X0303 4 2009-01-29 0 0001053221 METABASIS THERAPEUTICS INC MBRX 0001449708 Gumbiner Barry 11119 NORTH TORREY PINES ROAD LA JOLLA CA 92037 0 1 0 0 VP Clinical Development & CMO Stock Option (Right to Buy) 5.85 2009-01-29 4 D 0 50000 D 2016-09-29 Common Stock 50000 0 D Stock Option (Right to Buy) 7.24 2009-01-29 4 D 0 27875 D 2017-03-21 Common Stock 27875 0 D Stock Option (Right to Buy) 2.46 2009-01-29 4 D 0 11708 D 2018-02-01 Common Stock 11708 0 D Stock Option (Right to Buy) 2.46 2009-01-29 4 D 0 27875 D 2018-02-01 Common Stock 27875 0 D Stock Option (Right to Buy) 2.12 2009-01-29 4 D 0 5575 D 2018-04-01 Common Stock 5575 0 D Stock Option (Right to Buy) 1.00 2009-01-29 4 A 0 123033 A 2019-01-29 Common Stock 123033 123033 D The cancelled option provided for 25% of the shares vesting on the first anniversary of the grant date (9/29/2006), and the remaining shares vesting in equal monthly installments over the following three years. Pursuant to the Company's Offer to Exchange Stock Options, on January 29, 2009, the Company cancelled options granted to the reporting person in exchange for new options equal to the number of shares under the cancelled options. The cancelled option provided for 25% of the shares vesting on the first anniversary of the grant date (3/21/2007), and the remaining shares vesting in equal monthly installments over the following three years. The cancelled option provided for 100% of the shares vesting on the second anniversary of the grant date (2/1/2008). The cancelled option provided for 25% of the shares vesting on the first anniversary of the grant date (2/1/2008), and the remaining shares vesting in equal monthly installments over the following three years. The cancelled option provided for 25% of the shares vesting on the first anniversary of the grant date (4/1/2008), and the remaining shares vesting in equal monthly installments over the following three years. The option provides for 25% of the shares to vest six months from the grant date (1/29/2009) and the remaining shares to vest in equal monthly installments over three years beginning on the grant date. Trisha Millican, by Power of Attorney 2009-02-02