Polyethylene Glycol Interferon Alfa-2b (PEG Intron) Versus Interferon Alfa-2b (INTRON^® A) in the Treatment of Newly Diagnosed Chronic Myelogenous Leukemia (CML) (C98026)

Inclusion Criteria

* Has chronic phase CML diagnosed within 3 months prior to study enrollment
* Has chronic phase CML positive for Ph\^1 as confirmed by cytogenetic studies, performed by a central laboratory
* Has platelet count \>/= 50,000/microl
* Has hemoglobin \>/= 9.0 g/dL
* Has WBC count \>/=2000/microl but \</= 50,000/microl
* Has adequate hepatic and renal function, as defined by the following parameters obtained within 14 days prior to initiation of study treatment

  * serum glutamic oxaloacetic transaminase (SGOT) \<2 times upper limit of laboratory normal (ULN)
  * serum glutamic pyruvic transaminase SGPT \<2 times upper ULN
  * serum bilirubin \<2 times ULN
  * serum creatinine \<2.0 mg/dL
* Is fully recovered from any prior major surgery and must be at least 4 weeks postoperative
* Has Eastern Cooperative Oncology Group Performance Status of 0-2
* Has signed a written, voluntary informed consent before study entry, is willing to participate in this study, and is willing to complete all follow-up assessments

Exclusion Criteria:

* Has accelerated phase CML as defined by any of the following criteria.

  * peripheral blood myeloblasts \>/=15%
  * peripheral blood basophils \>/= 20%
  * peripheral blood myeloblasts plus promyelocytes \>/=30%
  * platelets \<100,000/microl, unrelated to therapy
* Has blastic phase CML (30% myeloblasts in peripheral blood or bone marrow)
* Is a candidate for and is planning to receive allogeneic, syngeneic, or autologous bone marrow transplantation within the next 12 months
* Has received prior treatment for their CML, except for hydroxyurea (collection of stem cells without using high dose chemotherapy for mobilization is acceptable)
* Has severe cardiovascular disease (i. e., arrhythmias requiring chronic treatment, congestive heart failure \[New York Heart Association (NYHA) Class III or IV\], or symptomatic ischemic heart disease)
* Has a history of a neuropsychiatric disorder requiring hospitalization
* Has thyroid dysfunction not responsive to therapy
* Has uncontrolled diabetes mellitus
* Has a history of seropositivity for human immunodeficiency virus
* Has active and/or uncontrolled infection, including active hepatitis
* Has a medical condition requiring chronic systemic corticosteroids
* Has a history of prior malignancies within the last 5 years, except for surgically cured non-melanoma skin cancer, or cervical carcinoma in situ
* Has received any experimental therapy within 30 days prior to enrollment in this study
* Is known to be actively abusing alcohol or drugs
* Is pregnant, nursing, or of reproductive potential and is not practicing an effective means of contraception