistamab is a bispecific antibody that binds BCMA and CD3 to redirect T cells to multiple myeloma cells. The aim of the MajesTEC-1 study was to evaluate the safety, tolerability, and preliminary efficacy of teclistamab in patients with relapsed or refractory multiple myeloma.

METHODS

This open-label, single-arm, phase 1 study enrolled patients with multiple myeloma who were relapsed, refractory, or intolerant to established therapies. Teclistamab was administered intravenously (range 0·3-19·2 μg/kg [once every 2 weeks] or 19·2-720 μg/kg [once per week]) or subcutaneously (range 80-3000 μg/kg [once per week]) in different cohorts, with step-up dosing for 38·4 μg/kg or higher doses. The primary objectives were to identify the recommended phase 2 dose (part one) and characterise teclistamab safety and tolerability at the recommended phase 2 dose (part two). Safety was assessed in all patients treated with at least one dose of teclistamab. Efficacy was analysed in response-evaluable patients (ie, patients who received at least one dose of teclistamab and had at least one post-baseline response evaluation). This ongoing trial is registered with ClinicalTrials.gov, NCT03145181.

FINDINGS

Between June 8, 2017, and March 29, 2021, 219 patients were screened for study inclusion, and 157 patients (median six previous therapy lines) were enrolled and received at least one dose of teclistamab (intravenous n=84; subcutaneous n=73). 40 patients were administered the recommended phase 2 dose, identified as once per week subcutaneous administration of teclistamab at 1500 μg/kg, after 60 μg/kg and 300 μg/kg step-up doses (median follow-up 6·1 months, IQR 3·6-8·2). There were no dose-limiting toxicities at the recommended phase 2 dose in part one. In the 40 patients treated at the recommended phase 2 dose, the most common treatment-emergent adverse events were cytokine release syndrome in 28 (70%; all grade 1 or 2 events) and neutropenia in 26 (65%) patients (grade 3 or 4 in 16 [40%]). The overall response rate in response-evaluable patients treated at the recommended phase 2 dose (n=40) was 65% (95% CI 48-79); 58% achieved a very good partial response or better. At the recommended phase 2 dose, the median duration of response was not reached. 22 (85%) of 26 responders were alive and continuing treatment after 7·1 months' median follow-up (IQR 5·1-9·1). At the recommended phase 2 dose, teclistamab exposure was maintained above target exposure levels, and consistent T-cell activation was reported.

INTERPRETATION

Teclistamab is a novel treatment approach for relapsed or refractory multiple myeloma. At the recommended phase 2 dose, teclistamab showed promising efficacy, with durable responses that deepened over time, and was well tolerated, supporting further clinical development.

FUNDING

Janssen Research & Development.

Updated results of a phase 1, first-in-human study of talquetamab, a G protein-coupled receptor family C group 5 member D (GPRC5D) × CD3 bispecific antibody, in relapsed/refractory multiple myeloma (MM)

8008

Background: New immunotherapy targets in MM are needed as patients (pts) continue to relapse. The orphan receptor GPRC5D is expressed on malignant plasma cells in MM. Talquetamab (JNJ-64407564) is a bispecific IgG4 antibody that redirects T cell killing to MM cells by binding to the novel target, GPRC5D, and CD3. We present updated results of talquetamab at the recommended phase 2 dose (RP2D) from a phase 1 trial in relapsed/refractory MM. Methods: Eligible pts with MM who had relapsed or refractory disease or were intolerant to standard therapies received talquetamab intravenously (IV; range 0.5–180 µg/kg) or subcutaneously (SC; range 5.0–800 µg/kg) weekly or biweekly. Primary objectives were identification of the RP2D (part 1) and talquetamab safety and tolerability at the RP2D (part 2). Adverse events (AEs) were graded by CTCAE v4.03 (cytokine release syndrome [CRS] per Lee 2014). Response was assessed per IMWG criteria. Results: As of Feb 8, 2021, 174 pts received talquetamab, 102 by IV and 72 by SC; in parts 1 and 2, 28 pts were treated at the RP2D, identified as weekly SC 405 µg/kg, with 10.0 and 60.0 µg/kg step-up doses. Pts treated at the RP2D had a median age of 61.5 y (range 46–80) and a median of 5.5 prior lines of therapy (range 2–14; 100%/79% triple-class/penta-drug exposed; 71%/18% triple-class/penta-drug refractory; 86% refractory to last line of therapy; 21% with prior B-cell maturation antigen–directed therapy). No dose-limiting toxicities occurred at the RP2D in part 1. Most common AEs at the RP2D were CRS (79%; grade 3 4%; median time to onset: day after SC injection), neutropenia (64%; grade 3/4 54%), anemia (57%; grade 3/4 29%) and dysgeusia (57%; all grade 1/2); infections were reported in 32% of pts (grade 3/4 4%) and neurotoxicity in 7% (grade 3/4 0). In all, 75% of pts dosed at the RP2D had skin-related AEs (grade 3/4 0), including 18% with nail disorders. The overall response rate at the RP2D in response-evaluable pts (n = 24) was 63%, with 50% reaching very good partial response or better; 9/17 (53%) evaluable triple-class refractory pts and 3/3 (100%) penta-drug refractory pts had a response. Median time to first confirmed response at the RP2D was 1.0 mo (range 0.2–3.8); responses were durable and deepened over time (median follow-up 6.2 mo [range 2.7–9.7+] for responders at the RP2D). At the RP2D, exposure was maintained over the maximum EC90 target level from an ex vivo cytotoxicity assay, and consistent T cell activation was seen. Conclusions: At the RP2D of weekly 405 µg/kg SC, talquetamab showed a high clinical response rate and was well-tolerated in pts with relapsed/refractory MM; based on pharmacokinetic data, other SC dosing strategies are being explored. The promising efficacy, safety profile and convenience of SC dosing support monotherapy development and combination approaches with this novel agent. Clinical trial information: NCT03399799.

