Cytokine release: A workshop proceedings on the state-of-the-science, current challenges and future directions.

In October 2013, the International Life Sciences Institute - Health and Environmental Sciences Institute Immunotoxicology Technical Committee (ILSI-HESI ITC) held a one-day workshop entitled, "Workshop on Cytokine Release: State-of-the-Science, Current Challenges and Future Directions". The workshop brought together scientists from pharmaceutical, academic, health authority, and contract research organizations to discuss novel approaches and current challenges for the use of in vitro cytokine release assays (CRAs) for the identification of cytokine release syndrome (CRS) potential of novel monoclonal antibody (mAb) therapeutics. Topics presented encompassed a regulatory perspective on cytokine release and assessment, case studies regarding the translatability of preclinical cytokine data to the clinic, and the latest state of the science of CRAs, including comparisons between mAb therapeutics within one platform and across several assay platforms, a novel physiological assay platform, and assay optimization approaches such as determination of FcR expression profiles and use of statistical tests. The data and approaches presented confirmed that multiple CRA platforms are in use for identification of CRS potential and that the choice of a particular CRA platform is highly dependent on the availability of resources for individual laboratories (e.g. positive and negative controls, number of human blood donors), the assay through-put required, and the mechanism-of-action of the therapeutic candidate to be tested. Workshop participants agreed that more data on the predictive performance of CRA platforms is needed, and current efforts to compare in vitro assay results with clinical cytokine assessments were discussed. In summary, many laboratories continue to focus research efforts on the improvement of the translatability of current CRA platforms as well explore novel approaches which may lead to more accurate, and potentially patient-specific, CRS prediction in the future.

Transforming growth factor-beta induces development of the T(H)17 lineage.

A new lineage of effector CD4+ T cells characterized by production of interleukin (IL)-17, the T-helper-17 (T(H)17) lineage, was recently described based on developmental and functional features distinct from those of classical T(H)1 and T(H)2 lineages. Like T(H)1 and T(H)2, T(H)17 cells almost certainly evolved to provide adaptive immunity tailored to specific classes of pathogens, such as extracellular bacteria. Aberrant T(H)17 responses have been implicated in a growing list of autoimmune disorders. T(H)17 development has been linked to IL-23, an IL-12 cytokine family member that shares with IL-12 a common subunit, IL-12p40 (ref. 8). The IL-23 and IL-12 receptors also share a subunit, IL-12Rbeta1, that pairs with unique, inducible components, IL-23R and IL-12Rbeta2, to confer receptor responsiveness. Here we identify transforming growth factor-beta (TGF-beta) as a cytokine critical for commitment to T(H)17 development. TGF-beta acts to upregulate IL-23R expression, thereby conferring responsiveness to IL-23. Although dispensable for the development of IL-17-producing T cells in vitro and in vivo, IL-23 is required for host protection against a bacterial pathogen, Citrobacter rodentium. The action of TGF-beta on naive T cells is antagonized by interferon-gamma and IL-4, thus providing a mechanism for divergence of the T(H)1, T(H)2 and T(H)17 lineages.

FDA Approval Summary: Pembrolizumab, Atezolizumab, and Cemiplimab-rwlc as Single Agents for First-Line Treatment of Advanced/Metastatic PD-L1-High NSCLC.

FDA's approval of cemiplimab-rwlc on February 22, 2021, follows prior approvals of pembrolizumab and atezolizumab for similar indications as first-line treatment for patients with programmed death ligand-1 (PD-L1)-high advanced non-small cell lung cancer (NSCLC). Approvals of these anti-PD-L1 agents were supported by statistically significant and clinically meaningful improvements in overall survival (OS) in international, multicenter, active-controlled randomized trials. In KEYNOTE-024, the OS HR was 0.60 [95% confidence interval (CI), 0.41-0.89; P = 0.005] favoring pembrolizumab over platinum-doublet chemotherapy. In IMpower110, the OS HR was 0.59 (95% CI, 0.40-0.89; P = 0.0106) favoring atezolizumab over platinum-doublet chemotherapy. In Study 1624, the OS HR was 0.68 (95% CI, 0.53-0.87; P = 0.0022) favoring cemiplimab-rwlc over platinum-doublet chemotherapy. The progression-free survival (PFS) effect sizes for these anti-PD-L1 antibodies were also comparable across their respective registrational trials, and their safety profiles were consistent with the anti-PD-L1 class adverse event profile. The consistent survival benefits and manageable toxicity profiles of these single-agent anti-PD-L1 antibodies have established them as important treatment options in the PD-L1-high NSCLC treatment landscape. FDA approvals of these anti-PD-L1 antibodies, based on their favorable benefit-risk profiles, present effective chemotherapy-free therapeutic options for patients with advanced PD-L1-high NSCLC in the United States.

