Phase I study of cediranib, an oral VEGFR inhibitor, in combination with selumetinib, an oral MEK inhibitor, in patients with advanced solid malignancies

PURPOSE

Targeting the vascular endothelial growth factor (VEGF) pathway improves progression free survival in multiple advanced malignancies but durable responses are uncommon. Inhibition of the VEGF pathway at multiple levels of signal transduction may improve clinical outcomes. Preclinical data with cediranib, an inhibitor of all 3 VEGF receptors, in combination with selumetinib, an inhibitor of MEK 1/2, demonstrated improved tumor control experimentally. This phase I trial was designed to test the two agents in combination to evaluate the tolerability, safety and assess disease response.

METHODS

Patients with advanced solid malignancies were enrolled into this phase I trial. Cediranib and selumetinib were dosed using a toxicity-adaptive isotonic design for the dose escalation/de-escalation of each agent. Both cediranib and selumetinib were administered daily and continuously. Cycles were 28 days in length.

RESULTS

Eighteen patients were enrolled. At all dose levels, dose limiting toxicities (DLT) were observed, which limited dose escalation and further evaluation. The maximum tolerated dose of cediranib and selumetinib in combination could not be determined. The best response of stable disease was observed in eight patients.

CONCLUSIONS

Cediranib and selumetinib in combination on a continuous schedule was not tolerable, with patients experiencing cardiovascular and other DLTs. Intermittent schedules may be needed to establish a safe and tolerable combination of cediranib and selumetinib.

CLO19-026: Determining the Treatment Decision of Tumors With Mixed Response

Introduction: Individuals receiving systemic anticancer therapies for advanced solid tumors routinely undergo imaging studies to assess the efficacy of the treatment. Mixed response (MR) to cancer therapy is a common but poorly described phenomenon. There is a paucity of data regarding both the incidence and possible mechanisms of this clinical quandary. Potential etiologies include tumor heterogeneity, differences in tumor microenvironment, and discrepancies in drug delivery to different tumor deposits. It is also possible that MR simply reflects differences in the rate of resistance emerging. MR represents a therapeutic dilemma for the clinician. Methods: Mixed tumor response was defined as: One tumor decreasing in size; one tumor increasing in size (classified as RECIST response/progressions), One tumor stable; another tumor progressing, One tumor stable; another tumor responding, New tumor; another tumor responding or remaining stable. Between 2015 and 2017, 120 restaging CT scans were reviewed of patients who had received at least 1 line of therapy for advanced cancer diagnosis which showed MR; hematologic malignancies were excluded. Charts were reviewed to determine the clinical decision that was made at the time of the MR. Results: A total of 120 scans with MR were reviewed from various solid tumor diagnoses. 38 scans were excluded due to loss of follow-up or death. Of the remaining 82 scans, therapy was switched in 30, the same therapy was continued in 50, and an additional agent was added to the current treatment in 2 cases (Table). Of the patients in which treatment was switched, 20% (6/30) showed response to treatment on the following scan. Of the cases that were kept on current treatment, none showed response on the following restaging scan which was done 6–8 weeks later. There were 4 (10%) deaths prior to the next scan in the group that had treatment switched and similarly 5 deaths (10%) prior to the next scan in the group in which treatment remained the same. Conclusion: MR is associated with a poor prognosis, irrespective of treatment decisions. These data are retrospective and our sample size is small, so definitive conclusions cannot be drawn. However, changing therapy when a MR is observed may be of benefit to some patients. A prospective evaluation to more accurately describe and understand the MR phenomenon is warranted.

Phase I dose-escalation study of MEDI-573, a bispecific, antiligand monoclonal antibody against IGFI and IGFII, in patients with advanced solid tumors

PURPOSE

This phase I, multicenter, open-label, single-arm, dose-escalation, and dose-expansion study evaluated the safety, tolerability, and antitumor activity of MEDI-573 in adults with advanced solid tumors refractory to standard therapy or for which no standard therapy exists.

EXPERIMENTAL DESIGN

Patients received MEDI-573 in 1 of 5 cohorts (0.5, 1.5, 5, 10, or 15 mg/kg) dosed weekly or 1 of 2 cohorts (30 or 45 mg/kg) dosed every 3 weeks. Primary end points included the MEDI-573 safety profile, maximum tolerated dose (MTD), and optimal biologic dose (OBD). Secondary end points included MEDI-573 pharmacokinetics (PK), pharmacodynamics, immunogenicity, and antitumor activity.

RESULTS

In total, 43 patients (20 with urothelial cancer) received MEDI-573. No dose-limiting toxicities were identified, and only 1 patient experienced hyperglycemia related to treatment. Elevations in levels of insulin and/or growth hormone were not observed. Adverse events observed in >10% of patients included fatigue, anorexia, nausea, diarrhea, and anemia. PK evaluation demonstrated that levels of MEDI-573 increased with dose at all dose levels tested. At doses >5 mg/kg, circulating levels of insulin-like growth factor (IGF)-I and IGFII were fully suppressed. Of 39 patients evaluable for response, none experienced partial or complete response and 13 had stable disease as best response.

