Abstract B19: The HSP90 inhibitor, AT13387, is effective against multiple mechanisms of kinase inhibitor resistance

Background: Treatment with kinase inhibitors, although initially effective in the clinic, frequently leads to resistance and relapse. Multiple mechanisms of resistance have been identified including mutation of the original targeted kinase or upregulation of downstream or parallel signaling pathways. Many oncogenic kinases are clients of HSP90, including KIT, B-RAFV600E and EML4/ALK and remain dependent on HSP90 even when secondary mutations arise. In addition, proteins in many signaling pathways also rely on HSP90 activity and are depleted when HSP90 is inhibited. Treatment with an HSP90 inhibitor is therefore a promising approach for addressing multiple mechanisms of kinase inhibitor resistance.

AT13387, a potent, fragment-derived HSP90 inhibitor, is currently under evaluation in a Phase II gastrointestinal stromal tumor (GIST) trial in combination with imatinib. AT13387 is effective in both imatinib-sensitive and imatinib-resistant GIST models, demonstrating HSP90 inhibition can overcome kinase inhibitor-resistance caused by secondary mutations in the drug target client, in this case KIT. Here we describe the activity of AT13387 in vemurafenib-resistant melanoma models. Multiple mechanisms of vemurafenib resistance have been identified. These frequently involve upregulation of the AKT (e.g. PTEN loss) or MEK/ERK (e.g. Ras mutation, BRAF splice variants) signaling pathways, rather than mutation at the vemurafenib-binding site in BRAFV600E.

Results: The effect of HSP90 inhibition on acquired vemurafenib resistance was investigated by generating resistant clones from the A375, vemurafenib-sensitive, cell line by continuous exposure to 2 μM vemurafenib. Proliferation and signalling in the vemurafenib-resistant pool of cells were insensitive to vemurafenib but potently inhibited by AT13387, indicating that HSP90 inhibition can overcome an acquired mechanism of vemurafenib resistance.

In established cell lines, two different mechanisms of vemurafenib resistance were investigated. The A2058 cell line is PTEN-null and overcomes BRAFV600E inhibition through upregulation of the AKT pathway, whilst RPMI7951 overexpresses COT, upregulating the MEK/ERK pathway and bypassing inhibition of BRAFV600E. The proliferation of both these cell lines was inhibited by AT13387 with GI50s of 31 and 37 nM respectively. AT13387 treatment depleted the levels of the client proteins, BRAF and CRAF, and in the RPMI7951 cell line, levels of COT were also seen to decrease. Signaling through both the AKT and MEK/ERK pathways was inhibited as indicated by a decrease in the levels of phosphoAKT, phosphoS6 and phosphoERK. This suggests that HSP90 inhibition can overcome upregulation of either the AKT or MEK/ERK pathways and so counteract multiple mechanisms of vemurafenib resistance.

AT13387 and vemurafenib could be combined in both the A2058 and RPMI7951 cell lines without any antagonistic effects, whilst culturing A375 cells in the presence of both AT13387 and vemurafenib prevented the development of vemurafenib-resistant clones. These data suggest that not only can AT13387 treatment overcome established resistance but that in combination it may also be a means of delaying the emergence of this resistance.

Conclusions: We have demonstrated that AT13387 can overcome kinase inhibitor resistance in both imatinib-resistant GIST and vemurafenib-resistant melanoma models. This suggests HSP90 inhibition may be a promising approach for combating multiple mechanisms of resistance to kinase inhibitors in the clinic and that AT13387 combinations may have the potential to delay the emergence of resistance.