FDA Approval Summary: Capmatinib and Tepotinib for the Treatment of Metastatic NSCLC Harboring MET Exon 14 Skipping Mutations or Alterations.

The FDA approved capmatinib and tepotinib on May 6, 2020, and February 3, 2021, respectively. Capmatinib is indicated for patients with metastatic non-small cell lung cancer (mNSCLC) whose tumors have a mutation leading to mesenchymal-epithelial transition (MET) exon 14 skipping as detected by an FDA-approved test. Tepotinib is indicated for mNSCLC harboring MET exon 14 skipping alterations. The approvals were based on trials GEOMETRY mono-1 (capmatinib) and VISION (tepotinib). In GEOMETRY mono-1, overall response rate (ORR) per Blinded Independent Review Committee (BIRC) was 68% [95% confidence interval (CI), 48-84] with median duration of response (DoR) 12.6 months (95% CI, 5.5-25.3) in 28 treatment-naïve patients and 41% (95% CI: 29, 53) with median DoR 9.7 months (95% CI, 5.5-13) in 69 previously treated patients with NSCLC with mutations leading to MET exon 14 skipping. In VISION, ORR per BIRC was 43% (95% CI: 32, 56) with median DoR 10.8 months (95% CI, 6.9-not estimable) in 69 treatment-naïve patients and 43% (95% CI, 33-55) with median DoR 11.1 months (95% CI, 9.5-18.5) in 83 previously-treated patients with NSCLC harboring MET exon 14 alterations. These are the first two therapies to be FDA approved specifically for patients with metastatic NSCLC with MET exon 14 skipping.

FDA Approval Summary: Entrectinib for the Treatment of NTRK gene Fusion Solid Tumors.

The FDA-approved entrectinib on August 15, 2019, for the treatment of adult and pediatric patients 12 years of age and older with solid tumors that have a neurotrophic tyrosine receptor kinase (NTRK) gene fusion without a known acquired resistance mutation, are metastatic or where surgical resection is likely to result in severe morbidity, and have progressed following treatment or have no satisfactory alternative therapy. Approval was based on demonstration of a durable overall response rate of 57% (95% confidence interval: 43-71), including a complete response rate of 7%, among 54 entrectinib-treated patients with 10 different tumor types harboring an NTRK fusion enrolled in one of three single-arm clinical trials. The durations of response ranged from 2.8 months to 26.0+ months; 68% of responses lasted ≥ 6 months. The most serious toxicities of entrectinib are congestive heart failure, central nervous system effects, skeletal fractures, hepatotoxicity, hyperuricemia, QT prolongation, and vision disorders. Adverse reactions were manageable through dose interruptions (46%), dose reductions (29%), or discontinuation of entrectinib (9%). This is the third approval of a cancer drug for treatment of a tissue agnostic, biomarker-defined cancer.

FDA Approval Summary: Pralsetinib for the Treatment of Lung and Thyroid Cancers With RET Gene Mutations or Fusions.

