Phase I study of PLX4032: Proof of concept for V600E BRAF mutation as a therapeutic target in human cancer

9000

Background: PLX4032 is an oral, selective inhibitor of the oncogenic V600E mutant BRAF kinase with preclinical activity. V600E BRAF is the most common kinase mutation in melanoma (60%), also found in colorectal carcinomas (10%), most anaplastic and papillary thyroid carcinomas, and low-grade serous ovarian carcinomas. Methods: Phase I, dose-escalation study designed to determine maximum tolerated dose (MTD), safety, pharmacokinetic (PK) / pharmacodynamic (PD), and efficacy (RECIST evaluation every 8 wks) of PLX4032 in sequential cohorts of 3 to 6 patients (pts). Plasma PK samples were collected on days 1, 8 and 15. Results: 54 pts have been enrolled: metastatic melanoma (n=49), thyroid (n=3), rectal (n=1), or ovarian carcinoma (n=1). 26 pts received a crystalline formulation (CF) continuously at doses from 100 mg BID to 1600 mg BID with associated exposures below target plasma levels. 28 pts received an optimized formulation with increased bioavailability, predicted to have 10-fold greater bioavailability, at doses from 160 mg BID to 1120 mg BID. AUC was dose-proportional and above target levels at 240 mg BID and higher. There was 1 DLT at 720 mg BID (G4 pancytopenia); treatment was restarted at 360 mg BID without myelosuppression. At 1120 mg BID, 3 of 5 pts had DLT (rash and fatigue). One pt had grade 3 increased ALT at 360 mg BID. 13 melanoma pts (77 %M1C) treated at doses of 240 mg BID or higher of the increased bioavailability formulation have a minimum follow-up of 8 weeks. 5 of the 7 BRAF V600E+ pts treated at ≥ 240 mg BID had tumor regression, up to 83%, with 1 confirmed partial response (PR) and 1 unconfirmed PR (too early); 2 of 4 pts with unknown V600E status had tumor regression, up to 50%, with 1 confirmed PR; 2 BRAF wild-type pts had progressive disease. All 7 pts with tumor regression remain progression-free, ranging from 4 to 14 months. 3 thyroid cancer pts with V600E mutations have tumor regression (range 9–16%) and are progression-free (4–7 months). Conclusions: Dose escalation of PLX4032 reached DLTs at 1120 mg BID. 720 mg BID is the current MTD, but 960 mg BID may be explored. PLX4032 exhibits antitumor activity in V600E BRAF mutant tumors. These observations confirm that V600E BRAF is a valid therapeutic target in human cancer.

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Preclinical development of a novel inhibitor of oncogenic B-Raf

13056

Background: The discovery of oncogenic B-Raf mutations in a majority of patients with metastatic melanoma, and in many tumors from patients with colorectal cancer and other cancers, presents the opportunity to develop oncogene-selective inhibitors with a favorable safety profile. Methods: Guided by co-crystallography, a novel chemical scaffold has been developed into a series of potent inhibitors of oncogenic B-Raf with selectivity versus wild-type B-Raf. From this series, a potent inhibitor has been chosen as a candidate for development. Results: Consistent with the structure-guided approach, this compound shows pronounced selectivity versus a wide array of over 70 other kinases covering all branches of the kinome. This selectivity translates to a wide cellular therapeutic index: inhibition of proliferation of a panel of cell lines bearing the V600E oncogenic B-Raf mutation occurs at IC50s ranging from 40–400 nM while inhibition of cell lines lacking oncogenic B-Raf occurs at IC50s greater than 6500 nM. This cell-based selectivity for the oncogenic B-Raf is greater than the selectivity shown in biochemical assays, supporting that tumor cells bearing the oncogenic B-Raf protein are more dependent on the MAP kinase pathway. Combination experiments with a series of cytotoxic and targeted clinical anti-cancer agents reveal multiple examples of synergistic inhibition of proliferation in vitro, and this synergy generally appears selectively in oncogenic B-Raf-bearing cells. The good oral bioavailability (F > 70%) allows for prolonged exposure in both rodents and non-rodents. Robust efficacy is evident in a murine COLO205 tumor xenograft model, with once-daily oral dosing at 20 mg/kg over 14 days resulting in > 80% inhibition of tumor growth with no effect on body weight. Conclusions: Since this compound is highly selective and targets a B-Raf variant that is absent in all non-transformed cells, it may have a broad therapeutic index, alone or in combination, for the treatment of patients with V600E oncogenic B-Raf tumors.