Teclistamab and talquetamab modulate levels of soluble B-cell maturation antigen in patients with relapsed and/or refractory multiple myeloma

8047

Background: B-cell maturation antigen (BCMA, CD269) is a single transmembrane protein that is selectively expressed in the B-cell lineage and is a validated target for multiple myeloma. BCMA exists as both surface protein and as a free soluble form (sBCMA). γ-secretase activity at the transmembrane domain leads to a shed BCMA protein fragment of approximately 6 kilodalton that can exist as free circulating sBCMA in blood. Teclistamab and talquetamab are CD3 bispecific antibodies that have been developed to recruit CD3+ T-cells to BCMA+ or GPRC5D+ multiple myeloma (MM) cells, respectively. The objective of this work was to evaluate sBCMA in relapsed and/or refractory MM patients in response to treatment with teclistamab or talquetamab. Methods: Serum samples from relapsed and/or refractory MM patients in teclistamab and talquetamab phase 1 studies (64007957MMY1001 and 64407564MMY1001) were collected (at various timepoints between baseline and cycle 4 or end of treatment) and analyzed for sBCMA by an electrochemiluminescence ligand binding assay. Soluble BCMA data were quantitatively analyzed in reference to patient’s tumor burden and response, as well as pharmacokinetic data. Results: Teclistamab and talquetamab modulated levels of sBCMA in patients with high ( ≥ 50%) and low ( < 50%) frequency of tumor plasma cells (TPCs), as well as in high and low risk cytogenetic groups. In cycle 3, majority of the responders had reduction in sBCMA [88% (50 out of 57) for teclistamab and 98% (49 out of 50) for talquetamab] compared to baseline. On the contrary, non-responders (progressive disease, stable disease, or minimal response) seemed to show an increase in sBCMA [80% (33 out of 41) for teclistamab and 49% (24 out of 49) for talquetamab] from baseline. Patients with deep responses tend to have higher magnitude of sBCMA reduction compared to others. Based on few patients who responded to teclistamab or talquetamab and then relapsed, sBCMA seemed to have an initial reduction followed by an increase in the levels. Soluble BCMA corelated with % bone marrow TPCs. Majority of patients with plasmacytoma (limited data) seemed to have high sBCMA; suggesting sBCMA could be a comprehensive marker for tumor burden. Teclistamab preliminary population pharmacokinetic analysis showed that sBCMA did not appear to impact teclistamab exposure, suggesting that sBCMA was not acting as a sink for teclistamab. Conclusions: Teclistamab and talquetamab induced changes in levels of sBCMA that correlated with clinical activity, further supporting clinical development of these bispecific antibodies. Lastly, the results support that sBCMA is a potential surrogate marker of myeloma tumor burden, and as a valuable marker for response in MM patients. Clinical trial information: NCT03145181 and NCT03399799.

Updated phase 1 results of teclistamab, a B-cell maturation antigen (BCMA) × CD3 bispecific antibody, in relapsed/refractory multiple myeloma (MM)

