Gleevec receives FDA priority review for gastrointestinal stromal tumors after surgery

Novartis has announced that Gleevec (imatinib mesylate) tablets, (known as Glivec (imatinib) outside the US, Canada and Israel), has been granted priority review status by the US Food and Drug Administration (FDA) as the first therapy to be reviewed for use after surgery in kit-positive gastrointestinal stromal tumors (GIST).

FDA priority review status is granted to therapies that could potentially fill a currently unmet medical need and accelerates the standard review timing from ten to six months. Similar regulatory submissions have been filed in the European Union and Switzerland and will be filed in other countries shortly.

The Gleevec submissions are based on data from a Phase III, double-blind, randomized, multicenter, international study of more than 700 GIST patients who had surgery to remove their tumors. The results showed a dramatic 89% reduction in risk of kit-positive GIST returning after surgery (adjuvant setting) in patients treated with Gleevec versus placebo.

In early 2007, the study met its primary efficacy endpoint, showing an advantage for Gleevec in recurrence-free survival. At that time, following the recommendation of the independent study data monitoring committee to stop the trial accrual early, the study investigators made public the interim results and offered Gleevec to patients receiving placebo.

Approximately half of all patients with newly diagnosed GIST are considered candidates for surgical resection, or removal of their tumors. Of those who have the surgery, about half will suffer a recurrence. If approved for this indication, Gleevec will be the first treatment option available to GIST patients after surgery to reduce the risk of disease recurrence or to possibly prevent the disease from returning.

"The dramatic clinical results from this study of Gleevec in the adjuvant GIST setting are especially encouraging when we consider the incremental benefit we typically see with other adjuvant therapies for solid tumors," said Rainer Boehm, MD, Executive Vice President, North American Region Head, Novartis Oncology. "The adjuvant use of Gleevec, if approved, would represent an important advance in the ongoing post-surgery management of GIST."

Gleevec is currently indicated in both the US and EU for the first-line treatment of metastatic or unresectable (inoperable) kit-positive GIST. If approved, the use of Gleevec for the treatment of GIST in the adjuvant setting would add to its eight current indications, which include Philadelphia chromosome-positive chronic myelogenous leukemia (Ph+ CML) and five other rare diseases. Novartis also has a therapy for the treatment of carcinoid tumors and acromegaly and multiple treatments in the pipeline targeting rare diseases.

Filing data

The study on which the regulatory filing is based compared the recurrence-free survival of GIST patients taking Gleevec 400 mg/day versus placebo for one year immediately following surgery. The results showed that 98% of patients receiving Gleevec remained recurrence free at one year following surgery compared to approximately 82% of those receiving placebo. This shows that as a result of adjuvant therapy with Gleevec, there was an 89% reduction in risk of GIST returning.

The study, known as ACOSOG Z90001, was conducted at multiple cancer centers throughout the US and Canada, under a Cooperative Research and Development Agreement between Novartis and the National Cancer Institute (NCI). The study was led by the American College of Surgeons Oncology Group (ACOSOG).

The investigators reported that Gleevec therapy was well tolerated by most patients, with side effects similar to those observed in previous clinical trials with Gleevec. These include nausea, diarrhea and swelling (edema).

About gastrointestinal stromal tumors (GIST)

Gastrointestinal stromal tumors (GIST) belong to a group of cancers known as soft tissue sarcomas. They are the most common sarcomas and can be found most often in the stomach and small intestine. The incidence of GIST is estimated to be 4,500 - 6,000 new cases per year in the US (15-20 cases per million population), of which more than 90% are kit-positive. Kit -- also known as CD117 -- is a protein that, when mutated, has been identified as one of the major causes of GIST.

About Gleevec

Gleevec (imatinib mesylate) tablets are indicated for the treatment of newly diagnosed adult patients with Philadelphia chromosome-positive chronic myeloid leukemia (Ph+ CML) in the chronic phase. Follow-up is limited to 5 years. Gleevec is also indicated for the treatment of patients with Ph+ CML in blast crisis (BC), accelerated phase (AP), or in chronic phase (CP) after failure of interferon-alpha (IFN-alpha) therapy; adult patients with relapsed or refractory Ph+ acute lymphoblastic leukemia (Ph+ ALL); adult patients with myelodysplastic/myeloproliferative diseases (MDS/MPD) associated with PDGFR (platelet-derived growth factor receptor) gene rearrangements; adult patients with aggressive systemic mastocytosis (ASM) without the D816V c-KIT mutation or with c-KIT mutational status unknown; adult patients with hypereosinophilic syndrome (HES) and/or chronic eosinophilic leukemia (CEL) who have the FIP1L1- PDGFR alpha fusion kinase (mutational analysis or FISH demonstration of CHIC2 allele deletion) and for patients with HES and/or CEL who are FIP1L1-PDGFR alpha fusion kinase-negative or unknown; adult patients with unresectable, recurrent, and/or metastatic dermatofibrosarcoma protuberans (DFSP); patients with KIT (CD117)-positive unresectable and/or metastatic malignant gastrointestinal stromal tumors (GIST). The effectiveness of Gleevec in GIST is based on objective response rate. There are no controlled trials demonstrating a clinical benefit, such as improvement in disease-related symptoms or increased survival.

