Blocking interleukin-6 activity with chimeric anti-IL6 monoclonal antibodies in multiple myeloma: effects on soluble IL6 receptor and soluble gp130

Soluble receptors in cancer: mechanisms, clinical significance, and therapeutic strategies

Soluble receptors are soluble forms of receptors found in the extracellular space. They have emerged as pivotal regulators of cellular signaling and disease pathogenesis. This review emphasizes their significance in cancer as diagnostic/prognostic markers and potential therapeutic targets. We provide an overview of the mechanisms by which soluble receptors are generated along with their functions. By exploring their involvement in cancer progression, metastasis, and immune evasion, we highlight the importance of soluble receptors, particularly soluble cytokine receptors and immune checkpoints, in the tumor microenvironment. Although current research has illustrated the emerging clinical relevance of soluble receptors, their therapeutic applications remain underexplored. As the landscape of cancer treatment evolves, understanding and targeting soluble receptors might pave the way for novel strategies for cancer diagnosis, prognosis, and therapy.

Monoclonal Antibodies for the Treatment of Multiple Myeloma: An Update

The past two decades have seen a revolution in multiple myeloma (MM) therapy with the introduction of several small molecules, mostly orally effective, whose mechanisms are based on proteasome inhibition, histone deacetylase (HDAC) blockade, and immunomodulation. Immunotherapeutic approaches to MM treatment using monoclonal antibodies (mAbs), while long in development, began to reap success with the identification of CD38 and SLAMF7 as suitable targets for development, culminating in the 2015 Food and Drug Administration (FDA) approval of daratumumab and elotuzumab, respectively. This review highlights additional mAbs now in the developmental pipeline. Isatuximab, another anti-CD38 mAb, currently is under study in four phase III trials and may offer certain advantages over daratumumab. Several antibody-drug conjugates (ADCs) in the early stages of development are described, including JNJ-63723283, which has attained FDA breakthrough status for MM. Other mAbs described in this review include denosumab, recently approved for myeloma-associated bone loss, and checkpoint inhibitors, although the future status of the latter combined with immunomodulators has been clouded by unacceptably high death rates that caused the FDA to issue clinical holds on several of these trials. Also highlighted are the therapies based on the B Cell Maturation Antigen (BCMA), another very promising target for anti-myeloma development.

Due to interleukin-6 type cytokine redundancy only glycoprotein 130 receptor blockade efficiently inhibits myeloma growth

Interleukin-6 has an important role in the pathophysiology of multiple myeloma where it supports the growth and survival of the malignant plasma cells in the bone marrow. It belongs to a family of cytokines which use the glycoprotein 130 chain for signal transduction, such as oncostatin M or leukemia inhibitory factor. Targeting interleukin-6 in plasma cell diseases is currently evaluated in clinical trials with monoclonal antibodies. Here, efforts were made to elucidate the contribution of interleukin-6 and glycoprotein 130 signaling in malignant plasma cell growth in vivo In the xenograft severe combined immune deficiency model employing our interleukin-6-dependent plasma cell line INA-6, the lack of human interleukin-6 induced autocrine interleukin-6 production and a proliferative response to other cytokines of the glycoprotein 130 family. Herein, mice were treated with monoclonal antibodies against human interleukin-6 (elsilimomab/B-E8), the interleukin-6 receptor (B-R6), and with an antibody blocking glycoprotein 130 (B-R3). While treatment of mice with interleukin-6 and interleukin-6 receptor antibodies resulted in a modest delay in tumor growth, the development of plasmacytomas was completely prevented with the anti-glycoprotein 130 antibody. Importantly, complete inhibition was also achieved using F(ab')2-fragments of monoclonal antibody B-R3. Tumors harbor activated signal transducer and activator of transcription 3, and in vitro, the antibody inhibited leukemia inhibitory factor stimulated signal transducer and activator of transcription 3 phosphorylation and cell growth, while being less effective against interleukin-6. In conclusion, the growth of INA-6 plasmacytomas in vivo under interleukin-6 withdrawal remains strictly dependent on glycoprotein 130, and other glycoprotein 130 cytokines may substitute for interleukin-6. Antibodies against glycoprotein 130 are able to overcome this redundancy and should be explored for a possible therapeutic window.