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Background: BCMA-targeted immunotherapies offer considerable promise for relapsed/refractory MM. Teclistamab (JNJ-64007957) is a BCMA × CD3 bispecific IgG4 antibody that redirects CD3+ T cells to BCMA-expressing MM cells. We present updated results of patients (pts) treated at the recommended phase 2 dose (RP2D) in the first-in-human phase 1 study of teclistamab. Methods: Eligible pts had MM and were relapsed, refractory or intolerant to established therapies. Primary objectives were to identify the RP2D (part 1) and characterize safety and tolerability of teclistamab at the RP2D (part 2). Teclistamab was given intravenously (IV; range 0.3–19.2 µg/kg [biweekly]; range 19.2–720 µg/kg [weekly]) or subcutaneously (SC; range 80.0–3000 µg/kg weekly) in different cohorts, with step-up dosing used for ≥38.4 µg/kg doses. Adverse events (AEs) were graded by CTCAE v4.03 (cytokine release syndrome [CRS] by Lee et al 2014). Response was assessed per IMWG criteria. Results: As of Feb 4, 2021, 156 pts received teclistamab (IV n = 84; SC n = 72). The RP2D, identified as weekly SC 1500 µg/kg teclistamab with 60.0 and 300 µg/kg step-up doses, was given to 40 pts (median follow-up 4.3 mo [range 1.1–10.4+]). Pts dosed at the RP2D (median age, 62.5 y [range, 39–84]; 65% male) had received a median of 5 prior lines of therapy (range 2–11; 100% triple-class exposed; 65% penta-drug exposed; 83% triple-class refractory; 35% penta-drug refractory; 85% refractory to their last line of therapy). There were no dose-limiting toxicities at the RP2D in part 1. The most common AEs at the RP2D were CRS (70%; grade 3/4 0) and neutropenia (60%; grade 3/4 40%); grade 1 neurotoxicity was reported in 1 (3%) pt. Median time to CRS onset was later with SC vs IV dosing (day after SC injection vs day of IV infusion). The overall response rate in response-evaluable pts treated at the RP2D (n = 40) was 65%; 58% achieved a very good partial response or better and 30% achieved a complete response (CR) or better; median time to first confirmed response was 1.0 mo (range 0.2–3.1). At the RP2D, median duration of response was not reached; 23 of 26 responders (88%), after median follow-up of 5.3 mo (range 1.2–10.4+), were alive and continuing on treatment with responses deepening over time. Of 14 evaluable pts across all cohorts, 9 with CR were minimal residual disease–negative at 10-6. At the RP2D, teclistamab exposure was sustained across the dosing interval and exceeded target levels, and consistent T cell activation was observed. Conclusions: Teclistamab at the RP2D (weekly 1500 µg/kg SC) was well-tolerated and showed encouraging efficacy with durable, deepening responses, supporting further investigation as monotherapy and in combination with other agents. With the extended exposure profile at the RP2D and delayed and low-grade CRS observed with SC administration, alternative SC dosing strategies are being explored. Clinical trial information: NCT03145181.

Gene signatures of tumor inflammation and epithelial-to-mesenchymal transition (EMT) predict responses to immune checkpoint blockade in lung cancer with high accuracy

OBJECTIVES

Treatment of non-small cell lung cancer (NSCLC) with immune checkpoint blockade (ICB) has resulted in striking clinical responses, but only in a subset of patients. The goal of this study was to evaluate transcriptional signatures previously reported in the literature in an independent cohort of NSCLC patients receiving ICB.

MATERIALS AND METHODS

This retrospective study analyzed transcriptional profiles from pre-treatment tumor samples of 52 chemotherapy-refractory advanced NSCLC patients treated with anti-PD1/PD-L1 therapy. Gene signatures based on published reports were created and examined for their association with response to therapy and progression-free and overall survival (PFS, OS).

RESULTS

Two signatures predicting response and outcomes were identified. One reflected the degree of immune infiltration and upregulation of interferon-gamma-induced genes. A second reflected the EMT status. Compared to those not responding to therapy, patients whose tumors responded to ICB had higher scores in an inflammatory gene signature (6.0 ± 2.9 vs -5.5 ± 3.4, p = 0.014) or a more epithelial phenotype (-1.7 ± 1.0 vs 2.1 ± 1.2, p = 0.016). Both signatures demonstrated a satisfactory predictive accuracy for response: AUC of 0.69 (95% CI: 0.54, 0.84) for the inflammatory and 0.70 (95% CI: 0.55, 0.85) for EMT signatures, respectively. A weighted score combining EMT and inflammatory signatures showed increased predictive value with AUC of 0.92 (95% CI: 0.85, 0.99). Kaplan-Meier curves for patients above and below the median combined score showed a significant separation for PFS and OS (all p < 0.01, log rank test).

CONCLUSIONS

The EMT/Inflammation signature score may be useful in directing checkpoint inhibitor therapy in lung cancer and suggests that reversal of EMT might augment efficacy of ICB.

Abstract A11: Preclinical assessment of CD3 bispecific antibody efficacy: A comparison of humanized mouse models bearing xenografts and syngeneic mouse models using surrogate antibodies

CD3 bispecific antibodies target both CD3 on T cells, and a tumor-specific antigen on cancer cells to harness the ability of cytotoxic T cells to eradicate solid tumors. Preclinical modeling of potential clinical leads in animal models can be challenging due to the need to have both a human immune system and a tumor model to study. Here we describe using various humanized mouse models in immune-compromised NSG mice as well as the use of surrogate antibodies in syngeneic models in mice with a competent immune system.