A multicenter, phase II study of infliximab plus gemcitabine in pancreatic cancer cachexia

To evaluate the safety and efficacy of infliximab administered with gemcitabine to treat cancer cachexia and to explore a functional measure of clinical benefit, investigators involved in this multicenter, phase II, placebo-controlled study randomized 89 patients with stage II-IV pancreatic cancer and cachexia to receive either placebo or 3 mg/ kg or 5 mg/kg of infliximab at weeks 0, 2, and 4 and then every 4 weeks to week 24; patients also received 1,000 mg/m2 of gemcitabine weekly from weeks 0-6 and then for 3 of every 4 weeks until their disease progressed. The primary endpoint was change in lean body mass (LBM) at 8 weeks from baseline; major secondary endpoints included overall survival, progression-free survival, Karnofsky performance status, and 6-minute walk test distance. In addition, quality of life was measured. The mean change in LBM at 8 weeks was +0.4 kg for patients receiving placebo, +0.3 kg for those receiving 3 mg/kg of infliximab, and +1.7 kg for those receiving 5 mg/kg of infliximab. No statistically significant differences in LBM or secondary endpoints were observed among the groups. Safety findings were similar in all groups. Adding infliximab to gemcitabine to treat cachexia in advanced pancreatic cancer patients was not associated with statistically significant differences in safety or efficacy when compared with placebo.

Tumor necrosis factor alpha as a new target for renal cell carcinoma: two sequential phase II trials of infliximab at standard and high dose

PURPOSE

Tumor necrosis factor alpha (TNF-alpha) may play a role in renal cell carcinoma (RCC). We performed two sequential phase II studies of infliximab, an anti-TNF-alpha monoclonal antibody, in patients with immunotherapy-resistant or refractory RCC.

PATIENTS AND METHODS

Patients progressing after cytokine therapy were treated with intravenous infliximab as follows: study 1 (19 patients), 5 mg/kg at weeks 0, 2, and 6, and then every 8 weeks; study 2 (18 patients), 10 mg/kg at weeks 0, 2, and 6, and then every 4 weeks. Treatment continued until disease progression (PD). Response was assessed according to Response Evaluation Criteria in Solid Tumors. Plasma levels of TNF-alpha, CCL2, and interleukin-6 (IL-6) were measured before and during treatment.

RESULTS

TNF-alpha and its receptors were detected in malignant cells in RCC biopsies. In study 1, three patients (16%) achieved partial response (PR) and three patients (16%) achieved stable disease (SD). Median duration of response (PR + SD) was 7.7 months (range, 5.0 to 40.5+ months). In study 2, 11 patients (61%) achieved SD. Median duration of response was 6.2 months (range, 3.5 to 24+ months). One patient developed grade 3 hypersensitivity and another died as a result of pulmonary infection/sepsis. Enzyme-linked immunosorbent assay analysis of plasma revealed that higher levels of TNF-alpha at baseline and higher levels of CCL2 during treatment were associated with PD. There were also correlations between higher levels of TNF-alpha, IL-6, and CCL2 and poor survival (< 12 months).

CONCLUSION

This is the first direct clinical evidence suggesting that TNF-alpha may be a therapeutic target in RCC. Plasma levels of TNF-alpha, IL-6, and CCL2 may have predictive and prognostic significance.

Alpha-v integrins as therapeutic targets in oncology

Integrins are heterodimeric cell adhesion receptors that mediate intercellular communication through cell-extracellular matrix interactions and cell-cell interactions. Integrins have been demonstrated to play a direct role in cancer progression, specifically in tumor cell survival, tumor angiogenesis, and metastasis. Therefore, agents targeted against integrin function have potential as effective anticancer therapies. Numerous anti-integrin agents, including monoclonal antibodies and small-molecule inhibitors, are in clinical development for the treatment of solid and hematologic tumors. This review focuses on the role of alpha(v) integrins in cancer progression, the current status of integrin-targeted agents in development, and strategies for the clinical development of anti-integrin therapies.

Preliminary results of a phase I study: A chimeric monoclonal anti IL-6 antibody CNTO 328 in combination with docetaxel in patients with hormone refractory prostate cancer