A phase I/II, multiple-dose, dose-escalation study of siltuximab, an anti-interleukin-6 monoclonal antibody, in patients with advanced solid tumors

PURPOSE

This phase I/II study evaluated safety, efficacy, and pharmacokinetics of escalating, multiple doses of siltuximab, a chimeric anti-interleukin (IL)-6 monoclonal antibody derived from a new Chinese hamster ovary (CHO) cell line in patients with advanced/refractory solid tumors.

EXPERIMENTAL DESIGN

In the phase I dose-escalation cohorts, 20 patients with advanced/refractory solid tumors received siltuximab 2.8 or 5.5 mg/kg every 2 weeks or 11 or 15 mg/kg every 3 weeks intravenously (i.v.). In the phase I expansion (n = 24) and phase II cohorts (n = 40), patients with Kirsten rat sarcoma-2 (KRAS)-mutant tumors, ovarian, pancreatic, or anti-EGF receptor (EGFR) refractory/resistant non-small cell lung cancer (NSCLC), colorectal, or H&N cancer received 15 mg/kg every 3 weeks. The phase II primary efficacy endpoint was complete response, partial response, or stable disease >6 weeks.

RESULTS

Eighty-four patients (35 colorectal, 29 ovarian, 9 pancreatic, and 11 other) received a median of three (range, 1-45) cycles. One dose-limiting toxicity occurred at 5.5 mg/kg. Common grade ≥3 adverse events were hepatic function abnormalities (15%), physical health deterioration (12%), and fatigue (11%). Ten percent of patients had siltuximab-related grade ≥3 adverse events. Neutropenia (4%) was the only possibly related adverse event grade ≥3 reported in >1 patient. Serious adverse events were reported in 42%; most were related to underlying disease. The pharmacokinetic profile of CHO-derived siltuximab appears similar to the previous cell line. No objective responses occurred; 5 of 84 patients had stable disease >6 weeks. Hemoglobin increased ≥1.5 g/dL in 33 of 47 patients. At 11 and 15 mg/kg, completely sustained C-reactive protein suppression was observed.

CONCLUSIONS

Siltuximab monotherapy appears to be well tolerated but without clinical activity in solid tumors, including ovarian and KRAS-mutant cancers. The recommended phase II doses were 11 and 15 mg/kg every 3 weeks.

A phase I, open-label study of siltuximab, an anti-IL-6 monoclonal antibody, in patients with B-cell non-Hodgkin lymphoma, multiple myeloma, or Castleman disease

PURPOSE

To evaluate the safety and pharmacokinetics of siltuximab, an anti-interleukin-6 chimeric monoclonal antibody (mAb) in patients with B-cell non-Hodgkin lymphoma (NHL), multiple myeloma, or Castleman disease.

EXPERIMENTAL DESIGN

In an open-label, dose-finding, 7 cohort, phase I study, patients with NHL, multiple myeloma, or symptomatic Castleman disease received siltuximab 3, 6, 9, or 12 mg/kg weekly, every 2 weeks, or every 3 weeks. Response was assessed in all disease types. Clinical benefit response (CBR; composite of hemoglobin, fatigue, anorexia, fever/night sweats, weight, largest lymph node size) was also evaluated in Castleman disease.