To reconstitute the human immune system, female NSG mice were inoculated either intravenously with PBMCs or intraperitoneally with T cells that were expanded and activated in vitro. Engraftment of human T cells was evaluated in PBMC and T-cell humanized NSG mice in peripheral blood. In the absence of treatment, PBMC humanized mice had a greater reconstitution of T cells in the peripheral blood (~10-40%) compared to T-cell humanized mice (~3-10%). An antibody-specific expansion of T cells was observed in the T-cell humanized model in response to CD3 bispecific treatment. The slower engraftment of effector T cells in the T-cell humanized model correlated with slower onset to GVHD (graft versus host disease), allowing for extended evaluation of antitumor responses. Bispecific CD3 redirection antibodies elicited antitumor efficacy and T-cell infiltration in various human xenografts in both T-cell and PBMC-humanized mouse models.

Additionally, mouse surrogate bispecific antibodies were generated that bind CD3 on mouse T cells. CT26 murine mouse colon carcinoma syngeneic tumors were transfected with a human cancer antigen for use in immune-competent Balb/c mice. Treatment with a surrogate bispecific molecule resulted in significant tumor growth inhibition (greater than 60%) and significant increase in life span.

To confirm the mechanism of action, histologic analyses of T-cell infiltration into tumors was performed as well as T-cell cytokine analysis. These data showed that the level of T-cell infiltration and cytokine production correlated well with in vivo efficacy, demonstrating a T cell-mediated elimination of antigen-presenting tumor cells.

In summary, both humanized mouse models and syngeneic mouse models using surrogate antibodies were successfully employed to study antitumor effects of CD3 bispecific antibodies.

Citation Format: Bethany Mattson, Krista Menard, Damon Hamon, Darlene Pizutti, Emily Chen, Margarita Romero, Kristen Chevalier, Karla Wiehagen, Mark Richter, Gerald Chu, Brenda Hertzog, Anna Hughes, John Alvarez, Raluca Verona, Colleen Kane, Sheri Moores, Sylvie Laquerre, Joseph Erhardt, Kathryn Packman. Preclinical assessment of CD3 bispecific antibody efficacy: A comparison of humanized mouse models bearing xenografts and syngeneic mouse models using surrogate antibodies [abstract]. In: Proceedings of the AACR Special Conference: Advances in Modeling Cancer in Mice: Technology, Biology, and Beyond; 2017 Sep 24-27; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(10 Suppl):Abstract nr A11.

TIM-3 Engagement Promotes Effector Memory T Cell Differentiation of Human Antigen-Specific CD8 T Cells by Activating mTORC1

T cell expression of TIM-3 following Ag encounter has been associated with a continuum of functional states ranging from effector memory T cells to exhaustion. We have designed an in vitro culture system to specifically address the impact of anti-TIM-3/TIM-3 engagement on human Ag-specific CD8 T cells during a normal response to Ag and found that anti-TIM-3 treatment enhances T cell function. In our in vitro T cell culture system, MART1-specific CD8 T cells were expanded from healthy donors using artificial APCs. To ensure that the T cells were the only source of TIM-3, cells were rechallenged with peptide-loaded artificial APCs in the presence of anti-TIM-3 Ab. In these conditions, anti-TIM-3 treatment promotes generation of effector T cells as shown by acquisition of an activated phenotype, increased cytokine production, enhanced proliferation, and a transcription program associated with T cell differentiation. Activation of mTORC1 has been previously demonstrated to enhance CD8 T cell effector function and differentiation. Anti-TIM-3 drives CD8 T cell differentiation through activation of the mTORC1 as evidenced by increased levels of phosphorylated S6 protein and rhebl1 transcript. Altogether these findings suggest that anti-TIM-3, together with Ag, drives differentiation in favor of effector T cells via the activation of mTOR pathway. To our knowledge, this is the first report demonstrating that TIM-3 engagement during Ag stimulation directly influences T cell differentiation through mTORC1.

Abstract 1641: Dual antibody blockade of TIM3 and PD1 on NYESO1 redirected human T cells leads to augmented control of lung cancer tumors

Background: Immunotherapy using checkpoint blockade has demonstrated impressive, durable responses in select patients with solid malignancies. This is especially true for the blockade of programmed death 1 (PD1). Currently, efforts are focused on understanding non-response. One hypothesis is that multiple inhibitory receptors (IRs) are upregulated on hypofunctional tumor-infiltrating lymphocytes (TILs) and necessitates blocking multiple IRs to increase the response rate. We describe data from a unique xenograft model of human lung cancer where tumor-reactive human T cells become hypofunctional and upregulate multiple IRs including PD1 and TIM3 (T cell immunoglobulin and mucin-domain containing-3). Combining a single IV dose of tumor-reactive T cells with blockade of both PD1 and TIM3 led to greater control of tumor growth than combining it with blockade of either alone.

