Film legend Kirk Douglas has asked a federal judge in Manhattan to spare his drug-dealer grandson a harsh prison sentence. Cameron Douglas also received a letter of support Tuesday from his actress stepmother, Catherine Zeta-Jones. She calls him a “considerate, worthy human being.” The son of Michael Douglas had pleaded guilty earlier this year to charges he peddled large quantities of methamphetamine out of a trendy Manhattan hotel. The charges carry a minimum term of 10 years behind bars. But lawyers for the admitted heroin addict argue he should get only 3 1/2 years at sentencing next week.