CONCLUSIONS

The MTD of MEDI-573 was not reached. The OBD was 5 mg/kg weekly or 30 or 45 mg/kg every 3 weeks. MEDI-573 showed preliminary antitumor activity in a heavily pretreated population and had a favorable tolerability profile, with no notable perturbations in metabolic homeostasis.

Phase I study of tanespimycin in combination with bortezomib in patients with advanced solid malignancies

PURPOSE

To determine the maximum tolerated dose (MTD) and characterize the dose-limiting toxicities (DLT) of tanespimycin when given in combination with bortezomib.

EXPERIMENTAL DESIGN

Phase I dose-escalating trial using a standard cohort "3+3" design performed in patients with advanced solid tumors. Patients were given tanespimycin and bortezomib twice weekly for 2 weeks in a 3 week cycle (days 1, 4, 8, 11 every 21 days).

RESULTS

Seventeen patients were enrolled in this study, fifteen were evaluable for toxicity, and nine patients were evaluable for tumor response. The MTD was 250 mg/m(2) of tanespimycin and 1.0 mg/m(2) of bortezomib when used in combination. DLTs of abdominal pain (13 %), complete atrioventricular block (7 %), fatigue (7 %), encephalopathy (7 %), anorexia (7 %), hyponatremia (7 %), hypoxia (7 %), and acidosis (7 %) were observed. There were no objective responses. One patient had stable disease.

CONCLUSIONS

The recommended phase II dose for twice weekly 17-AAG and PS341 are 250 mg/m(2) and 1.0 mg/m(2), respectively, on days 1, 4, 8 and 11 of a 21 day cycle.

A phase II clinical trial of ixabepilone (Ixempra; BMS-247550; NSC 710428), an epothilone B analog, in patients with metastatic renal cell carcinoma

PURPOSE

Ixabepilone (Ixempra; BMS-247550) is an epothilone B analog and nontaxane microtubule-stabilizing compound with clinical activity in a range of solid tumors. This phase II study was conducted to assess the efficacy and safety of ixabepilone in patients with metastatic renal cell carcinoma.

EXPERIMENTAL DESIGN

Patients with metastatic renal cell carcinoma who had measurable disease and had not received previous cytotoxic or targeted therapy were treated with 6 mg/m(2) ixabepilone i.v. daily for 5 days every 3 weeks. Levels of Glu-terminated and acetylated tubulin, markers of microtubule stabilization, were assessed by Western blot. VHL gene mutation status was determined by sequencing.

RESULTS

Eighty-seven patients received a total of 590 cycles, with a median of 5 cycles (range, 1-29). The overall response rate was 13% (Response Evaluation Criteria in Solid Tumor). One patient had a complete response, 10 patients had partial responses, and 59 patients had stable disease. The median duration of response was 5.5 months. The median overall survival of renal cell carcinoma Motzer grade 0 and 1 patients with clear cell histology was 19.25 months. Treatment-related adverse events were primarily alopecia, gastrointestinal toxicity, neuropathy, and fatigue. Biopsies were done at baseline and after five doses of ixabepilone. Microtubule target engagement was achieved in 84.6% to 92.3% of patients evaluated. No correlation was identified between the target engagement, VHL gene mutation status, and clinical response.

CONCLUSION

Ixabepilone can cause tumor regression in some patients with metastatic renal cell carcinoma and could be considered in combination regimens with other therapies.

Mechanisms of multidrug resistance: the potential role of microtubule-stabilizing agents

Antimitotic agents that target the dynamic equilibrium between the microtubule polymer and tubulin heterodimers are key components of chemotherapeutic regimens for various solid tumors. These agents can be divided into two major classes based on their effect on microtubule polymerization and the mass of microtubule polymers: those that inhibit polymerization, such as the vinca alkaloids and those that stabilize microtubules, such as the taxanes and epothilones. The taxanes paclitaxel (Taxol) and docetaxel (Taxotere) were the first antimicrotubule agents approved for use in solid tumors, but their usefulness is often limited by development of drug resistance. The epothilones are distinguished from the taxanes structurally and functionally and have been shown in vitro and in preclinical models to have superior potency to the taxanes. The epothilones are not susceptible to P-glycoprotein-mediated efflux and have shown activity against taxane-resistant tumors. Other natural-product microtubule-stabilizing agents also have promising pharmacologic profiles. This article discusses mechanisms of drug resistance and summarizes scientific and clinical data supporting the potential of novel microtubule-stabilizing agents for achieving broad antitumor efficacy without the emergence of drug resistance. The ability to reduce the development of resistance with the epothilones and other microtubule-stabilizing agents may provide additional treatment options at the time of presentation and in the setting of taxane resistance.