15521

Background: High serum levels of pro-inflammatory cytokine IL-6 may impact the progression and survival of metastatic hormone refractory prostate cancer (HRPC). CNTO328, an anti IL-6 monoclonal antibody, inhibited prostate tumor growth in several preclinical xenograft mouse models. Methods: This Phase 1, open label study evaluates the safety, pharmacokinetics (PK), and pharmacodynamics of CNTO328 at three dose levels (6mg/kg q2 weeks, 9mg/kg q3 weeks and 12mg/kg q3 weeks) in combination with docetaxel (75mg/m2 q3 weeks) in men with metastatic HPRC. C-reactive protein (CRP), a surrogate biomarker of serum IL-6, and circulating tumor cells (CTC) are evaluated. Results: Eight patients with a median baseline PSA value of 56.8 ng/ml (range 13.6- 436.9 ng/ml) were treated in the first cohort (6 mg/kg CNTO328 q2 weeks in combination with docetaxel 75 mg/m2 q3 weeks). At baseline, 6 patients (75%) had detectable CRP and 6 patients had detectable CTCs. The median number of CNTO328 doses and docetaxel cycles administered was 6 (CNTO328: range 3 to 11 doses; docetaxel: range 3 to 13 cycles). No first-cycle DLT was observed for this combination. Three patients discontinued treatment due to docetaxel-related grade 3 adverse events (deep vein thrombosis, hyperbilirubinemia, and nail changes) after 6, 11, and 13 cycles of docetaxel, respectively. Serum CRP decreased to below detectable levels 7 days after the first dose of CNTO328 in all patients with measurable values at baseline and remained undetectable throughout treatment. Two patients with post-treatment CTC values showed CTC reduction from 82 to1, and 127 to1, respectively. Six of 8 patients had = 50% PSA reductions and all had stable or improved bone scans and/or CT scans. PK of CNTO328 and docetaxel, alone and in combination, will be presented. Conclusions: Thus far, anti-IL6 therapy with CNTO328 at 6mg/kg q2 weeks in combination with docetaxel 75mg/m2 q3 week has been feasible and tolerable. Complete suppression of CRP and PSA reduction provide evidence of biological and anti-tumor activity of this approach and support further testing.

[Table: see text]

Are inflammatory cytokines the common link between cancer-associated cachexia and depression?

The prevalence of depression among patients diagnosed with cancer is higher than among the general medical population and is associated with faster tumor progression and shortened survival time. Cancer-related depression often occurs in association with anorexia and cachexia, although until recently the relationship between these conditions has not been well understood. Cachexia is associated with poorer quality of life and survival outcomes and is theeventual cause of death in approximately 30% of all patients with cancer. Recent evidence has linked elevated levels of inflammatory cytokines with both depression and cachexia, and experiments have shown that introducing cytokines induces depression and cachectic symptoms in both humans and rodents, suggesting that there may be a common etiology at the molecular level. Therapeutic agents targeting specific cytokine molecules, such as interleukin-6 or tumor necrosis factor-alpha, are currently being evaluated for their potential to simultaneously treat both depression and cachexia pharmacologically. This review summarizes the available data suggesting a dual role for cytokines in the development of cancer-related depression and cachexia and describes how biologic therapies targeting specific cytokines may improve outcomes beyond depression and cachexia, such as survival and quality of life.

Targeted anti-interleukin-6 monoclonal antibody therapy for cancer: a review of the rationale and clinical evidence

Interleukin (IL)-6, a pleiotropic cytokine with varied systemic functions, plays a major role in inflammatory processes. It modulates the transcription of several liver-specific genes during acute inflammatory states, particularly C-reactive protein, and controls the survival of normal plasmablastic cells. In addition, IL-6 has been implicated in hematopoiesis as a cofactor in stem cell amplification and differentiation. This article is the first review of clinical studies in the 1990s with anti-IL-6 monoclonal antibodies (mAbs) in the treatment of patients with cancer and related lymphoproliferative disorders. In six clinical studies of mAbs to IL-6 with BE-8 or CNTO 328 in patients with multiple myeloma, renal cell carcinoma, and B-lymphoproliferative disorders, anti-IL-6 mAb treatment decreased C-reactive protein levels in all patients. In most patients, levels decreased below detectable limits. The antibodies were well tolerated, and no serious adverse effects were observed in the vast majority of studies. The fact that anti-IL-6 mAb therapy decreased the incidence of cancer-related anorexia and cachexia may also be useful in the treatment of cancer patients.