RESULTS

Sixty-seven patients received a median of 16 siltuximab doses for a median of 8.5 (maximum 60.5) months; 29 were treated 1 year or longer. There was no dose-limiting toxicity, antibodies to siltuximab, or apparent dose-toxicity relationship. The most frequently reported possible drug-related adverse events were thrombocytopenia (25%), hypertriglyceridemia (19%), neutropenia (19%), leukopenia (18%), hypercholesterolemia (15%), and anemia (10%). None of these events led to dose delay/discontinuation except for neutropenia and thrombocytopenia (n = 1 each). No treatment-related deaths occurred. C-reactive protein (CRP) suppression was most pronounced at 12 mg/kg every 3 weeks. Mean terminal-phase half-life of siltuximab ranged 17.73 to 20.64 days. Thirty-two of 37 (86%) patients with Castleman disease improved in 1 or more CBR component; 12 of 36 evaluable Castleman disease patients had radiologic response [complete response (CR), n = 1; partial response (PR), n = 11], including 8 of 19 treated with 12 mg/kg; 2 of 14 (14%) evaluable NHL patients had PR; 2 of 13 (15%) patients with multiple myeloma had CR.

CONCLUSION

No dose-related or cumulative toxicity was apparent across all disease indications. A dose of 12 mg/kg every 3 weeks was recommended on the basis of the high response rates in Castleman disease and the sustained CRP suppression. Randomized studies are ongoing in Castleman disease and multiple myeloma.

Future perspectives: should Th17 cells be considered as a possible therapeutic target in acute myeloid leukemia patients receiving allogeneic stem cell transplantation?

Th17 cells seem to promote proinflammatory effects, and their development seems to depend on intracellular signaling initiated by IL1β, supported by IL6 and IL23 and mediated by STAT3 and RORC2. Even though primary human AML cells may affect Th17 development through their constitutive cytokine release, the levels of circulating Th17 cells in older patients with untreated AML do not differ from healthy controls and show only minor variations during and following conventional intensive chemotherapy. IL17-A is the signature cytokine of Th17 cells, but in vitro studies have failed to demonstrate a direct antileukemic effect of IL17 on primary human AML cells for most patient samples. However, several observations suggest that Th17 cells mediate antileukemic effects through other mechanisms and are important in allogeneic stem cell transplantation. Firstly, genetic variants in IL23/Th17 pathway have a prognostic impact with regard to both development of GVHD and posttransplant infections. Secondly, circulating IL17-secreting cells are detected during early posttransplant pancytopenia, and their ability to release IL17 is associated with later GVHD. Thirdly, a high number of Th17 cells in allogeneic stem cell grafts are associated with later acute GVHD, levels of circulating Th17 cells are increased at the onset of acute GVHD, and these levels normalize during treatment. In the present article, we review previous studies of Th17 cells in AML and in the development of GVHD, possible therapeutic strategies and available therapeutic tools for targeting of Th17 cells.

Antibody-based therapies in multiple myeloma

The unmet need for improved multiple myeloma (MM) therapy has stimulated clinical development of monoclonal antibodies (mAbs) targeting either MM cells or cells of the bone marrow (BM) microenvironment. In contrast to small-molecule inhibitors, therapeutic mAbs present the potential to specifically target tumor cells and directly induce an immune response to lyse tumor cells. Unique immune-effector mechanisms are only triggered by therapeutic mAbs but not by small molecule targeting agents. Although therapeutic murine mAbs or chimeric mAbs can cause immunogenicity, the advancement of genetic recombination for humanizing rodent mAbs has allowed large-scale production and designation of mAbs with better affinities, efficient selection, decreasing immunogenicity, and improved effector functions. These advancements of antibody engineering technologies have largely overcome the critical obstacle of antibody immunogenicity and enabled the development and subsequent Food and Drug Administration (FDA) approval of therapeutic Abs for cancer and other diseases.

Siltuximab, a novel anti-interleukin-6 monoclonal antibody, for Castleman's disease

PURPOSE

Interleukin-6 (IL-6) has emerged as a key factor in the pathogenesis of the atypical lymphoproliferative disorder Castleman's disease (CD). Siltuximab is a new anti-IL-6, chimeric monoclonal antibody with potential therapeutic benefit in patients with CD.