Safety information

Fetal harm can occur when Gleevec is administered to a pregnant woman; therefore, women of childbearing potential should be advised to not become pregnant while taking Gleevec tablets and to avoid breast-feeding while taking Gleevec tablets because of the potential for serious adverse reactions in nursing infants. Sexually active female patients taking Gleevec should use adequate contraception. If the patient does become pregnant while taking Gleevec, the patient should be advised of the potential hazard to the fetus.

In adult Ph+ CML patients, severe (NCI Grades 3/4) lab abnormalities -- including neutropenia (3.6%-48%), anemia (1%-42%), thrombocytopenia (<1%-33%) and hepatotoxicity (approx 5%) -- and severe adverse experiences (NCI Grades 3/4), including severe fluid retention (e.g., pleural effusion, pulmonary edema, and ascites) and superficial edema (1.3%-11%), hemorrhage (1.8%-19%), and musculoskeletal pain (2%-9%) were reported among patients receiving Gleevec*. Severe fluid retention appears to be dose-related, was more common in the advanced-phase studies (where the dosage was 600 mg/day), and is more common in the elderly.

* Numbers indicate the range of percentages in 4 studies among adult patients with Ph+ CML in blast crisis, accelerated phase, and chronic phase.

In HES/CEL patients, instances of Grade 3 leukopenia, neutropenia, lymphopenia, and anemia were reported.

For DFSP, severe (NCI Grades 3/4) lab abnormalities included anemia (17%), thrombocytopenia (17%), neutropenia (8%) and increased creatinine (8%).

In GIST, severe (NCI Grades 3/4) lab abnormalities (400 mg/day; 600 mg/day) -- including neutropenia (10%; 11%), anemia (3%; 9%), thrombocytopenia (0%; 1%) and hepatotoxicity (6%; 8%) -- and severe adverse experiences (NCI Grades 3/4), including severe fluid retention (e.g., pleural effusion or ascites; 3%; 8%) and superficial edema (6%; 5%), hemorrhage (6%; 11%), abdominal pain (11%; 4%), nausea (6%; 4%), diarrhea (3%; 7%) and musculoskeletal pain (6%; 1%) were reported among patients receiving Gleevec.

Severe congestive heart failure and left ventricular dysfunction have occasionally been reported. Most of the patients with reported cardiac events have had other comorbidities and risk factors, including advanced age and previous medical history of cardiac disease. Patients with cardiac disease or risk factors for cardiac failure should be monitored carefully, and any patient with signs or symptoms consistent with cardiac failure should be evaluated and treated.

Dose adjustments may be necessary due to hepatotoxicity, other nonhematologic adverse reactions, or hematologic adverse reactions. Therapy with Gleevec was discontinued for drug-related adverse reactions in 2.4% to 5% of adult patients with Ph+ CML and for adverse reactions in 5% of KIT+ GIST patients. None of the 5 patients in the ASM study discontinued Gleevec due to drug-related events or abnormal laboratory values. Complete blood counts should be performed weekly for the first month, biweekly for the second month, and periodically thereafter as clinically indicated (for example, every 2-3 months).

A 25% decrease in the recommended dose should be used for patients with severe hepatic impairment.

Some GIST patients (5%) were reported to have severe gastrointestinal (GI) bleeds and/or intratumoral bleeds. GI tumor sites may have been the source of GI bleeds.

Patients should be weighed and monitored regularly for signs and symptoms of edema, which can be serious or life-threatening. There have also been reports, including fatalities, of cardiac tamponade, cerebral edema, increased intracranial pressure, papilledema, and GI perforation.

In patients with HES and cardiac involvement, cases of cardiogenic shock/left ventricular dysfunction have been associated with the initiation of imatinib therapy. The condition was reported to be reversible with the administration of systemic steroids, circulatory support measures, and temporarily withholding imatinib. MDS/MPD disease and systemic mastocytosis may be associated with high eosinophil levels. Performance of an echocardiogram and determination of serum troponin should therefore be considered in patients with HES/CEL, and in patients with MDS/MPD or ASM associated with high eosinophil levels. If either is abnormal, the prophylactic use of systemic steroids (1-2 mg/kg) for 1-2 weeks concomitantly with imatinib should be considered at the initiation of therapy.