The FDA granted accelerated approval for pralsetinib on September 4, 2020 for non-small cell lung cancer (NSCLC) and December 1, 2020 for thyroid cancer, for: (i) adult patients with metastatic RET fusion-positive NSCLC, (ii) adult and pediatric patients ≥12 years of age with advanced or metastatic RET-mutant medullary thyroid cancer who require systemic therapy, and (iii) adult and pediatric patients ≥12 years of age with advanced or metastatic RET fusion-positive thyroid cancer who require systemic therapy and who are radioactive iodine refractory (if radioactive iodine is appropriate). Approval was based on the results of a multicenter, open-label, multi-cohort clinical trial (ARROW, NCT03037385), demonstrating substantial overall response rates (ORR) and durable responses in patients with RET-altered tumors. ORRs within the approved patient populations ranged from 57% [95% confidence interval (CI), 46-68] in patients with RET fusion-positive NSCLC previously treated with platinum chemotherapy to 89% (95% CI, 52-100) in patients with RET fusion-positive thyroid cancer, with response duration of at least 6 months in most responders. The product label includes warnings and precautions for pneumonitis, hypertension, hepatotoxicity, hemorrhagic events, tumor lysis syndrome, risk of impaired wound healing, and embryo-fetal toxicity. This article summarizes the major considerations during FDA review leading to the approval of pralsetinib.

FDA Approval Summary: Lurbinectedin for the Treatment of Metastatic Small Cell Lung Cancer.

On June 15, 2020, the FDA granted accelerated approval to lurbinectedin for the treatment of adult patients with metastatic small cell lung cancer (SCLC) with disease progression on or after platinum-based chemotherapy. Approval was granted on the basis of the clinically meaningful effects on overall response rate (ORR) and duration of response (DOR), and the safety profile observed in a multicenter, open-label, multicohort clinical trial (PM1183-B-005-14, NCT02454972), referred to as Study B-005, in patients with advanced solid tumors. The trial included a cohort of 105 patients with metastatic SCLC who had disease progression on or after platinum-based chemotherapy. The confirmed ORR determined by investigator assessment using RECIST 1.1 in the approved SCLC patient population was 35% [95% confidence interval (CI): 26-45], with a median DOR of 5.3 (95% CI: 4.1-6.4) months. The drug label includes warnings and precautions for myelosuppression, hepatotoxicity, and embryo-fetal toxicity. This is the first drug approved by the FDA in over 20 years in the second line for patients with metastatic SCLC. Importantly, this approval includes an indication for patients who have platinum-resistant disease, representing an area of particular unmet need.

FDA Approval Summary: Selpercatinib for the Treatment of Lung and Thyroid Cancers with RET Gene Mutations or Fusions.

On May 8, 2020, the FDA granted accelerated approval to selpercatinib for (i) adult patients with metastatic RET fusion-positive non-small cell lung cancer (NSCLC), (ii) adult and pediatric patients ≥12 years of age with advanced or metastatic RET-mutant medullary thyroid cancer who require systemic therapy, and (iii) adult and pediatric patients ≥12 years of age with advanced or metastatic RET fusion-positive thyroid cancer who require systemic therapy and who are radioactive iodine refractory (if radioactive iodine is appropriate). Approval was granted on the basis of the clinically important effects on the overall response rate (ORR) with prolonged duration of responses observed in a multicenter, open-label, multicohort clinical trial (LIBRETTO-001, NCT03157128) in patients whose tumors had RET alterations. ORRs within the approved patient populations ranged from 64% [95% confidence interval (CI), 54-73] in prior platinum-treated RET fusion-positive NSCLC to 100% (95% CI, 63-100) in systemic therapy-naïve RET fusion-positive thyroid cancer, with the majority of responders across indications demonstrating responses of at least 6 months. The product label includes warnings and precautions for hepatotoxicity, hypertension, QT interval prolongation, hemorrhagic events, hypersensitivity, risk of impaired wound healing, and embryo-fetal toxicity. This is the first approval of a drug specifically for patients with RET alterations globally.

FDA Approval Summary: Selumetinib for Plexiform Neurofibroma.