A phase I study of paclitaxel for mobilization of peripheral blood progenitor cells

We conducted a phase I trial to determine the dose and schedule of paclitaxel, when given together with filgrastim, which would optimally promote mobilization of stem cells with tolerable toxicity. Dose escalation began at 275 mg/m2 3 h infusion. Dose-limiting neuropathy was observed at the 300 mg/m2 dose level. A second dose escalation was conducted utilizing 24 h infusion schedules, beginning at 225 mg/m2. Dose escalation was continued by 25 mg/m2 increments to 300 mg/m2, at which dose neuropathy was again dose-limiting. The recommended dose and schedule of paclitaxel for the purpose of mobilization of stem cells, when given together with filgrastim, are 275 mg/m2 as a 24 h infusion. The median stem cell yield after this dose of paclitaxel was 6.6 x 10(6) CD34+ cells/kg/apheresis (range 3.6 x 10(6)-7.7 x 10(6)).

Bi-weekly vincristine, epirubicin and methylprednisolone in alkylator-refractory multiple myeloma

Nine patients with poor-prognosis, alkylator-refractory stage III multiple myeloma (MM) were treated with a 23-h continuous infusion (CI) of a compatible mixture of vincristine (VCR) and epirubicin (EPI) daily for 4 days along with a daily 1-h infusion of high-dose methyl prednisolone (MP) to total of 5 days (VEMP); cycles were repeated every 2 weeks when possible, usually on an outpatient basis. WHO grade 3 or 4 neutropenia and infection were the predominant toxicities encountered, necessitating some treatment delays and dose reductions. Two patients died during treatment. Peripheral neuropathy necessitated discontinuation of the VCR in six patients without obvious loss of efficacy of the regimen. Skeletal muscle dysfunction and cardiomyopathy did not occur; trivial ECG abnormalities occurred during a minority of infusions but were of indeterminate relationship to the chemotherapy. Confusion occurred in two patients; alopecia was frequent but reversible, and mild/moderate dyspepsia and stomatitis were common but easily managed. Eight patients achieved a partial response (PR); another patient experienced early death during his second cycle before response assessment. The median survival from the first VEMP administration was 9 months (range, 1-64 + months), the median response duration was 7 months (range, 1-64 + months). Two patients experienced responses too short to be clinically relevant (< or = 2 months). An analysis of weekly paraprotein estimations suggests that the intended bi-weekly cycle length may be optimal. Six of these nine patients derived major benefit from this bi-weekly regimen, which deserves further exploration.

Combination chemotherapy with teniposide (VM26) and carboplatin in small cell lung cancer

Seventy patients with previously untreated histologically proven small cell lung cancer (SCLC) were treated with a combination of teniposide 60 mg/m2 intravenously (i.v.) on days 1 through 5 and carboplatin 400 mg/m2 i.v. on day 1 every 28 days for six courses. Patients with limited stage disease, (LD) who achieved a response, subsequently received 2,000 cGy prophylactic cranial and 3,000 cGy involved field thoracic radiotherapy. Of the 70 patients, 62 were evaluable for response: 47 patients (76%) achieved an objective response; 14 of 29 patients (48%) with LD had a complete response (CR), with a partial response (PR) plus CR rate of 76%. Seven of 33 patients (21%) with extensive disease (ED) achieved a CR, with a combined PR and CR rate of 76%. Median time to progression (TTP) for all responders was 292 days (42 weeks). Median duration of survival for all LD patients was 415 days (59 weeks). Survival for LD patients was 88% at 6 months, 61% at 12 months, and 29% at 18 months. Median survival duration for all patients in the study was 311 days (44 weeks), with a survival of 79% at 6 months, 44% at 1 year, and 16% at 18 months. Myelosuppression was the main toxicity, with World Health Organization (WHO) grade 3 or 4 infection occurring in 33% of patients. Two patients died of pneumonia, one complicated by renal failure, and another suffered cardiac arrest related to treatment. The high activity of this drug combination justifies its use as a first-line treatment of previously untreated SCLC.