Bullous dermatologic reactions (eg, erythema multiforme and Stevens- Johnson syndrome) have also been reported. In some cases, the reaction recurred upon re-challenge. Several postmarketing reports describe patients able to tolerate the reintroduction of Gleevec at a lower dose with or without concomitant corticosteroids or antihistamines following resolution or improvement of the bullous reaction.

Consider potential toxicities-specifically liver, kidney and cardiac toxicity, and immunosuppression from long-term use.

Gleevec is metabolized by the CYP3A4 isoenzyme and is an inhibitor of CYP3A4, CYP2D6 and CYP2C9. Dosage of Gleevec should increase by at least 50%, and clinical response should be carefully monitored, in patients receiving Gleevec with a potent CYP3A4 inducer such as rifampin or phenytoin. Examples of commonly used drugs that may significantly interact with Gleevec include ketoconazole, acetaminophen, warfarin, erythromycin and phenytoin. (Please see full Prescribing Information for other potential drug interactions).

For daily dosing of 800 mg and above, dosing should be accomplished using the 400 mg tablets to reduce exposure to iron.

Common side effects of Gleevec tablets

The majority of adult Ph+ CML patients who received Gleevec in clinical studies experienced adverse reactions at some time, but most were mild to moderate in severity. The most frequently reported adverse reactions (all Grades) were superficial edema (60%-74%), nausea (50%-73%), muscle cramps (28%-62%), vomiting (23%-58%), diarrhea (43%-57%), musculoskeletal pain (38%- 49%) and rash and related terms (36%-47%).*+

* Numbers indicate the range of percentages in 4 studies among adult patients with Ph+ CML in blast crisis, accelerated phase, and chronic phase.

+ For more detailed study information, please see full Prescribing Information.

The adverse reactions and safety profile for Ph+ ALL, MDS/MPD, ASM and HES/CEL were generally similar to the safety profile for Ph+ CML.

The most frequently reported drug-related adverse reactions reported in the Ph+ ALL studies were mild nausea, vomiting, diarrhea, myalgia, muscle cramps and rash, which were easily manageable. Superficial edemas were also a common finding in all studies and were described primarily as periorbital or lower-limb edemas. However, these edemas were rarely severe and may be managed with diuretics, other supportive measures, or, in some patients, by reducing the dose of Gleevec.

Frequently reported adverse reactions (all Grades) in the seven MDS/MPD patients assessed were nausea (57%); diarrhea and muscle cramps (43% each); anemia, fatigue, arthralgia and periorbital edema (29% each).

All ASM patients experienced at least one adverse reaction at some time. The most frequently reported adverse reactions were diarrhea, nausea, ascites, muscle cramps, dyspnea, fatigue, peripheral edema, anemia, pruritus, rash and lower respiratory tract infection.

All HES/CEL patients experienced at least one adverse reaction, the most common being gastrointestinal, cutaneous and musculoskeletal disorders. Hematologic abnormalities were also frequent, with instances of Grade 3 leukopenia, neutropenia, lymphopenia and anemia.

Frequently reported adverse reactions (all Grades) in the 12 DFSP patients assessed included nausea and fatigue (42% each); periorbital, peripheral and eye edema (33% each); diarrhea, vomiting, rash, lacrimation increased and anemia (25% each); face edema, pyrexia, exertional dyspnea, rhinitis, and anorexia (17% each).

The majority of patients who received Gleevec in the GIST study experienced adverse reactions at some time. Most adverse reactions were mild to moderate in severity. The most frequently reported adverse reactions (400 mg/day; 600 mg/day) (all Grades) were superficial edema (81%; 77%), nausea (63%; 74%), muscle cramps (47%; 58%), diarrhea (59%; 70%), fatigue (48%; 53%), abdominal pain (40%; 37%), rash and related terms (38%; 53%), vomiting (38%; 35%), musculoskeletal pain (37%; 30%) and hemorrhage (26%; 34%).*

* For more detailed study information, please see full Prescribing Information.

Supportive care may help management of some mild-to-moderate adverse reactions so that the prescribed dose can be maintained whenever possible. However, in some cases, either a dose reduction or interruption of treatment with Gleevec may be necessary.

Gleevec tablets should be taken with food and a large glass of water to minimize GI irritation. Gleevec tablets should not be taken with grapefruit juice and other foods known to inhibit CYP3A4.

Patients should be informed to take Gleevec exactly as prescribed, not to change their dose or stop taking Gleevec unless they are told to do so by their doctor. If patients miss a dose, they should be advised to take their dose as soon as possible unless it is almost time for their next dose, in which case the missed dose should not be taken. A double dose should not be taken to make up for any missed dose.