On April 10, 2020, the FDA approved selumetinib (KOSELUGO, AstraZeneca) for the treatment of pediatric patients 2 years of age and older with neurofibromatosis type 1 who have symptomatic, inoperable plexiform neurofibromas. Approval was based on demonstration of a durable overall response rate per Response Evaluation in Neurofibromatosis and Schwannomatosis criteria and supported by observed clinical improvements in plexiform neurofibroma-related symptoms and functional impairments in 50 pediatric patients with inoperable plexiform neurofibromas in a single-arm, multicenter trial. The overall reponse rate per NCI investigator assessment was 66% (95% confidence interval, 51-79) with at least 12 months of follow-up. The median duration of response was not reached, and 82% of responding patients experienced duration of response ≥12 months. Clinical outcome assessment endpoints provided supportive efficacy data. Risks of selumetinib are consistent with MAPK (MEK) inhibitor class effects, including ocular, cardiac, musculoskeletal, gastrointestinal, and dermatologic toxicities. Safety was assessed across a pooled database of 74 pediatric patients with plexiform neurofibromas and supported by adult and pediatric selumetinib clinical trial data in cancer indications. The benefit-risk assessment for selumetinib in patients with inoperable plexiform neurofibromas was considered favorable.

Galpha13 mediates a signal that is essential for proliferation and survival of thymocyte progenitors.

G protein signaling via the Galpha12 family (Galpha12 and Galpha13) has not been well studied in T cells. To investigate whether Galpha12 and Galpha13 are involved in thymopoiesis, we expressed the regulator of G protein signaling domain of p115RhoGEF to inhibit Galpha12 and Galpha13 during thymopoiesis. Fetal thymus organ cultures seeded with p115DeltaDH-expressing progenitor cells showed impaired thymopoiesis with a block at the CD4-CD8-CD44-CD25+ (DN3) stage. Using Galpha13 or Galpha12 minigenes, we demonstrated that Galpha13, but not Galpha12, is required for thymopoiesis. T progenitor cells expressing p115DeltaDH showed reduced proliferation and increased cell death. T cell receptor stimulation of the fetal thymus organ cultures did not rescue the block. Overexpression of the antiapoptotic gene Bcl2 rescued the defect in DN3 cells and partially rescued T cell development. Therefore, Galpha13-mediated signaling is necessary in early thymocyte proliferation and survival.

Modulation of NFAT-dependent gene expression by the RhoA signaling pathway in T cells.

We have reported previously that p115Rho guanine nucleotide exchange factor, its upstream activator Galpha13, and its effector RhoA are able to inhibit HIV-1 replication. Here, we show that RhoA is able to inhibit HIV-1 gene expression through the NFAT-binding site in the HIV long-terminal repeat. Constitutively active NFAT counteracts the inhibitory activity of RhoA, and inhibition of NFAT activation also inhibits HIV-1 gene expression. We have shown further that RhoA inhibits NFAT-dependent transcription and IL-2 production in human T cells. RhoA does not inhibit nuclear localization of NFAT but rather, inhibits its transcriptional activity. In addition, RhoA decreases the level of acetylated histone H3, but not NFAT occupancy, at the IL-2 promoter. These data suggest that activation of RhoA can modulate IL-2 gene expression by inhibiting the transcriptional activity of NFAT and chromatin structure at the IL-2 promoter during T cell activation.

FDA Approval Summary: Trabectedin for Unresectable or Metastatic Liposarcoma or Leiomyosarcoma Following an Anthracycline-Containing Regimen.

On October 23, 2015, the FDA approved trabectedin, a new molecular entity for the treatment of patients with unresectable or metastatic liposarcoma or leiomyosarcoma who received a prior anthracycline-containing regimen. Approval was based on results of a single, randomized, active-controlled, 518-patient, multicenter study comparing the safety and efficacy of trabectedin 1.5 mg/m2 as a 24-hour continuous intravenous (i.v.) infusion once every 3 weeks with dacarbazine 1,000 mg/m2 i.v. once every 3 weeks. Treatment with trabectedin resulted in a statistically significant improvement in progression-free survival (PFS), with a PFS of 4.2 months and 1.5 months for trabectedin and dacarbazine, respectively (HR, 0.55; 95% confidence interval, 0.44-0.70; unstratified log-rank test, P < 0.001). The most common adverse reactions (≥20%) were nausea, fatigue, vomiting, constipation, decreased appetite, diarrhea, peripheral edema, dyspnea, and headache. Serious adverse reactions included anaphylaxis, neutropenic sepsis, rhabdomyolysis, hepatotoxicity, cardiomyopathy, and extravasation resulting in tissue necrosis. A postmarketing trial was required to evaluate the serious risk of cardiomyopathy. This approval provides another treatment option in a setting where no drug has been shown to improve overall survival. A key regulatory consideration during review of this application was the use of PFS as an endpoint to support regular approval of trabectedin. Clin Cancer Res; 23(24); 7448-53. ©2017 AACR.