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Mometasone furoate administered once daily is as effective as twice-daily administration for treatment of mild-to-moderate persistent asthma

BACKGROUND

Despite current recommendations, many patients with persistent asthma are still treated with bronchodilators alone.

OBJECTIVE

The safety and efficacy of two once daily dosing regimens (200 microg and 400 microg) of mometasone furoate (MF) administered in the morning by using a dry-powder inhaler (DPI) were compared with those of a twice daily dosing regimen (200 microg administered twice daily) in patients with mild-to-moderate persistent asthma previously taking only inhaled beta(2)-adrenergic agonists.

METHODS

All patients (306 patients; age range, 12-70 years) were given a diagnosis of asthma for at least 6 months before enrollment in this 12-week, placebo-controlled, double-blind, randomized study. The primary efficacy variable was change in FEV(1) from baseline to endpoint (last evaluable visit).

RESULTS

At endpoint, FEV(1) was significantly improved (P < or =.02) after MF-DPI 400 microg once daily morning treatment and MF-DPI 200 microg twice daily treatment (16.0% and 16.1%, respectively) compared with placebo (5.5%). The improvement seen with MF-DPI 200 microg once daily morning treatment (10.4%) was not significantly different from that with placebo. Secondary efficacy variables also showed significant improvement for the MF-DPI 400 microg once daily morning treatment group and the MF-DPI 200 microg twice daily treatment group compared with the placebo group. All doses of MF administered by means of a DPI were well tolerated.

CONCLUSION

This is the first study to demonstrate that a total daily dose of 400 microg of MF administered by means of a DPI is an effective treatment for patients with mild-to-moderate persistent asthma previously taking only inhaled beta(2)-adrenergic agonists. This treatment was equally effective when administered either as a once daily or twice daily regimen.

A dose-ranging study of mometasone furoate aqueous nasal spray in children with seasonal allergic rhinitis

BACKGROUND

The efficacy and safety of mometasone furoate aqueous nasal spray (MFNS; Nasonex) 200 microg once daily for the treatment and prophylaxis of seasonal allergic rhinitis (SAR) and treatment of perennial rhinitis have been demonstrated in adults. However, the dose response of MFNS in pediatric patients has not yet been characterized.

OBJECTIVE

This study was conducted to determine the dose-response relationship of 3 different doses of MFNS in a pediatric population.

METHODS

This was a multicenter, double-blind, active- and placebo-controlled study of 679 children 6 to 11 years of age with histories of SAR and documented positive skin test responses. Patients were randomized to one of the following treatment groups for 4 weeks: MFNS 25 microgram once daily, MFNS 100 microgram once daily, MFNS 200 microgram once daily, beclomethasone dipropionate 84 microgram twice daily (168 microgram/day), or placebo. Physician evaluations were performed at days 4, 8, 15, and 29, and patient evaluations were analyzed for days 1 to 15 and 16 to 29.

RESULTS

The mean reduction from baseline in physician-evaluated total nasal symptom scores at day 8 (the primary efficacy variable) was significantly greater in the MFNS and beclomethasone dipropionate groups than in the placebo group (P </=.02). No significant differences were observed among the 3 MFNS groups. However, as treatment continued, symptoms in patients treated with MFNS 100 or 200 microgram once daily continued to improve, whereas those treated with MFNS 25 microgram once daily demonstrated little further improvement. By day 29, MFNS 100 and 200 microgram once daily both were significantly more effective than MFNS 25 microgram once daily in relieving symptoms of SAR, but MFNS 200 microgram provided no additional benefit over MFNS 100 microgram. All doses of MFNS were well tolerated, and cosyntropin stimulation tests performed before and after treatment found no evidence of hypothalamic-pituitary-adrenal axis suppression.