METHODS

We report interim results from an open-label, dose-finding, seven-cohort, phase I study in which patients with symptomatic, multicentric or unresectable, unicentric CD received siltuximab at 1-, 2-, or 3-week intervals. The main efficacy end point of clinical benefit response (CBR) was defined as a composite of clinical and laboratory measures relevant to the management of CD. In addition, radiologic response was independently assessed by using modified Cheson criteria.

RESULTS

Eighteen (78%) of 23 patients (95% CI, 56% to 93%) achieved CBR, and 12 patients (52%) demonstrated objective tumor response. All 11 patients (95% CI, 72% to 100%) treated with the highest dose of 12 mg/kg achieved CBR, and eight patients (73%) achieved objective tumor response. Overall objective-response duration ranged from 44 to > or = 889 days, and one patient had complete response for > or = 318 days. Hemoglobin increased markedly in 19 patients (median increase, 2.1 g/dL; range, 0.2 to 4.7 g/dL) in the absence of transfusion or erythropoiesis-stimulating agents. No dose-limiting toxicity was reported, and only three patients had grade 3 or higher adverse events after a median exposure of 331 days (range, 1 to 1,148 days).

CONCLUSION

These interim results strongly suggest that siltuximab is an effective treatment with favorable safety for the management of CD. An additional study is planned to fully evaluate safety and efficacy at the recommended dose of 12 mg/kg every 3 weeks.

The role of IGF-1 as a major growth factor for myeloma cell lines and the prognostic relevance of the expression of its receptor

A plethora of myeloma growth factors (MGFs) has been identified, but their relative importance and cooperation have not been determined. We investigated 5 MGFs (interleukin-6 [IL-6], insulin-like growth factor type 1 [IGF-1], hepatocyte growth factor [HGF], HB-epidermal growth factor [HB-EGF], and a proliferation-inducing ligand [APRIL]) in serum-free cultures of human myeloma cell lines (HMCLs). In CD45(-) HMCLs, an autocrine IGF-1 loop promoted autonomous survival whereas CD45(+) HMCLs could not survive without addition of MGFs, mainly IGF-1 and IL-6. IGF-1 was the major one: its activity was abrogated by an IGF-1R inhibitor only, whereas IL-6, HGF, or HB-EGF activity was inhibited by both IGF-1R- and receptor-specific inhibition. APRIL activity was inhibited by its specific inhibitor only. Of the investigated MGFs and their receptors, only expressions of IGF-1R and IL-6R in multiple myeloma cells (MMCs) of patients delineate a group with adverse prognosis. This is mainly explained by a strong association of IGF-1R and IL-6R expression and t(4;14) translocation, but IGF-1R expression without t(4;14) can also have a poor prognosis. Thus, IGF-1-targeted therapy, eventually in combination with anti-IL-6 therapy, could be promising in a subset of patients with MMCs expressing IGF-1R.

CNTO 328, a monoclonal antibody to IL-6, inhibits human tumor-induced cachexia in nude mice

IL-6 is a multifunctional cytokine implicated in several cancers. IL-6 is a growth factor for certain tumors and contributes to drug resistance, cachexia and bone resorption. Cachexia is characterized by progressive weight loss and depletion of host reserves of adipose tissue and skeletal muscle. We have developed CNTO 328 (cCLB8), a human-mouse chimeric MAb to IL-6 (K(d) approx. 10(-12) M) that inhibits IL-6 function. A phase I study with CNTO 328 in multiple myeloma patients demonstrated that the antibody was safe and had a circulating half-life of approximately 17 days. Since IL-6 is implicated in cachexia, we hypothesized that CNTO 328 could inhibit tumor-induced cachexia. We used 2 human tumor-induced cachexia models in nude mice. In the first model, human melanoma cells were inoculated in female nude mice. Control treated animals lost 19% (+/-7.7%) body weight from day 0 to day 31, whereas CNTO 328 (10 mg/kg)-treated animals lost only 1.5% (+/-1.3%) body weight from day 0 to day 31 (p = 0.023). In the second cachexia model, human prostate tumor cells were injected into male nude mice. By day 29, control treated animals lost 6% (+/-3.5%) body weight, whereas CNTO 328 (10 mg/kg)-treated animals gained 7% (+/-4%) body weight (p = 0.01). Since CNTO 328 blocks human IL-6 but not mouse IL-6, the data indicate that tumor cell-secreted IL-6 directly contributes to body weight loss, highlighting the potential role for CNTO 328 as an anticachectic agent.