The efficacy of combination chemotherapy with cisplatin and gemcitabine in patients with advanced adrenal cortical carcinoma (ACC)

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Background: ACC is a rare, but highly lethal disease for which more effective systemic therapies are needed. Prior studies have concluded that cisplatin and doxorubicin have single agent activity and that combinations of these and other agents, most notably etoposide, may have additive or synergistic effects. However, the majority of responses are neither complete nor durable. Anecdotal evidence of activity by gemcitabine in patients with ACC motivated the present analysis, designed to assess the efficacy of cisplatin and gemcitabine in combination in patients with metastatic ACC. Methods: 18 patients with metastatic disease were evaluated. Patient’s ages ranged from 19 to 63 years with a median age of 46 years. 5 patients were treated at initial presentation, while 13 were treated after disease progression on or following a previous chemotherapy regimen. Among the latter, the median number of prior regimens was 1, with a median of 4 prior drugs. Sites of metastases included lung (10/18), liver (12/18), retroperitoneum/adrenal bed (5/18) and bone (2/20). The starting dosages were 100 mg/m2 of cisplatin and 1250 mg/m2 of gemcitabine. A total of 56 cycles were administered to 18 patients, with a range of 2 to 12 cycles and a median of 3. Results: The toxicity of this regimen in this patient population was similar to that reported with this regimen in other tumor types. The partial response rate was 11% with an additional 16% of patients demonstrating cytoreduction that did not meet the criteria for a partial response. Conclusions: We conclude that the combination of cisplatin and gemcitabine has activity in ACC. While the superiority of this combination over single agent platinum is not established, the combination does not appear to be superior enough to warrant its routine use, especially in patients with more indolent disease, where single agent platinum can be followed by single agent gemcitabine. An attribute this combination has over other regimens used in patients with ACC, notably those incorporating doxorubicin and/or etoposide, is that it can be given at full doses without excessive toxicity to patients with hormone producing tumors in combination with ketoconazole.

No significant financial relationships to disclose.

Microtubule targeting agents: basic mechanisms of multidrug resistance (MDR)

Multidrug resistance (MDR) results in the loss of activity of anticancer agents against cells possessing the MDR phenotype. In some cases, tumor cells are intrinsically resistant to chemotherapeutic drugs (intrinsic resistance), while in other instances cells become resistant after exposure to cytotoxic agents (acquired resistance). MDR has a significant impact on the management of patients with solid tumors, including those with breast cancer, where it has been previously correlated with a decreased response to treatment and a poor prognosis. Taxanes are among the most important components of chemotherapy regimens to treat recurrent breast cancer. In taxane-refractory cells, the two mechanisms most commonly associated with the development of MDR are the overexpression of members of the ATP-binding cassette family of transporters, of which P-glycoprotein is the best known, and alterations of tubulin, which is the cellular target of the taxanes. In vitro and in vivo models have been developed to study the development of MDR and to assess the potential clinical application of MDR modulators. However, despite promising advances using MDR modulators in preclinical models, clinical applications have met with limited success. Novel strategies are needed to circumvent the development of drug resistance. New cytotoxic agents capable of evading MDR offer hope for patients with breast cancer.

Multiple congenital ocular anomalies with bilateral agenesis of the urinary tract

A 1,350 gm female infant with features of the Potter syndrome (dysplasia renofacialis) had multiple ocular anomalies. Absence of keratocytes in the central corneal stroma, cataract, retinal ganglion cell and nerve fiber hypoplasia, loss of optic nerve bundles, and angiomatoid proliferation in the area of the optic disc are most striking. Some of these findings, especially in the cornea, may reflect mesoectodermal dysgenesis. Abnormal ocular angiogenesis may well comprise a part of Potter's syndrome.

Ocular abnormality in myotonic dystrophy

A 61-year-old white woman with terminal myotonic dystrophy exhibited advanced peripheral and central retinopathy. Retinal lesions were characterized by hyperpigmentation, common, though nonspecific, in myotonic dystrophy. They resemble both heredo (tapetoretinal) and idiopathic involutional degenerations but rarely cause severe visual impairment. Neither the type nor degree of retinopathy appears to correlate with other ocular features or with the stage of the underlying disease. Our histologic observations confirm and extend those previously described. Electron microscopy suggests a primary disorder of mitochondria which may also affect smooth muscle and the myocardium.

Capillaries of South African diabetics. IV. Relation to retinopathy

The muscle capillaries of diabetic subjects, with and without retinopathy, have been measured. The groups with retinopathy had significantly thicker laminae than those without the fundal changes. No significant difference was found between the group with proliferative retinopathy and the group with nonproliferative retinopathy. The focal and segmental nature of the basal lamina thickening was confirmed by the increasing standard deviation of the measurements within and among capillaries. This study also confirms the fact that, at least for muscle capillaries, an apparent relationship exists between the thickness of the basal lamina of these vessels and the presence of clinical retinopathy.