CONCLUSION

These results indicate that the most appropriate therapeutic dosage of MFNS in the treatment of SAR in children 6 to 11 years of age is 100 microgram once daily. In addition, MFNS at doses up to 200 microgram once daily for 4 weeks was well tolerated and had no detectable effects on hypothalamic-pituitary-adrenal axis function.

Assessment by nasal biopsy of long-term use of mometasone furoate aqueous nasal spray (Nasonex) in the treatment of perennial rhinitis

Allergic rhinitis is associated with specific histopathologic changes in the nasal mucosa including squamous metaplasia and local eosinophilia. Previous studies have shown that mometasone furoate aqueous nasal spray is effective and well tolerated in reducing perennial rhinitis and seasonal allergic rhinitis symptoms. We undertook a multicenter, open-label study to evaluate, by nasal biopsy, the tissue changes associated with mometasone furoate use (200 microg/day) during a 12-month treatment period in patients with perennial rhinitis. Of the 69 patients enrolled in the study, 52 completed all 12 months of treatment. Nasal biopsy specimens obtained from patients at baseline and after treatment were evaluated in a blinded fashion by computerized image analysis, qualitative histologic examination, and immunocytochemistry. Morphologic examination of nasal biopsy specimens showed a decrease in focal metaplasia, no change in epithelial thickness, and no sign of atrophy after treatment with mometasone furoate. Immunocytochemical analyses of nasal biopsy specimens obtained before and after treatment revealed a significant decrease in major basic protein-positive eosinophils and tryptase-positive mast cells in the epithelium and lamina propria after treatment. Mometasone furoate appeared to attenuate the inflammatory process by reducing the extent of inflammatory cell infiltration, particularly of eosinophils. This study demonstrated that long-term administration of mometasone furoate is not associated with adverse tissue changes in the nasal mucosa of patients with perennial rhinitis.

Comparison of once daily mometasone furoate (Nasonex) and fluticasone propionate aqueous nasal sprays for the treatment of perennial rhinitis. 194-079 Study Group

BACKGROUND

Mometasone furoate (Nasonex), in a new once-daily aqueous nasal spray formulation, has been shown to be as effective and well-tolerated as twice-daily beclomethasone dipropionate aqueous nasal spray in treating symptoms of seasonal allergic rhinitis and perennial rhinitis.

OBJECTIVE

To compare the effectiveness and tolerability of mometasone furoate to placebo and of fluticasone propionate aqueous nasal spray, all treatments administered once-daily, in patients with perennial rhinitis.

METHODS

This was a 3-month, randomized, double-blind, double dummy, parallel group study in 550 patients, aged 12 to 77 years, at 25 centers in Canada, Latin America, and Europe. Patients allergic to at least one perennial allergen, with confirmed allergy history, skin test positivity, and moderate to severe symptomatology, were eligible to receive one of the following treatments, once daily in the morning: mometasone furoate 200 micrograms, fluticasone propionate 200 micrograms, or placebo. The primary efficacy variable was the change from baseline in total AM plus PM diary nasal symptom score over the first 15 days of treatment.

RESULTS

Four hundred fifty-nine patients were valid for efficacy. For the primary efficacy variable, mometasone furoate was significantly (P < .01) more effective than placebo and was not statistically different from fluticasone propionate (percent reductions from baseline were 37, 39, and 22 for mometasone furoate, fluticasone propionate, and placebo, respectively). Generally, similar trends were seen for physician-evaluated total nasal symptoms, and patient-rated and physician-rated overall condition and response to therapy. Overall, mometasone furoate was at least as effective as fluticasone propionate at equivalent doses. There was no evidence of tachyphylaxis. All treatments were well tolerated.

CONCLUSION

Mometasone furoate and fluticasone propionate adequately controlled symptoms of perennial rhinitis and were well tolerated.