Materials/Methods: The A549 human lung cancer cell line was transduced to stably express the cancer-testis antigen, NYESO1, expressed in the contact of HLA-A2 (A549-A2-ESO). 5x106 A549-A2-ESO cells were injected subcutaneously into the flanks NSG mice. Activated T cells from healthy donors were lentivirally transduced with a TCR targeting NYESO1 (Ly95). After two weeks when tumors were established and measured ~150mm3, the mice were randomly assigned to one of the following treatments: 1) untreated, 2) non-transduced (NTD) T cells plus anti-PD1 and anti-TIM3 Ab, 3) Ly95 T cells, 4) Ly95 T cells + anti-PD1 Ab, 5) Ly95 T cells + anti-TIM3 Ab, 6) Ly95 T cells + anti-PD1 and anti-TIM3 Ab. T cells were injected IV at a single dose of 10x106/mouse. Abs were injected intraperitonealy (IP) at 10mg/kg every 5 days from the time of T cell injection. Tumor volumes were measured serially. At the end, the mice were sacrificed and the tumors were harvested, digested, and processed into single cell suspension. Flow cytometry was performed to look at degree of TIL infiltration and expression of surface markers. Ficoll gradient was used to isolate the T cells to conduct functional analyses.

Results/Conclusion: By twenty days post T cell injection, the tumors in the Ly95 T cell group (3) were ~30% smaller than that of the untreated (1) and the NTD T cell + Ab group (2). Anti-PD1 Ab augmented Ly95 T cell control of tumor (4) (further decrease in size by ~30%) (4). Anti-TIM3 Ab had no effect on Ly95 T cell tumor control (5). Anti-PD1 plus anti-TIM3 Abs had the greatest augmentation on Ly95 T cell control of tumor size (6) (greater than 50% reduction in tumor size compared Ly95 T cells alone) The greatest TIL infiltration and ex-vivo TIL function were seen in tumors that received Ly95 T cell + anti-PD1 and anti-TIM3 Abs. Flow cytometry analysis revealed dynamic, adaptive upregulation of one IR when another IR was blocked. This explained why augmentation of Ly95 T cell control of tumor was greatest with combinatorial Ab blockade.

Citation Format: Edmund Moon, Soyeon Kim, Shaun O'Brien, Naomi Saint Jean, Raluca Verona, Linda Snyder, Yangbing Zhao, Steven Albelda. Dual antibody blockade of TIM3 and PD1 on NYESO1 redirected human T cells leads to augmented control of lung cancer tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1641. doi:10.1158/1538-7445.AM2017-1641

TIM-3 Suppresses Anti-CD3/CD28-Induced TCR Activation and IL-2 Expression through the NFAT Signaling Pathway

TIM-3 (T cell immunoglobulin and mucin-domain containing protein 3) is a member of the TIM family of proteins that is preferentially expressed on Th₁ polarized CD4⁺ and CD8⁺ T cells. Recent studies indicate that TIM-3 serves as a negative regulator of T cell function (i.e. T cell dependent immune responses, proliferation, tolerance, and exhaustion). Despite having no recognizable inhibitory signaling motifs, the intracellular tail of TIM-3 is apparently indispensable for function. Specifically, the conserved residues Y265/Y272 and surrounding amino acids appear to be critical for function. Mechanistically, several studies suggest that TIM-3 can associate with interleukin inducible T cell kinase (ITK), the Src kinases Fyn and Lck, and the p85 phosphatidylinositol 3-kinase (PI3K) adaptor protein to positively or negatively regulate IL-2 production via NF-κB/NFAT signaling pathways. To begin to address this discrepancy, we examined the effect of TIM-3 in two model systems. First, we generated several Jurkat T cell lines stably expressing human TIM-3 or murine CD28-ECD/human TIM-3 intracellular tail chimeras and examined the effects that TIM-3 exerts on T cell Receptor (TCR)-mediated activation, cytokine secretion, promoter activity, and protein kinase association. In this model, our results demonstrate that TIM-3 inhibits several TCR-mediated phenotypes: i) NF-kB/NFAT activation, ii) CD69 expression, and iii) suppression of IL-2 secretion. To confirm our Jurkat cell observations we developed a primary human CD8⁺ cell system that expresses endogenous levels of TIM-3. Upon TCR ligation, we observed the loss of NFAT reporter activity and IL-2 secretion, and identified the association of Src kinase Lck, and PLC-γ with TIM-3. Taken together, our results support the conclusion that TIM-3 is a negative regulator of TCR-function by attenuating activation signals mediated by CD3/CD28 co-stimulation.

Abstract 4706: TCR engineered adoptive T-cell therapy for lung cancer is augmented by combined PD1 and TIM3 antibody blockade

INTRODUCTION:

ACT has shown great promise in melanoma and hematologic malignancies; however one major limitation of engineered T cells targeting solid tumors is likely to be tumor microenvironment-induced hypofunction of the T cells. To study and limit this problem, we have developed a model in which human T cells engineered to target the antigen NYESO1 using a high-affinity engineered TCR (Ly95) are injected into mice bearing human A549 lung cancer cells. Using this model we demonstrate upregulation of PD1 and TIM3 on Ly95 TILs. We were able to augment T cell anti-tumor activity by combining Ly95 T cell therapy with anti-hPD1 and anti-hTIM3 antibodies.