FDA Approval Summary: TAS-102.

The FDA approved TAS-102 (Lonsurf; Taiho Oncology, Inc.) for the treatment of patients with metastatic colorectal cancer (mCRC) who have been previously treated with fluoropyrimidine-, oxaliplatin-, and irinotecan-based chemotherapy; an anti-VEGF biological therapy; and if RAS wild type, an anti-EGFR therapy. In an international, multicenter, double-blinded, placebo-controlled trial (TPU-TAS-102-301, herein referred to as RECOURSE), 800 patients with previously treated mCRC were randomly allocated (2:1) to receive either TAS-102 35 mg/m2 orally twice daily after meals on days 1 through 5 and 8 through 12 of each 28-day cycle (n = 534) or matching placebo (n = 266). The trial demonstrated a statistically significant improvement in overall survival for those randomized to receive TAS-102, with a median survival of 7.1 months in the TAS-102 arm [confidence interval (CI), 6.5-7.8] and 5.3 months in the placebo arm [CI, 4.6-6.0; hazard ratio (HR), 0.68; 95% CI, 0.58-0.81; P < 0.001, stratified log-rank test]. The trial also demonstrated a statistically significant prolongation of progression-free survival (HR, 0.47; 95% CI, 0.40-0.55; P < 0.001). The most common adverse reactions, in order of decreasing frequency, observed in the patients who received TAS-102 were anemia, neutropenia, asthenia/fatigue, nausea, thrombocytopenia, decreased appetite, diarrhea, vomiting, abdominal pain, and pyrexia. Adverse events led to discontinuation of TAS-102 in 3.6% of patients, and 13.7% required a dose reduction. The most common adverse reactions leading to dose reduction were neutropenia, anemia, febrile neutropenia, fatigue, and diarrhea. Clin Cancer Res; 23(12); 2924-7. ©2017 AACR.

U.S. FDA Approval Summary: Nivolumab for Treatment of Unresectable or Metastatic Melanoma Following Progression on Ipilimumab.

On December 22, 2014, the FDA granted accelerated approval to nivolumab (OPDIVO; Bristol-Myers Squibb) for the treatment of patients with unresectable or metastatic melanoma and disease progression following ipilimumab and, if BRAF V600 mutation positive, a BRAF inhibitor. Approval was based on a clinically meaningful, durable objective response rate (ORR) in a non-comparative analysis of 120 patients who received 3 mg/kg of nivolumab intravenously every 2 weeks with at least 6-month follow-up in an ongoing, randomized, open-label, active-controlled clinical trial. The ORR as assessed by a blinded independent review committee per RECIST v1.1 was 31.7% (95% confidence interval, 23.5-40.8). Ongoing responses were observed in 87% of responding patients, ranging from 2.6+ to 10+ months. In 13 patients, the response duration was 6 months or longer. The risks of nivolumab, including clinically significant immune-mediated adverse reactions (imARs), were assessed in 268 patients who received at least one dose of nivolumab. The FDA review considered whether the ORR and durations of responses were reasonably likely to predict clinical benefit, the adequacy of the safety database, and systematic approaches to the identification, description, and patient management for imARs in product labeling. Clin Cancer Res; 23(14); 3484-8. ©2017 AACR.

FDA Approval Summary: Accelerated Approval of Pembrolizumab for Second-Line Treatment of Metastatic Melanoma.