Comparison of once daily mometasone furoate (Nasonex) and fluticasone propionate aqueous nasal sprays for the treatment of perennial rhinitis. The 194-079 Study Group

BACKGROUND

Mometasone furoate (Nasonex), in a new once-daily aqueous nasal spray formulation, has been shown to be as effective and well-tolerated as twice-daily beclomethasone dipropionate aqueous nasal spray in treating symptoms of seasonal allergic rhinitis and perennial rhinitis.

OBJECTIVE

To compare the effectiveness and tolerability of mometasone furoate to placebo and to fluticasone propionate aqueous nasal spray, all treatments administered once-daily, in patients with perennial rhinitis.

METHODS

This was a 3-month, randomized, double-blind, double dummy, parallel group study in 550 patients, aged 12 to 77 years, at 25 centers in Canada, Latin America, and Europe. Patients allergic to at least one perennial allergen, with confirmed allergy history, skin test positivity, and moderate to severe symptomatology, were eligible to receive one of the following treatments, once daily in the morning: mometasone furoate 200 micrograms, fluticasone propionate 200 micrograms, or placebo. The primary efficacy variable was the change from baseline in total AM plus PM diary nasal symptom score over the first 15 days of treatment.

RESULTS

Four hundred fifty-nine patients were valid for efficacy. For the primary efficacy variable, mometasone furoate was significantly (P < .01) more effective than placebo and was not statistically different from fluticasone propionate (percent reductions from baseline were 37, 39, and 22 for mometasone furoate, fluticasone propionate, and placebo, respectively). Generally, similar trends were seen for physician-evaluated total nasal symptoms, and patient-rated and physician-rated overall condition and response to therapy. Overall, mometasone furoate was at least as effective as fluticasone propionate at equivalent doses. There was no evidence of tachyphylaxis. All treatments were well tolerated.

CONCLUSION

Mometasone furoate and fluticasone propionate adequately controlled symptoms of perennial rhinitis and were well tolerated.

A placebo- and active-controlled randomized trial of prophylactic treatment of seasonal allergic rhinitis with mometasone furoate aqueous nasal spray

BACKGROUND

Topical nasal corticosteroids have become a mainstay of treatment for the symptoms of seasonal allergic rhinitis (SAR). It is likely that topical corticosteroids, by blocking an initial influx of inflammatory cells in the nasal mucosa induced by aeroallergens, may have a preventive effect on nasal allergy symptoms when administered before the pollen season.

OBJECTIVE

This study was designed to assess the efficacy and safety of an 8-week course of mometasone furoate nasal spray (MFNS), 200 micrograms once daily, in the treatment of SAR compared with beclomethasone dipropionate aqueous nasal spray (BDP), 168 micrograms twice daily, and placebo vehicle, when treatment is initiated before the anticipated onset of the ragweed season.

METHODS

Three hundred forty-nine patients with SAR to ragweed pollen from nine centers in the Northeast and Midwest of the United States were randomized to one of the three intranasal study medications (MFNS, 200 micrograms once daily, BDP, 168 micrograms twice daily, or placebo vehicle), starting 4 weeks before the estimated start of the ragweed season.

RESULTS

The proportion of "minimal symptom" days (total nasal symptom score < or = 2) was statistically significantly higher in both the MFNS and BDP groups when compared with the placebo vehicle group (p < 0.01). The two active treatment groups were not statistically significantly different from each other. MFNS and BDP displayed a similar safety profile that did not differ from placebo.

CONCLUSIONS

This suggests that MFNS, 200 micrograms (once daily), is a useful therapy in the prophylactic treatment of SAR.