Materials and Methods:

In vitro: Human T cells activated by anti-CD3/CD28 Dynabeads and transduced with lentivirus had 50% expression of Ly95 TCR as measured by flow cytometry. They were cocultured with marked tumor cells to measure IFNγ release and antigen-specific killing. In vivo: Immunodeficient mice with 200mm3 flank A549-A2-ESO (AAE) tumors received 107 T cells via tail vein. Three weeks later, tumors were harvested/digested, and human TILs were isolated/assessed for tumor killing/IFNγ secretion. This was repeated after the TILs were rested for 24hrs at 37°C/5%CO2. The number of TILs and PD1/TIM3 expression on the isolated TILs were assessed by flow cytometry at fresh harvest and post rest. The in vivo experiment was repeated comparing Ly95 T cells alone vs. Ly95 T cells plus either/both intraperitoneal (IP) anti-hPD1 or/and IP anti-hTIM3 at 10mg/kg every 5 days.

Results:

Ly95 TCR T cells were able to kill AAE tumor cells and secrete high amounts of IFNγ in an antigen-specific/dose dependent fashion after 18hr coculture. 107 IV Ly95 T cells were able to slow AAE flank tumor growth as compared to control tumors (498mm3 vs. 1009mm3, p&lt;0.05.) Flow cytometric analysis of harvested/digested tumors revealed that 5.2% of the tumor digest was human TILs. Freshly isolated TILs were hypofunctional in their ability to kill tumor cells and release IFNγ when compared to cryopreserved Ly95 T cells (p&lt;0.05.) After overnight rest away from tumor, TILs improved in function. Further analysis revealed that Ly95 TILs had upregulated their expression of PD1 and TIM3 (increase from 5 to 40% in PD1 and from 17 to 50% in TIM3.) Combining a single Ly95 T cell IV injection with multiple IP anti-hPD1 and anti-hTIM3 injections resulted in 43% reduction in flank tumor size compared to Ly95 T cell injection alone (189mm3 vs. 332mm3, p&lt;0.05.)

Conclusions:

The PD1 and TIM3 pathways are involved in tumor-induced hypofunction of TCR engineered TILs. Combining anti-hPD1 and anti-hTIM3 antibodies with TCR T cells, and likely CAR T cells, will likely enhance the efficacy of these approaches in lung cancer and other solid tumors.

Citation Format: Edmund K. Moon, Raghuveer Ranganathan, Xiaojun Liu, Raluca Verona, Linda Snyder, Carl H. June, Yangbing Zhao, Steven M. Albelda. TCR engineered adoptive T-cell therapy for lung cancer is augmented by combined PD1 and TIM3 antibody blockade. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4706. doi:10.1158/1538-7445.AM2015-4706

Abstract B269: Effects of blocking aberrantly expressed CSF-1R in Hodgkin lymphoma

The human genome contains a large number of repetitive elements that have been suspected to play a role in human diseases. Recent literature has shown that aberrant activation of one of these repetitive elements, a long terminal repeat (LTR), leads to lineage inappropriate expression of the CSF-1 receptor (CSF-1R) transcript in Hodgkin's lymphoma (HL) clinical samples and cell lines. CSF1-R, also known as Feline McDonough Sarcoma (FMS), is the receptor for CSF-1 and IL-34, and under normal circumstances it plays an important role in monocyte survival, proliferation, and differentiation as well as osteoclast generation. Aberrant expression of CSF-1R has been shown previously to support proliferation and survival in HL cells. To confirm the role of CSF-1R in HL, we determined that 17 of 17 HL clinical samples and 7 of 7 HL cell lines were positive for the aberrant CSF-1R transcript by TaqMan and traditional PCR, while non-HL cell lines were negative for the aberrant CSF-1R transcript. The HL lines were further characterized for surface expression of CSF-1R by flow cytometry and CSF-1 secretion by ELISA. L-1236 cells expressed the highest levels of CSF-1R and CSF-1. Treatment of the HL cell lines with CSF-1R-Fc, resulted in reduced viability in four of the five lines, consistent with the hypothesis that HL cell lines are sensitive to CSF-1 as a growth factor. Additionally, it was found that treating the L-1236 HL cell line with the CSF-1R small molecule inhibitor JNJ-40646527 had a significant effect on viability of the HL cell line L-1236, with an IC50 of 264 nM at 72 hrs. JNJ-40646527 did not have a significant effect on the viability of several other HL cell lines. These results indicate that aberrant LTR driven CSF-1R expression may play a role in the pathogenesis of Hodgkin's lymphoma (HL) and could be a potential target for Hodgkin's lymphoma therapy.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B269.