Measurements of IL-6, soluble IL-6 receptor and soluble gp130 in sera of B-cell lymphoma patients. Does viscum album treatment affect these parameters?

Interleukin-6 (IL-6) can be involved in several diseases including lymphoid malignancies. This cytokine binds to soluble IL-6 receptor (sIL-6R) circulating in blood, leading to signal transduction via gp130. Soluble IL-6R shows agonistic activity for IL-6, and the soluble form of gp130 (sgp130) an antagonistic effect against the complex IL-6/sIL-6R. Viscum album extract (Iscador) as an immunomodulator is used in the treatment of malignant disorders. In this study we investigated the effect of this treatment on the serum levels of IL-6, sIL-6R and sgp130 in B-cell lymphoma patients (n = 27), in comparison to healthy controls (n = 28). Twenty-one of 27 patients had been treated previously with chemo/radiotherapy. The patients were divided into two groups; those with short-term (investigated before and during treatment) or those with long-term Viscum album (VA) therapy (investigated during therapy). The serum levels of the three parameters were determined by ELISA. In patients having short-term treatment IL-6 values were similar to those of controls. During long-term therapy the values were significantly lower (P<0.05). The values of sIL-6R were elevated only in long-term treated patients (P<0.05), the values of sgp130 in both short-term (P<0.05) and in long-term treated patients (P=0.001). There is a significant correlation (P<0.05) between levels of sIL-6R and sgp130 in both therapy groups at 24 hours after injection. This indicates that the potent effect of sIL-6R on the biological activity of IL-6 could be inhibited by sgp130 as antagonist. Clinical data show that half of the patients (6/12) with long-term treatment had a continuous complete remission, whereas only 2/15 patients with short-term treatment had a complete remission.

Investigation of interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R) and soluble gp130 (sgp130) in sera of cancer patients

The serum levels of interleukin-6 (IL-6), sIL-6R and sgp130 were investigated in 76 cancer patients in comparison with 28 healthy controls. IL-6 is a multifunctional cytokine involved in certain malignant diseases. Soluble IL-6 receptor as agonist enhances the biological effect of released IL-6. Soluble gp130 as antagonist inhibits the effect of the IL-6/sIL-6R complex. Patients with different types of tumour (breast/gastrointestinal/uterine/ovarian/renal/bladder) were divided into four groups according to tumour stage and previous therapy (stage I + II without or after chemo-/radiotherapy, stage III + IV without or after chemo-/radiotherapy). The distribution of different tumour histotypes was similar in each group of patients. The levels of the three serum parameters were determined by ELISA. At each tumour stage either without or after chemo-/radiotherapy, the serum values of IL-6 were found to be not significantly different from those of controls. The values of sIL-6R were significantly elevated in stage I + II (P < 0.02) patients, with a borderline significance in stage III + IV (P = 0.06), in both cases only when no additional therapy was initiated. The serum values of sgp130 increased significantly at each tumour stage both without and after chemo-/radiotherapy (P < 0.001). A significant correlation was found between the values of sIL-6R and sgp130 in stage I + II (P < 0.02) and III + IV (P < 0.004) patients, in both cases without chemo-/radiotherapy. There were no other significant correlations. In conclusion, the simultaneous measurement of IL-6, sIL-6R and sgp130 in sera is an important factor in evaluating the biological effect of IL-6 in malignant disease. This is the first report to investigate sgp130 in cancer patients with different types of tumour.