Once-daily mometasone furoate aqueous nasal spray (Nasonex) in seasonal allergic rhinitis: an active- and placebo-controlled study

Mometasone furoate aqueous nasal spray (Nasonex) was compared with beclomethasone dipropionate (BDP) aqueous nasal spray in a double-blind, randomized, placebo-controlled, double-dummy, parallel-group study of adults with moderate to severe seasonal allergic rhinitis. Patients allergic to at least one tree and/or grass aeroallergen received one of the following regimens for up to 4 weeks; mometasone furoate 100 micrograms once daily [OD] (n = 126) or 200 micrograms OD (n = 126), BDP 200 micrograms twice daily (n = 126), or only placebo spray (n = 123). Physician-rated nasal and total symptom scores, and global evaluation of overall condition and therapeutic response by physicians and patients, showed that the three active treatments were equally effective, and all three were significantly superior to placebo at most time points. Overall, mometasone furoate 200 micrograms OD demonstrated somewhat greater numerical, but not statistical, superiority to mometasone furoate 100 micrograms OD at the earliest evaluation time point. At the end of treatment, complete or marked relief was obtained in 77% of patients with mometasone furoate 100 micrograms/day, 79% with mometasone furoate 200 micrograms/day, and 74% with BDP, compared with 54% of placebo vehicle control patients. Mometasone furoate and BDP were equally well tolerated. It was concluded that mometasone furoate adequately controls symptoms of moderate to severe seasonal allergic rhinitis, offers the advantage of OD treatment, and is well tolerated.

Once daily mometasone furoate aqueous nasal spray is as effective as twice daily beclomethasone dipropionate for treating perennial allergic rhinitis patients

BACKGROUND

Perennial allergic rhinitis is chronic and persistent, may lead to a constellation of secondary complaints including sinusitis, mouth-breathing, and some symptoms resembling a permanent cold, and often requires constant medical intervention. Well-tolerated nasal corticosteroids, alone or in combination with antihistamines, have been found to be very effective in treating this condition.

OBJECTIVE

To compare the effectiveness and tolerability of mometasone furoate aqueous suspension, a new once daily nasal spray, to placebo vehicle and to beclomethasone dipropionate, administered twice daily, in patients with perennial allergic rhinitis.

METHODS

This was a randomized, double-blind, placebo-controlled, double-dummy, parallel group study, in 427 patients age 12 years and older at 24 centers in Canada and Europe. Patients allergic to at least one perennial allergen, confirmed by medical history, skin testing, and adequate symptomatology were eligible to receive one of the following regimens for 3 months: mometasone furoate, 200 micrograms only daily; beclomethasone dipropionate, 200 micrograms twice daily (400 micrograms total dose); or placebo vehicle control. The primary efficacy variable was the change from baseline in total AM plus PM diary nasal symptom score over the first 15 days of treatment.

RESULTS

Three hundred eighty-seven patients were valid for efficacy. For the primary efficacy variable, mometasone furoate was significantly (P < or = .01) more effective than placebo and was indistinguishable from beclomethasone dipropionate. Similar trends were seen among individual symptoms, physician symptom evaluations, and therapeutic response. There was no evidence of tachyphylaxis. All treatments were well tolerated.

CONCLUSIONS

Mometasone furoate nasal spray adequately controls symptoms of perennial allergic rhinitis, offers the advantage of once daily treatment, and is well tolerated.

Friend virus production and heme synthesis in primary mouse spleen cell cultures

A cell culture method has been developed in which spleen cells from Friend virus (FV) infected mice can be studied for virus production as well as erythroid differentiation. Primary spleen cell cultures from plethoric Balb/c mice were initiated at 24, 48 or 73 h after FV infection. These cells manifested a well-defined wave of heme synthesis at approximately 64, 48, or 23 h, respectively, of cell culture. Assays for spleen focus-forming virus (SFFV) and helper murine leukemia virus (MuLV-F) production in these cultures revealed that the peak rates of production of both viruses occurred at essentially the same time as the peaks of heme synthesis. The time at which the peaks of virus production and heme synthesis occurred in vitro was related to the time interval after infection (80-105 h) rather than the time at which the cells were placed in cell culture or the number of hours of cell culture. Medium change experiments suggested that the temporal relation between heme synthesis and virus production was an intrinsic feature of FVP infected cells in this in vitro system.