Citation Format: Liam Campion, Nikki Deangelis, Catherine Ferrante, Raluca Verona, Shobha Seetharam, Carl Manthey, Linda Snyder. Effects of blocking aberrantly expressed CSF-1R in Hodgkin lymphoma. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B269.

Repression of the Arf tumor suppressor by E2F3 is required for normal cell cycle kinetics

Tumor development is dependent upon the inactivation of two key tumor-suppressor networks, p16(Ink4a)-cycD/cdk4-pRB-E2F and p19(Arf)-mdm2-p53, that regulate cellular proliferation and the tumor surveillance response. These networks are known to intersect with one another, but the mechanisms are poorly understood. Here, we show that E2F directly participates in the transcriptional control of Arf in both normal and transformed cells. This occurs in a manner that is significantly different from the regulation of classic E2F-responsive targets. In wild-type mouse embryonic fibroblasts (MEFs), the Arf promoter is occupied by E2F3 and not other E2F family members. In quiescent cells, this role is largely fulfilled by E2F3b, an E2F3 isoform whose function was previously undetermined. E2f3 loss is sufficient to derepress Arf, triggering activation of p53 and expression of p21(Cip1). Thus, E2F3 is a key repressor of the p19(Arf)-p53 pathway in normal cells. Consistent with this notion, Arf mutation suppresses the activation of p53 and p21(Cip1) in E2f3-deficient MEFs. Arf loss also rescues the known cell cycle re-entry defect of E2f3(-/-) cells, and this correlates with restoration of appropriate activation of classic E2F-responsive genes. Our data also demonstrate a direct role for E2F in the oncogenic activation of Arf. Specifically, we observe recruitment of the endogenous activating E2Fs, E2F1, and E2F3a, to the Arf promoter. Thus, distinct E2F complexes directly contribute to the normal repression and oncogenic activation of Arf. We propose that monitoring of E2F levels and/or activity is a key component of Arf's ability to respond to inappropriate, but not normal cellular proliferation.

E2f3 is critical for normal cellular proliferation

E2F is a family of transcription factors that regulate both cellular proliferation and differentiation. To establish the role of E2F3 in vivo, we generated an E2f3 mutant mouse strain. E2F3-deficient mice arise at one-quarter of the expected frequency, demonstrating that E2F3 is important for normal development. To determine the molecular consequences of E2F3 deficiency, we analyzed the properties of embryonic fibroblasts derived from E2f3 mutant mice. Mutation of E2f3 dramatically impairs the mitogen-induced, transcriptional activation of numerous E2F-responsive genes. We have been able to identify a number of genes, including B-myb, cyclin A, cdc2, cdc6, and DHFR, whose expression is dependent on the presence of E2F3 but not E2F1. We further show that a critical threshold level of one or more of the E2F3-regulated genes determines the timing of the G(1)/S transition, the rate of DNA synthesis, and thereby the rate of cellular proliferation. Finally, we show that E2F3 is not required for cellular immortalization but is rate limiting for the proliferation of the resulting tumor cell lines. We conclude that E2F3 is critical for the transcriptional activation of genes that control the rate of proliferation of both primary and tumor cells.

E2f3 is critical for normal cellular proliferation

E2F is a family of transcription factors that regulate both cellular proliferation and differentiation. To establish the role of E2F3 in vivo, we generated an E2f3 mutant mouse strain. E2F3-deficient mice arise at one-quarter of the expected frequency, demonstrating that E2F3 is important for normal development. To determine the molecular consequences of E2F3 deficiency, we analyzed the properties of embryonic fibroblasts derived from E2f3 mutant mice. Mutation of E2f3 dramatically impairs the mitogen-induced, transcriptional activation of numerous E2F-responsive genes. We have been able to identify a number of genes, including B-myb,cyclin A, cdc2, cdc6, and DHFR, whose expression is dependent on the presence of E2F3 but not E2F1. We further show that a critical threshold level of one or more of the E2F3-regulated genes determines the timing of the G1/S transition, the rate of DNA synthesis, and thereby the rate of cellular proliferation. Finally, we show that E2F3 is not required for cellular immortalization but is rate limiting for the proliferation of the resulting tumor cell lines. We conclude that E2F3 is critical for the transcriptional activation of genes that control the rate of proliferation of both primary and tumor cells.

E2F-6, a member of the E2F family that can behave as a transcriptional repressor

The E2F family of proteins is required to establish the correct cell-cycle-dependent transcription of genes that direct the process of cell division. All previously identified E2F proteins can act in a similar manner; depending on whether or not they are associated with the cell cycle inhibitors the retinoblastoma protein (pRB), p107, or p130, they can either repress or activate the transcription of E2F-responsive genes. We now report the cloning and characterization of another E2F family member, E2F-6, whose structure is reminiscent of the dominant inhibitors of other transcription factor families. The dimerization and DNA binding properties of E2F-6 are similar to those of the other E2F family members. However, it is not regulated by pRB, p107, or p130, and it is unable to activate transcription. Instead, it can act to repress the transcription of E2F responsive genes by countering the activity of the other E2F complexes via a pRB-, p107-, or p130-independent mechanism.

