- Females of childbearing potential (FCBP) must have a negative pregnancy test (sensitivity of at least 25 mIU/mL) performed once before ibrutinib and a total of two negative tests before initiating lenalidomide; a FCBP is a sexually mature woman who: 1) has achieved menarche at some point; 2) has not undergone a hysterectomy or bilateral oophorectomy; or 3) has not been naturally postmenopausal for at least 24 consecutive months (i.e., has had menses at any time in the preceding 24 consecutive months); the pre- ibrutinib pregnancy test will be initiated at enrollment; the first pre-lenalidomide test will be performed within 10-14 days of starting lenalidomide (cycle 0, day 15), and the second pre- lenalidomide test (3rd total test) will be within 24 hours of the first dose of lenalidomide; the patient may not receive lenalidomide until the study doctor has verified that the results of these pregnancy tests are negative; pregnancy tests (if applicable) are then to be conducted weekly during the first month, and monthly thereafter in women with a regular menstrual cycle, as well as at study discontinuation, and at day 28 following study discontinuation; if menstrual cycles are irregular, pregnancy testing will be conducted weekly for the first month, and then every 14 days while on the study, at study discontinuation, and at days 14 and 28 following study drug discontinuation; pregnancy testing and counseling are to be performed if a patient misses her period or if there is any abnormality in menstrual bleeding; should a woman become pregnant or suspect she is pregnant while she is participating in this study, she should inform her treating physician immediately; further, FCBP must either commit to continued abstinence from heterosexual intercourse or begin TWO acceptable methods of birth control: one highly effective method and one additional effective method AT THE SAME TIME, at least 28 days before starting lenalidomide; FCBP must also agree to ongoing pregnancy testing; men must agree to use a latex condom during sexual contact with a FCBP, even if they have had a successful vasectomy; male and female patients, must agree to use highly effective methods of birth control (e.g. condoms, implants, injectables, combined oral contraceptives, some intrauterine devices [IUDs], complete sexual abstinence, or sterilized partner) during the period of therapy and for 90 days after the last dose of study drug; all patients must be counseled by a trained counselor every 28 days about pregnancy precautions and risks of fetal exposure