Teniposide (VM-26) and carboplatin as initial therapy for small cell lung cancer

Forty-four patients with previously untreated histologically proven small cell lung cancer (SCLC) were treated with a combination of teniposide 60 mg/m2 intravenously (IV) on days 1 through 5 and carboplatin 400 mg/m2 IV on day 1 every 28 days for six courses. Patients with limited disease (LD) subsequently received prophylactic cranial and thoracic radiotherapy. Of the 44 patients, 40 were evaluable for response: 31 (78%) achieved an objective response; 9 of 18 patients (50%) with LD had a complete response (CR), with a partial response (PR) plus CR rate of 78%. Two of 22 patients (9%) with extensive disease achieved a CR, with a combined PR and CR rate of 77%. Median duration of response for all evaluable patients was 253 days (36 weeks). Median duration of survival for LD patients was 368 days (52 weeks). Survival of LD patients was 86% at 6 months, 52% at 12 months, and 26% at 18 months. Median duration of survival for all patients in the study was 275 days, with a survival of 79% at 6 months, 36% at 1 year, and 12% at 18 months. Myelosuppression was the main toxicity, with World Health Organization (WHO) grade 3 or 4 infection occurring in 38% of patients. However, no patient died of sepsis or hemorrhage. Treatment was otherwise well tolerated, with no neurotoxicity or nephrotoxicity documented. The high activity of this drug combination justifies its use as first-line treatment of previously untreated SCLC.

A randomized trial of empirical antibiotic therapy with one of four beta-lactam antibiotics in combination with netilmicin in febrile neutropenic patients

Over a two year period 174 evaluable episodes of fever in neutropenic patients were treated in a randomized study comparing four beta-lactam antibiotics, each given in combination with netilmicin. Exclusions included episodes due to viral or fungal infection, and trial violations. Most patients were receiving treatment for leukaemia, including 18% undergoing bone marrow transplantation. The overall response rate (EORTC criteria) was 66%, ranging from 56% for cefoperazone to 76% for mezlocillin. Microbial documentation was obtained in 31% of episodes; Gram-positive isolates were most frequent but Pseudomonas aeruginosa was found in 18 patients. In patients with microbiologically documented infection 70% improved, overall--from 40% with cefoperazone to 80% with piperacillin (P less than 0.05). Nephrotoxicity was seen in 6.7% and was associated with severe documented sepsis. Hypokalaemia was seen in 29% and was most marked in patients receiving ticarcillin. Rashes occurred in 6.6% overall, with no difference between the groups. Ototoxicity, shown by serial audiograms, was seen in 4.7% of patients. No evidence of vestibular dysfunction was seen in 62 patients studied. Of thirteen deaths due to the primary infection, seven were caused by Ps. aeruginosa and five by fungi.

High-dose melphalan with autologous bone marrow transplant. Treatment of poor prognosis tumors

Seventeen patients were treated with high-dose melphalan with autologous bone marrow transplant (ABMT) and cyclophosphamide pretreatment. All of the patients had marrow reconstitution. Although there was one death caused by infection, high-dose melphalan with ABMT causes toxicity that is generally acceptable, and can achieve a high-response rate, but with responses of short duration in tumors resistant to standard-dose combination chemotherapy. In other poor-prognosis tumors that are sensitive to chemotherapy, or can be debulked surgically, or locally irradiated, high-dose melphalan with ABMT given as late intensification therapy may significantly prolong time to relapse, and ultimately prolong survival.

Ketoconazole versus nystatin plus amphotericin B for fungal prophylaxis in severely immunocompromised patients

72 patients severely immunocompromised by their underlying disease (marrow aplasia, acute leukaemia, or solid tumour) or by the treatment they were receiving, or both, were randomised to receive antifungal prophylaxis with either oral ketoconazole or conventional doses of oral amphotericin B and nystatin. All patients also had gut decontamination with non-absorbable antibiotics, skin antisepsis, sterile food, and oral cotrimoxazole. Protection against fungal infection was significantly superior with ketaconazole. When patients who had received allogeneic bone-marrow transplant were studied separately, there was no significant difference between the two treatments, probably because there was a fall-off in ketoconazole absorption from the end of the third week after the transplant. However, ketoconazole greatly reduced the likelihood of fungal infection in non-transplant patients.