E2F activity is regulated by cell cycle-dependent changes in subcellular localization

E2F directs the cell cycle-dependent expression of genes that induce or regulate the cell division process. In mammalian cells, this transcriptional activity arises from the combined properties of multiple E2F-DP heterodimers. In this study, we show that the transcriptional potential of individual E2F species is dependent upon their nuclear localization. This is a constitutive property of E2F-1, -2, and -3, whereas the nuclear localization of E2F-4 is dependent upon its association with other nuclear factors. We previously showed that E2F-4 accounts for the majority of endogenous E2F species. We now show that the subcellular localization of E2F-4 is regulated in a cell cycle-dependent manner that results in the differential compartmentalization of the various E2F complexes. Consequently, in cycling cells, the majority of the p107-E2F, p130-E2F, and free E2F complexes remain in the cytoplasm. In contrast, almost all of the nuclear E2F activity is generated by pRB-E2F. This complex is present at high levels during G1 but disappears once the cells have passed the restriction point. Surprisingly, dissociation of this complex causes little increase in the levels of nuclear free E2F activity. This observation suggests that the repressive properties of the pRB-E2F complex play a critical role in establishing the temporal regulation of E2F-responsive genes. How the differential subcellular localization of pRB, p107, and p130 contributes to their different biological properties is also discussed.

[Nonbacterial thrombotic endocarditis related to hepatocarcinoma]

A case of a woman with nonbacterial thrombotic endocarditis (NBTE) associated with hepatocarcinoma is here presented. Epidemiologic and clinicopathologic aspects are reviewed, early clinical suspicion may prevent embolization. it represents the first case reported in the national literature.

[Peutz-Jeghers syndrome. Apropos a familial case at Hospital Arzobispo Loayza]

The Peutz-Jeghers syndrome is a rare dominant autosomic, entity characterized by hyperpigmented lesions on the lips, hands and feet; with presence of gastrointestinal polyps producing acute or chronic anemia, intestinal obstruction, and/or abdominal pain. This polyps histologically are hamartomas; recent studies indicate a real risk for transformations in the malignant neoplasia. The high and low endoscopies and the intraoperative enteroscopy with polypectomy are the election treatment, improving prognosis quality on these patients. We describe a familiar case of a female patient 24 years old showing a repeated picture of intestinal subocclusion; her brother presented a similar clinical picture, and her mother presented the same syndrome, dying of carcinoma in the colon; also her child, at one and a half year old presented hyperpigmented lesions on the lips.

[A solid epithelial papillary-cystic pancreatic tumor. A report of a clinical case and review of the literature]

Solid and papillary epithelial tumor of the pancreas is an uncommon neoplasm of low malignant potential, which occurs mainly in adolescent and young adult females. We report the case of a 17 years old woman, who presented with an abdominal mass, which was diagnosed cytologically by aspiration. The surgical procedure was total excision. Six months post surgery the patient is healthy. As this is a very unusual occurrence, a review of the literature has been made on clinical, histological, radiological and surgical features.

L1 (LINE-1) retrotransposable elements provide a "fossil" record of the phylogenetic history of murid rodents

The single most difficult problem in phylogenetic analysis is deciding whether a shared taxonomic character is due to common ancestry or one that appeared independently due to convergence, parallelism, or reversion to an ancestral state. Mammalian L1 retrotransposons undergo periodic amplifications in which multiple copies of the elements are interspersed in the genome. Because these elements apparently are transmitted only by inheritance and are retained in the genome, a shared L1 amplification event can only be an inherited ancestral character. We propose that L1 amplification events can be an excellent tool for analyzing mammalian evolution and demonstrate here how we addressed several refractory problems in rodent systematics using L1 DNA as a taxonomic character.

[Tubercular liver abscess: a case report and discussion of the literature]

A case of an isolated tuberculous abscess of the liver in a 47-years-old woman with a 2-year history of disease is presented. Only 17 similar cases have been reported previously in the literature. The symptomatology of this patient, confused initially with a chronic calculous cholecystitis and then with an hepatic pyogenic abscess exemplify what has been described for this rare disease presentation. A review of the pertinent literature is presented.

Distinctive hair changes (pili torti) in Rapp-Hodgkin ectodermal dysplasia syndrome

An 8-year-old girl with narrow nose, small mouth, maxillary hypoplasia, cleft palate, hypodontia and hypohidrosis is described. Her scalp hair was coarse, dry and wiry. Microscopic examination showed the hair to be twisted at irregular intervals on its long axis, as seen in pili torti. Her mother has the same features; as a child, she had identical hair and is now bald. Both mother and daughter display signs and symptoms of Rapp-Hodgkin's ectodermal dysplasia. The autosomal dominant inheritance of the disease is further supported by the findings in this family.