On September 4, 2014, the FDA approved pembrolizumab (KEYTRUDA; Merck Sharp & Dohme Corp.) with a recommended dose of 2 mg/kg every 3 weeks by intravenous infusion for the treatment of patients with unresectable or metastatic melanoma who have progressed following treatment with ipilimumab and, if BRAF V600 mutation positive, a BRAF inhibitor. Approval was based on demonstration of objective tumor responses with prolonged response durations in 89 patients enrolled in a randomized, multicenter, open-label, dose-finding, and activity-estimating phase 1 trial. The overall response rate (ORR) by blinded independent central review per RECIST v1.1 was 24% (95% confidence interval, 15-34); with 6 months of follow-up, 86% of responses were ongoing. The most common (≥20%) adverse reactions were fatigue, cough, nausea, pruritus, rash, decreased appetite, constipation, arthralgia, and diarrhea. Immune-mediated adverse reactions included pneumonitis, colitis, hepatitis, hypophysitis, and thyroid disorders. The benefits of the observed ORR with prolonged duration of responses outweighed the risks of immune-mediated adverse reactions in this life-threatening disease and represented an improvement over available therapy. Important regulatory issues in this application were role of durability of response in the evaluation of ORR for accelerated approval, reliance on data from a first-in-human trial, and strategies for dose selection. Clin Cancer Res; 23(19); 5666-70. ©2017 AACR.

FDA approval summary: vemurafenib for treatment of unresectable or metastatic melanoma with the BRAFV600E mutation.

On August 17, 2011, the U.S. Food and Drug Administration (FDA) approved vemurafenib tablets (Zelboraf, Hoffmann-LaRoche Inc.) for the treatment of patients with unresectable or metastatic melanoma with the BRAF(V600E) mutation as detected by an FDA-approved test. The cobas 4800 BRAF V600 Mutation Test (Roche Molecular Systems, Inc.) was approved concurrently. An international, multicenter, randomized, open-label trial in 675 previously untreated patients with BRAF(V600E) mutation-positive unresectable or metastatic melanoma allocated 337 patients to receive vemurafenib, 960 mg orally twice daily, and 338 patients to receive dacarbazine, 1,000 mg/m(2) intravenously every 3 weeks. Overall survival was significantly improved in patients receiving vemurafenib [HR, 0.44; 95% confidence interval (CI), 0.33-0.59; P < 0.0001]. Progression-free survival was also significantly improved in patients receiving vemurafenib (HR, 0.26; 95% CI, 0.20-0.33; P < 0.0001). Overall response rates were 48.4% and 5.5% in the vemurafenib and dacarbazine arms, respectively. The most common adverse reactions (≥30%) in patients treated with vemurafenib were arthralgia, rash, alopecia, fatigue, photosensitivity reaction, and nausea. Cutaneous squamous cell carcinomas or keratoacanthomas were detected in approximately 24% of patients treated with vemurafenib. Other adverse reactions included hypersensitivity, Stevens-Johnson syndrome, toxic epidermal necrolysis, uveitis, QT prolongation, and liver enzyme laboratory abnormalities.

Contrasting roles for all-trans retinoic acid in TGF-beta-mediated induction of Foxp3 and Il10 genes in developing regulatory T cells.

Extrathymic induction of regulatory T (T reg) cells is essential to the regulation of effector T cell responses in the periphery. In addition to Foxp3, T reg cell expression of suppressive cytokines, such as IL-10, is essential for peripheral tolerance, particularly in the intestines. TGF-beta has been shown to induce expression of Foxp3 as well as IL10 and the vitamin A metabolite; all-trans retinoic acid (RA [at-RA]) has been found to enhance the former. We report that in contrast to its enhancement of TGF-beta-mediated Foxp3 induction, at-RA potently inhibits the TGF-beta-mediated induction of Il10 in naive CD4 T cells. Thus, mucosal DC subsets that are active producers of at-RA inhibit induction of Il10 in naive CD4 T cells while promoting induction of Foxp3. Accordingly, mice with vitamin A deficiency have increased numbers of IL-10-competent T reg cells. Activation of DCs by certain Toll-like receptors (TLRs), particularly TLR9, suppresses T cell induction of Foxp3 and enables induction of Il10. Collectively, our data indicate that at-RA has reciprocal effects on the induction of Foxp3 and Il10 in developing CD4(+) T reg cells and suggest that TLR9-dependent inhibition of at-RA production by antigen-presenting cells might represent one mechanism to promote the development of IL-10-expressing T cells.